The fiber strapdown inertial navigation system （FSINS）/dead reckoning （DR）/Beidou double-star integrated navigation scheme is proposed aiming at the need of land fighting-vehicle independence positioning. The meas...The fiber strapdown inertial navigation system （FSINS）/dead reckoning （DR）/Beidou double-star integrated navigation scheme is proposed aiming at the need of land fighting-vehicle independence positioning. The measurement information fusion technology is studied by introducing the FSINS/DR/Beidou double-star integrated scheme. Several specific methods for the information fusion are discussed, and a Kalman filter is designed for the information fusion. Experimental results show that the design of the integrated scheme can improve the positioning accuracy of the navigation system.展开更多
Structural relationships between the Neoproterozoic rock complexes of a continental massif, island arc and back-arc basin geodynamic affinities are described and considered in this work based on field observations wit...Structural relationships between the Neoproterozoic rock complexes of a continental massif, island arc and back-arc basin geodynamic affinities are described and considered in this work based on field observations within the northeastern segment of the Central Taimyr tectonic zone distinguished in the late Hercynian fold- thrust belt of Taimyr Peninsula. As is established for the first time, rock complexes of the continental massif with the early Late Riphean （Tonian-Cryogenian） volcanogenic-sedimentary cover occur in the study region as the allochthonous syn- and post-sedimentary thrust sheets buried in or thrust over deposits of a back-arc basin, which accumulated in the terminal Late Riphean （Cryogcnian）-initial Vendian （Ediacaran）. These and other results of the large-scale structural observations elucidate important details of the region tectonic development in the Late Precambrian, when two lateral ensembles of the Neoproterozoic structures originated in the region. In the first half of the Neoproterozoic, the regional tectonic ensemble included the oceanic plate abut on the continental massif with a primitive volcano-plutonic belt. The subsequent system of an island arc and marginal back- arc basin originated in the second half of the Neoproterozoic and existed approximately till the mid-Vendian （Ediacaran） phase of the intense formation of thrust sheets in the region.展开更多
When the liquid propellant thruster works,its plume field would contain many propellant liquid droplets,especially at pulse state.Liquid droplets may move along with the gas flow and deposit on the components of space...When the liquid propellant thruster works,its plume field would contain many propellant liquid droplets,especially at pulse state.Liquid droplets may move along with the gas flow and deposit on the components of spacecraft as contamination.The simulation of the plume field involving the gas molecules and liquid droplets is an important part in contamination studies of thruster plume.Based on the PWS software developed by Beihang University(BUAA),axial-symmetric two-phase direct simulation Monte Carlo(DSMC) method is used with the liquid droplet taken as a kind of solid particle.The computation of gas-to-particle effect and gas reflection on the particle surface are decoupled.The inter-particle collision is also considered.The gas parameters at nozzle exit of 120N engine after 20 ms pulse work are taken as the entrance condition of the numerical simulation.Four test cases are conducted for comparison of different collision modules.Simulation results show that the effects of liquid propellant droplets mainly concentrate near the axis line of engine.The particle-to-gas collision would cause evident differences in the gas field and subtle differences in the particle phase.The liquid droplets in the plume field are generally accelerated and convected by the gas molecules.The DSMC method is proved to be a feasible solver to numerically simulate the two-phase flow involving solid phase and rarefied gas flow.展开更多
Palynological data are used to draw paleoecological inferences for the Dalichai Formation,northeast of Semnan,northeastern Iran.All samples examined yield well-preserved,diverse palynofloras consisting predominantly o...Palynological data are used to draw paleoecological inferences for the Dalichai Formation,northeast of Semnan,northeastern Iran.All samples examined yield well-preserved,diverse palynofloras consisting predominantly of miospores;dinoflagellate cysts,foraminiferal test linings,and fungal spores occur as minor constituents.Fifty-four species of spores(37 genera),18species of pollen(9 genera),and 16 species of dinoflagellate cysts(13 genera)are recognized.Co-occurrence of such miospore species with known vertical ranges as Klukisporites variegatus,Sellaspora asperata,Murospora florida,and Concavissimisporites verrucosus suggests a Middle Jurassic(Bajocian-Callovian)age for the host strata,thus corroborating the available paleozoological evidence.Such spore species as Klukisporites,Cyathidites,and Dictyophyllidites known to have been produced by Pterophyta dominate the palynofloras.Thus the contemporaneous coastal vegetation was characterized by predominance of Pterophyta whereas representatives of Ginkgophyta,Pteridospermophyta,Lycophyta,Coniferophyta,and Bryophyta were rarely represented.This reconstruction implies that a moist,warm climate prevailed in northeastern Iran during the Middle Jurassic(Bajocian-Callovian).This is confirmed by occurrence of fungal spores accompanied by such warm water dinoflagellate cysts as Mendicodinium groenlandicum,Pareodinia ceratophora,and Gonyaulacysta jurassica.Abundance of Amorphous Organic Matter(AOM)signifies a shallow,low-energy,dysoxic-anoxic depositional site for the host strata.Furthermore,the ratio of AOM to marine palynomorphs as well as abundance of blade-shaped to eqiudimensional opaque palynomacerals could indicate low sedimentation rate in a shallow,low-oxygenated marine environment.Additionally,occurrence of chorate dinoflagellate cysts(e.g.,Adnatosphaeridium caulleryi)and acritarchs bearing relatively long processes(e.g.,Micrhystridium)possibly suggests deepening upward in the study section.展开更多
文摘The fiber strapdown inertial navigation system （FSINS）/dead reckoning （DR）/Beidou double-star integrated navigation scheme is proposed aiming at the need of land fighting-vehicle independence positioning. The measurement information fusion technology is studied by introducing the FSINS/DR/Beidou double-star integrated scheme. Several specific methods for the information fusion are discussed, and a Kalman filter is designed for the information fusion. Experimental results show that the design of the integrated scheme can improve the positioning accuracy of the navigation system.
