期刊文献+
共找到3,103篇文章
< 1 2 156 >
每页显示 20 50 100
Spatial-temporal distribution and geochemistry of highly evolved Mesozoic granites in Great Xing’an Range,NE China:Discriminant criteria and geological significance
1
作者 WU Haoran YANG Hao +4 位作者 GE Wenchun JI Zheng DONG Yu JING Yan JING Jiahao 《Global Geology》 2024年第1期20-34,共15页
Highly evolved granite is an important sign of the mature continent crust and closely associated with deposits of rare metals.In this work,the authors undertake systematically zircon U-Pb ages and whole rock elemental... Highly evolved granite is an important sign of the mature continent crust and closely associated with deposits of rare metals.In this work,the authors undertake systematically zircon U-Pb ages and whole rock elemental data for highly evolved granitic intrusions from the Great Xing’an Range(GXR),NE China,to elucidate their discriminant criteria,spatial-temporal distribution,differentiation and geodynamic mecha-nism.Geochemical data of these highly evolved granites suggest that high w(SiO_(2))(>70%)and differentiation index(DI>88)could be quantified indicators,while strong Eu depletion,high TE_(1,3),lowΣREE and low Zr/Hf,Nb/Ta,K/Rb could only be qualitative indicators.Zircon U-Pb ages suggest that the highly evolved gran-ites in the GXR were mainly formed in Late Mesozoic,which can be divided into two major stages:Late Ju-rassic-early Early Cretaceous(162-136 Ma,peak at 138 Ma),and late Early Cretaceous(136-106 Ma,peak at 126 Ma).The highly evolved granites are mainly distributed in the central-southern GXR,and display a weakly trend of getting younger from northwest to southeast,meanwhile indicating the metallogenic potential of rare metals within the central GXR.The spatial-temporal distribution,combined with regional geological data,indicates the highly evolved Mesozoic granites in the GXR were emplaced in an extensional environ-ment,of which the Late Jurassic-early Early Cretaceous extension was related to the closure of the Mongol-Okhotsk Ocean and roll-back of the Paleo-Pacific Plate,while the late Early Cretaceous extension was mainly related to the roll-back of the Paleo-Pacific Plate. 展开更多
关键词 highly evolved granite Great Xing’an Range spatial-temporal distribution extensional environment
下载PDF
The Spatial-Temporal Distribution Patterns of Dyke Swarms in Central Asia and their Tectonic Significance: Case Studies in Eastern Tianshan and Western Junggar 被引量:1
2
作者 FENG Qianwen LI Jinyi LIU Jianfeng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期152-153,共2页
Dykes are a special kind of intrusive rocks which were formed by deep magma intruded into the existing brittle fractures in the crust.Dykes swarms in different tectonic environments are very significant to re-construc... Dykes are a special kind of intrusive rocks which were formed by deep magma intruded into the existing brittle fractures in the crust.Dykes swarms in different tectonic environments are very significant to re-construct the 展开更多
关键词 deep Asia Case Studies in Eastern Tianshan and Western Junggar The spatial-temporal distribution Patterns of Dyke Swarms in Central Asia and their Tectonic Significance
下载PDF
Comparative Study and Spatial-Temporal Distribution of Regolith and Rock Geochemical Data from Xingmeng-North China
3
作者 TANG Kun WANG Xueqiu +3 位作者 CHI Qinghua ZHOU Jian LIU Dongsheng LIU Hanliang 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2017年第S1期229-230,共2页
1 Introduction Geochemical mapping at national and continental scales continues to present challenges worldwide due to variations in geologic and geotectonic units.Use of the proper sampling media can provide rich inf... 1 Introduction Geochemical mapping at national and continental scales continues to present challenges worldwide due to variations in geologic and geotectonic units.Use of the proper sampling media can provide rich information on 展开更多
关键词 In Comparative Study and spatial-temporal distribution of Regolith and Rock Geochemical Data from Xingmeng-North China ROCK REE
下载PDF
CONCEPT, DISTRIBUTION LAW AND FORMATION MACHANISM OF INLAND SALINE ALKALINE WETLAND─ ─ Taking Songliao Plain for Example 被引量:5
4
作者 SUN Guang you1, LUO Xin zheng2 , YI Fu ke1 , ZHANG Xiao ping1 (1.Changchun Institute of Geography, the Chinese Academy of Sciences,Changchun 130021,P.R.China 2.Institute of Geography, Academy of Henan Province, Zhengzhou 450052,P.R.China) 《Chinese Geographical Science》 SCIE CSCD 2000年第3期63-69,共2页
