The rotation of the Earth's liquid core creates the Nearly Diurnal Free Wobble (NDFW). It is one of the problems of researching the Earth's liquid core for us to retrieve the parameters of the Earth's Free...The rotation of the Earth's liquid core creates the Nearly Diurnal Free Wobble (NDFW). It is one of the problems of researching the Earth's liquid core for us to retrieve the parameters of the Earth's Free Core Nutation (FCN),from the Earth's liquid core resonance of gravity tide waves on the diurnal frequency band. Since 1987, some scientists in many different countries have come to calculate the parameters of FCN by using the observational data of gravity tide waves on the diumal frequency band. They basically followed the Stacking method, which needed five diurnal waves for the resolution. In this paper, authors introduced the Aky-Btk value method with clearly geometrical meaning as a new method, which only requires three very high signal-noise-ratio waves o1, K1 and P1 for the resolution. Authors chose the observational data of the three superconducting gravimeter stations respectively located in Cantley of Canada, Wuhan of China and Brussels of Belgium, to compute the parameters of FCN. It was the first time that the observational results of the parameters of FCN obtained from gravitational tide were in accord with the parameters of FCN gained from VLBI since 1987.展开更多
The impact of orbital parameters on the climate of China in the Holocene is simulated from 11kaBP to 0kaBP with an interval of 1ka using National Center for Atmospheric Research (NCAR) Community Atmosphere Model versi...The impact of orbital parameters on the climate of China in the Holocene is simulated from 11kaBP to 0kaBP with an interval of 1ka using National Center for Atmospheric Research (NCAR) Community Atmosphere Model version 2 (CAM2). The geographic distributions of summer precipitation around both 9kaBP and 4kaBP were realistically captured by CAM2, compared to the proxy data collected from 80 stations. Among all orbital parameters, the precession plays a major role in computing solar radiation, which dominates the variations of summer precipitation over China during the Holocene. The summers around 9kaBP were the wettest in China. Later on, the precipitation gradually reduced to the minimum around 0kaBP by about 10%. This tremendous change occurred from the Northeast China and the eastern Inner Mongolia extending southwestwards to the Qinghai-Tibet Plateau, especially over the Qinghai-Tibet Plateau.展开更多
Focusing on carrying out GPS occultation observat io ns with a receiver set on LEO satellite, this paper develops the LEO orbit simul ation system based on which the occultation events can be simulated taking into acc...Focusing on carrying out GPS occultation observat io ns with a receiver set on LEO satellite, this paper develops the LEO orbit simul ation system based on which the occultation events can be simulated taking into account the geometric relationship of the satellites and the field of view of th e receiver antenna. In this paper, the impacts of 4 types of LEO orbit parameter s including argument of latitude (AOL), right ascension of ascending node (RAAN) , orbit height and orbit inclination on the distribution and number of occultati on events observed with a single LEO satellite are discussed through simulat ion and some conclusions are drawn.展开更多
The recent Galileo spacecraft explored Jupiter and its satellite system and provided us with new geodetic data. In order to discuss the dynamical parameters and secular tidal effect of Io, the theory of synchronous s...The recent Galileo spacecraft explored Jupiter and its satellite system and provided us with new geodetic data. In order to discuss the dynamical parameters and secular tidal effect of Io, the theory of synchronous satellite is described in detail. Using the new geodetic data of Io, two sets of Io's internal structure models are constructed based on the asthenosphere assumption. The liberation parameters α,β,γ and dynamical flattening H are calculated for the models of Io. A comparison of Io with the Moon indicates that they are quite different in many characteristics in spite of the fact that they are approximately equal in mass and size and that they both orbit synchronously.展开更多
