A multidimensional gas chromatographic technique with heartcutting was used for the determination of complex isomeric mixtures of tetra- chlorodibenzo-p-dioxins(TCDDs)which could not be completely separated on a singl...A multidimensional gas chromatographic technique with heartcutting was used for the determination of complex isomeric mixtures of tetra- chlorodibenzo-p-dioxins(TCDDs)which could not be completely separated on a single capillary column.When using so-called heartcutting technique ,only the interested single peak or section of the fraction eluting from the first column was transferred onto the second column with different stationary phase.Flame ionization detection was used as the monitor detector and electron capture detection as the main detector.This arrangement offers complete separation and avoids interference of the possible remained chlorinated solvents.The separation power of multi- dimensional GC was demonstrated by the determination of TCDD isomers.展开更多
The foundation of ad hoc networks lies in the guarantee of continuous connectivity.However,critical nodes,whose failure can easily destroy network connectivity,will influence the ad hoc network connectivity significan...The foundation of ad hoc networks lies in the guarantee of continuous connectivity.However,critical nodes,whose failure can easily destroy network connectivity,will influence the ad hoc network connectivity significantly.To protect the network efficiently,critical nodes should be identified accurately and rapidly.Unlike existing critical node identification methods for unknown topology that identify critical nodes according to historical information,this paper develops a critical node identification method to relax the prior topology information condition about critical nodes.Specifically,we first deduce a theorem about the minimum communication range for a node through the number of nodes and deployment ranges,and prove the universality of the theorem in a realistic two-dimensional scenario.After that,we analyze the relationship between communication range and degree value for each node and prove that the greater number of nodes within the communication range of a node,the greater degree value of nodes with high probability.Moreover,we develop a novel strategy to improve the accuracy of critical node identification without topology information.Finally,simulation results indicate the proposed strategy can achieve high accuracy and low redundancy while ensuring low time consumption in the scenarios with unknown topology information in ad hoc networks.展开更多
The location determination technology based on simple delay evaluations or GPS is not accurate enough or even impossible in urban and indoor environments due to the multi path propagation.To enhance the location accur...The location determination technology based on simple delay evaluations or GPS is not accurate enough or even impossible in urban and indoor environments due to the multi path propagation.To enhance the location accuracy and reduce the operation cost within these environments, this paper proposes a novel hybrid location determination technology which combines CELL ID with the database correlation method. The proposed method generate the prediction database of path loss according to CELL ID, and after the computation the smallest squared error of measured path loss and the prediction path loss, the location of the mobile terminal is decided by the coordinates of the best matching matrix entry.展开更多
Location technology is the key part of location based service. Different technologies have different accuracy, modifying to network and cost of operating. Also these technologies have limitation to network. This paper...Location technology is the key part of location based service. Different technologies have different accuracy, modifying to network and cost of operating. Also these technologies have limitation to network. This paper compares existing popular location technologies and gives some suggestions about choosing of location technologies in GSM and CDMA systems.展开更多
基金funded by the European Commission funded ICT-FP7 IP Project EFIPSANS under Grant No. INFSO-ICT-215549the National Basic Research Program of China ("973"Program) under Grant No. 2009CB320504
文摘A multidimensional gas chromatographic technique with heartcutting was used for the determination of complex isomeric mixtures of tetra- chlorodibenzo-p-dioxins(TCDDs)which could not be completely separated on a single capillary column.When using so-called heartcutting technique ,only the interested single peak or section of the fraction eluting from the first column was transferred onto the second column with different stationary phase.Flame ionization detection was used as the monitor detector and electron capture detection as the main detector.This arrangement offers complete separation and avoids interference of the possible remained chlorinated solvents.The separation power of multi- dimensional GC was demonstrated by the determination of TCDD isomers.
基金supported by the National Natural Science Foundation of China(62231020)the Youth Innovation Team of Shaanxi Universities。
文摘The foundation of ad hoc networks lies in the guarantee of continuous connectivity.However,critical nodes,whose failure can easily destroy network connectivity,will influence the ad hoc network connectivity significantly.To protect the network efficiently,critical nodes should be identified accurately and rapidly.Unlike existing critical node identification methods for unknown topology that identify critical nodes according to historical information,this paper develops a critical node identification method to relax the prior topology information condition about critical nodes.Specifically,we first deduce a theorem about the minimum communication range for a node through the number of nodes and deployment ranges,and prove the universality of the theorem in a realistic two-dimensional scenario.After that,we analyze the relationship between communication range and degree value for each node and prove that the greater number of nodes within the communication range of a node,the greater degree value of nodes with high probability.Moreover,we develop a novel strategy to improve the accuracy of critical node identification without topology information.Finally,simulation results indicate the proposed strategy can achieve high accuracy and low redundancy while ensuring low time consumption in the scenarios with unknown topology information in ad hoc networks.
基金This research was supported by University IT Research Center ProjectKorea
文摘The location determination technology based on simple delay evaluations or GPS is not accurate enough or even impossible in urban and indoor environments due to the multi path propagation.To enhance the location accuracy and reduce the operation cost within these environments, this paper proposes a novel hybrid location determination technology which combines CELL ID with the database correlation method. The proposed method generate the prediction database of path loss according to CELL ID, and after the computation the smallest squared error of measured path loss and the prediction path loss, the location of the mobile terminal is decided by the coordinates of the best matching matrix entry.
基金This work is supported by University IT Research Center ProjectKorea
文摘Location technology is the key part of location based service. Different technologies have different accuracy, modifying to network and cost of operating. Also these technologies have limitation to network. This paper compares existing popular location technologies and gives some suggestions about choosing of location technologies in GSM and CDMA systems.