The paper, taking Songliao Plain for example, studied the concept, distribution law and formation mechanism of inland saline alkaline wetland. The inland saline alkaline wetland is distributed over the inland region o... The paper, taking Songliao Plain for example, studied the concept, distribution law and formation mechanism of inland saline alkaline wetland. The inland saline alkaline wetland is distributed over the inland region of arid or semi arid climate; it is the wet or slightly stagnant environment, forming saline alkaline soil and salt vegetation and making the geogra phical environment fonming complex with an ecosystem of saline alkaline wetland. The laws of zone nature and non zone nature control the distribution of the inland saline alkaline wetland that extensively spreads in north part of China and other countries. The inland saline alkaline wetland is formed jointly by atmosphere, hydrosphere, lithosphere and biosphere including intellectual sphere. Under the special condition, the artificial activity is possibly the key function. In order to improve the human environment, it is a great duty confronting the whole world to rationally transform the inland saline alkaline wetland. Therefore, we presented an anti inland theory to promote the environment transformation. 展开更多
关键词 Songliao Plain INLAND SALINE ALKALINE WETLAND WETLAND distribution law WETLAND CONCEPT WETLAND FORMATION mechanism
下载PDF
A Research of the Finding and Distribution Law of Taisui in Modern China 被引量:11
5
作者 Chao-Jiang Wang Shi-Qing Wang 《Agricultural Sciences》 2015年第4期407-414,共8页
The academic world is still uncertain about the classification of Taisui. It is debating whether Taisui is living or not, myxomycete complex or fungi. The passage studies the 228 finding reports of Taisui in modern Ch... The academic world is still uncertain about the classification of Taisui. It is debating whether Taisui is living or not, myxomycete complex or fungi. The passage studies the 228 finding reports of Taisui in modern China. It confirms that the first finding time of Taisui in modern China is 1963, and the first reported time is 1992. Taisui has been found in 25 administrative divisions. Taisui occurs the most times in Shandong Province. Besides, provinces where Taisui has been found most times are in northern China. Finding locations of Taisui vary from place to place. Taisui is most often found in normal earth layer, with different burying depth. Taisui is mainly found through seeing, tramping, and digging. Taisui findings lack subjective motivations and are connected with the life and production of the finders. Conclusion: Taisui is an object growing in earth layer. 展开更多
关键词 Taisui Finding law distribution law China in MODERN TIMES
下载PDF
Seepage field distribution and water inflow laws of tunnels in water-rich regions 被引量:6
6
作者 LI Zheng CHEN Zi-quan +2 位作者 HE Chuan MA Chun-chi DUAN Chao-ran 《Journal of Mountain Science》 SCIE CSCD 2022年第2期591-605,共15页
Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the str... Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures. 展开更多
关键词 Water-rich tunnel Seepage field distribution Water inflow law Construction period Operation period
下载PDF
The spatial-temporal evolution of coherent structures in log law region of turbulent boundary layer 被引量:4
7
作者 Xiao-Bo Zheng Nan.Jiang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2015年第1期16-24,共9页
The spatial-temporal evolution of coherent structures (CS) is significant for turbulence control and drag re- duction. Among the CS, low and high speed streak structures show typical burst phenomena. The analysis wa... The spatial-temporal evolution of coherent structures (CS) is significant for turbulence control and drag re- duction. Among the CS, low and high speed streak structures show typical burst phenomena. The analysis was based on a time series of three-dimensional and three-component (3D-3C) velocity fields of the flat plate turbulent boundary layer (TBL) measured by a Tomographic and Time-resolved PIV (Tomo TRPIV) system. Using multi-resolution wavelet transform and conditional sampling method, we extracted the intrinsic topologies and found that the streak structures appear in bar-like patterns. Furthermore, we seized locations and velocity information of transient CS, and then calculated the propagation velocity of CS based on spatial-temporal cross-correlation scanning. This laid a foundation for further studies on relevant dynamics properties. 展开更多
关键词 Log law region in TBL. spatial-temporal cross-correlation Tomographic TRPIV Coherent structures Low and high speed streaks Multi-resolution wavelet de-composition
下载PDF
Applicability of law of mass action to distribution of manganese between slag melts and liquid iron 被引量:1
8
作者 张鉴 《中国有色金属学会会刊:英文版》 CSCD 2001年第5期778-783,共6页