The ion-acoustic(IA) mode exhibiting various orbital angular momentum(OAM) states is examined in a plasma with drifting electrons.The constituent plasma species are modeled with a non-gyrotropic Maxwellian distributio...The ion-acoustic(IA) mode exhibiting various orbital angular momentum(OAM) states is examined in a plasma with drifting electrons.The constituent plasma species are modeled with a non-gyrotropic Maxwellian distribution and discussion of dispersion relation and growth rate of twisted IA waves under various conditions is presented.In the domain of kinetic model,the twisted IA waves are characterized by Laguerre-Gaussian(LG) solutions,where plasma distribution function and electric field are decomposed into axial and azimuthal components.The plasma response function is obtained under paraxial approximations and investigated for threshold condition of instability growth rate with helical electric field structures.The impact of an extra electron specie on the instability is demonstrated through a comparison of twisted waves for single and double electron species.展开更多
Two versions of the Chinese Academy of Sciences Flexible Global Ocean-Atmosphere-Land System model(CASFGOALS),version f3-L and g3,are used to simulate the two interglacial epochs of the mid-Holocene and the Last Inter...Two versions of the Chinese Academy of Sciences Flexible Global Ocean-Atmosphere-Land System model(CASFGOALS),version f3-L and g3,are used to simulate the two interglacial epochs of the mid-Holocene and the Last Interglacial in phase 4 of the Paleoclimate Modelling Intercomparison Project(PMIP4),which aims to study the impact of changes in orbital parameters on the Earth’s climate.Following the PMIP4 experimental protocols,four simulations for the mid-Holocene and two simulations for the Last Interglacial have been completed,and all the data,including monthly and daily outputs for the atmospheric,oceanic,land and sea-ice components,have been released on the Earth System Grid Federation(ESGF)node.These datasets contribute to PMIP4 and CMIP6(phase 6 of the Coupled Model Intercomparison Project)by providing the variables necessary for the two interglacial periods.In this paper,the basic information of the CAS-FGOALS models and the protocols for the two interglacials are briefly described,and the datasets are validated using proxy records.Results suggest that the CAS-FGOALS models capture the large-scale changes in the climate system in response to changes in solar insolation during the interglacial epochs,including warming in mid-to-high latitudes,changes in the hydrological cycle,the seasonal variation in the extent of sea ice,and the damping of interannual variabilities in the tropical Pacific.Meanwhile,disagreements within and between the models and the proxy data are also presented.These datasets will help the modeling and the proxy data communities with a better understanding of model performance and biases in paleoclimate simulations.展开更多
To optimize cutting control parameters and provide scientific evidence for controlling cutting forces,cutting force modeling and cutting control parameter optimization are researched with one tool adopted to orbital d...To optimize cutting control parameters and provide scientific evidence for controlling cutting forces,cutting force modeling and cutting control parameter optimization are researched with one tool adopted to orbital drill holes in aluminum alloy 6061.Firstly,four cutting control parameters(tool rotation speed,tool revolution speed,axial feeding pitch and tool revolution radius)and affecting cutting forces are identified after orbital drilling kinematics analysis.Secondly,hybrid level orthogonal experiment method is utilized in modeling experiment.By nonlinear regression analysis,two quadratic prediction models for axial and radial forces are established,where the above four control parameters are used as input variables.Then,model accuracy and cutting control parameters are analyzed.Upon axial and radial forces models,two optimal combinations of cutting control parameters are obtained for processing a13mm hole,corresponding to the minimum axial force and the radial force respectively.Finally,each optimal combination is applied in verification experiment.The verification experiment results of cutting force are in good agreement with prediction model,which confirms accracy of the research method in practical production.展开更多
