Earth’s near space,located in the region between 20 and 100 km above sea level,is characterized by extreme conditions,such as low temperature,low atmospheric pressure,harsh radiation,and extreme dryness.These conditi...Earth’s near space,located in the region between 20 and 100 km above sea level,is characterized by extreme conditions,such as low temperature,low atmospheric pressure,harsh radiation,and extreme dryness.These conditions are analogous to those found on the surface of Mars and in the atmosphere of Venus,making Earth’s near space a unique natural laboratory for astrobiological research.To address essential astrobiological questions,teams from the Chinese Academy of Sciences(CAS)have developed a scientific balloon platform,the CAS Balloon-Borne Astrobiology Platform(CAS-BAP),to study the effects of near space environmental conditions on the biology and survival strategies of representative organisms in this terrestrial analog.Here,we describe the versatile Biological Samples Exposure Payload(BIOSEP)loaded on the CAS-BAP with respect to its structure and function.The primary function of BIOSEP is to expose appropriate biological specimens to the harsh conditions of near space and subsequently return the exposed samples to laboratories for further analysis.Four successful flight missions in near space from 2019 to 2021 have demonstrated the high reliability and efficiency of the payload in communicating between hardware and software units,recording environmental data,exposing sample containers,protecting samples from external contamination,and recovering samples.Understanding the effects of Earth’s near space conditions on biological specimens will provide valuable insights into the survival strategies of organisms in extreme environments and the search for life beyond Earth.The development of BIOSEP and associated biological exposure experiments will enhance our understanding of the potential for life on Mars and the habitability of the atmospheric regions of other planets in the solar system and beyond.展开更多
Since the beginning of the 21st century,major earthquakes have frequently occurred worldwide.To explore the impact of astronomical factors on earthquakes,in this study,the statistical analysis method of correlation is...Since the beginning of the 21st century,major earthquakes have frequently occurred worldwide.To explore the impact of astronomical factors on earthquakes,in this study,the statistical analysis method of correlation is used to systematically analyze the effects of astronomical factors,such as solar activity,Earth’s rotation,lunar declination angle,celestial tidal force,and other phenomena on M≥8 global earthquakes at the beginning of the 21st century.With regard to solar activity,this study focuses on the analysis of the 11-year and century cycles of solar activity.The causal relationship of the Earth’s rotation is not obvious in this work and previous works;in contrast,the valley period of the solar activity century cycle may be an important astronomical factor leading to the frequent occurrence of global earthquakes at the beginning of the 21st century.This topic warrants further study.展开更多
The rotation of the Earth and the related length of the day (LOD) are predominantly affected by tidal dissipation through the Moon and the growth of the Earth’s core. Due to the increased concentration of mass around...The rotation of the Earth and the related length of the day (LOD) are predominantly affected by tidal dissipation through the Moon and the growth of the Earth’s core. Due to the increased concentration of mass around the rotation axis of the spinning Earth during the growth of the core the rotation should have been accelerated. Controversially the tidal dissipation by the Moon, which is mainly dependent on the availability of open shallow seas and the kind of Moon escape from a nearby position, acts towards a deceleration of the rotating Earth. Measurements of LOD for Phanerozoic and Precambrian times open ways to solve questions concerning the geodynamical history of the Earth. These measurements encompass investigations of growth patterns in fossils and depositional patterns in sediments (Cyclostratigraphy, Tidalites, Stromatolites, Rhythmites). These patterns contain information on the LOD and on the changing distance between Earth and Moon and can be used as well for a discussion about the growth of the Earth’s core. By updating an older paper with its simple approach as well as incorporating newly published results provided by the geoscientific community, a moderate to fast growth of the core in a hot early Earth will be favored controversially to the assumption of a delayed development of the core in an originally cold Earth. Core development with acceleration of Earth’s rotation and the contemporaneous slowing down due to tidal dissipation during the filling of the ocean may significantly interrelate.展开更多
An improved frequency shift method is proposed to remove the flat earth phase in ATI-SAR ocean surface motion detection in this study. First, two conventional flat earth effect removal methods(i.e., the frequency shif...An improved frequency shift method is proposed to remove the flat earth phase in ATI-SAR ocean surface motion detection in this study. First, two conventional flat earth effect removal methods(i.e., the frequency shift method and the orbital parameter method) are introduced and compared. Then, two improvements to frequency shift method are suggested. In the first improvement, the phase diagram is divided into several sub-blocks to calculate the phase fringe frequency. In the second improvement, a function between the phase of land regions and position is fitted to correct the residual flat earth phase based on the phase of the land regions that tend toward zero in an along-track interferogram. It is found that the improved frequency shift method is greatly improved;and it agrees well with the orbital parameter method, and achieves similar accuracy.展开更多