According to the law of mass action and the coexistence theory of slag structure, the distribution of manganese between MnO FeO SiO 2 and MgO MnO FeO SiO 2 slag melts as well as liquid iron was analyzed. It is shown t... According to the law of mass action and the coexistence theory of slag structure, the distribution of manganese between MnO FeO SiO 2 and MgO MnO FeO SiO 2 slag melts as well as liquid iron was analyzed. It is shown that K ′ Mn and K MnO are only dependent on temperature and don’t change with basicities and compositions of slag melts. So the distribution of manganese between the above mentioned slag melts and molten iron obeys the law of mass action. But analysis of experimental results from other sources shows that K ′ Mn and K MnO really change with basicities of slag, which is probably arisen from not approaching equilibrium under low basicity slag melts. 展开更多
关键词 manganese distribution the law of mass action the coexistence theory of slag structure mass action concentration
下载PDF
Relativistic Corrections to the Maxwellian Distribution for Astrophysical and Fusion Plasmas
9
作者 Amaury de Kertanguy 《Journal of Applied Mathematics and Physics》 2023年第8期2414-2428,共15页
We present calculations and improvement inspired by the work of Lorenzo Zaninetti, published in 2020, it concerns a problem whose origin dates back 1911 with so called Maxwell-Jüttner distribution these lies on t... We present calculations and improvement inspired by the work of Lorenzo Zaninetti, published in 2020, it concerns a problem whose origin dates back 1911 with so called Maxwell-Jüttner distribution these lies on the Lorentz factor , with . This work uses powerful modern software for a reconstruction of Zaninetti work, which computes with special functions, these are included in the Mathematica software, as by instance Bessel and Meijer G-functions ready to manipulate. A progress is made, it is possible to perform an integral that is not computed in Zaninetti paper. This author connects the correct relativistic probability law: the Maxwell-Jüttner to the synchrotron emissivity with a magnetic B field, this work generalize these results, using the linear Stark effect and deals with an electric field E. 展开更多
关键词 Maxwell-Jüttner distribution Relativity Modification to Maxwell law Lorentz Factor Linear Stark Effect Plasma Physics
下载PDF
Plastic zone distribution laws and its types of surrounding rock in large-span roadway 被引量:14
10
作者 Li Chong Xu Jinhai +1 位作者 PanJianzhong Ma Chao 《International Journal of Mining Science and Technology》 2012年第1期23-28,共6页
In order to study the distribution laws and types of plastic zone of surrounding rock in large-span roadway, we analyzed the distribution laws with different spans and lateral pressures using FLAC 3D numerical calcula... In order to study the distribution laws and types of plastic zone of surrounding rock in large-span roadway, we analyzed the distribution laws with different spans and lateral pressures using FLAC 3D numerical calculation software. Based on the roadway support difficulty and distribution laws of the plastic zone of surrounding rock, we defined the large-span roadway and classified the types of large-span rectangular roadways. As a result, the distribution laws of the plastic zone on surrounding rock in a rectangular roadway with different spans and lateral pressures were obtained. The results show that the area of the plastic zone on surrounding rock increased with the increase of the spans and lateral pressures, and the plastic zone was symmetrical to the center line of roadway. At k = 0.5, 1.0, 1.5, and 2.0, the plastic zone presented "addleshape" distribution, "ellipse" distribution, "thin and high" distribution and "inverse trapezium" distribution, respectively. In addition, we classified the roadways into four types according to the different lateral pressures and spans, including small-span, moderate-span, large-span and extreme-large-span roadways. 展开更多
关键词 大跨度巷道 围岩塑性区 分布规律 围岩类型 横向压力 FLAC3D 矩形巷道 四舍五入
下载PDF
Revisiting the Curie-Von Schweidler Law for Dielectric Relaxation and Derivation of Distribution Function for Relaxation Rates as Zipf’s Power Law and Manifestation of Fractional Differential Equation for Capacitor 被引量:1
11
作者 Shantanu Das 《Journal of Modern Physics》 2017年第12期1988-2012,共25页
