Heterogeneity of permeability in fractured media is a hot research topic in hydrogeology. Numerous approaches have been proposed to characterize heterogeneity in the last several decades. However, little attention has...Heterogeneity of permeability in fractured media is a hot research topic in hydrogeology. Numerous approaches have been proposed to characterize heterogeneity in the last several decades. However, little attention has been paid to correlate permeability heterogeneity with geological information. In the present study, several causes of permeability heterogeneity, that is, lithology, tectonism, and depth, are identified. The unit absorption values （denoted as ω）, which are results obtained from the packer test, are employed to represent permeability. The variability of permeability in sandstone-mudstone is so significant that the value of unit absorptions span 3-4 orders of magnitude at any depth with several test sections. By declustering, it has been found that under a similar tectonic history, the means of permeability differ greatly at different formations as a result of different mudrock contents. It has also been found that in the same formation, permeability can be significantly increased as a result of faulting. The well-known phenomenon, the decrease in permeability with depth, is found to be caused by the fractures in the rock mass, and the relationship between permeability and depth can be established in the form of logoω-logd. After subtracting the trend of ω with absolute depth, the mean of the residual value at each relative depth can be well correlated with the distribution of mudstone. The methods proposed in this paper can be utilized to research in similar study areas.展开更多
The peaks over threshold（POT） methods are used for the univariate and multivariate extreme value analyses of the wave and wind records collected from a hydrometric station in the South China Sea. A new multivariate ...The peaks over threshold（POT） methods are used for the univariate and multivariate extreme value analyses of the wave and wind records collected from a hydrometric station in the South China Sea. A new multivariate POT method： Multivariate GPD（MGPD） model is proposed, which can be built easily according to developed parametric models and is a natural distribution of multivariate POT methods. A joint threshold selection approach is used in the MGPD model well. Finally, sensitivity analyses are carried out to calculate the return values of the base shear, and two declustering schemes are compared in this study.展开更多
Heterogeneity of permeability in fractured media is a hot research topic in hydrogeology and numerous approaches had been proposed to characterize heterogeneity in the past several decades.However。
In recent years,the number and size of data centers and cloud storage systems has increased.These two corresponding trends are dra matically increasing energy consumption and disk failure in emerging facilities.This p...In recent years,the number and size of data centers and cloud storage systems has increased.These two corresponding trends are dra matically increasing energy consumption and disk failure in emerging facilities.This paper describes a new chunk-based proportion al-power layout called CPPL to address the issues.Our basic idea is to leverage current proportional-power layouts by using declus tering techniques.In this way,we can manage power at a much finer-grained level.CPPL includes a primary disk group and a large number of secondary disks.A primary disk group contains one copy of available datasets and is always active in order to respond to in coming requests.Other copies of data are placed on secondary disks in declusterd way for power-efficiency and parallel recovery at a finer-grained level.Through comprehensive theoretical proofs and experiments,we conclude that CPPL can save more power and achieve a higher recovery speed than current solutions.展开更多
基金support by the National Natural Science Foundation of China(No.40528003 and 50639090)
文摘Heterogeneity of permeability in fractured media is a hot research topic in hydrogeology. Numerous approaches have been proposed to characterize heterogeneity in the last several decades. However, little attention has been paid to correlate permeability heterogeneity with geological information. In the present study, several causes of permeability heterogeneity, that is, lithology, tectonism, and depth, are identified. The unit absorption values （denoted as ω）, which are results obtained from the packer test, are employed to represent permeability. The variability of permeability in sandstone-mudstone is so significant that the value of unit absorptions span 3-4 orders of magnitude at any depth with several test sections. By declustering, it has been found that under a similar tectonic history, the means of permeability differ greatly at different formations as a result of different mudrock contents. It has also been found that in the same formation, permeability can be significantly increased as a result of faulting. The well-known phenomenon, the decrease in permeability with depth, is found to be caused by the fractures in the rock mass, and the relationship between permeability and depth can be established in the form of logoω-logd. After subtracting the trend of ω with absolute depth, the mean of the residual value at each relative depth can be well correlated with the distribution of mudstone. The methods proposed in this paper can be utilized to research in similar study areas.
基金supported by the Major Project Research of the Ministry of Railways of the People’s Republic of China(Grant No.2010-201)
文摘The peaks over threshold（POT） methods are used for the univariate and multivariate extreme value analyses of the wave and wind records collected from a hydrometric station in the South China Sea. A new multivariate POT method： Multivariate GPD（MGPD） model is proposed, which can be built easily according to developed parametric models and is a natural distribution of multivariate POT methods. A joint threshold selection approach is used in the MGPD model well. Finally, sensitivity analyses are carried out to calculate the return values of the base shear, and two declustering schemes are compared in this study.
文摘Heterogeneity of permeability in fractured media is a hot research topic in hydrogeology and numerous approaches had been proposed to characterize heterogeneity in the past several decades.However。
基金supported in part by the US National Science FoundationGrant CCF-0811413,CNS-1115665,CCF-1337244National ScienceFoundation Early Career Award 0953946
文摘In recent years,the number and size of data centers and cloud storage systems has increased.These two corresponding trends are dra matically increasing energy consumption and disk failure in emerging facilities.This paper describes a new chunk-based proportion al-power layout called CPPL to address the issues.Our basic idea is to leverage current proportional-power layouts by using declus tering techniques.In this way,we can manage power at a much finer-grained level.CPPL includes a primary disk group and a large number of secondary disks.A primary disk group contains one copy of available datasets and is always active in order to respond to in coming requests.Other copies of data are placed on secondary disks in declusterd way for power-efficiency and parallel recovery at a finer-grained level.Through comprehensive theoretical proofs and experiments,we conclude that CPPL can save more power and achieve a higher recovery speed than current solutions.