Concentrations and distribution patterns of rare earth elements(REEs)in the intertidal flat of Tianjin were studied using P(507) resin and ICP-MS analytical technology. The results show that average concentrations of ...Concentrations and distribution patterns of rare earth elements(REEs)in the intertidal flat of Tianjin were studied using P(507) resin and ICP-MS analytical technology. The results show that average concentrations of REEs in the filtered(dissolved REEs), unfiltered and interstitial water are 0.461 μg·L^(-1), 4.98 μg·L^(-1) and 0.845 μg·L^(-1), respectively. Their distribution patterns are similar to those in inland natural rivers, but quite different from those in oceans. The average concentrations of REEs in sediments and suspended matters are 161.2 (mg·L^(-1)) and 168.1 mg·L^(-1), respectively, which are much lower than those in sediments of natural rivers but higher than those in sediments of the continental shelf of East China Sea. It is suggested that REEs in sediments and suspended matters of intertidal flat can have mainly originated from terrestrial soils and thus their transportation and transformation processes are similar with those in rivers, and different from those in continental shelves. Pollutants discharged into the Bohai Bay do·not cause significant effect on REEs in the intertidal flat of Tianjin yet.展开更多
A modern view of the properties of chemical elements has confirmed the theory of the hot origin of the Earth. The next step in developing this theory was the hypothesis of the initial hydride Earth. In this work, we a...A modern view of the properties of chemical elements has confirmed the theory of the hot origin of the Earth. The next step in developing this theory was the hypothesis of the initial hydride Earth. In this work, we attempted to find additional evidence for this hypothesis and show additional effects that flow from it. The effect of the physical properties of atoms and ions on their behavior during the formation of the Earth was studied. The maximum contribution to the distribution of elements was made by those elements whose content in the original protoplanets of the disk was the maximum. Correlation dependence is obtained, which allows one to calculate the distribution of elements in the protoplanetary disk. It was shown that hydrogen was the main element in the proto substance located in the zone of the Earth’s formation. In this case, various chemical compounds formed, most represented by hydrogen compounds—hydrides. Since the pressure inside the Earth is 375 GPa, this factor forces the chemical compounds to adopt stoichiometry and structure that would not be available in atmospheric conditions. It is shown that many chemical elements at high pressure in a hydrogen medium form simple hydrides and super hydrides—polyhydrides with high hydrogen content. Pressure leads to a higher density of matter inside the planet. Given the possibility of forming polyhydrides, there is the possibility of binding the initially available hydrogen in an amount that can reach 49.3 mole%. Young Earth could contain about 10.7 mass% of hydrogen in hydrides, polyhydrides, and adsorbed form is almost twice higher than previous estimates. This fact additionally confirms the theory of the original hydride Earth. In hydrides, the occurrence of the phenomenon of superconductivity was discovered. Polyhydrides were shown as potential superconductors with a high critical temperature above 200 K. We, based on these data, hypothesized the presence of superconducting properties in the Earth’s core, which explains the presence of a magnetic field in the Earth, as well as the unevenness and instability of this field and the possibility of migration of the Earth’s poles. The fact that the Earth has a hydroid core causes its change in time due to the instability of hydrides. Arranged several possible models of the destruction of the Earth’s core. The calculations showed that both models give close results. These results give predictions that can be measured. The proposed models also made it possible to estimate the initial size of the Earth. Possible ways of further testing the hypothesis of the initial hydride Earth is shown.展开更多
It is well known that a variation in the direction of Earth’s rotation axis is a real astronomical phenomenon, named nutation. It is interesting if a variation of this axis can take place only in intensity, in the si...It is well known that a variation in the direction of Earth’s rotation axis is a real astronomical phenomenon, named nutation. It is interesting if a variation of this axis can take place only in intensity, in the simplest theoretical case of only two rigid body dynamics. This paper presents two positions of the Moon during its monthly orbit, where a sudden variation of Earth’s rotation axis in intensity can take place. The duration of this phenomenon is limited in time, maybe an instant or a day, and then a vortex can appear.展开更多