The classical power law relaxation, i.e. relaxation of current with inverse of power of time for a step-voltage excitation to dielectric—as popularly known as Curie-von Schweidler law is empirically derived and is ob... The classical power law relaxation, i.e. relaxation of current with inverse of power of time for a step-voltage excitation to dielectric—as popularly known as Curie-von Schweidler law is empirically derived and is observed in several relaxation experiments on various dielectrics studies since late 19th Century. This relaxation law is also regarded as “universal-law” for dielectric relaxations;and is also termed as power law. This empirical Curie-von Schewidler relaxation law is then used to derive fractional differential equations describing constituent expression for capacitor. In this paper, we give simple mathematical treatment to derive the distribution of relaxation rates of this Curie-von Schweidler law, and show that the relaxation rate follows Zipf’s power law distribution. We also show the method developed here give Zipfian power law distribution for relaxing time constants. Then we will show however mathematically correct this may be, but physical interpretation from the obtained time constants distribution are contradictory to the Zipfian rate relaxation distribution. In this paper, we develop possible explanation that as to why Zipfian distribution of relaxation rates appears for Curie-von Schweidler Law, and relate this law to time variant rate of relaxation. In this paper, we derive appearance of fractional derivative while using Zipfian power law distribution that gives notion of scale dependent relaxation rate function for Curie-von Schweidler relaxation phenomena. This paper gives analytical approach to get insight of a non-Debye relaxation and gives a new treatment to especially much used empirical Curie-von Schweidler (universal) relaxation law. 展开更多
关键词 Power law RELAXATION RATE distribution FRACTIONAL Derivative FRACTIONAL Integration Curie-Von Schweidler law Time-Constants Laplace INTEGRAL Zipf’s law INTEGRAL Representation Time Dependent RELAXATION RATE Scale Dependent RELAXATION RATE Non-Debye RELAXATION
下载PDF
An optimized framework for degree distribution in LT codes based on power law
12
作者 Asim Muhammad Choi GoangSeog 《Journal of Central South University》 SCIE EI CAS 2013年第10期2693-2699,共7页
LT codes are practical realization of digital fountain codes, which provides the concept of rateless coding. In this scheme, encoded symbols are generated infinitely from k information symbols. Decoder uses only(1+α)... LT codes are practical realization of digital fountain codes, which provides the concept of rateless coding. In this scheme, encoded symbols are generated infinitely from k information symbols. Decoder uses only(1+α)k number of encoded symbols to recover the original information. The degree distribution function in the LT codes helps to generate a random graph also referred as tanner graph. The artifact of tanner graph is responsible for computational complexity and overhead in the LT codes. Intuitively, a well designed degree distribution can be used for an efficient implementation of LT codes. The degree distribution function is studied as a function of power law, and LT codes are classified into two different categories: SFLT and RLT codes. Also, two different degree distributions are proposed and analyzed for SFLT codes which guarantee optimal performance in terms of computational complexity and overhead. 展开更多
关键词 FOUNTAIN CODES degree distribution OVERHEAD COMPUTATIONAL COMPLEXITY power law
下载PDF
Power Law Distributions in the Experiment for Adjustment of the Ion Source of the NBI System
13
作者 韩筱璞 胡纯栋 《Plasma Science and Technology》 SCIE EI CAS CSCD 2005年第6期3102-3104,共3页
The experiential adjustment process in an experiment on the ion source of the neutral beam injector system for the HT-7 Tokamak is reported in this paper. With regard to the data obtained in the same condition, in arr... The experiential adjustment process in an experiment on the ion source of the neutral beam injector system for the HT-7 Tokamak is reported in this paper. With regard to the data obtained in the same condition, in arranging the arc current intensities of every shot with a decay rank, the distributions of the arc current intensity correspond to the power laws, and the distribution obtained in the condition with the cryo-pump corresponds to the double Pareto distribution. Using the similar study method, the distributions of the arc duration are close to the power laws too. These power law distributions are formed rather naturally instead of being the results of purposeful seeking. 展开更多
关键词 power law distribution adjustment experiment ion source double Pareto distribution
下载PDF
Power-law Distribution of Normal Fault Displacement and Length and Estimation of Extensional Strain due to Normal Faults:A Case Study of the Sierra de San Miguelito, Mexico 被引量:1
14
作者 XUShunshan A.F.NIETO-SAMANIEGO S.A.ALANIZ-ALVAREZ 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2005年第1期36-42,共7页
