The principle of three-level delineation is adopted in determination of a potential seismic source for the new National Seismic Ground Motion Parameters Zoning Map of China,to embody the inhomogeneity of the spatial d...The principle of three-level delineation is adopted in determination of a potential seismic source for the new National Seismic Ground Motion Parameters Zoning Map of China,to embody the inhomogeneity of the spatial distribution of background seismic activity and induct a uniform seismotectonic model for each seismotectonic region. Based on achievements of determining potential seismic sources in southwestern China,this paper introduces the basic characteristics, historical earthquakes magnitude and frequency distribution,identification of deformation mechanism of main active tectonic structures for the Longmenshan and Chengdu seismotectonic region in the Longmenshan seismic region,establishes the seismogenic model for each seismotectonic region,and identifies the upper limit of background earthquakes. A simple method is also put forward for calculating the spatial distribution function of a background seismic source.展开更多
The average bit error rate(ABER) performance of a decode-and-forward(DF) based relay-assisted free-space optical(FSO) communication system over gamma-gamma distribution channels considering the pointing errors is stud...The average bit error rate(ABER) performance of a decode-and-forward(DF) based relay-assisted free-space optical(FSO) communication system over gamma-gamma distribution channels considering the pointing errors is studied. With the help of Meijer's G-function, the probability density function(PDF) and cumulative distribution function(CDF) of the aggregated channel model are derived on the basis of the best path selection scheme. The analytical ABER expression is achieved and the system performance is then investigated with the influence of pointing errors, turbulence strengths and structure parameters. Monte Carlo(MC) simulation is also provided to confirm the analytical ABER expression.展开更多
This paper is to study the two-dimensional stress distribution of a finite functionally graded material (FGM) plate with a circular hole under arbitrary constant loads. Using the method of piece-wise homogeneous layer...This paper is to study the two-dimensional stress distribution of a finite functionally graded material (FGM) plate with a circular hole under arbitrary constant loads. Using the method of piece-wise homogeneous layers, the stress analysis of the finite FGM plate having radial arbitrary elastic properties is made based on the complex variable method combined with the least square boundary collocation technique. Numerical results of stress distribution around the hole are then presented for different loading conditions, different material properties and different plate sizes, respectively. It is shown that the stress concentration in the finite plate is generally enhanced compared with the case of an infinite plate, but it can be significantly reduced by choosing proper change ways of the radial elastic modulus.展开更多
Precipitation heterogeneity has a nontrivial influence on human life. Many studies have analyzed precipitation heterogeneity but none have proposed a systematic graded index for its evaluation, and therefore, its true...Precipitation heterogeneity has a nontrivial influence on human life. Many studies have analyzed precipitation heterogeneity but none have proposed a systematic graded index for its evaluation, and therefore, its true characteristics have not been expressed. After comparisons of various methods, the precipitation concentration degree(PCD) method was selected to study precipitation heterogeneity. In addition to the PCD, normal distribution functions, cumulative frequencies, and percentiles were used to establish a graded index for evaluating precipitation heterogeneity. A comprehensive evaluation of precipitation heterogeneity was performed, and its spatiotemporal variation in China from 1960 to 2013 was analyzed. The results indicated that(1) seven categories of precipitation heterogeneity were identified(high centralization, moderate centralization, mild centralization, normal, mild dispersion, moderate dispersion, and high dispersion) and(2) during the study period, the precipitation in more parts of China tended to be normal or dispersed, which is beneficial to human activities.展开更多
基金sponsored by the Study on the Determination of the Seismicity Parameters of Background Source-A Case Study of the Longmenshan Seismic Statistical Zone,Earthquake Administration of Sichuan Province
文摘The principle of three-level delineation is adopted in determination of a potential seismic source for the new National Seismic Ground Motion Parameters Zoning Map of China,to embody the inhomogeneity of the spatial distribution of background seismic activity and induct a uniform seismotectonic model for each seismotectonic region. Based on achievements of determining potential seismic sources in southwestern China,this paper introduces the basic characteristics, historical earthquakes magnitude and frequency distribution,identification of deformation mechanism of main active tectonic structures for the Longmenshan and Chengdu seismotectonic region in the Longmenshan seismic region,establishes the seismogenic model for each seismotectonic region,and identifies the upper limit of background earthquakes. A simple method is also put forward for calculating the spatial distribution function of a background seismic source.
基金supported by the National Natural Science Foundation of China(No.61474090)the Fundamental Research Funds for the Central Universities(No.JB160105)the 111 Project of China(No.B08038)
文摘The average bit error rate(ABER) performance of a decode-and-forward(DF) based relay-assisted free-space optical(FSO) communication system over gamma-gamma distribution channels considering the pointing errors is studied. With the help of Meijer's G-function, the probability density function(PDF) and cumulative distribution function(CDF) of the aggregated channel model are derived on the basis of the best path selection scheme. The analytical ABER expression is achieved and the system performance is then investigated with the influence of pointing errors, turbulence strengths and structure parameters. Monte Carlo(MC) simulation is also provided to confirm the analytical ABER expression.
基金supported by the National Natural Science Foundation of China (Grant No. 10972103)the Ph.D. Programs Foundation of Ministry of Education of China (Grant No. 20093218110004)+1 种基金the Funding of Jiangsu Innovation Program for Graduate Education (Grant No.CXZZ11_0191)Funding for Outstanding Doctoral Dissertation in NUAA (Grant No. BCXJ11-03)
文摘This paper is to study the two-dimensional stress distribution of a finite functionally graded material (FGM) plate with a circular hole under arbitrary constant loads. Using the method of piece-wise homogeneous layers, the stress analysis of the finite FGM plate having radial arbitrary elastic properties is made based on the complex variable method combined with the least square boundary collocation technique. Numerical results of stress distribution around the hole are then presented for different loading conditions, different material properties and different plate sizes, respectively. It is shown that the stress concentration in the finite plate is generally enhanced compared with the case of an infinite plate, but it can be significantly reduced by choosing proper change ways of the radial elastic modulus.
基金National Natural Science Foundation of China,No.41171090National Social Science Foundation of China,No.14AZD094,No.14XSK019
文摘Precipitation heterogeneity has a nontrivial influence on human life. Many studies have analyzed precipitation heterogeneity but none have proposed a systematic graded index for its evaluation, and therefore, its true characteristics have not been expressed. After comparisons of various methods, the precipitation concentration degree(PCD) method was selected to study precipitation heterogeneity. In addition to the PCD, normal distribution functions, cumulative frequencies, and percentiles were used to establish a graded index for evaluating precipitation heterogeneity. A comprehensive evaluation of precipitation heterogeneity was performed, and its spatiotemporal variation in China from 1960 to 2013 was analyzed. The results indicated that(1) seven categories of precipitation heterogeneity were identified(high centralization, moderate centralization, mild centralization, normal, mild dispersion, moderate dispersion, and high dispersion) and(2) during the study period, the precipitation in more parts of China tended to be normal or dispersed, which is beneficial to human activities.
