This paper introduces the significance of indoor positioning and analyzes the related problems. The latest research on indoor positioning is introduced. Further, the positioning accuracy and the cost of typical local ...This paper introduces the significance of indoor positioning and analyzes the related problems. The latest research on indoor positioning is introduced. Further, the positioning accuracy and the cost of typical local and wide area indoor positioning systems are compared. The results of the comparison show that Time & Code Division-Orthogonal Frequency Division Multiplexing (TC-OFDM) is a system that can achieve real-time meter-accuracy of indoor positioning in a wide area. Finally, in this paper, we indicate that the seamless high-accuracy indoor positioning in a wide area is the development trend of indoor positioning. The seamless Location Based Services (LBS) architecture based on a heterogeneous network, key technologies in indoor positioning for decimeter-accuracy and seamless outdoor and indoor Geographic Information System (GIS) are elaborated as the most important research fields of future indoor positioning.展开更多
The meta-instable state(MIS)is the final stage before fault instability during stick-slip movement.Thus,identification of MIS is of great significance for assessing earthquake hazard in fault zones.A rock sample with ...The meta-instable state(MIS)is the final stage before fault instability during stick-slip movement.Thus,identification of MIS is of great significance for assessing earthquake hazard in fault zones.A rock sample with a precut planar fault was loaded on a horizontally biaxial servo-controlled press machine to create stick-slip conditions.Digital images of the sample surface were taken by a high-speed camera at a rate of 1000 frames per second during the stick-slip motion and processed using a 2D digital image correlation method to obtain the displacement field.We define a synergism coefficient that describes the relative dispersion of the accumulative fault slip.The results reveal that:(1)a local pre-slip area spreads very slowly along the fault before the MIS develops.It extends at a higher but still slow speed during meta-instable state I(MIS-I).During the final^1.5%of MIS,in meta-instable state II(MIS-II),the local pre-slip area first extends at a speed of^0.9 m/s,and then expands out of the observed image area at a very high speed.These results indicate that the local pre-slip area transforms from a state of quasi-static extension in MIS-I to quasi-dynamic extension in MIS-II.(2)The synergism coefficient of the fault slip decreases to half of its original value in MIS-I and to a quarter of its original value in MIS-II.This continuous decrease of synergism coefficient indicates that the strengthening of fault slip synergism is a characteristic of MIS.(3)Furthermore,the unstable sliding stage includes three sliding processes:initial-,fast-,and adjusted-sliding.There are two pauses between the three sliding processes.展开更多
A sequential design and global optimization method is proposed to coordinately design local and widearea controllers to enhance the overall stability of largescale power system.The sequential design is used to assign ...A sequential design and global optimization method is proposed to coordinately design local and widearea controllers to enhance the overall stability of largescale power system.The sequential design is used to assign the distributed local power system stabilizer (LPSS) and high-voltage direct current (HVDC) wide-area stabilizing controller (HVDC-WASC) to the concerned damping modes.The global optimization is used to simultaneously optimize all the overall control gains of LPSSs and HVDCWASC.Moreover,the optimization model,which has an adaptive ability of searching and updating dominant oscillation modes,is established.Both the linear analysis and nonlinear simulation results verify the effectiveness of the proposed design method in enhancing the stability of large-scale power systems.展开更多
Remote sensing techniques have the potential to provide information on agricultural crops quantitatively , instantaneously and above all nondestructively over large areas . Crop simulation models describe the relation...Remote sensing techniques have the potential to provide information on agricultural crops quantitatively , instantaneously and above all nondestructively over large areas . Crop simulation models describe the relationship between physiological processes in plants and environmental growing conditions. The integration between remote sensing data and crop growth simulation model is an important trend for yield estimation and prediction, since remote sensing can provide information on the actual status of the agricultural crop. In this study, a new model(Rice-SRS) was developed based mainly on ORYZA1 model and modified to accept remote sensing data as input from different sources. The model can accept three kinds of NDVI data: NOAA AVHRR(LAC)-NDVI,NOAA AVHRR(GAC)-NDVI and radiometric measurements-NDVI. The integration between NOAA AVHRR (LAC) data and simulation model as applied to Rice-SRS resulted in accurate estimates for rice yield in the Shaoxing area, reduced the estimating error to 1.027%,0.794% and (-0.787%) for early, single, and late season respectively. Utilizing NDVI data derived from NOAA AVHRR (GAC) as input in Rice-SRS can yield good estimation for rice yield with the average error (-7.43%). Testing the new model for radiometric measurements showed that the average estimation error for 10 varieties under early rice conditions was less than 1%.展开更多
基金This work was supported by the National High Technology Research and Development Program (863 Program) of China under Grant No.2012AA120801the National High Technology Research and Development Program (863 Program) of China under Grant No.2012AA120802
文摘This paper introduces the significance of indoor positioning and analyzes the related problems. The latest research on indoor positioning is introduced. Further, the positioning accuracy and the cost of typical local and wide area indoor positioning systems are compared. The results of the comparison show that Time & Code Division-Orthogonal Frequency Division Multiplexing (TC-OFDM) is a system that can achieve real-time meter-accuracy of indoor positioning in a wide area. Finally, in this paper, we indicate that the seamless high-accuracy indoor positioning in a wide area is the development trend of indoor positioning. The seamless Location Based Services (LBS) architecture based on a heterogeneous network, key technologies in indoor positioning for decimeter-accuracy and seamless outdoor and indoor Geographic Information System (GIS) are elaborated as the most important research fields of future indoor positioning.
