BACKGROUND The 2018 ovarian-adnexal reporting and data system(O-RADS)guidelines are aimed at providing a system for consistent reports and risk stratification for ovarian lesions found on ultrasound.It provides key ch...BACKGROUND The 2018 ovarian-adnexal reporting and data system(O-RADS)guidelines are aimed at providing a system for consistent reports and risk stratification for ovarian lesions found on ultrasound.It provides key characteristics and findings for lesions,a lexicon of descriptors to communicate findings,and risk characterization and associated follow-up recommendation guidelines.However,the ORADS guidelines have not been validated in North American institutions or amongst less experienced readers.AIM To evaluate the diagnostic accuracy and inter-reader reliability of ultrasound ORADS risk stratification amongst less experienced readers in a North American institution with and without pre-test training.METHODS A single-center retrospective study was performed using 100 ovarian/adnexal lesions of varying O-RADS scores.Of these cases,50 were allotted to a training cohort and 50 to a testing cohort via a non-randomized group selection process in order to approximately equal distribution of O-RADS categories both within and between groups.Reference standard O-RADS scores were established through consensus of three fellowship-trained body imaging radiologists.Three PGY-4 residents were independently evaluated for diagnostic accuracy and inter-reader reliability with and without pre-test O-RADS training.Sensitivity,specificity,positive predictive value,negative predictive value(NPV),and area under the curve(AUC)were used to measure accuracy.Fleiss kappa and weighted quadratic(pairwise)kappa values were used to measure inter-reader reliability.Statistical significance was P<0.05.RESULTS Mean patient age was 40±16 years with lesions ranging from 1.2 to 22.5 cm.Readers demonstrated excellent specificities(85%-100%pre-training and 91%-100%post-training)and NPVs(89%-100%pre-training and 91-100%post-training)across the O-RADS categories.Sensitivities were variable(55%-100%pre-training and 64%-100%post-training)with malignant ORADS 4 and 5 Lesions pre-training and post-training AUC values of 0.87-0.95 and 0.94-098,respectively(P<0.001).Nineteen of 22(86%)misclassified cases in pre-training were related to mischaracterization of dermoid features or wall/septation morphology.Fifteen of 17(88%)of posttraining misclassified cases were related to one of these two errors.Fleiss kappa inter-reader reliability was‘good’and pairwise inter-reader reliability was‘very good’with pre-training and post-training assessment(k=0.76 and 0.77;and k=0.77-0.87 and 0.85-0.89,respectively).CONCLUSION Less experienced readers in North America achieved excellent specificities and AUC values with very good pairwise inter-reader reliability.They may be subject to misclassification of potentially malignant lesions,and specific training around dermoid features and smooth vs irregular inner wall/septation morphology may improve sensitivity.展开更多
For the purpose of enhancing reliability of aileron of Airbus new-generation A350 XWB,an evaluation of aileron reliability on the basis of maintenance data is presented in this paper.Practical maintenance data contain...For the purpose of enhancing reliability of aileron of Airbus new-generation A350 XWB,an evaluation of aileron reliability on the basis of maintenance data is presented in this paper.Practical maintenance data contains large number of censoring samples, information uncertainty of which makes it hard to evaluate reliability of aileron actuator.Considering that true lifetime of censoring sample has identical distribution with complete sample, if censoring sample is transformed into complete sample, conversion frequency of censoring sample can be estimated according to frequency of complete sample.On the one hand, standard life table estimation and product limit method are improved on the basis of such conversion frequency, enabling accurate estimation of various censoring samples.On the other hand, by taking such frequency as one of the weight factors and integrating variance of order statistics under standard distribution, weighted least square estimation is formed for accurately estimating various censoring samples.Large amounts of experiments and simulations show that reliabilities of improved life table and improved product limit method are closer to the true value and more conservative; moreover, weighted least square estimate（WLSE）, with conversion frequency of censoring sample and variances of order statistics as the weights, can still estimate accurately with high proportion of censored data in samples.Algorithm in this paper has good effect and can accurately estimate the reliability of aileron actuator even with small sample and high censoring rate.This research has certain significance in theory and engineering practice.展开更多
In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed a...In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed and evaluated based on automatic vehicle location （AVL） data. Based on the statistical analysis of the bus transit travel time, six indices including the coefficient of variance, the width of travel time distribution, the mean commercial speed, the congestion frequency, the planning time index and the buffer time index are proposed. Moreover, a framework for evaluating bus transit travel time reliability is constructed. Finally, a case study on a certain bus route in Suzhou is conducted. Results show that the proposed evaluation index system is simple and intuitive, and it can effectively reflect the efficiency and stability of bus operations. And a distinguishing feature of bus transit travel time reliability is the temporal pattern. It varies across different time periods.展开更多
This paper presents the data on operation reliability indices and relevant analyses toward China's conventional power generating units in 2009.The units brought into the statistical analysis include 100-MW or abov...This paper presents the data on operation reliability indices and relevant analyses toward China's conventional power generating units in 2009.The units brought into the statistical analysis include 100-MW or above thermal generating units,40-MW or above hydro generating units,and all nuclear generating units.The reliability indices embodied include utilization hours,times and hours of scheduled outages,times and hours of unscheduled outages,equivalent forced outage rate and equivalent availability factor.展开更多
Portable Pilot Units(PPU)play an important role in modern pilotage.With more than 20 years’PPU development and practice,a comprehensive data analysis is conducted in this paper.The reliabilities and accuracy of diffe...Portable Pilot Units(PPU)play an important role in modern pilotage.With more than 20 years’PPU development and practice,a comprehensive data analysis is conducted in this paper.The reliabilities and accuracy of different sensors are compared.Finally,the risk of PPU piloting and the corresponding countermeasures is discussed.展开更多
基金Supported by RSNA Research&Education Foundation Medical Student Grant#RMS2020.
