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The fractal or scaling perspective on progressively generated intra-urban clusters from street junctions

International Journal of Digital Earth 2023年第1期16卷 1944-1961页

作者： Biao He Renzhong Guo Minmin Li Ying Jing Zhigang Zhao Wei Zhu Chen Zhang Chengyue Zhang Ding Ma Research Institute for Smart Cities School of Architecture and Urban PlanningShenzhen University&MNR Technology Innovation Center of Territorial&Spatial Big Data&MNR Key Laboratory of Urban Land Resources Monitoring and Simulation&Guangdong-Hong Kong-Macao Joint Laboratory for Smart CitiesShenzhenPeople’s Republic of China Guangdong Laboratory of Artificial Intelligence and Digital Economy(SZ) ShenzhenPeople’s Republic of China Ningbo Institute of Technology School of EconomicsZhejiang UniversityNingboPeople’s Republic of China School of Resource and Environmental Sciences Wuhan UniversityWuhanPeople’s Republic of China

The underlying complexity of urban space can be manifested by its fractal forms and scaling *** paper examines these characteristics at the intra-urban scale through the lens of clustered street junctions(including road ends)in two Chinese metropolitan areas:Beijing and *** derived the cluster sets with Euclidean distance thresholds starting at 100 meters(m)and ending at 1000 m,and outlined each cluster using a concave-hull method to maintain their original irregular *** each delimited cluster,we examined four urban attributes:gross domestic product,number of street nodes,polygon area,and *** analysis revealed that power law distribution applied to almost every cluster set in terms of the four attributes,but varied from one attribute to another or from city to city,represented primarily byfluctuated power law exponents and ht-index values whose profiles along with the cluster growth can effectively characterize the urban ***,we computed the spectrum of intra-urban scaling exponents with cluster size increments,contributing new insights into the allometric relationships between urban configuration and function.

关键词： Spatial clustering urban structure urban function power law intra-urban scaling law

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EXACT SOLUTION OF THE DEGREE DISTRIBUTION FOR AN EVOLVING NETWORK

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Acta Mathematica Scientia 2009年第3期29卷 723-730页

作者：侯振挺孔祥星 School of Mathematics Central South UniversityChangsha 410075 China

In this paper we propose a simple evolving network with link additions as well as removals. The preferential attachment of link additions is similar to BA model’s, while the removal rule is newly added. From the perspective of Markov chain, we give the exact solution of the degree distribution and show that whether the network is scale-free or not depends on the parameter m, and the degree exponent varying in （3, 5] is also depend on m if scale-free.

关键词： evolving networks preferential attachment difference equation power law

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TWO MODELS FOR ROLL WAVES IN A MUD LAYER

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Journal of Hydrodynamics 1995年第2期7卷 1-16页

作者： Chiang C. Mei Ko-fei Liu Chiu-on Ng(Department of Civil and Environmental Engineering Massachusetts Institute of Technology,Cambridge,MA USA) Massachusetts Inst of Technology Cambridge United States

As has been extensively reported by hydraulic engineers in China, the flow of hyperconcentrated fluid mud in rivers is often pulsating and appears as roll waves. We report here two theories for such pulsating flows besed on two constitutive laws: the power law and Bingham plastic law. In order to account for the nonlinear bores convective inertia is kept in the approximate long wave equations. Kar man's momentum integral method with an assumed velocity profile is then employed. Results of the linearized instability analyses are *** bores are obtained either as stationary wave solutions or as the long- time limit of unstable disturbances which are initially infinitesimal. Implications on ho scour is examined.

关键词： hyperconcentrated fluid mud pulsating flow power law Bingham plastic law

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Statistical properties of nucleotide clusters in DNA sequences

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2005年第5期6卷 408-412页

作者：成军章林溪 Department of Physics Jinhua University Jinhua 321017 China Department of Physics Zhejiang University Hangzhou 310027 China

Using the complete genome of Plasmodium falciparum 3D7 which has 14 chromosomes as an example, we have examined the distribution functions for the amount of C or G and A or T consecutively and non-overlapping blocks of m bases in this system. The function P(S) about the number of the consecutive C-G or A-T content cluster conforms to the relation P(S)∝e? ; αs values of the scaling exponent αCG are much larger than αAT; and αAT of 14 chromosomes are hardly changed, whereas αCG of 14 chromosomes have a number of fluctuations. We found maximum value of A-T cluster size is much larger than C-G, which implies the existence of large A-T cluster. Our study of the width function ξ(m) of cluster C-G content showed that follows good power law ξ(m)∝m?γ. The average γ for 14 chromosomes is 0.931. These investigations provide some insight into the nucleotide clusters of DNA sequences, and help us understand other properties of DNA sequences.