Asian aridity can be traced back to the early Cenozoic(e.g.,Guo et al.,2008;Licht et al.,2016;Li et al.,2018a).Previous modelling studies focus mainly on the monsoon climate during the early Cenozoic,and studies for t...Asian aridity can be traced back to the early Cenozoic(e.g.,Guo et al.,2008;Licht et al.,2016;Li et al.,2018a).Previous modelling studies focus mainly on the monsoon climate during the early Cenozoic,and studies for the Asian aridity are still limited(e.g.,Huber and Goldner,2012;Zhang et al.,2012;Li et al.,2018b).Here Asian aridity during the early Cenozoic is investigated through climate modelling by changing atmospheric CO2 concentration,orbital parameters,and topography.展开更多
The mid-Pliocene warm period was the most recent geological period in Earth's history that featured long-term warming. Both geological evidence and model results indicate that East Asian summer winds (EASWs) streng...The mid-Pliocene warm period was the most recent geological period in Earth's history that featured long-term warming. Both geological evidence and model results indicate that East Asian summer winds (EASWs) strengthened in monsoonal China, and that East Asian winter winds (EAWWs) weakened in northern monsoonal China during this period, as compared to the pre-industrial period. However, the corresponding mechanisms are still unclear. In this paper, the results of a set of numerical simulations are reported to analyze the effects of changed boundary conditions on the mid-Pliocene East Asian monsoon climate, based on PRISM3 (Pliocene Research Interpretation and Synoptic Mapping) palaeoenvironmental recon- struction. The model results showed that the combined changes of sea surface temperatures, atmospheric CO2 concentration, and ice sheet extent were necessary to generate an overall warm climate on a large scale, and that these factors exerted the greatest effects on the strengthening of EASWs in monsoonal China. The orographic change produced significant local warming and had the greatest effect on the weakening of EAWWs in northern monsoonal China in the mid-Pliocene. Thus, these two factors both had important but different effects on the monsoon change. In comparison, the effects of vegetational change on the strengthened EASWs and weakened EAWWs were relatively weak. The changed monsoon winds can be ex- plained by a reorganization of the meridional temperature gradient and zonal thermal contrast. Moreover, the effect of orbital parameters cannot be ignored. Results showed that changes in orbital parameters could have marked!y affected the EASWs and EAWWs, and caused significant short-term oscillations in the mid-Pliocene monsoon climate in East Asia.展开更多
A quantitative analysis of limit cycles and homoclinic orbits, and the bifurcation curve for the Bogdanov-Takens system are discussed. The parameter incremental method for approximate analytical-expressions of these p...A quantitative analysis of limit cycles and homoclinic orbits, and the bifurcation curve for the Bogdanov-Takens system are discussed. The parameter incremental method for approximate analytical-expressions of these problems is given. These analytical-expressions of the limit cycle and homoclinic orbit are shown as the generalized harmonic functions by employing a time transformation. Curves of the parameters and the stability characteristic exponent of the limit cycle versus amplitude are drawn. Some of the limit cycles and homoclinic orbits phase portraits are plotted. The relationship curves of parameters μ and A with amplitude a and the bifurcation diagrams about the parameter are also given. The numerical accuracy of the calculation results is good.展开更多
For the two_parameter family of planar mapping, a method to stabilize an unstable fixed point without stable manifold embedding in hyperchaos is introduced. It works by adjusting the two parameters in each iteration o...For the two_parameter family of planar mapping, a method to stabilize an unstable fixed point without stable manifold embedding in hyperchaos is introduced. It works by adjusting the two parameters in each iteration of the map. The explicit expressions for the parameter adjustments are derived, and strict proof of convergence for method is given.展开更多