Every year on 22 April, we have celebrated Earth Day and the beautiful planet we call home. Earth Day, established in 1970, has been used to highlight our planet’s environmental challenges and raise awareness of the ...Every year on 22 April, we have celebrated Earth Day and the beautiful planet we call home. Earth Day, established in 1970, has been used to highlight our planet’s environmental challenges and raise awareness of the importance of protecting our world for future generations [1]. To provide the protection of our planet, we should explain Earth’s environmental challenges to the best of our knowledge in frames of contemporary Geophysics. This paper gives a short overview of the developed Hypersphere World-Universe Model (WUM) and pay particular attention to the principal role of Dark Matter (DM) in the Earth’s life. In this manuscript, we discuss different aspects of the Earth: a condition of Young Earth before the Beginning of life on It;Internal Structure;“The 660-km Boundary” that we named Geomagma;Random Variations of Earth’s Rotational Speed on a daily basis;Origin of Moon;Expanding Earth;Internal Heating;Faint Young Sun paradox;Geocorona and Planetary Coronas;High-Energy Atmospheric Physics. WUM proposed principally different ways to solve the problems of Internal Heating, Origin of the Moon, and Faint Young Sun paradox based on DM core of the Earth. The Model revealed the fact that the Sun Activity causes the Geomagma Activity and, as a consequence, Random Variations of Earth’s Rotational Speed by the varying Sun’s magnetic field.展开更多
On the basis of the ideal gas model, the polarization of charges in the mantle was obtained, a physical and mathematical model was constructed, and estimated calculations of the dipole mode of the Earth’s magnetic fi...On the basis of the ideal gas model, the polarization of charges in the mantle was obtained, a physical and mathematical model was constructed, and estimated calculations of the dipole mode of the Earth’s magnetic field were performed, taking into account the speed of its angular rotation, the parameters of density and temperature, the chemical composition, the ionization potential, the dielectric constant and the percentage of the main chemical compounds of the mantle substance.展开更多
The precision of Earth＇s gravitational field from GRACE up to degree and order 120 was studied for different inter-satellite ranges using the improved energy conservation principle. Our simulated result shows that： ...The precision of Earth＇s gravitational field from GRACE up to degree and order 120 was studied for different inter-satellite ranges using the improved energy conservation principle. Our simulated result shows that： For long wavelength （L≤20） at degree 20, the cumulative geoid-height error gradually decreased with increasing range, from 0. 052 cm for 110 km to 1. 156 times and 1. 209 times as large for 220 km and 330 kin, respectively. For medium-wavelength （ 100 ≤ L ≤ 120） at degree 120, the cumulative geoid-height error de- creased from 13. 052 cm for 110 km, to 1. 327 times and 1. 970 times as large for the ranges of 220 km and 330 km, respectively; By adopting an optimal range of 220 ± 50 km, we can suppress considerably the loss of precision in the measurement of the Earth＇ s long-wavelength and medium-wavelength gravitational field.展开更多
Steel H13 was put in non toxic salt bath with addition of CeO 2 for co diffusion of sulfur, nitrogen and carbon and followed by oxidation treatment. The effect of rare earths on the improvement of wear resistance a...Steel H13 was put in non toxic salt bath with addition of CeO 2 for co diffusion of sulfur, nitrogen and carbon and followed by oxidation treatment. The effect of rare earths on the improvement of wear resistance and high temperature oxidation resistance of steel H13 was studied using scanning electron microscope, energy dispersive spectrometry and X ray diffraction. The results show that compared to the surface treatment without rare earth addition, the treatment with addition of rare earths improves the wear resistance and high temperature resistance to oxidation of steel H13. Under the conditions of 30 N and 2 h, the wear weight loss was decreased by 40%, and the friction coefficient was reduced from 0 25 to 0 22; whereas for 150 N and 0 2 h, the wear weight loss was decreased by 24%, and the friction coefficient was reduced from 0 35 to 0 32. For the oxidation at 700 ℃ and 4 h, the rate of weight gain decreased to only about 1/30 of that without rare earths.展开更多
The Earth is taken as a triaxial rigid body, which rotates freely in the Euclidian space. The starting equations are the Euler dynamic equations, with A smaller than B and B smaller than C. The Euler equations are sol...The Earth is taken as a triaxial rigid body, which rotates freely in the Euclidian space. The starting equations are the Euler dynamic equations, with A smaller than B and B smaller than C. The Euler equations are solved, and the numerical results are provided. In the calculations, the following parameters are used: (C-B)/A=0.003 273 53; (B-A)/C=0.000 021 96; (C-A)/B=0.003 295 49, and the mean angular velocity of the Earth's rotation, ω =0.000 072 921 15 rad/s. Calculations show that, besides the self-rotation of the Earth and the free Euler procession of its rotation, there exists the free nutation: the nutation angle, or the angle between the Earth's momentary rotation axis and the mean axis that periodically change with time. The free nutation is investigated.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA17010505)