文摘Structural relationships between the Neoproterozoic rock complexes of a continental massif, island arc and back-arc basin geodynamic affinities are described and considered in this work based on field observations within the northeastern segment of the Central Taimyr tectonic zone distinguished in the late Hercynian fold- thrust belt of Taimyr Peninsula. As is established for the first time, rock complexes of the continental massif with the early Late Riphean （Tonian-Cryogenian） volcanogenic-sedimentary cover occur in the study region as the allochthonous syn- and post-sedimentary thrust sheets buried in or thrust over deposits of a back-arc basin, which accumulated in the terminal Late Riphean （Cryogcnian）-initial Vendian （Ediacaran）. These and other results of the large-scale structural observations elucidate important details of the region tectonic development in the Late Precambrian, when two lateral ensembles of the Neoproterozoic structures originated in the region. In the first half of the Neoproterozoic, the regional tectonic ensemble included the oceanic plate abut on the continental massif with a primitive volcano-plutonic belt. The subsequent system of an island arc and marginal back- arc basin originated in the second half of the Neoproterozoic and existed approximately till the mid-Vendian （Ediacaran） phase of the intense formation of thrust sheets in the region.
文摘When the liquid propellant thruster works,its plume field would contain many propellant liquid droplets,especially at pulse state.Liquid droplets may move along with the gas flow and deposit on the components of spacecraft as contamination.The simulation of the plume field involving the gas molecules and liquid droplets is an important part in contamination studies of thruster plume.Based on the PWS software developed by Beihang University(BUAA),axial-symmetric two-phase direct simulation Monte Carlo(DSMC) method is used with the liquid droplet taken as a kind of solid particle.The computation of gas-to-particle effect and gas reflection on the particle surface are decoupled.The inter-particle collision is also considered.The gas parameters at nozzle exit of 120N engine after 20 ms pulse work are taken as the entrance condition of the numerical simulation.Four test cases are conducted for comparison of different collision modules.Simulation results show that the effects of liquid propellant droplets mainly concentrate near the axis line of engine.The particle-to-gas collision would cause evident differences in the gas field and subtle differences in the particle phase.The liquid droplets in the plume field are generally accelerated and convected by the gas molecules.The DSMC method is proved to be a feasible solver to numerically simulate the two-phase flow involving solid phase and rarefied gas flow.
文摘Palynological data are used to draw paleoecological inferences for the Dalichai Formation,northeast of Semnan,northeastern Iran.All samples examined yield well-preserved,diverse palynofloras consisting predominantly of miospores;dinoflagellate cysts,foraminiferal test linings,and fungal spores occur as minor constituents.Fifty-four species of spores(37 genera),18species of pollen(9 genera),and 16 species of dinoflagellate cysts(13 genera)are recognized.Co-occurrence of such miospore species with known vertical ranges as Klukisporites variegatus,Sellaspora asperata,Murospora florida,and Concavissimisporites verrucosus suggests a Middle Jurassic(Bajocian-Callovian)age for the host strata,thus corroborating the available paleozoological evidence.Such spore species as Klukisporites,Cyathidites,and Dictyophyllidites known to have been produced by Pterophyta dominate the palynofloras.Thus the contemporaneous coastal vegetation was characterized by predominance of Pterophyta whereas representatives of Ginkgophyta,Pteridospermophyta,Lycophyta,Coniferophyta,and Bryophyta were rarely represented.This reconstruction implies that a moist,warm climate prevailed in northeastern Iran during the Middle Jurassic(Bajocian-Callovian).This is confirmed by occurrence of fungal spores accompanied by such warm water dinoflagellate cysts as Mendicodinium groenlandicum,Pareodinia ceratophora,and Gonyaulacysta jurassica.Abundance of Amorphous Organic Matter(AOM)signifies a shallow,low-energy,dysoxic-anoxic depositional site for the host strata.Furthermore,the ratio of AOM to marine palynomorphs as well as abundance of blade-shaped to eqiudimensional opaque palynomacerals could indicate low sedimentation rate in a shallow,low-oxygenated marine environment.Additionally,occurrence of chorate dinoflagellate cysts(e.g.,Adnatosphaeridium caulleryi)and acritarchs bearing relatively long processes(e.g.,Micrhystridium)possibly suggests deepening upward in the study section.
