In South China four depositional sequences are recognized in the upper part of Upper Devonian and Tournaisian. They are named SQ0 SQ1, SQ2 and SQ3 in ascending order. SQ0 is Strunian (uppermost Devonian), and the othe...In South China four depositional sequences are recognized in the upper part of Upper Devonian and Tournaisian. They are named SQ0 SQ1, SQ2 and SQ3 in ascending order. SQ0 is Strunian (uppermost Devonian), and the other three Tournaisian in age. These four depositional sequences appear to correlate fairly well with the four sequence recognized in Europe, North America and other areas. This may suggest that these sequences are synchronous depos- its resulted from the eustatic changes. The present study on sequence stratigraphy, biostratigraphy and event stratigraphy indicates that in neritic facies areas of South China, the Devonian-Carboniferous boundary, matching the boundary between Siphonodella praesulcata zone and S. sulcata zone in pelagic facies areas, is not only higher than the top of the Cystophrentis zone, but also higher than the top of the Devonian-Carboniferous boundary event bed. In neritic facies areas, the Devonian-Carbonifrerous boundary is marked by the most distinct transgressive surface within the Cystophrentiseudouralina interval zone, i. e. at the base of the TST of the SQ1. This boundary coincides with the top surface of the event bed resulted from the eustatic fall, and approximately corresponds to the basal part of Rseudouralina assemblage zone.展开更多
Alluvial channel has always adjusted itself to the equilibrium state of sediment transport after it was artificially or naturally disturbed. How to maintain the equilibrium state of sediment transport and keep the riv...Alluvial channel has always adjusted itself to the equilibrium state of sediment transport after it was artificially or naturally disturbed. How to maintain the equilibrium state of sediment transport and keep the river regime stable has always been the concerns of fluvial geomorphologists. The channel in the middle and lower reaches of the Yangtze River is characterized by the staggered distribution of the bifurcated river and the single-thread river. The change of river regime is more violently in the bifurcated river than in the single-thread river. Whether the adjustment of the river regime in the bifurcated river can pass through the single-thread river and propagate to the downstream reaches affects the stabilities of the overall river regime. Studies show that the barrier river reach can block the upstream channel adjustment from propagating to the downstream reaches; therefore, it plays a key role in stabilizing the river regime. This study investigates 34 single-thread river reaches in the mid- dle and lower reaches of the Yangtze River. On the basis of the systematic summarization of the fluvial process of the middle and lower reaches of the Yangtze River, the control factors of barrier river reach are summarized and extracted： the planar morphology of single-thread and meandering; with no flow deflecting node distributed in the upper or middle part of the river reach; the hydraulic geometric coefficient is less than 4; the longitudinal gradient is greater than 12‰, the clay content of the concave bank is greater than 9.5%, and the median diameter of the bed sediment is greater than 0.158 mm. From the Navier-Stokes equation ,the calculation formula of the bending radius of flow dynamic axis is deduced and then the roles of these control factors on restricting the migration of the flow dynamic axis and the formation of the barrier river reach are analyzed. The barrier river reach is considered Such. When the ratio of the migration force of the flow dynamic boundary is less than 1 under different flow展开更多
In this paper,we investigate the existence of solutions and analyze the large-time behavior for Gurtin-Maccamy population model involving conformable fractional derivatives.As a preliminary step,we construct a generic...In this paper,we investigate the existence of solutions and analyze the large-time behavior for Gurtin-Maccamy population model involving conformable fractional derivatives.As a preliminary step,we construct a generic structure of the solution associated with our proposed model by utilizing some basic properties and tools of conformable fractional calculus.We establish the existence of a unique solution of the given model with the given initial conditions.At last,by using the upper and lower solutions for the characteristic equation,we define the upper and lower boundaries for the obtained solution and describe the large-time behavior of the total population.展开更多
