To reduce the error in transfer alignment caused by reference information delay,a time delay estimation method is developed based on least-squares curve fitting of the angular rate integration.First,the gyro sensor me...To reduce the error in transfer alignment caused by reference information delay,a time delay estimation method is developed based on least-squares curve fitting of the angular rate integration.First,the gyro sensor measurements of the main strapdown inertial navigation system（M-SINS） and the slave strapdown inertial navigation system（S-SINS） are recorded for a few seconds and the integration of the data is calculated.Then,the possible maximum range of the delay value is defined and the points of the curve at different intervals are moved.The square of the differences between the corresponding points are calculated.Finally,the delay estimation can be acquired by the least-squares curve fitting of the M-SINS and the S-SINS.A delay compensation method by local data shifting is also presented.The simulation results demonstrate the effectiveness of delay estimation and indicate that the estimation accuracy is independent of the delay value.And the local data shifting compensation method can effectively reduce the errors of the transfer alignment caused by the reference information delay.展开更多
A new approach is presented by means of a new general ansitz and some relations among Jacobian elliptic functions, which enables one to construct more new exact solutions of nonlinear differential-difference equations...A new approach is presented by means of a new general ansitz and some relations among Jacobian elliptic functions, which enables one to construct more new exact solutions of nonlinear differential-difference equations. As an example, we apply this new method to Hybrid lattice, diseretized mKdV lattice, and modified Volterra lattice. As a result, many exact solutions expressible in rational formal hyperbolic and elliptic functions are conveniently obtained with the help of Maple.展开更多
The maximum entropy distribution, which consists of various recognized theoretical distributions, is a better curve to estimate the design thickness of sea ice. Method of moment and empirical curve fitting method are ...The maximum entropy distribution, which consists of various recognized theoretical distributions, is a better curve to estimate the design thickness of sea ice. Method of moment and empirical curve fitting method are common-used parameter estimation methods for maximum entropy distribution. In this study, we propose to use the particle swarm optimization method as a new parameter estimation method for the maximum entropy distribution, which has the advantage to avoid deviation introduced by simplifications made in other methods. We conducted a case study to fit the hindcasted thickness of the sea ice in the Liaodong Bay of Bohai Sea using these three parameter-estimation methods for the maximum entropy distribution. All methods implemented in this study pass the K-S tests at 0.05 significant level. In terms of the average sum of deviation squares, the empirical curve fitting method provides the best fit for the original data, while the method of moment provides the worst. Among all three methods, the particle swarm optimization method predicts the largest thickness of the sea ice for a same return period. As a result, we recommend using the particle swarm optimization method for the maximum entropy distribution for offshore structures mainly influenced by the sea ice in winter, but using the empirical curve fitting method to reduce the cost in the design of temporary and economic buildings.展开更多
A new single degree-of-freedom （1 DOF） resonance device was developed. It mainly comprises a linear motor, a vibrating screen, a supporting spring set, a supporting frame and a damper set. Forces acting on the vibra...A new single degree-of-freedom （1 DOF） resonance device was developed. It mainly comprises a linear motor, a vibrating screen, a supporting spring set, a supporting frame and a damper set. Forces acting on the vibrating screen were found. A differential equation for describing the forces was set up. Equations that were used to evaluate the exciting force and exciting frequency in resonance were derived from the solution to the differential equation. In addition, an equation for evaluating the deformed magnitude of the damping springs in the damper set was presented so that the suitable damping may be obtained. Finally, a Matlab/Simulink model of the new i DOF resonance device was also built. Displacement-time curves of the vibrating screen under four conditions were obtained in the use of the Matlab/Simulink simulation. The curves indicate that it can shorten the time for the vibrating screen to be into the stable resonance with increasing the damping, and it can lengthen the time with increasing the vibrated mass or amplitude, but every given angular frequency cannot acquire the desired amplitude value of resonance.展开更多