This paper systematically investigates the local distortion and electron paramagnetic resonance (EPR) parameter for CdCl2:V^2+ and CsMgX3:V^2+ (X=Cl, Br) systems on the basis of the complete energy matrix, in ...This paper systematically investigates the local distortion and electron paramagnetic resonance (EPR) parameter for CdCl2:V^2+ and CsMgX3:V^2+ (X=Cl, Br) systems on the basis of the complete energy matrix, in which not only the contributions due to the spin-orbit coupling of the central ions but also that of the ligands are considered. To describe the difference of overlapping between d-orbits and p orbit, two spin-orbit coupling coefficients are introduced. By simulating the crystal field parameter and EPR parameter, the local distortion parameters are studied and the relationships between the EPR parameter and the spin-orbit coupling coefficients as well as divergent parameter are discussed. These results show that the local structures exhibit compression distortion for CdCl2:V^2+ and elongation distortions for CsMgX3:V^2+ (X:Cl, Br), respectively. It notes that the empirical formula R≈RH T (ri - rh)/2 is not suitable for CdCl2:V^2+ and CsMgX3:V^2+ (X=Cl, Br) systems. The contributions of ligand to spin-orbit coupling interaction cannot be neglected for strong covalent systems, especially for V^2+ doped in CsMgBr3:V^2+.展开更多
文摘The rotation of the Earth's liquid core creates the Nearly Diurnal Free Wobble (NDFW). It is one of the problems of researching the Earth's liquid core for us to retrieve the parameters of the Earth's Free Core Nutation (FCN),from the Earth's liquid core resonance of gravity tide waves on the diurnal frequency band. Since 1987, some scientists in many different countries have come to calculate the parameters of FCN by using the observational data of gravity tide waves on the diumal frequency band. They basically followed the Stacking method, which needed five diurnal waves for the resolution. In this paper, authors introduced the Aky-Btk value method with clearly geometrical meaning as a new method, which only requires three very high signal-noise-ratio waves o1, K1 and P1 for the resolution. Authors chose the observational data of the three superconducting gravimeter stations respectively located in Cantley of Canada, Wuhan of China and Brussels of Belgium, to compute the parameters of FCN. It was the first time that the observational results of the parameters of FCN obtained from gravitational tide were in accord with the parameters of FCN gained from VLBI since 1987.
基金R&D Special Found for Public Welfare Industry (meteorology) (GYHY200706010)National Science Foundation for Post-doctoral Scientists of China (4131482-051)
文摘The impact of orbital parameters on the climate of China in the Holocene is simulated from 11kaBP to 0kaBP with an interval of 1ka using National Center for Atmospheric Research (NCAR) Community Atmosphere Model version 2 (CAM2). The geographic distributions of summer precipitation around both 9kaBP and 4kaBP were realistically captured by CAM2, compared to the proxy data collected from 80 stations. Among all orbital parameters, the precession plays a major role in computing solar radiation, which dominates the variations of summer precipitation over China during the Holocene. The summers around 9kaBP were the wettest in China. Later on, the precipitation gradually reduced to the minimum around 0kaBP by about 10%. This tremendous change occurred from the Northeast China and the eastern Inner Mongolia extending southwestwards to the Qinghai-Tibet Plateau, especially over the Qinghai-Tibet Plateau.
文摘Focusing on carrying out GPS occultation observat io ns with a receiver set on LEO satellite, this paper develops the LEO orbit simul ation system based on which the occultation events can be simulated taking into account the geometric relationship of the satellites and the field of view of th e receiver antenna. In this paper, the impacts of 4 types of LEO orbit parameter s including argument of latitude (AOL), right ascension of ascending node (RAAN) , orbit height and orbit inclination on the distribution and number of occultati on events observed with a single LEO satellite are discussed through simulat ion and some conclusions are drawn.
文摘The recent Galileo spacecraft explored Jupiter and its satellite system and provided us with new geodetic data. In order to discuss the dynamical parameters and secular tidal effect of Io, the theory of synchronous satellite is described in detail. Using the new geodetic data of Io, two sets of Io's internal structure models are constructed based on the asthenosphere assumption. The liberation parameters α,β,γ and dynamical flattening H are calculated for the models of Io. A comparison of Io with the Moon indicates that they are quite different in many characteristics in spite of the fact that they are approximately equal in mass and size and that they both orbit synchronously.
