Accurate positioning is one of the essential requirements for numerous applications of remote sensing data,especially in the event of a noisy or unreliable satellite signal.Toward this end,we present a novel framework...Accurate positioning is one of the essential requirements for numerous applications of remote sensing data,especially in the event of a noisy or unreliable satellite signal.Toward this end,we present a novel framework for aircraft geo-localization in a large range that only requires a downward-facing monocular camera,an altimeter,a compass,and an open-source Vector Map(VMAP).The algorithm combines the matching and particle filter methods.Shape vector and correlation between two building contour vectors are defined,and a coarse-to-fine building vector matching(CFBVM)method is proposed in the matching stage,for which the original matching results are described by the Gaussian mixture model(GMM).Subsequently,an improved resampling strategy is designed to reduce computing expenses with a huge number of initial particles,and a credibility indicator is designed to avoid location mistakes in the particle filter stage.An experimental evaluation of the approach based on flight data is provided.On a flight at a height of 0.2 km over a flight distance of 2 km,the aircraft is geo-localized in a reference map of 11,025 km~2using 0.09 km~2aerial images without any prior information.The absolute localization error is less than 10 m.展开更多
目的综合蒙特卡洛模拟(monte carlo simulation,MCS)和敏感性分析重新评估局灶性癫痫患者中普瑞巴林推荐剂量的适宜性。方法设定正常肾功能患者多次服用批准剂量达稳态后产生的药时⁃曲线下面积(plasma concentration⁃time curve,AUC)为...目的综合蒙特卡洛模拟(monte carlo simulation,MCS)和敏感性分析重新评估局灶性癫痫患者中普瑞巴林推荐剂量的适宜性。方法设定正常肾功能患者多次服用批准剂量达稳态后产生的药时⁃曲线下面积(plasma concentration⁃time curve,AUC)为目标治疗范围,计算各给药方案的达标概率(probability of target attainment,PTA),并以PTA>90%作为优选方案的标准。结果除终末期肾病(end⁃stage renal disease,ESRD)外,其他肾功能损害亚组中批准剂量的PTA均大于90%。此外,敏感性分析显示性别,体重,食物状态,给药间隔和肌酐清除率的变化未显著影响推荐剂量的PTA。结论模拟结果支持普瑞巴林在轻度、中度与重度肾功能不全患者中的FDA批准剂量,但在ESRD患者中的批准剂量偏高。展开更多
Subpixel localization techniques for estimating the positions of point-like images captured by pixelated image sensors have been widely used in diverse optical measurement fields.With unavoidable imaging noise,there i...Subpixel localization techniques for estimating the positions of point-like images captured by pixelated image sensors have been widely used in diverse optical measurement fields.With unavoidable imaging noise,there is a precision limit(PL)when estimating the target positions on image sensors,which depends on the detected photon count,noise,point spread function(PSF)radius,and PSF’s intra-pixel position.Previous studies have clearly reported the effects of the first three parameters on the PL but have neglected the intra-pixel position information.Here,we develop a localization PL analysis framework for revealing the effect of the intra-pixel position of small PSFs.To accurately estimate the PL in practical applications,we provide effective PSF(e PSF)modeling approaches and apply the Cramér–Rao lower bound.Based on the characteristics of small PSFs,we first derive simplified equations for finding the best PL and the best intra-pixel region for an arbitrary small PSF;we then verify these equations on real PSFs.Next,we use the typical Gaussian PSF to perform a further analysis and find that the final optimum of the PL is achieved at the pixel boundaries when the Gaussian radius is as small as possible,indicating that the optimum is ultimately limited by light diffraction.Finally,we apply the maximum likelihood method.Its combination with e PSF modeling allows us to successfully reach the PL in experiments,making the above theoretical analysis effective.This work provides a new perspective on combining image sensor position control with PSF engineering to make full use of information theory,thereby paving the way for thoroughly understanding and achieving the final optimum of the PL in optical localization.展开更多