The first version of the Brazilian Oceano- graphic Modeling and Observation Network （REMO） ocean data assimilation system into the Hybrid Coordi- nate Ocean Model （HYCOM） （RODAS H） has recently been constructed ...The first version of the Brazilian Oceano- graphic Modeling and Observation Network （REMO） ocean data assimilation system into the Hybrid Coordi- nate Ocean Model （HYCOM） （RODAS H） has recently been constructed for research and operational purposes. The system is based on a multivariate Ensemble Optimal Interpolation （EnOI） scheme and considers the high fre- quency variability of the model error co-variance matrix. The EnOl can assimilate sea surface temperature （SST）, satellite along-track and gridded sea level anomalies （SLA）, and vertical profiles of temperature （T） and salinity （S） from Argo. The first observing system experiment was carried out over the Atlantic Ocean （78°S-50°N, 100°W-20°E） with HYCOM forced with atmospheric reanalysis from 1 January to 30 June 2010. Five integra- tions were performed, including the control run without assimilation. In the other four, different observations were assimilated： SST only （A SST）; Argo T-S profiles only （AArgo）; along-track SLA only （A_SLA）; and all data employed in the previous runs （A_All）. The A_SST, A_Argo, and A_SLA runs were very effective in improv- ing the representation of the assimilated variables, but they had relatively little impact on the variables that were not assimilated. In particular, only the assimilation of S was able to reduce the deviation of S with respect to ob- servations. Overall, the A_All run produced a good analy- sis by reducing the deviation of SST, T, and S with respect to the control run by 39%, 18%, and 30%, respectively, and by increasing the correlation of SLA by 81%.展开更多
Receiver operating characteristic （ROC） curve is often used to study and compare two- sample problems in medicine. When more information may be available on one treatment than the other, one can improve estimator of...Receiver operating characteristic （ROC） curve is often used to study and compare two- sample problems in medicine. When more information may be available on one treatment than the other, one can improve estimator of ROC curve if the auxiliary population information is taken into account. The authors show that the empirical likelihood method can be naturally adapted to make efficient use of the auxiliary information to such problems. The authors propose a smoothed empirical likelihood estimator for ROC curve with some auxiliary information in medical studies. The proposed estimates are more efficient than those ROC estimators without any auxiliary information, in the sense of comparing asymptotic variances and mean squared error （MSE）. Some asymptotic properties for the empirical likelihood estimation of ROC curve are established. A simulation study is presented to demonstrate the performance of the proposed estimators.展开更多
基金The National Basic Research Program of China(973 Program) (No. 613121030201)the Fundamental Research of Commission of Science,Technology and Industry for National Defense (No. C1420080224)
文摘To reduce the error in transfer alignment caused by reference information delay,a time delay estimation method is developed based on least-squares curve fitting of the angular rate integration.First,the gyro sensor measurements of the main strapdown inertial navigation system（M-SINS） and the slave strapdown inertial navigation system（S-SINS） are recorded for a few seconds and the integration of the data is calculated.Then,the possible maximum range of the delay value is defined and the points of the curve at different intervals are moved.The square of the differences between the corresponding points are calculated.Finally,the delay estimation can be acquired by the least-squares curve fitting of the M-SINS and the S-SINS.A delay compensation method by local data shifting is also presented.The simulation results demonstrate the effectiveness of delay estimation and indicate that the estimation accuracy is independent of the delay value.And the local data shifting compensation method can effectively reduce the errors of the transfer alignment caused by the reference information delay.
基金supported by National Natural Science Foundation of China and the Natural Science Foundation of Shandong Province
文摘A new approach is presented by means of a new general ansitz and some relations among Jacobian elliptic functions, which enables one to construct more new exact solutions of nonlinear differential-difference equations. As an example, we apply this new method to Hybrid lattice, diseretized mKdV lattice, and modified Volterra lattice. As a result, many exact solutions expressible in rational formal hyperbolic and elliptic functions are conveniently obtained with the help of Maple.
基金supported by the National Natural Science Foundation of China (Nos. 51279186, 51479183, 51509227)the Shandong Province Natural Science Foundation, China (No. ZR2014EEQ030)the Fundamental Research Funds for the Central Universities (No. 201413003)
文摘The maximum entropy distribution, which consists of various recognized theoretical distributions, is a better curve to estimate the design thickness of sea ice. Method of moment and empirical curve fitting method are common-used parameter estimation methods for maximum entropy distribution. In this study, we propose to use the particle swarm optimization method as a new parameter estimation method for the maximum entropy distribution, which has the advantage to avoid deviation introduced by simplifications made in other methods. We conducted a case study to fit the hindcasted thickness of the sea ice in the Liaodong Bay of Bohai Sea using these three parameter-estimation methods for the maximum entropy distribution. All methods implemented in this study pass the K-S tests at 0.05 significant level. In terms of the average sum of deviation squares, the empirical curve fitting method provides the best fit for the original data, while the method of moment provides the worst. Among all three methods, the particle swarm optimization method predicts the largest thickness of the sea ice for a same return period. As a result, we recommend using the particle swarm optimization method for the maximum entropy distribution for offshore structures mainly influenced by the sea ice in winter, but using the empirical curve fitting method to reduce the cost in the design of temporary and economic buildings.