Lower Triassic conodont biostratigraphy has been well studied around the world in the past decades, but the Induan-Olenekian boundary （IOB） remains undecided. The Novispathodus waageni group has been taxonomically r...Lower Triassic conodont biostratigraphy has been well studied around the world in the past decades, but the Induan-Olenekian boundary （IOB） remains undecided. The Novispathodus waageni group has been taxonomically re-assessed based on abundant new materials from the Jianshi and Chaohu sections, South China. New study shows that Nv. waageni typically possesses： （1） an approximately equi-dimentional P1 blade element, （2） an accurate upper profile with denticle height descending in both directions, （3） a denticulated posterior edge （lower denticles posterior of the highest denticle）, and （4） a round basal cavity outline. Of the three proposed subspecies of the waageni species, both Nv. waageni waageni （Sweet, 1970） and Nv. w. eowaageni （Zhao and Orchard, 2005） are valid, and the former differs clearly from Nv. w. eowaageni in having （1） a slightly higher length/height ratio （holotype=1.30 ： 1.23）, （2） a thicker blade, sometimes with medial thickening, （3） fewer （broader） denticles per unit length, （4） generally recurved denticles, not straight and upright, （5） highest denticles closer to posterior, （6） common differentiation of a posterior cusp, and （7） more sinuous basal profile, with increased posterior upturning. A third subspecies illustrated as Nv. waageni n. subsp. A sensu Goudemand, 2014 is not conspecific with older individuals of Nv. w. eowaageni, and also cannot be as- signed to the Nv. waageni group. Abundant new materials demonstrate a clear ontogenic process for Nv. w. eowaageni, indicating that Nv. w. eowaageni occurring in the Induan-Olenekian boundary （IOB） succession is rather stable. Small, earlier individuals （i.e., those from Bed 225 in Jianshi） are referred to as Nv. w. eowaageni Morphotype A, and are thought to have likely evolved from Ns. dieneri Morphotype 3, and to be the precursor of mature elements ofNv. w. eowaageni. The first appearance datum of Nv. w. eowaageni therefore is an ideal mark defining the IOB.展开更多
In this paper,we define lower-dimensional volumes of spin manifolds with boundary.We compute thelower-dimensional volume Vol^((2,2)) for 5-dimensional and 6-dimensional spin manifolds with boundary and we also getthe ...In this paper,we define lower-dimensional volumes of spin manifolds with boundary.We compute thelower-dimensional volume Vol^((2,2)) for 5-dimensional and 6-dimensional spin manifolds with boundary and we also getthe Kastler-Kalau-Walze type theorem in this case.展开更多
The pyrite-type FeO_(2)and FeO_(2)H were synthesized at the pressure-temperature conditions relevant to Earth’s deep lower mantle.Through the water-iron reaction,the pyrite-phase is a good candidate to explain the ch...The pyrite-type FeO_(2)and FeO_(2)H were synthesized at the pressure-temperature conditions relevant to Earth’s deep lower mantle.Through the water-iron reaction,the pyrite-phase is a good candidate to explain the chemical heterogeneities and seismological anomalies at the bottom of the mantle.The solid solution of pyrite-type FeO_(2)and FeO_(2)H,namely the FeO_(2)Hx(0≤x≤1),is particularly interesting and introduces puzzling chemical states for both the O and H atoms in the deep mantle.While the role of H in the FeO_(2)–FeO_(2)H system has been primarily investigated,discrepancies remain.In this work,we summarize recent progress on the pyrite-phase,including FeO_(2),FeO_(2)H,and FeO_(2)Hx,which is critical for understanding the water cycling,redox equilibria,and compositional heterogenicities in the deep lower mantle.展开更多
Based on the clarifications of the deterioration characteristics of the lower Yellow River (LYR), the influence of river deterioration on flood discharging capacity is studied through theoretical derivation and analys...Based on the clarifications of the deterioration characteristics of the lower Yellow River (LYR), the influence of river deterioration on flood discharging capacity is studied through theoretical derivation and analysis of field data. This study indicates that response of flood discharging capacity to river deterioration is nonlinear. Sediment depositions in the main channel cause the reductions of dominant discharge and thus the increase of initial flood stage. Reductions in the channel width result in the increases of the rising rate of flood stage and the decrease of flood discharging capacity.展开更多
Oceanic turbulence plays an important role in coastal flow. However, as the effect of an uneven lower boundary on the adjacent turbulence is still not well understood, we explore the mechanics of nearshore turbulence ...Oceanic turbulence plays an important role in coastal flow. However, as the effect of an uneven lower boundary on the adjacent turbulence is still not well understood, we explore the mechanics of nearshore turbulence with a turbulence-resolving numerical model known as a large-eddy-simulation model for an idealized scenario in a coastal region for which the lower boundary is a solid sinusoidal wave. The numerical simulation demonstrates how the mechanical energy of the current is transferred into local turbulence mixing, and shows the changes in turbulent intensity over the continuous phase change of the lower topography. The strongest turbulent kinetic energy is concentrated above the trough of the wavy surface. The turbulence mixing is mainly generated by the shear forces; the magnitude of shear production has a local maximum over the crest of the seabed topography, and there is an asymmetry in the shear production between the leeward and windward slopes. The numerical results are consistent with results from laboratory experiments. Our analysis provides an important insight into the mechanism of turbulent kinetic energy production and development.展开更多
This paper presents new existence results for singular discrete boundary value problems. In particular our nonlinearity may be singular in its dependent variable and is allowed to change sign.