基金supported by the National Natural Science Foundation of China(Grant No.41172180)Basic Research Funds from the Institute of Geology,China Earthquake Administration(Grant No.IGCEA1203)
文摘The meta-instable state(MIS)is the final stage before fault instability during stick-slip movement.Thus,identification of MIS is of great significance for assessing earthquake hazard in fault zones.A rock sample with a precut planar fault was loaded on a horizontally biaxial servo-controlled press machine to create stick-slip conditions.Digital images of the sample surface were taken by a high-speed camera at a rate of 1000 frames per second during the stick-slip motion and processed using a 2D digital image correlation method to obtain the displacement field.We define a synergism coefficient that describes the relative dispersion of the accumulative fault slip.The results reveal that:(1)a local pre-slip area spreads very slowly along the fault before the MIS develops.It extends at a higher but still slow speed during meta-instable state I(MIS-I).During the final^1.5%of MIS,in meta-instable state II(MIS-II),the local pre-slip area first extends at a speed of^0.9 m/s,and then expands out of the observed image area at a very high speed.These results indicate that the local pre-slip area transforms from a state of quasi-static extension in MIS-I to quasi-dynamic extension in MIS-II.(2)The synergism coefficient of the fault slip decreases to half of its original value in MIS-I and to a quarter of its original value in MIS-II.This continuous decrease of synergism coefficient indicates that the strengthening of fault slip synergism is a characteristic of MIS.(3)Furthermore,the unstable sliding stage includes three sliding processes:initial-,fast-,and adjusted-sliding.There are two pauses between the three sliding processes.
基金supported by the National Natural Science Foundation of China(NSFC)(No.51377001,No.61233008,No.61304092,)the International Science and Technology Cooperation Program of China(No.2015DFR70850)+1 种基金the State Grid Science and Technology Project of China(No.5216A014007V)the Science and Technology Project of Hunan Power Company of China(No.5216A213509X)
文摘A sequential design and global optimization method is proposed to coordinately design local and widearea controllers to enhance the overall stability of largescale power system.The sequential design is used to assign the distributed local power system stabilizer (LPSS) and high-voltage direct current (HVDC) wide-area stabilizing controller (HVDC-WASC) to the concerned damping modes.The global optimization is used to simultaneously optimize all the overall control gains of LPSSs and HVDCWASC.Moreover,the optimization model,which has an adaptive ability of searching and updating dominant oscillation modes,is established.Both the linear analysis and nonlinear simulation results verify the effectiveness of the proposed design method in enhancing the stability of large-scale power systems.
文摘Remote sensing techniques have the potential to provide information on agricultural crops quantitatively , instantaneously and above all nondestructively over large areas . Crop simulation models describe the relationship between physiological processes in plants and environmental growing conditions. The integration between remote sensing data and crop growth simulation model is an important trend for yield estimation and prediction, since remote sensing can provide information on the actual status of the agricultural crop. In this study, a new model(Rice-SRS) was developed based mainly on ORYZA1 model and modified to accept remote sensing data as input from different sources. The model can accept three kinds of NDVI data: NOAA AVHRR(LAC)-NDVI,NOAA AVHRR(GAC)-NDVI and radiometric measurements-NDVI. The integration between NOAA AVHRR (LAC) data and simulation model as applied to Rice-SRS resulted in accurate estimates for rice yield in the Shaoxing area, reduced the estimating error to 1.027%,0.794% and (-0.787%) for early, single, and late season respectively. Utilizing NDVI data derived from NOAA AVHRR (GAC) as input in Rice-SRS can yield good estimation for rice yield with the average error (-7.43%). Testing the new model for radiometric measurements showed that the average estimation error for 10 varieties under early rice conditions was less than 1%.