文摘BACKGROUND The 2018 ovarian-adnexal reporting and data system(O-RADS)guidelines are aimed at providing a system for consistent reports and risk stratification for ovarian lesions found on ultrasound.It provides key characteristics and findings for lesions,a lexicon of descriptors to communicate findings,and risk characterization and associated follow-up recommendation guidelines.However,the ORADS guidelines have not been validated in North American institutions or amongst less experienced readers.AIM To evaluate the diagnostic accuracy and inter-reader reliability of ultrasound ORADS risk stratification amongst less experienced readers in a North American institution with and without pre-test training.METHODS A single-center retrospective study was performed using 100 ovarian/adnexal lesions of varying O-RADS scores.Of these cases,50 were allotted to a training cohort and 50 to a testing cohort via a non-randomized group selection process in order to approximately equal distribution of O-RADS categories both within and between groups.Reference standard O-RADS scores were established through consensus of three fellowship-trained body imaging radiologists.Three PGY-4 residents were independently evaluated for diagnostic accuracy and inter-reader reliability with and without pre-test O-RADS training.Sensitivity,specificity,positive predictive value,negative predictive value(NPV),and area under the curve(AUC)were used to measure accuracy.Fleiss kappa and weighted quadratic(pairwise)kappa values were used to measure inter-reader reliability.Statistical significance was P<0.05.RESULTS Mean patient age was 40±16 years with lesions ranging from 1.2 to 22.5 cm.Readers demonstrated excellent specificities(85%-100%pre-training and 91%-100%post-training)and NPVs(89%-100%pre-training and 91-100%post-training)across the O-RADS categories.Sensitivities were variable(55%-100%pre-training and 64%-100%post-training)with malignant ORADS 4 and 5 Lesions pre-training and post-training AUC values of 0.87-0.95 and 0.94-098,respectively(P<0.001).Nineteen of 22(86%)misclassified cases in pre-training were related to mischaracterization of dermoid features or wall/septation morphology.Fifteen of 17(88%)of posttraining misclassified cases were related to one of these two errors.Fleiss kappa inter-reader reliability was‘good’and pairwise inter-reader reliability was‘very good’with pre-training and post-training assessment(k=0.76 and 0.77;and k=0.77-0.87 and 0.85-0.89,respectively).CONCLUSION Less experienced readers in North America achieved excellent specificities and AUC values with very good pairwise inter-reader reliability.They may be subject to misclassification of potentially malignant lesions,and specific training around dermoid features and smooth vs irregular inner wall/septation morphology may improve sensitivity.
基金supported by the National Natural Science Foundation of China (Nos.61403198, 61079013 and 61079014)Youth Foundation of Jiangsu Province in China (No.BK20140827)+2 种基金Key Programs of Natural Science Foundation of Chinathe China Civil Aviation Joint Fund (No.60939003)Natural Science Foundation of Jiangsu Province in China (No.BK2011737)
文摘For the purpose of enhancing reliability of aileron of Airbus new-generation A350 XWB,an evaluation of aileron reliability on the basis of maintenance data is presented in this paper.Practical maintenance data contains large number of censoring samples, information uncertainty of which makes it hard to evaluate reliability of aileron actuator.Considering that true lifetime of censoring sample has identical distribution with complete sample, if censoring sample is transformed into complete sample, conversion frequency of censoring sample can be estimated according to frequency of complete sample.On the one hand, standard life table estimation and product limit method are improved on the basis of such conversion frequency, enabling accurate estimation of various censoring samples.On the other hand, by taking such frequency as one of the weight factors and integrating variance of order statistics under standard distribution, weighted least square estimation is formed for accurately estimating various censoring samples.Large amounts of experiments and simulations show that reliabilities of improved life table and improved product limit method are closer to the true value and more conservative; moreover, weighted least square estimate（WLSE）, with conversion frequency of censoring sample and variances of order statistics as the weights, can still estimate accurately with high proportion of censored data in samples.Algorithm in this paper has good effect and can accurately estimate the reliability of aileron actuator even with small sample and high censoring rate.This research has certain significance in theory and engineering practice.
基金The Soft Science Research Project of Ministry of Housing and Urban-Rural Development of China (No. 2008-k5-14)
文摘In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed and evaluated based on automatic vehicle location （AVL） data. Based on the statistical analysis of the bus transit travel time, six indices including the coefficient of variance, the width of travel time distribution, the mean commercial speed, the congestion frequency, the planning time index and the buffer time index are proposed. Moreover, a framework for evaluating bus transit travel time reliability is constructed. Finally, a case study on a certain bus route in Suzhou is conducted. Results show that the proposed evaluation index system is simple and intuitive, and it can effectively reflect the efficiency and stability of bus operations. And a distinguishing feature of bus transit travel time reliability is the temporal pattern. It varies across different time periods.
文摘This paper presents the data on operation reliability indices and relevant analyses toward China's conventional power generating units in 2009.The units brought into the statistical analysis include 100-MW or above thermal generating units,40-MW or above hydro generating units,and all nuclear generating units.The reliability indices embodied include utilization hours,times and hours of scheduled outages,times and hours of unscheduled outages,equivalent forced outage rate and equivalent availability factor.
基金supported by Key Project in the National Science and Technology Pillar Program(Grant No.2015BAG20B05)the Fund of National Engineering Research Center for Water Transport Safety(No.16KA03).
文摘Portable Pilot Units(PPU)play an important role in modern pilotage.With more than 20 years’PPU development and practice,a comprehensive data analysis is conducted in this paper.The reliabilities and accuracy of different sensors are compared.Finally,the risk of PPU piloting and the corresponding countermeasures is discussed.