文摘Earth’s near space,located in the region between 20 and 100 km above sea level,is characterized by extreme conditions,such as low temperature,low atmospheric pressure,harsh radiation,and extreme dryness.These conditions are analogous to those found on the surface of Mars and in the atmosphere of Venus,making Earth’s near space a unique natural laboratory for astrobiological research.To address essential astrobiological questions,teams from the Chinese Academy of Sciences(CAS)have developed a scientific balloon platform,the CAS Balloon-Borne Astrobiology Platform(CAS-BAP),to study the effects of near space environmental conditions on the biology and survival strategies of representative organisms in this terrestrial analog.Here,we describe the versatile Biological Samples Exposure Payload(BIOSEP)loaded on the CAS-BAP with respect to its structure and function.The primary function of BIOSEP is to expose appropriate biological specimens to the harsh conditions of near space and subsequently return the exposed samples to laboratories for further analysis.Four successful flight missions in near space from 2019 to 2021 have demonstrated the high reliability and efficiency of the payload in communicating between hardware and software units,recording environmental data,exposing sample containers,protecting samples from external contamination,and recovering samples.Understanding the effects of Earth’s near space conditions on biological specimens will provide valuable insights into the survival strategies of organisms in extreme environments and the search for life beyond Earth.The development of BIOSEP and associated biological exposure experiments will enhance our understanding of the potential for life on Mars and the habitability of the atmospheric regions of other planets in the solar system and beyond.
文摘Since the beginning of the 21st century,major earthquakes have frequently occurred worldwide.To explore the impact of astronomical factors on earthquakes,in this study,the statistical analysis method of correlation is used to systematically analyze the effects of astronomical factors,such as solar activity,Earth’s rotation,lunar declination angle,celestial tidal force,and other phenomena on M≥8 global earthquakes at the beginning of the 21st century.With regard to solar activity,this study focuses on the analysis of the 11-year and century cycles of solar activity.The causal relationship of the Earth’s rotation is not obvious in this work and previous works;in contrast,the valley period of the solar activity century cycle may be an important astronomical factor leading to the frequent occurrence of global earthquakes at the beginning of the 21st century.This topic warrants further study.
文摘The rotation of the Earth and the related length of the day (LOD) are predominantly affected by tidal dissipation through the Moon and the growth of the Earth’s core. Due to the increased concentration of mass around the rotation axis of the spinning Earth during the growth of the core the rotation should have been accelerated. Controversially the tidal dissipation by the Moon, which is mainly dependent on the availability of open shallow seas and the kind of Moon escape from a nearby position, acts towards a deceleration of the rotating Earth. Measurements of LOD for Phanerozoic and Precambrian times open ways to solve questions concerning the geodynamical history of the Earth. These measurements encompass investigations of growth patterns in fossils and depositional patterns in sediments (Cyclostratigraphy, Tidalites, Stromatolites, Rhythmites). These patterns contain information on the LOD and on the changing distance between Earth and Moon and can be used as well for a discussion about the growth of the Earth’s core. By updating an older paper with its simple approach as well as incorporating newly published results provided by the geoscientific community, a moderate to fast growth of the core in a hot early Earth will be favored controversially to the assumption of a delayed development of the core in an originally cold Earth. Core development with acceleration of Earth’s rotation and the contemporaneous slowing down due to tidal dissipation during the filling of the ocean may significantly interrelate.
基金The National Key Research and Development Program of China under contract No.2016YFC1402703the National Natural Science Foundation of China under contract Nos 61471136 and 61501130
文摘An improved frequency shift method is proposed to remove the flat earth phase in ATI-SAR ocean surface motion detection in this study. First, two conventional flat earth effect removal methods(i.e., the frequency shift method and the orbital parameter method) are introduced and compared. Then, two improvements to frequency shift method are suggested. In the first improvement, the phase diagram is divided into several sub-blocks to calculate the phase fringe frequency. In the second improvement, a function between the phase of land regions and position is fitted to correct the residual flat earth phase based on the phase of the land regions that tend toward zero in an along-track interferogram. It is found that the improved frequency shift method is greatly improved;and it agrees well with the orbital parameter method, and achieves similar accuracy.
