The problem of mobile localization for wireless sensor network has attracted considerable attention in recent years. The localization accuracy will drastically grade in non-line of sight(NLOS) conditions. In this pape...The problem of mobile localization for wireless sensor network has attracted considerable attention in recent years. The localization accuracy will drastically grade in non-line of sight(NLOS) conditions. In this paper, we propose a mobile localization strategy based on Kalman filter. The key technologies for the proposed method are the NLOS identification and mitigation. The proposed method does not need the prior knowledge of the NLOS error and it is independent of the physical measurement ways. Simulation results show that the proposed method owns the higher localization accuracy when compared with other methods.展开更多
This paper presents a nonlinear finite element method to resolve the problem of the nonlinear contact between the drillstring and hole wall by using a Multi-directional Contact Gap Element (MCGE) contacting at appropr...This paper presents a nonlinear finite element method to resolve the problem of the nonlinear contact between the drillstring and hole wall by using a Multi-directional Contact Gap Element (MCGE) contacting at appropriate positions in each beam element. The method was successfully applied to the Daqing Oil Field GP1 well. It was shown that the drillstring's contact resistance at any well depth could be obtained by calculations and that as the error in the calculation of the hole top load is below 10%, the calculation result can provide theoretical basis for the design and operation of drillstrings.展开更多
Cu-Zn-Al alloy of one dimensional nano-structure was prepared and thestructure of obtained nano-material was characterized by transmission electron microscope (TEM). Itwas shown that there are non-linear oscillations ...Cu-Zn-Al alloy of one dimensional nano-structure was prepared and thestructure of obtained nano-material was characterized by transmission electron microscope (TEM). Itwas shown that there are non-linear oscillations on the surface of Cu-Zn-Al alloy and theconsanguineous connection exists between non-linear oscillation and the growth process of onedimensional nano-structure. The diameter of one dimensional nano-structure is about 40 nm, and theratio of length to diameter is over 40. Finally, the growth mechanism of one dimensionalnano-structure was also studied.展开更多
基金supported by the National Natural Science Foundation of China under Grant No. 61403068, No. 61232016, No. U1405254 and No. 61501100Fundamental Research Funds for the Central Universities of China under Grant No. N130323002 and No. N130323004+3 种基金Natural Science Foundation of Hebei Province under Grant No. F2015501097 and No. F2016501080Scientific Research Fund of Hebei Provincial Education Department under Grant No. Z2014078the PAPD fundNEUQ internal funding under Grant No. XNB201509 and XNB201510
文摘The problem of mobile localization for wireless sensor network has attracted considerable attention in recent years. The localization accuracy will drastically grade in non-line of sight(NLOS) conditions. In this paper, we propose a mobile localization strategy based on Kalman filter. The key technologies for the proposed method are the NLOS identification and mitigation. The proposed method does not need the prior knowledge of the NLOS error and it is independent of the physical measurement ways. Simulation results show that the proposed method owns the higher localization accuracy when compared with other methods.
文摘This paper presents a nonlinear finite element method to resolve the problem of the nonlinear contact between the drillstring and hole wall by using a Multi-directional Contact Gap Element (MCGE) contacting at appropriate positions in each beam element. The method was successfully applied to the Daqing Oil Field GP1 well. It was shown that the drillstring's contact resistance at any well depth could be obtained by calculations and that as the error in the calculation of the hole top load is below 10%, the calculation result can provide theoretical basis for the design and operation of drillstrings.
基金This work was financially supported by the National Climbing Programme of China (No. 1999-444)the Natural Science Foundation of Tianjin (No.003805611 and 033610611) the Center of Liuhui Application Mathematics of Nankai University and Tianjin Univers
文摘Cu-Zn-Al alloy of one dimensional nano-structure was prepared and thestructure of obtained nano-material was characterized by transmission electron microscope (TEM). Itwas shown that there are non-linear oscillations on the surface of Cu-Zn-Al alloy and theconsanguineous connection exists between non-linear oscillation and the growth process of onedimensional nano-structure. The diameter of one dimensional nano-structure is about 40 nm, and theratio of length to diameter is over 40. Finally, the growth mechanism of one dimensionalnano-structure was also studied.
