The indoor positioning system based on fingerprint receives more and more attention due to its high positioning accuracy and time efficiency.In the existing positioning approaches,much consideration is given to the po...The indoor positioning system based on fingerprint receives more and more attention due to its high positioning accuracy and time efficiency.In the existing positioning approaches,much consideration is given to the positioning accuracy improvement by using the angle of signal,but the optimization of access points(APs)deployment is ignored.In this circumstance,an adaptive APs deployment approach is proposed.First of all,the criterion of reference points(RPs)effective coverage is proposed,and the number of deployed APs in target environment is obtained by using the region partition algorithm and full coverage algorithm.Secondly,the wireless signal propagation model is established for target environment,and meanwhile based on the initial APs deployment,the simulation fingerprint database is constructed for the sake of establishing the discrimination function with respect to fingerprint database.Thirdly,the greedy algorithm is applied to optimize APs deployment.Finally,the extensive experiments show that the proposed approach is capable of achieving adaptive APs deployment as well as improving positioning accuracy.展开更多
The earth surface in the Sichuan Basin and its periphery is geologically complex,which causes low signal-to-noise ratio of seismic data,poor imaging quality of seismic profiles and great difficulty in data acquisition...The earth surface in the Sichuan Basin and its periphery is geologically complex,which causes low signal-to-noise ratio of seismic data,poor imaging quality of seismic profiles and great difficulty in data acquisition.In order to ensure high-quality operation of the seismic survey project in the complex surface of the Sichuan Basin,researchers have been working continuously to solve the bottleneck problems in the seismic acquisition technology for complex surface in recent years.In addition,the upgrading of acquisition technology and operation capacity is promoted effectively by means of technical innovation,and a series of key technologies for seismic acquisition are developed.And the following application results of this series of technologies are obtained.First,the optimization design technology of the geometry based on wave equation forward modeling and actual data,combined with prestack migration imaging can show the influence of different acquisition schemes on the prestack imaging effect of complex targets more directly,which makes the seismic acquisition scheme more economic and effective.Second,by extracting landform risks and surface obstacle information intelligently,combined with field fine reconnaissance,landform risk identification and hierarchical evaluation and indoors intelligent optimization of well-shot physical point deployment are conducted,and thus the GISt intelligent deployment technology of shot point in complex surface is formed,which effectively reduces the risks of operation.Third,the cavity excitation technology which reduces the initial pressure of explosive pulse and extends the explosive action time of explosives can increase the conversion rate of rock excitation energy into effective elastic wave energy and the reflected energy and improve the quality of seismic single shot data.Fourth,combination of the automatic evaluation technology for field seismic data acquired in mountainous regions and the KL-GMLiveQC1.0 software can improve the evaluation efficiency,reduce the evaluation cost and ensure the high-quality acquisition of seismic data in complex surface.In conclusion,this series of key seismic acquisition technologies greatly improve the signal-to-noise ratio and resolution of seismic data,lay a foundation for fine reservoir prediction,and ensure the continuous important breakthrough of three-dimensional natural gas exploration and development in the gas fields of marine carbonate rock,shale gas,volcanic rock and shallow tight sandstone gas in the Sichuan Basin.展开更多
The advent of low loss optical fiber has consistently led us to the ultra-broadband era, where bandwidths exceeding 1 Gb/s are commonplace. This Review reviews the early history of fiber access, pointing out some of t...The advent of low loss optical fiber has consistently led us to the ultra-broadband era, where bandwidths exceeding 1 Gb/s are commonplace. This Review reviews the early history of fiber access, pointing out some of the lasting design choices and signature features of fiber access. The progress of the various passive optical network technologies is also reviewed, and some views regarding the future trends of fiber in the access.展开更多
基金supported by the National Natural Science Foundation of China (61771083,61704015)the Program for Changjiang Scholars and Innovative Research Team in University (IRT1299)+2 种基金the Special Fund of Chongqing Key Laboratory (CSTC)the Fundamental and Frontier Research Project of Chongqing (CSTC2017jcyj AX0380, CSTC2015jcyj BX0065)the University Outstanding Achievement Transformation Project of Chongqing (KJZH17117)
文摘The indoor positioning system based on fingerprint receives more and more attention due to its high positioning accuracy and time efficiency.In the existing positioning approaches,much consideration is given to the positioning accuracy improvement by using the angle of signal,but the optimization of access points(APs)deployment is ignored.In this circumstance,an adaptive APs deployment approach is proposed.First of all,the criterion of reference points(RPs)effective coverage is proposed,and the number of deployed APs in target environment is obtained by using the region partition algorithm and full coverage algorithm.Secondly,the wireless signal propagation model is established for target environment,and meanwhile based on the initial APs deployment,the simulation fingerprint database is constructed for the sake of establishing the discrimination function with respect to fingerprint database.Thirdly,the greedy algorithm is applied to optimize APs deployment.Finally,the extensive experiments show that the proposed approach is capable of achieving adaptive APs deployment as well as improving positioning accuracy.
基金Project supported by Project 4-“Research and Application of Key Geophysical Technologies of Carbonate Rocks in Sichuan Basin”(No.:2016E-06-04)under the Major Science and Technology Special Project of PetroChina Company Limited“Research and Application of Key Technologies for Natural Gas Production of 30 Billion Cubic Meters in Southwest Oil and Gas Field”.
文摘The earth surface in the Sichuan Basin and its periphery is geologically complex,which causes low signal-to-noise ratio of seismic data,poor imaging quality of seismic profiles and great difficulty in data acquisition.In order to ensure high-quality operation of the seismic survey project in the complex surface of the Sichuan Basin,researchers have been working continuously to solve the bottleneck problems in the seismic acquisition technology for complex surface in recent years.In addition,the upgrading of acquisition technology and operation capacity is promoted effectively by means of technical innovation,and a series of key technologies for seismic acquisition are developed.And the following application results of this series of technologies are obtained.First,the optimization design technology of the geometry based on wave equation forward modeling and actual data,combined with prestack migration imaging can show the influence of different acquisition schemes on the prestack imaging effect of complex targets more directly,which makes the seismic acquisition scheme more economic and effective.Second,by extracting landform risks and surface obstacle information intelligently,combined with field fine reconnaissance,landform risk identification and hierarchical evaluation and indoors intelligent optimization of well-shot physical point deployment are conducted,and thus the GISt intelligent deployment technology of shot point in complex surface is formed,which effectively reduces the risks of operation.Third,the cavity excitation technology which reduces the initial pressure of explosive pulse and extends the explosive action time of explosives can increase the conversion rate of rock excitation energy into effective elastic wave energy and the reflected energy and improve the quality of seismic single shot data.Fourth,combination of the automatic evaluation technology for field seismic data acquired in mountainous regions and the KL-GMLiveQC1.0 software can improve the evaluation efficiency,reduce the evaluation cost and ensure the high-quality acquisition of seismic data in complex surface.In conclusion,this series of key seismic acquisition technologies greatly improve the signal-to-noise ratio and resolution of seismic data,lay a foundation for fine reservoir prediction,and ensure the continuous important breakthrough of three-dimensional natural gas exploration and development in the gas fields of marine carbonate rock,shale gas,volcanic rock and shallow tight sandstone gas in the Sichuan Basin.
文摘The advent of low loss optical fiber has consistently led us to the ultra-broadband era, where bandwidths exceeding 1 Gb/s are commonplace. This Review reviews the early history of fiber access, pointing out some of the lasting design choices and signature features of fiber access. The progress of the various passive optical network technologies is also reviewed, and some views regarding the future trends of fiber in the access.