关键词： DNA sequence Plasmodium falciparum 3D7 Nucleotide clusters power law

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Average cluster sizes and cluster size distributions of superfine nickel particles in light media

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Journal of Central South University 2009年第3期16卷 399-404页

作者：李敬生杜飞虎王娟 School of Chemistry and Chemical Engineering Jiangsu University

Effects of shear rates on average cluster sizes (ACSs) and cluster size distributions (CSDs) in uni- and bi-systems of partly charged superfine nickel particles were investigated by Brownian dynamics, and clustering properties in these systems were compared with those in non-polar systems. The results show that the ACSs in bi-polar systems are larger than those in the non-polar systems. In uni-polar systems the behavior of clustering property differs: at the lower ionic concentration (10%), repulsive force is not strong enough to break clusters, but may greatly weaken them. The clusters are eventually cracked into smaller ones only when concentration of uni-polar charged particles is large enough. In this work, the ionic concentration is 20%. The relationship between ACS and shear rates follows power law in a exponent range of 0.176-0.276. This range is in a good agreement with the range of experimental data, but it is biased towards the lower limit slightly.

关键词： ionic concentration average cluster sizes cluster size distribution power law

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Quantitative study of atmospheric effects in spaceborne InSAR measurements

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Journal of Central South University of Technology 2005年第4期12卷 494-498页

作者：李志伟丁晓利朱建军邹峥嵘 School of Info-physics and Geomatics Engineering Central South University Changsha 410083 ChinaDepartment of Land Surveying and Geo-informatics Hong Kong Polytechnic University Kowloon Hong Kong China Department of Land Surveying and Geo-informatics Hong Kong Polytechnic University Kowloon Hong Kong China School

Atmospheric effects on interferometric synthetic aperture radar(InSAR) measurements are quantitatively studied based on a tandem pair of SAR data and a month-long continuous GPS tracking data obtained at six stations. Differential atmospheric signals extracted from the SAR data for two selected areas show apparent power law characteristics. The RMS values of the signals are 2.04 and 3.66 rad respectively for the two areas. These differential delays can potentially cause in the two areas peak-to-peak deformation errors of 3.64 and 6.52cm, respectively, at the 95% confidence level and Gaussian distribution. The respective potential peak-to-peak DEM errors are 123 and 221 m. The GPS tropospheric total zenith delays estimate indicates that a peak-to-peak error of about 7.8cm can potentially be caused in a SAR interferogram with only 1 d interval at the 95% confidence level. The error increases to about 9.6cm for 10 d interval. The potential peak-to-peak DEM and deformation errors estimated from GPS total zenith delay measurements are however quite similar to those estimated from InSAR data. This provides us with a useful tool to pre-estimate the potential atmospheric effects in a SAR interferogram before we order the SAR images. Nevertheless, the results reveal that even in a small area the atmospheric delays can obscure centimetre level ground displacements and introduce a few hundred meters of errors to derived DEM.

关键词： atmospheric effect InSAR GPS power law total zenith delay

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Self-organized Criticality Model for Ocean Internal Waves

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Communications in Theoretical Physics 2009年第3期51卷 490-494页

作者： WANG Gang LIN Min QIAO Fang-Li HOU Yi-Jun Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China First Institute of Oceanography State Oceanic Administration Qingdao 266061 China Key laboratory of Marine Science and .~Tumerical Modeling （MASNUM） State Oceanic Administration Qingdao 266061 China College of Mathematics Ocean University of China Qingdao 266071 China

In this paper, we present a simple spring-block model for ocean internal waves based on the self-organized criticality （SOC）. The oscillations of the water blocks in the model display power-law behavior with an exponent of -2 in the frequency domain, which is similar to the current and sea water temperature spectra in the actual ocean and the universal Garrett and Munk deep ocean internal wave model [Geophysical Fluid Dynamics 2 （1972） 225; J. Geophys. Res. 80 （1975） 291]. The influence of the ratio of the driving force to the spring coefficient to SOC behaviors in the model is also discussed.

