The mechanism of interaction between the energy flows of the far-field ship noise and the near-field platform is studied, and the characteristics of frequency-time azimuth spec- trum is discussed. Based on normal mode...The mechanism of interaction between the energy flows of the far-field ship noise and the near-field platform is studied, and the characteristics of frequency-time azimuth spec- trum is discussed. Based on normal modes theory in acoustic vector fields, the model of the near-field platform is established, and the simulated result is similar to the investigation in shallow water. The frequency-time aziinuth spectrum of the energy flow is investigated by the vector hydrophone changes with frequency. The energy flow of the far-field ship noise interacts with the near-field platform, so four kinds of stripes are shown in the frequency4ime azimuth spectrum, which is the same with the investigation of sea trial. The estimation of direction of arrival appears inaccuracy, and varies with frequency. The main factor that affects the charac- teristics of frequency-time azimuth spectrum of resultant energy flow is the difference of sound pressure level. The estimation of the direction of arrival benefits from this when a number of sources exist in shallow water.展开更多
Recently,Ahmed et al.(Commun Stat Theory Methods 47(2):324-343,2018)have introduced the idea of simultaneously estimating means of two sensitive variables by collecting one scrambled response and another pseudo-respon...Recently,Ahmed et al.(Commun Stat Theory Methods 47(2):324-343,2018)have introduced the idea of simultaneously estimating means of two sensitive variables by collecting one scrambled response and another pseudo-response.In this paper,we extend their idea to the simultaneous estimation of two means by making use of the forced quantitative randomized response model of Gjestvang and Singh(Metrika 66(2):243-257,2007)but then re-scrambling the scrambled scores.This idea of re-scrambling already scrambled responses seems completely new in the field of randomized response sampling.The performance of the proposed forced quantitative randomized response model has been investigated analytically as well as empirically.展开更多
We propose a nonparametric change point estimator in the distributions of a sequence of independent observations in terms of the test statistics given by Huˇskov′a and Meintanis(2006) that are based on weighted empi...We propose a nonparametric change point estimator in the distributions of a sequence of independent observations in terms of the test statistics given by Huˇskov′a and Meintanis(2006) that are based on weighted empirical characteristic functions. The weight function ω(t; a) under consideration includes the two weight functions from Huˇskov′a and Meintanis(2006) plus the weight function used by Matteson and James(2014),where a is a tuning parameter. Under the local alternative hypothesis, we establish the consistency, convergence rate, and asymptotic distribution of this change point estimator which is the maxima of a two-side Brownian motion with a drift. Since the performance of the change point estimator depends on a in use, we thus propose an algorithm for choosing an appropriate value of a, denoted by a_s which is also justified. Our simulation study shows that the change point estimate obtained by using a_s has a satisfactory performance. We also apply our method to a real dataset.展开更多
Inaccurate estimation of surface reflectance characteristics is one of the substantial sources of uncertainty in satellite aerosol optical property retrieval algorithms.Bidirectional reflectance distribution function(...Inaccurate estimation of surface reflectance characteristics is one of the substantial sources of uncertainty in satellite aerosol optical property retrieval algorithms.Bidirectional reflectance distribution function(BRDF)models are frequently employed by retrieval algorithms to obtain the reflective properties of diverse surface types.This study,aerosol optical depth(AOD),fine mode AOD(AODF),coarse mode AOD(AODC),absorbing AOD(AAOD),single scattering albedo(SSA),Angstrom exponent(AE),absorbing AE(AAE),and scattering AE(SAE)are retrieved by the GRASP/Component algorithm with Ross_Li and Rahman-Pinty-Verstraete(RPV)models.Results indicate overall consistency in AOD,AODF,and AODC between the 2 models,with slightly better performance in North and Central America,Europe,and southern Africa.In northern Africa,the Middle East,and eastern Asia,there is slightly worse performance.Generally,the Ross_Li model yields slightly lower values for AOD and AODF,and the difference in AOD retrieval uncertainty seems primarily due to AODF.AODC retrieved by Ross_Li tends to be overestimated compared to RPV,with higher uncertainties.Uncertainties in AAOD and SSA retrievals are more complex,with the RPV model producing higher AAOD values in southern Europe and western North America.SSA retrievals are more scattered,with larger root mean square error,yet lower relative deviations due to generally larger values.The RPV model yields slightly lower SSA values,with good consistency in southern Europe and southern Asia.Uncertainties in AE,AAE,and SAE retrievals are significant,particularly in AAE,where the largest bias is observed.Improving the accuracy of AAOD inversion might reduce the uncertainty in AAE.展开更多
文摘The mechanism of interaction between the energy flows of the far-field ship noise and the near-field platform is studied, and the characteristics of frequency-time azimuth spec- trum is discussed. Based on normal modes theory in acoustic vector fields, the model of the near-field platform is established, and the simulated result is similar to the investigation in shallow water. The frequency-time aziinuth spectrum of the energy flow is investigated by the vector hydrophone changes with frequency. The energy flow of the far-field ship noise interacts with the near-field platform, so four kinds of stripes are shown in the frequency4ime azimuth spectrum, which is the same with the investigation of sea trial. The estimation of direction of arrival appears inaccuracy, and varies with frequency. The main factor that affects the charac- teristics of frequency-time azimuth spectrum of resultant energy flow is the difference of sound pressure level. The estimation of the direction of arrival benefits from this when a number of sources exist in shallow water.