The Sierra de San Miguelito is a relatively uplifted area and is constituted by a large amount of silicic volcanic rocks with ages from middle to late Cenozoic. The normal faults of the Sierra de San Miguelito are Dom... The Sierra de San Miguelito is a relatively uplifted area and is constituted by a large amount of silicic volcanic rocks with ages from middle to late Cenozoic. The normal faults of the Sierra de San Miguelito are Domino-style and nearly parallel. The cumulative length and displacement of the faults obey power-law distribution. The fractal dimension of the fault traces is -1.49. Using the multi-line one-dimensional sampling, the calculated exponent of cumulative fault displacements is -0.66. A cumulative curve combining measurements of all four sections yielded a slope of -0.63. The displacement-length plot shows a non-linear relationship and large dispersion of data. The large dispersion in the plot is mainly due to the fault linkage during faulting. An estimation of extensional strain due to the normal faults is ca. 0.1830. The bed extension strain is always less than or equal to the horizontal extension strain. The deformation in the Sierra de San Miguelito occurred near the surface, producing pervasive faults and many faults are too small to appear in maps and sections at common scales. The stretching produced by small faults reach ca. 33% of the total horizontal elongation. 展开更多
关键词 power-law distribution normal faults small faults finite strain Mexico
下载PDF
Study on the Size Distribution and Similarity Law of Bubble Nuclei in Water
15
作者 YAO Xiong-liang LI Zhi-peng +1 位作者 SUN Long-quan CHEN Wei-chu 《China Ocean Engineering》 SCIE EI CSCD 2021年第3期432-442,共11页
To study the distribution characteristics and similarity laws of nuclei under different pressures,based on the selfdesigned decompression chamber and the acoustic measuring system,the size distributions of nuclei in t... To study the distribution characteristics and similarity laws of nuclei under different pressures,based on the selfdesigned decompression chamber and the acoustic measuring system,the size distributions of nuclei in the degassed tap water under negative ambient pressures were measured.A number density distribution function of nuclei based on the modified Weibull distribution function was proposed and verified by the experimental measurement results and some published data of nuclei size distribution.Based on this nuclei number density distribution function,the similarity law of the nuclei size distribution was analyzed:in the scale experiment,the value of exponential in the similarity law of the nuclei number density should be determined by the nuclei size distribution of the water in the prototype experiment and the actual nuclei size distribution of the water in the model experiment.And a precondition is that the nuclei size distributions are similar. 展开更多
关键词 nuclei number density distribution function MICROBUBBLE ambient pressure similarity law
下载PDF
LAWS GOVERNING THE DISTRIBUTION OF LEAD-ZINC DEPOSITS IN CHINA
16
作者 YIN Hanhui(Changsha Institute of Geotectonics, Academia Sinica, Changsha, 410013, China ) 《Geotectonica et Metallogenia》 1997年第Z2期78-88,共11页
An attempt is made in this paper to describe the following laws governing the distribution of lead-zinc deposits in China: spatial distribution laws, temporal distribution laws, deep level control laws, and deposits a... An attempt is made in this paper to describe the following laws governing the distribution of lead-zinc deposits in China: spatial distribution laws, temporal distribution laws, deep level control laws, and deposits association and zoning laws. 展开更多
关键词 Lead-zinc DEPOSITS spatial-temporal distribution DEEP level control lawS DEPOSITS ASSOCIATION and ZONING lawS
下载PDF
THERMAL PROPERTIES AND TEMPERATURE DISTRIBUTION OF SNOW/FIRN ON THE LAW DOWE ICE CAP, ANTARCTICA
17
作者 Ren Jiawen, Qin Dahe and Huang Maohuan Lanzhou Institute of Glaciology and Geocryology, Chinese Academy of Sciences, Lanzhou, 730000, China 《Chinese Journal of Polar Science》 1991年第2期38-46,共9页
Based on detailed measurements of density and a numerous data on temperature in shallow boreholes (about 20m deep), the thermal properties and temperature distribution of snow / firn layer on the Law Dome ice cap, Ant... Based on detailed measurements of density and a numerous data on temperature in shallow boreholes (about 20m deep), the thermal properties and temperature distribution of snow / firn layer on the Law Dome ice cap, Antarctica, are discussed. According to a review of works on thermal properties of snow by Yen (1981), a relationship between thermal conductivity (K) and density (ρ) is proposed to be expressed by a formula, K=0.0784+2.697/ρ2. Then an eqation of heat transfer in a deformed ununiform medium is applied and solved analytically by two approaches. Comparison of calculated and measured temperatures indicates that the difference is mainly dependent on the determination of boundary donditions. 展开更多
关键词 law Dome Ice Cap snow-firn layer thermal properties temperature distribution.