关键词： self-organized criticality power law internal waves power spectrum

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Ultraslow electron-phonon scattering and polaron formation in magnetite

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Journal of Materiomics 2022年第1期8卷 150-155页

作者： Adrian Radoń DariuszŁukowiec Patryk Włodarczyk Łukasiewicz Research Network-Institute of Non-Ferrous Metals Sowinskiego 5 St.44-100GliwicePoland Faculty of Mechanical Engineering Silesian University of TechnologyKonarskiego 18 a St.44-100GliwicePoland

The comprehensive analysis of AC electrical conductivity in magnetite was performed in order to find relations between the formation of polarons,phonons and conduction by a virtual free electron *** analysis performed here for the first time shows experimental data for the behavior of electrons for magnetite with the scattering time shifted to the GHz *** to our study,the DC electrical conductivity can be described by the virtual free electron gas model,and high frequency conductivity can be described by the combination of the Drude model for disordered materials and Jonscher's universal power *** observed peak at the imaginary part of AC conductivity was related to the scattering time of the electron-phonon *** interaction between electrons and thermally formed phonons results in the formation of large polarons,and these are responsible for high frequency conductivity in magnetite.

关键词： Magnetite Drude model power law Electrical conductivity Virtual free electron gas

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Atmospheric and Oceanic Science Letters 2014年第4期7卷 320-323页

作者： SONG Zong-Peng HU Fei XU Jing-Jing CHENG Xue-Ling State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences University of Chinese Academy of Sciences

Time series of wind speed are composed of large and small ramp structures. Data analysis reveals a power law relation between the linear slope of ramp structures and the time scale. This suggests that these ramp structures of wind speed have a self-similar characteristic. The lower limit of the self-similar scale range was 2 s. The upper limit is unexpectedly large at 27 rain. Data are collected from grassland, city, and lake areas. Although these data have different underlying surfaces, all of them clearly show a power law relation, with slight differences in their power exponents.

关键词： ramp structure self-similarity power law time series of wind speed

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The particular species determining spatial heterogeneity in shady and terrace on the Qinghai-Tibetan Plateau,China

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Research in Cold and Arid Regions 2023年第1期15卷 39-47页

作者： XiaoMing Mou YingWen Yu Min Zhao YuQiang Li Masae Shiyomi Northwest Institute of Eco-Environment and Resources Naiman Desertification Research StationChinese Academy of SciencesLanzhouGansu 730000China State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems College of Pastoral Agriculture Science and TechnologyLanzhou UniversityLanzhouGansu 730020China Ibaraki University Professor EmeritusBunkyo 2-1Mito 310-8512Japan

Spatial patterns of plant species and patchy community are important properties in ***,research regarding spatial patterns of formed patches with various species has not fully advanced until *** purpose is to clarify differences in spatial pattern formed by species and community constructed under shady and terrace *** three common Kobresia-Carex patches(Size 1,0.6–0.9 m^(2);Size 2,3.0–3.8 m^(2) and Size 3,6.5–8.8 m^(2))were selected in shady and terrace on the Qinghai-Tibetan Plateau,and corresponding quadrats of 1m1m,2m2m and 3m3m were placed for S1,S2 and S3 patches,*** surveyed quadrats were divided into 20cm20cm large cells(L-cells),and further divided into four 10cm10cm small cells(S-cells).We used the binary occurrence system(presence/absence data)to record occurrences of all species in *** analysis shows that the power law model was well able to determine the spatial distribution pattern of species or patchy community in shady and *** species and patches show aggregated distribution in shady and terrace *** the shady habitat,the relative spatial heterogeneity(ε)of individual plant species was lowest at presence frequency(P)of 0.1–0.3,whereas in the terrace habitatεwas lowest at P<0.1,andεincreased monotonically with increasing *** most dominant species,P andεvalues were higher in terrace than those in *** concluded that the dominant species largely determine spatial heterogeneity of the Kobresia-Carex patches,while companion and rare species have weak influence on the community-level heterogeneity in shady and terrace habitats.

关键词： Dominant species power law Qinghai-Tibetan Plateau Spatial heterogeneity Vegetation patches

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