文摘Recently,Ahmed et al.(Commun Stat Theory Methods 47(2):324-343,2018)have introduced the idea of simultaneously estimating means of two sensitive variables by collecting one scrambled response and another pseudo-response.In this paper,we extend their idea to the simultaneous estimation of two means by making use of the forced quantitative randomized response model of Gjestvang and Singh(Metrika 66(2):243-257,2007)but then re-scrambling the scrambled scores.This idea of re-scrambling already scrambled responses seems completely new in the field of randomized response sampling.The performance of the proposed forced quantitative randomized response model has been investigated analytically as well as empirically.
基金supported by Natural Sciences and the Engineering Research Council of Canada (Grant No. 105557-2012)National Natural Science Foundation for Young Scientists of China (Grant No. 11201108)+1 种基金the National Statistical Research Plan Project (Grant No. 2012LZ009)the Humanities and Social Sciences Project from Ministry of Education of China (Grant No. 12YJC910007)
文摘We propose a nonparametric change point estimator in the distributions of a sequence of independent observations in terms of the test statistics given by Huˇskov′a and Meintanis(2006) that are based on weighted empirical characteristic functions. The weight function ω(t; a) under consideration includes the two weight functions from Huˇskov′a and Meintanis(2006) plus the weight function used by Matteson and James(2014),where a is a tuning parameter. Under the local alternative hypothesis, we establish the consistency, convergence rate, and asymptotic distribution of this change point estimator which is the maxima of a two-side Brownian motion with a drift. Since the performance of the change point estimator depends on a in use, we thus propose an algorithm for choosing an appropriate value of a, denoted by a_s which is also justified. Our simulation study shows that the change point estimate obtained by using a_s has a satisfactory performance. We also apply our method to a real dataset.
基金supported by the National Natural Science Foundation of China(42275195 and 42375188)Youth Innovation Team of China Meteorological Administration(CMA2024QN13).
文摘Inaccurate estimation of surface reflectance characteristics is one of the substantial sources of uncertainty in satellite aerosol optical property retrieval algorithms.Bidirectional reflectance distribution function(BRDF)models are frequently employed by retrieval algorithms to obtain the reflective properties of diverse surface types.This study,aerosol optical depth(AOD),fine mode AOD(AODF),coarse mode AOD(AODC),absorbing AOD(AAOD),single scattering albedo(SSA),Angstrom exponent(AE),absorbing AE(AAE),and scattering AE(SAE)are retrieved by the GRASP/Component algorithm with Ross_Li and Rahman-Pinty-Verstraete(RPV)models.Results indicate overall consistency in AOD,AODF,and AODC between the 2 models,with slightly better performance in North and Central America,Europe,and southern Africa.In northern Africa,the Middle East,and eastern Asia,there is slightly worse performance.Generally,the Ross_Li model yields slightly lower values for AOD and AODF,and the difference in AOD retrieval uncertainty seems primarily due to AODF.AODC retrieved by Ross_Li tends to be overestimated compared to RPV,with higher uncertainties.Uncertainties in AAOD and SSA retrievals are more complex,with the RPV model producing higher AAOD values in southern Europe and western North America.SSA retrievals are more scattered,with larger root mean square error,yet lower relative deviations due to generally larger values.The RPV model yields slightly lower SSA values,with good consistency in southern Europe and southern Asia.Uncertainties in AE,AAE,and SAE retrievals are significant,particularly in AAE,where the largest bias is observed.Improving the accuracy of AAOD inversion might reduce the uncertainty in AAE.
