In this paper we extend the construction of the field of rational numbers from the ring of integers to an arbitrary commutative ordered semigroup. We first construct a fractional ordered semigroup and a homomorphism ...In this paper we extend the construction of the field of rational numbers from the ring of integers to an arbitrary commutative ordered semigroup. We first construct a fractional ordered semigroup and a homomorphism φs ： R → S^-1 R. Secondly, we characterize the commutative ordered semigroup so constructed by a universal mapping property.展开更多
The temporal variability and spatial pattern of the Arctic Oscillation(AO)simulated in the historical experiment of26 coupled climate models participating in the Coupled Model Intercomparison Project Phase 5(CMIP5)are...The temporal variability and spatial pattern of the Arctic Oscillation(AO)simulated in the historical experiment of26 coupled climate models participating in the Coupled Model Intercomparison Project Phase 5(CMIP5)are evaluated.Spectral analysis of the monthly AO index indicates that 23 out of the 26 CMIP5 models exhibit no statistically significant spectral peak in the historical experiment,as seen in the observations.These models are able to reproduce the AO pattern in the sea level pressure anomaly field during boreal winter,but the intensity of the AO pattern tends to be overestimated in all the models.The zonal-mean zonal wind anomalies associated with the AO is dominated by a meridional dipole in the mid-high latitudes of the Northern Hemisphere during boreal winter,which is well reproduced by only a few models.Most models show significant biases in both strength and location of the dipole compared to the observation.In considering the temporal variability as well as spatial structures in both horizontal and vertical directions,the MPI-ESM-P model reproduces an AO pattern that resembles the observation the best.展开更多
A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force d...A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force design, a dynamic model of reference linear drift frequency in the horizontal plane is introduced. The dynamic surface control(DSC) is used to design a control strategy for the DP. Compared with the traditional back-stepping methods, the dynamic surface control combined with radial basis function(RBF) neural networks(NNs) can avoid differentiating intermediate variables repeatedly in every design step due to the introduction of a first order filter. Low frequency motions obtained from total motions by a low pass filter are chosen to be the inputs for the RBF NNs which are used to approximate the low frequency wave force. Considering the propellers' wear and tear, the effect of filtering frequencies for the control force is discussed. Based on power consumptions and positioning requirements, the NN centers are determined. Moreover, the RBF NNs used to approximate the total wave force are built to monitor the disturbances. With the DP assistance, the results of fully coupled dynamic response simulations are given to illustrate the effectiveness of the proposed control strategy.展开更多
In this paper we will first prove that the nontrivial L p solutions of the vector refinement equation exist if and only if the corresponding subdivision scheme with a suitable initial function converges in L p...In this paper we will first prove that the nontrivial L p solutions of the vector refinement equation exist if and only if the corresponding subdivision scheme with a suitable initial function converges in L p without assumption of the stability of the solutions. Then we obtain a characterization of the convergence of the subdivision scheme in terms of the mask. This gives a complete answer to the existence of L p solutions of the refinement equation and the convergence of the corresponding subdivision schemes.展开更多
基金Supported by the Natural Science Foundation of Hubei Province in China（2004D006）
文摘In this paper we extend the construction of the field of rational numbers from the ring of integers to an arbitrary commutative ordered semigroup. We first construct a fractional ordered semigroup and a homomorphism φs ： R → S^-1 R. Secondly, we characterize the commutative ordered semigroup so constructed by a universal mapping property.
基金supported by the National Basic Research Program of China(No.2010CB950501&2010CB950404)the National Natural Science Foundation of China(No.41205058)the China Postdoctoral Sci-ence Foundation(No.2012M510634)
文摘The temporal variability and spatial pattern of the Arctic Oscillation(AO)simulated in the historical experiment of26 coupled climate models participating in the Coupled Model Intercomparison Project Phase 5(CMIP5)are evaluated.Spectral analysis of the monthly AO index indicates that 23 out of the 26 CMIP5 models exhibit no statistically significant spectral peak in the historical experiment,as seen in the observations.These models are able to reproduce the AO pattern in the sea level pressure anomaly field during boreal winter,but the intensity of the AO pattern tends to be overestimated in all the models.The zonal-mean zonal wind anomalies associated with the AO is dominated by a meridional dipole in the mid-high latitudes of the Northern Hemisphere during boreal winter,which is well reproduced by only a few models.Most models show significant biases in both strength and location of the dipole compared to the observation.In considering the temporal variability as well as spatial structures in both horizontal and vertical directions,the MPI-ESM-P model reproduces an AO pattern that resembles the observation the best.
基金funded by the National Basic Research Program of China (Grant Nos. 2011CB013702 and 2011CB013703)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China (Grant No. 50921001)
文摘A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force design, a dynamic model of reference linear drift frequency in the horizontal plane is introduced. The dynamic surface control(DSC) is used to design a control strategy for the DP. Compared with the traditional back-stepping methods, the dynamic surface control combined with radial basis function(RBF) neural networks(NNs) can avoid differentiating intermediate variables repeatedly in every design step due to the introduction of a first order filter. Low frequency motions obtained from total motions by a low pass filter are chosen to be the inputs for the RBF NNs which are used to approximate the low frequency wave force. Considering the propellers' wear and tear, the effect of filtering frequencies for the control force is discussed. Based on power consumptions and positioning requirements, the NN centers are determined. Moreover, the RBF NNs used to approximate the total wave force are built to monitor the disturbances. With the DP assistance, the results of fully coupled dynamic response simulations are given to illustrate the effectiveness of the proposed control strategy.
文摘In this paper we will first prove that the nontrivial L p solutions of the vector refinement equation exist if and only if the corresponding subdivision scheme with a suitable initial function converges in L p without assumption of the stability of the solutions. Then we obtain a characterization of the convergence of the subdivision scheme in terms of the mask. This gives a complete answer to the existence of L p solutions of the refinement equation and the convergence of the corresponding subdivision schemes.