下载PDF
Leak Detection in Water Distribution Systems Using Bayesian Theory and Fisher’s Law 被引量:1
18
作者 张宏伟 王丽娟 《Transactions of Tianjin University》 EI CAS 2011年第3期181-186,共6页
A leak detection method based on Bayesian theory and Fisher’s law was developed for water distribution systems. A hydraulic model was associated with the parameters of leaks (location, extent). The randomness of para... A leak detection method based on Bayesian theory and Fisher’s law was developed for water distribution systems. A hydraulic model was associated with the parameters of leaks (location, extent). The randomness of parameter values was quantified by probability density function and updated by Bayesian theory. Values of the parameters were estimated based on Fisher’s law. The amount of leaks was estimated by back propagation neural network. Based on flow characteristics in water distribution systems, the location of leaks can be estimated. The effectiveness of the proposed method was illustrated by simulated leak data of node pressure head and flow rate of pipelines in a test pipe network, and the leaks were spotted accurately and renovated on time. 展开更多
关键词 贝叶斯理论 泄漏检测 配水系统 Fisher法 概率密度函数 数值估计 BP神经网络 水力模型
下载PDF
Power Law Exponents for Vertical Velocity Distributions in Natural Rivers
19
作者 Hae-Eun Lee Chanjoo Lee +2 位作者 Youg-Jeon Kim Ji-Sung Kim Won Kim 《Engineering(科研)》 2013年第12期933-942,共10页
While log law is an equation theoretically derived for near-bed region, in most cases, power law has been researched by experimental methods. Thus, many consider it as an empirical equation and fixed power law exponen... While log law is an equation theoretically derived for near-bed region, in most cases, power law has been researched by experimental methods. Thus, many consider it as an empirical equation and fixed power law exponents such as 1/6 and 1/7 are generally applied. However, exponent of power law is an index representing bed resistance related with relative roughness and furthermore influences the shapes of vertical velocity distribution. The purpose of this study is to investigate characteristics of vertical velocity distribution of the natural rivers by testing and optimizing previous methods used for determination of power law exponent with vertical velocity distribution data collected with ADCPs during the years of 2005 to 2009 from rivers in South Korea. Roughness coefficient has been calculated from the equation of Limerinos. And using theoretical and empirical formulae, and representing relationships between bed resistance and power law exponent, it has been evaluated whether the exponents suggested by these equations appropriately reproduce vertical velocity distribution of actual rivers. As a result, it has been confirmed that there is an increasing trend of power law exponent as bed resistance increases. Therefore, in order to correctly predict vertical velocity distribution in the natural rivers, it is necessary to use an exponent that reflects flow conditions at the field. 展开更多
关键词 Vertical VELOCITY distribution Power law EXPONENT Natural RIVERS Field Measurement Flow Resistance
下载PDF
A Theoretical Explanation of the Causes of Popular Elements and Income Power Law Distribution Based on Data Analysis
20
作者 DONG Chun 《Psychology Research》 2022年第6期362-368,共7页
The known statistical data show that the distribution of popular elements and people’s income presents the characteristics of power law distribution.At present,the explanation for this phenomenon is mostly through th... The known statistical data show that the distribution of popular elements and people’s income presents the characteristics of power law distribution.At present,the explanation for this phenomenon is mostly through the“rich get richer”theory,but the author believes that this theory has major flaws and fails to provide a reasonable explanation for many phenomena.Therefore,the author expands some empirical and recognized theories in a similar direction in logic,and derives a logical mathematical model through the derivation of mathematical formulas,so as to explain the phenomenon that the distribution of popular elements and people’s income presents a power-law distribution.Then,by analyzing various characteristics of social networks and comparing them with some phenomena in nature,the conclusion can be extended to all self-organizing groups in nature. 展开更多
关键词 social network POPULARITY INCOME power law distribution
下载PDF
上一页 1 2 156 下一页 到第
使用帮助 返回顶部