由于人们对无线通信的需求的增加以及通信质量的不断提升,无线局域网(Wireless Local Area Networks,WLAN)的接入点(Access Point,AP)部署问题在优化领域受到了越来越多的关注。目前,大量的文献都在研究WLAN规划问题,并提出了一系列优...由于人们对无线通信的需求的增加以及通信质量的不断提升,无线局域网(Wireless Local Area Networks,WLAN)的接入点(Access Point,AP)部署问题在优化领域受到了越来越多的关注。目前,大量的文献都在研究WLAN规划问题,并提出了一系列优化技术。然而,这些技术的寻优能力在面对复杂的AP部署场景时就会下降。为了解决复杂的WLAN规划问题,本文在前人工作的基础上,提出了一种改进型多智能体优化算法。该算法基于分布式人工智能,从AP角度和全局角度来优化AP的布局。展开更多
文摘Accurate positioning is one of the essential requirements for numerous applications of remote sensing data,especially in the event of a noisy or unreliable satellite signal.Toward this end,we present a novel framework for aircraft geo-localization in a large range that only requires a downward-facing monocular camera,an altimeter,a compass,and an open-source Vector Map(VMAP).The algorithm combines the matching and particle filter methods.Shape vector and correlation between two building contour vectors are defined,and a coarse-to-fine building vector matching(CFBVM)method is proposed in the matching stage,for which the original matching results are described by the Gaussian mixture model(GMM).Subsequently,an improved resampling strategy is designed to reduce computing expenses with a huge number of initial particles,and a credibility indicator is designed to avoid location mistakes in the particle filter stage.An experimental evaluation of the approach based on flight data is provided.On a flight at a height of 0.2 km over a flight distance of 2 km,the aircraft is geo-localized in a reference map of 11,025 km~2using 0.09 km~2aerial images without any prior information.The absolute localization error is less than 10 m.
文摘目的综合蒙特卡洛模拟(monte carlo simulation,MCS)和敏感性分析重新评估局灶性癫痫患者中普瑞巴林推荐剂量的适宜性。方法设定正常肾功能患者多次服用批准剂量达稳态后产生的药时⁃曲线下面积(plasma concentration⁃time curve,AUC)为目标治疗范围,计算各给药方案的达标概率(probability of target attainment,PTA),并以PTA>90%作为优选方案的标准。结果除终末期肾病(end⁃stage renal disease,ESRD)外,其他肾功能损害亚组中批准剂量的PTA均大于90%。此外,敏感性分析显示性别,体重,食物状态,给药间隔和肌酐清除率的变化未显著影响推荐剂量的PTA。结论模拟结果支持普瑞巴林在轻度、中度与重度肾功能不全患者中的FDA批准剂量,但在ESRD患者中的批准剂量偏高。
基金the support from the National Natural Science Foundation of China(51827806)the National Key Research and Development Program of China(2016YFB0501201)the Xplorer Prize funded by the Tencent Foundation。
文摘Subpixel localization techniques for estimating the positions of point-like images captured by pixelated image sensors have been widely used in diverse optical measurement fields.With unavoidable imaging noise,there is a precision limit(PL)when estimating the target positions on image sensors,which depends on the detected photon count,noise,point spread function(PSF)radius,and PSF’s intra-pixel position.Previous studies have clearly reported the effects of the first three parameters on the PL but have neglected the intra-pixel position information.Here,we develop a localization PL analysis framework for revealing the effect of the intra-pixel position of small PSFs.To accurately estimate the PL in practical applications,we provide effective PSF(e PSF)modeling approaches and apply the Cramér–Rao lower bound.Based on the characteristics of small PSFs,we first derive simplified equations for finding the best PL and the best intra-pixel region for an arbitrary small PSF;we then verify these equations on real PSFs.Next,we use the typical Gaussian PSF to perform a further analysis and find that the final optimum of the PL is achieved at the pixel boundaries when the Gaussian radius is as small as possible,indicating that the optimum is ultimately limited by light diffraction.Finally,we apply the maximum likelihood method.Its combination with e PSF modeling allows us to successfully reach the PL in experiments,making the above theoretical analysis effective.This work provides a new perspective on combining image sensor position control with PSF engineering to make full use of information theory,thereby paving the way for thoroughly understanding and achieving the final optimum of the PL in optical localization.
文摘由于人们对无线通信的需求的增加以及通信质量的不断提升,无线局域网(Wireless Local Area Networks,WLAN)的接入点(Access Point,AP)部署问题在优化领域受到了越来越多的关注。目前,大量的文献都在研究WLAN规划问题,并提出了一系列优化技术。然而,这些技术的寻优能力在面对复杂的AP部署场景时就会下降。为了解决复杂的WLAN规划问题,本文在前人工作的基础上,提出了一种改进型多智能体优化算法。该算法基于分布式人工智能,从AP角度和全局角度来优化AP的布局。