文摘A new single degree-of-freedom （1 DOF） resonance device was developed. It mainly comprises a linear motor, a vibrating screen, a supporting spring set, a supporting frame and a damper set. Forces acting on the vibrating screen were found. A differential equation for describing the forces was set up. Equations that were used to evaluate the exciting force and exciting frequency in resonance were derived from the solution to the differential equation. In addition, an equation for evaluating the deformed magnitude of the damping springs in the damper set was presented so that the suitable damping may be obtained. Finally, a Matlab/Simulink model of the new i DOF resonance device was also built. Displacement-time curves of the vibrating screen under four conditions were obtained in the use of the Matlab/Simulink simulation. The curves indicate that it can shorten the time for the vibrating screen to be into the stable resonance with increasing the damping, and it can lengthen the time with increasing the vibrated mass or amplitude, but every given angular frequency cannot acquire the desired amplitude value of resonance.
基金financially supported by the Brazilian State oil company Petróleo Brasileiro S. A. (Petrobras) and Agência Nacional de Petróleo (ANP), Gás Natural e Biocombustíveis, Brazil, via the Oceanographic Modeling and Observation Network (REMO)support of the Coordenao de Aperfeioamento de Pessoal de Nível Superior (CAPES), Ministry of Education of Brazil (Proc. BEX 3957/13-6)
文摘The first version of the Brazilian Oceano- graphic Modeling and Observation Network （REMO） ocean data assimilation system into the Hybrid Coordi- nate Ocean Model （HYCOM） （RODAS H） has recently been constructed for research and operational purposes. The system is based on a multivariate Ensemble Optimal Interpolation （EnOI） scheme and considers the high fre- quency variability of the model error co-variance matrix. The EnOl can assimilate sea surface temperature （SST）, satellite along-track and gridded sea level anomalies （SLA）, and vertical profiles of temperature （T） and salinity （S） from Argo. The first observing system experiment was carried out over the Atlantic Ocean （78°S-50°N, 100°W-20°E） with HYCOM forced with atmospheric reanalysis from 1 January to 30 June 2010. Five integra- tions were performed, including the control run without assimilation. In the other four, different observations were assimilated： SST only （A SST）; Argo T-S profiles only （AArgo）; along-track SLA only （A_SLA）; and all data employed in the previous runs （A_All）. The A_SST, A_Argo, and A_SLA runs were very effective in improv- ing the representation of the assimilated variables, but they had relatively little impact on the variables that were not assimilated. In particular, only the assimilation of S was able to reduce the deviation of S with respect to ob- servations. Overall, the A_All run produced a good analy- sis by reducing the deviation of SST, T, and S with respect to the control run by 39%, 18%, and 30%, respectively, and by increasing the correlation of SLA by 81%.
基金This research was partially supported by National Natural Science Funds for Distinguished Young Scholar under Grant No. 70825004 and National Natural Science Foundation of China （NSFC） under Grant No. 10731010, the National Basic Research Program under Grant No. 2007CB814902, Creative Research Groups of China under Grant No.10721101 and Shanghai University of Finance and Economics through Project 211 Phase III and Shanghai Leading Academic Discipline Project under Grant No. B803.
文摘Receiver operating characteristic （ROC） curve is often used to study and compare two- sample problems in medicine. When more information may be available on one treatment than the other, one can improve estimator of ROC curve if the auxiliary population information is taken into account. The authors show that the empirical likelihood method can be naturally adapted to make efficient use of the auxiliary information to such problems. The authors propose a smoothed empirical likelihood estimator for ROC curve with some auxiliary information in medical studies. The proposed estimates are more efficient than those ROC estimators without any auxiliary information, in the sense of comparing asymptotic variances and mean squared error （MSE）. Some asymptotic properties for the empirical likelihood estimation of ROC curve are established. A simulation study is presented to demonstrate the performance of the proposed estimators.