文摘The ion-acoustic(IA) mode exhibiting various orbital angular momentum(OAM) states is examined in a plasma with drifting electrons.The constituent plasma species are modeled with a non-gyrotropic Maxwellian distribution and discussion of dispersion relation and growth rate of twisted IA waves under various conditions is presented.In the domain of kinetic model,the twisted IA waves are characterized by Laguerre-Gaussian(LG) solutions,where plasma distribution function and electric field are decomposed into axial and azimuthal components.The plasma response function is obtained under paraxial approximations and investigated for threshold condition of instability growth rate with helical electric field structures.The impact of an extra electron specie on the instability is demonstrated through a comparison of twisted waves for single and double electron species.
基金This study was supported by the National Key R&D Program for Developing Basic Sciences(Grant Nos.2016YFC1401401 and 2016YFC1401601)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDA19060102 and XDB42000000)the National Natural Science Foundation of China(Grants Nos.91958201,41530426,41576025,41576026,41776030,41931183,41976026 and 41376002).
文摘Two versions of the Chinese Academy of Sciences Flexible Global Ocean-Atmosphere-Land System model(CASFGOALS),version f3-L and g3,are used to simulate the two interglacial epochs of the mid-Holocene and the Last Interglacial in phase 4 of the Paleoclimate Modelling Intercomparison Project(PMIP4),which aims to study the impact of changes in orbital parameters on the Earth’s climate.Following the PMIP4 experimental protocols,four simulations for the mid-Holocene and two simulations for the Last Interglacial have been completed,and all the data,including monthly and daily outputs for the atmospheric,oceanic,land and sea-ice components,have been released on the Earth System Grid Federation(ESGF)node.These datasets contribute to PMIP4 and CMIP6(phase 6 of the Coupled Model Intercomparison Project)by providing the variables necessary for the two interglacial periods.In this paper,the basic information of the CAS-FGOALS models and the protocols for the two interglacials are briefly described,and the datasets are validated using proxy records.Results suggest that the CAS-FGOALS models capture the large-scale changes in the climate system in response to changes in solar insolation during the interglacial epochs,including warming in mid-to-high latitudes,changes in the hydrological cycle,the seasonal variation in the extent of sea ice,and the damping of interannual variabilities in the tropical Pacific.Meanwhile,disagreements within and between the models and the proxy data are also presented.These datasets will help the modeling and the proxy data communities with a better understanding of model performance and biases in paleoclimate simulations.
基金Supported by the National Natural Science Foundation of China(50975141)the Aviation Science Fund(20091652018,2010352005)the National Science and Technology Major Project of the Ministry of Science and Technology of China(2012ZX04003031-4)
文摘To optimize cutting control parameters and provide scientific evidence for controlling cutting forces,cutting force modeling and cutting control parameter optimization are researched with one tool adopted to orbital drill holes in aluminum alloy 6061.Firstly,four cutting control parameters(tool rotation speed,tool revolution speed,axial feeding pitch and tool revolution radius)and affecting cutting forces are identified after orbital drilling kinematics analysis.Secondly,hybrid level orthogonal experiment method is utilized in modeling experiment.By nonlinear regression analysis,two quadratic prediction models for axial and radial forces are established,where the above four control parameters are used as input variables.Then,model accuracy and cutting control parameters are analyzed.Upon axial and radial forces models,two optimal combinations of cutting control parameters are obtained for processing a13mm hole,corresponding to the minimum axial force and the radial force respectively.Finally,each optimal combination is applied in verification experiment.The verification experiment results of cutting force are in good agreement with prediction model,which confirms accracy of the research method in practical production.
基金granted by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA20070103)the National Natural Science Foundation of China(Grant Nos.41775088 and 41625018).
文摘Asian aridity can be traced back to the early Cenozoic(e.g.,Guo et al.,2008;Licht et al.,2016;Li et al.,2018a).Previous modelling studies focus mainly on the monsoon climate during the early Cenozoic,and studies for the Asian aridity are still limited(e.g.,Huber and Goldner,2012;Zhang et al.,2012;Li et al.,2018b).Here Asian aridity during the early Cenozoic is investigated through climate modelling by changing atmospheric CO2 concentration,orbital parameters,and topography.