文摘Concentrations and distribution patterns of rare earth elements(REEs)in the intertidal flat of Tianjin were studied using P(507) resin and ICP-MS analytical technology. The results show that average concentrations of REEs in the filtered(dissolved REEs), unfiltered and interstitial water are 0.461 μg·L^(-1), 4.98 μg·L^(-1) and 0.845 μg·L^(-1), respectively. Their distribution patterns are similar to those in inland natural rivers, but quite different from those in oceans. The average concentrations of REEs in sediments and suspended matters are 161.2 (mg·L^(-1)) and 168.1 mg·L^(-1), respectively, which are much lower than those in sediments of natural rivers but higher than those in sediments of the continental shelf of East China Sea. It is suggested that REEs in sediments and suspended matters of intertidal flat can have mainly originated from terrestrial soils and thus their transportation and transformation processes are similar with those in rivers, and different from those in continental shelves. Pollutants discharged into the Bohai Bay do·not cause significant effect on REEs in the intertidal flat of Tianjin yet.
文摘A modern view of the properties of chemical elements has confirmed the theory of the hot origin of the Earth. The next step in developing this theory was the hypothesis of the initial hydride Earth. In this work, we attempted to find additional evidence for this hypothesis and show additional effects that flow from it. The effect of the physical properties of atoms and ions on their behavior during the formation of the Earth was studied. The maximum contribution to the distribution of elements was made by those elements whose content in the original protoplanets of the disk was the maximum. Correlation dependence is obtained, which allows one to calculate the distribution of elements in the protoplanetary disk. It was shown that hydrogen was the main element in the proto substance located in the zone of the Earth’s formation. In this case, various chemical compounds formed, most represented by hydrogen compounds—hydrides. Since the pressure inside the Earth is 375 GPa, this factor forces the chemical compounds to adopt stoichiometry and structure that would not be available in atmospheric conditions. It is shown that many chemical elements at high pressure in a hydrogen medium form simple hydrides and super hydrides—polyhydrides with high hydrogen content. Pressure leads to a higher density of matter inside the planet. Given the possibility of forming polyhydrides, there is the possibility of binding the initially available hydrogen in an amount that can reach 49.3 mole%. Young Earth could contain about 10.7 mass% of hydrogen in hydrides, polyhydrides, and adsorbed form is almost twice higher than previous estimates. This fact additionally confirms the theory of the original hydride Earth. In hydrides, the occurrence of the phenomenon of superconductivity was discovered. Polyhydrides were shown as potential superconductors with a high critical temperature above 200 K. We, based on these data, hypothesized the presence of superconducting properties in the Earth’s core, which explains the presence of a magnetic field in the Earth, as well as the unevenness and instability of this field and the possibility of migration of the Earth’s poles. The fact that the Earth has a hydroid core causes its change in time due to the instability of hydrides. Arranged several possible models of the destruction of the Earth’s core. The calculations showed that both models give close results. These results give predictions that can be measured. The proposed models also made it possible to estimate the initial size of the Earth. Possible ways of further testing the hypothesis of the initial hydride Earth is shown.
文摘It is well known that a variation in the direction of Earth’s rotation axis is a real astronomical phenomenon, named nutation. It is interesting if a variation of this axis can take place only in intensity, in the simplest theoretical case of only two rigid body dynamics. This paper presents two positions of the Moon during its monthly orbit, where a sudden variation of Earth’s rotation axis in intensity can take place. The duration of this phenomenon is limited in time, maybe an instant or a day, and then a vortex can appear.
文摘Every year on 22 April, we have celebrated Earth Day and the beautiful planet we call home. Earth Day, established in 1970, has been used to highlight our planet’s environmental challenges and raise awareness of the importance of protecting our world for future generations [1]. To provide the protection of our planet, we should explain Earth’s environmental challenges to the best of our knowledge in frames of contemporary Geophysics. This paper gives a short overview of the developed Hypersphere World-Universe Model (WUM) and pay particular attention to the principal role of Dark Matter (DM) in the Earth’s life. In this manuscript, we discuss different aspects of the Earth: a condition of Young Earth before the Beginning of life on It;Internal Structure;“The 660-km Boundary” that we named Geomagma;Random Variations of Earth’s Rotational Speed on a daily basis;Origin of Moon;Expanding Earth;Internal Heating;Faint Young Sun paradox;Geocorona and Planetary Coronas;High-Energy Atmospheric Physics. WUM proposed principally different ways to solve the problems of Internal Heating, Origin of the Moon, and Faint Young Sun paradox based on DM core of the Earth. The Model revealed the fact that the Sun Activity causes the Geomagma Activity and, as a consequence, Random Variations of Earth’s Rotational Speed by the varying Sun’s magnetic field.
文摘On the basis of the ideal gas model, the polarization of charges in the mantle was obtained, a physical and mathematical model was constructed, and estimated calculations of the dipole mode of the Earth’s magnetic field were performed, taking into account the speed of its angular rotation, the parameters of density and temperature, the chemical composition, the ionization potential, the dielectric constant and the percentage of the main chemical compounds of the mantle substance.
基金supported by the Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences for Distinguished Young Scholar(KZCX2-EW-QN114)the National Natural Science Foundation of China(41004006,41131067,11173049)+5 种基金the Merit-based Scientific Research Foundation of the State Ministry of Human Resources and Social Security of China for Returned Overseas Chinese Scholars(2011)the Open Research Fund Program of the Key Laboratory of Geo-Informatics of State Bureau of Surveying and Mapping(201031)the Open Research Fund Program of the Key Laboratory of Computational Geodynamics of Chinese Academy of Sciences(2011-04)the Frontier Field Program of Knowledge Innovation of Institute of Geodesy and Geophysics of Chinese Academy of Sciencesthe Open Fund of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(PLN1113)the Hubei Province Key Laboratory of Refractories and Ceramics Ministry-Province jointly-Constructed Cultivation Base for State key Laboratory(G201009)
文摘The precision of Earth＇s gravitational field from GRACE up to degree and order 120 was studied for different inter-satellite ranges using the improved energy conservation principle. Our simulated result shows that： For long wavelength （L≤20） at degree 20, the cumulative geoid-height error gradually decreased with increasing range, from 0. 052 cm for 110 km to 1. 156 times and 1. 209 times as large for 220 km and 330 kin, respectively. For medium-wavelength （ 100 ≤ L ≤ 120） at degree 120, the cumulative geoid-height error de- creased from 13. 052 cm for 110 km, to 1. 327 times and 1. 970 times as large for the ranges of 220 km and 330 km, respectively; By adopting an optimal range of 220 ± 50 km, we can suppress considerably the loss of precision in the measurement of the Earth＇ s long-wavelength and medium-wavelength gravitational field.
文摘Steel H13 was put in non toxic salt bath with addition of CeO 2 for co diffusion of sulfur, nitrogen and carbon and followed by oxidation treatment. The effect of rare earths on the improvement of wear resistance and high temperature oxidation resistance of steel H13 was studied using scanning electron microscope, energy dispersive spectrometry and X ray diffraction. The results show that compared to the surface treatment without rare earth addition, the treatment with addition of rare earths improves the wear resistance and high temperature resistance to oxidation of steel H13. Under the conditions of 30 N and 2 h, the wear weight loss was decreased by 40%, and the friction coefficient was reduced from 0 25 to 0 22; whereas for 150 N and 0 2 h, the wear weight loss was decreased by 24%, and the friction coefficient was reduced from 0 35 to 0 32. For the oxidation at 700 ℃ and 4 h, the rate of weight gain decreased to only about 1/30 of that without rare earths.
基金Funded by the National Natural Science Foundation of China (No.40574004).
文摘The Earth is taken as a triaxial rigid body, which rotates freely in the Euclidian space. The starting equations are the Euler dynamic equations, with A smaller than B and B smaller than C. The Euler equations are solved, and the numerical results are provided. In the calculations, the following parameters are used: (C-B)/A=0.003 273 53; (B-A)/C=0.000 021 96; (C-A)/B=0.003 295 49, and the mean angular velocity of the Earth's rotation, ω =0.000 072 921 15 rad/s. Calculations show that, besides the self-rotation of the Earth and the free Euler procession of its rotation, there exists the free nutation: the nutation angle, or the angle between the Earth's momentary rotation axis and the mean axis that periodically change with time. The free nutation is investigated.