基金supported by the Strategic Priority Research Program (Grant No. XDB03020602) of the Chinese Academy of Sciencesby the National Natural Science Foundation of China (Grant Nos. 41175072 and 41305073)
文摘The mid-Pliocene warm period was the most recent geological period in Earth's history that featured long-term warming. Both geological evidence and model results indicate that East Asian summer winds (EASWs) strengthened in monsoonal China, and that East Asian winter winds (EAWWs) weakened in northern monsoonal China during this period, as compared to the pre-industrial period. However, the corresponding mechanisms are still unclear. In this paper, the results of a set of numerical simulations are reported to analyze the effects of changed boundary conditions on the mid-Pliocene East Asian monsoon climate, based on PRISM3 (Pliocene Research Interpretation and Synoptic Mapping) palaeoenvironmental recon- struction. The model results showed that the combined changes of sea surface temperatures, atmospheric CO2 concentration, and ice sheet extent were necessary to generate an overall warm climate on a large scale, and that these factors exerted the greatest effects on the strengthening of EASWs in monsoonal China. The orographic change produced significant local warming and had the greatest effect on the weakening of EAWWs in northern monsoonal China in the mid-Pliocene. Thus, these two factors both had important but different effects on the monsoon change. In comparison, the effects of vegetational change on the strengthened EASWs and weakened EAWWs were relatively weak. The changed monsoon winds can be ex- plained by a reorganization of the meridional temperature gradient and zonal thermal contrast. Moreover, the effect of orbital parameters cannot be ignored. Results showed that changes in orbital parameters could have marked!y affected the EASWs and EAWWs, and caused significant short-term oscillations in the mid-Pliocene monsoon climate in East Asia.
基金the National Natural Science Foundation of China (No.10672193)
文摘A quantitative analysis of limit cycles and homoclinic orbits, and the bifurcation curve for the Bogdanov-Takens system are discussed. The parameter incremental method for approximate analytical-expressions of these problems is given. These analytical-expressions of the limit cycle and homoclinic orbit are shown as the generalized harmonic functions by employing a time transformation. Curves of the parameters and the stability characteristic exponent of the limit cycle versus amplitude are drawn. Some of the limit cycles and homoclinic orbits phase portraits are plotted. The relationship curves of parameters μ and A with amplitude a and the bifurcation diagrams about the parameter are also given. The numerical accuracy of the calculation results is good.
文摘For the two_parameter family of planar mapping, a method to stabilize an unstable fixed point without stable manifold embedding in hyperchaos is introduced. It works by adjusting the two parameters in each iteration of the map. The explicit expressions for the parameter adjustments are derived, and strict proof of convergence for method is given.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10774103 and 10974138)
文摘This paper systematically investigates the local distortion and electron paramagnetic resonance (EPR) parameter for CdCl2:V^2+ and CsMgX3:V^2+ (X=Cl, Br) systems on the basis of the complete energy matrix, in which not only the contributions due to the spin-orbit coupling of the central ions but also that of the ligands are considered. To describe the difference of overlapping between d-orbits and p orbit, two spin-orbit coupling coefficients are introduced. By simulating the crystal field parameter and EPR parameter, the local distortion parameters are studied and the relationships between the EPR parameter and the spin-orbit coupling coefficients as well as divergent parameter are discussed. These results show that the local structures exhibit compression distortion for CdCl2:V^2+ and elongation distortions for CsMgX3:V^2+ (X:Cl, Br), respectively. It notes that the empirical formula R≈RH T (ri - rh)/2 is not suitable for CdCl2:V^2+ and CsMgX3:V^2+ (X=Cl, Br) systems. The contributions of ligand to spin-orbit coupling interaction cannot be neglected for strong covalent systems, especially for V^2+ doped in CsMgBr3:V^2+.