文摘In South China four depositional sequences are recognized in the upper part of Upper Devonian and Tournaisian. They are named SQ0 SQ1, SQ2 and SQ3 in ascending order. SQ0 is Strunian (uppermost Devonian), and the other three Tournaisian in age. These four depositional sequences appear to correlate fairly well with the four sequence recognized in Europe, North America and other areas. This may suggest that these sequences are synchronous depos- its resulted from the eustatic changes. The present study on sequence stratigraphy, biostratigraphy and event stratigraphy indicates that in neritic facies areas of South China, the Devonian-Carboniferous boundary, matching the boundary between Siphonodella praesulcata zone and S. sulcata zone in pelagic facies areas, is not only higher than the top of the Cystophrentis zone, but also higher than the top of the Devonian-Carboniferous boundary event bed. In neritic facies areas, the Devonian-Carbonifrerous boundary is marked by the most distinct transgressive surface within the Cystophrentiseudouralina interval zone, i. e. at the base of the TST of the SQ1. This boundary coincides with the top surface of the event bed resulted from the eustatic fall, and approximately corresponds to the basal part of Rseudouralina assemblage zone.
基金National Natural Science Foundation of China, No.51379155, No.51339001, No.51579185 National Key Research Program of China, No.2016YFC0402306, No.2016YFC04022310, No.2016YFC0402106 CentraI Public Research Institutes Fundamental Research, No.TKS 160103
文摘Alluvial channel has always adjusted itself to the equilibrium state of sediment transport after it was artificially or naturally disturbed. How to maintain the equilibrium state of sediment transport and keep the river regime stable has always been the concerns of fluvial geomorphologists. The channel in the middle and lower reaches of the Yangtze River is characterized by the staggered distribution of the bifurcated river and the single-thread river. The change of river regime is more violently in the bifurcated river than in the single-thread river. Whether the adjustment of the river regime in the bifurcated river can pass through the single-thread river and propagate to the downstream reaches affects the stabilities of the overall river regime. Studies show that the barrier river reach can block the upstream channel adjustment from propagating to the downstream reaches; therefore, it plays a key role in stabilizing the river regime. This study investigates 34 single-thread river reaches in the mid- dle and lower reaches of the Yangtze River. On the basis of the systematic summarization of the fluvial process of the middle and lower reaches of the Yangtze River, the control factors of barrier river reach are summarized and extracted： the planar morphology of single-thread and meandering; with no flow deflecting node distributed in the upper or middle part of the river reach; the hydraulic geometric coefficient is less than 4; the longitudinal gradient is greater than 12‰, the clay content of the concave bank is greater than 9.5%, and the median diameter of the bed sediment is greater than 0.158 mm. From the Navier-Stokes equation ,the calculation formula of the bending radius of flow dynamic axis is deduced and then the roles of these control factors on restricting the migration of the flow dynamic axis and the formation of the barrier river reach are analyzed. The barrier river reach is considered Such. When the ratio of the migration force of the flow dynamic boundary is less than 1 under different flow
文摘In this paper,we investigate the existence of solutions and analyze the large-time behavior for Gurtin-Maccamy population model involving conformable fractional derivatives.As a preliminary step,we construct a generic structure of the solution associated with our proposed model by utilizing some basic properties and tools of conformable fractional calculus.We establish the existence of a unique solution of the given model with the given initial conditions.At last,by using the upper and lower solutions for the characteristic equation,we define the upper and lower boundaries for the obtained solution and describe the large-time behavior of the total population.
基金supported by four NSFC grants (Nos.41473006, 41572091, 41673011, 41772007)one grant from the State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences (Wuhan)
文摘Lower Triassic conodont biostratigraphy has been well studied around the world in the past decades, but the Induan-Olenekian boundary （IOB） remains undecided. The Novispathodus waageni group has been taxonomically re-assessed based on abundant new materials from the Jianshi and Chaohu sections, South China. New study shows that Nv. waageni typically possesses： （1） an approximately equi-dimentional P1 blade element, （2） an accurate upper profile with denticle height descending in both directions, （3） a denticulated posterior edge （lower denticles posterior of the highest denticle）, and （4） a round basal cavity outline. Of the three proposed subspecies of the waageni species, both Nv. waageni waageni （Sweet, 1970） and Nv. w. eowaageni （Zhao and Orchard, 2005） are valid, and the former differs clearly from Nv. w. eowaageni in having （1） a slightly higher length/height ratio （holotype=1.30 ： 1.23）, （2） a thicker blade, sometimes with medial thickening, （3） fewer （broader） denticles per unit length, （4） generally recurved denticles, not straight and upright, （5） highest denticles closer to posterior, （6） common differentiation of a posterior cusp, and （7） more sinuous basal profile, with increased posterior upturning. A third subspecies illustrated as Nv. waageni n. subsp. A sensu Goudemand, 2014 is not conspecific with older individuals of Nv. w. eowaageni, and also cannot be as- signed to the Nv. waageni group. Abundant new materials demonstrate a clear ontogenic process for Nv. w. eowaageni, indicating that Nv. w. eowaageni occurring in the Induan-Olenekian boundary （IOB） succession is rather stable. Small, earlier individuals （i.e., those from Bed 225 in Jianshi） are referred to as Nv. w. eowaageni Morphotype A, and are thought to have likely evolved from Ns. dieneri Morphotype 3, and to be the precursor of mature elements ofNv. w. eowaageni. The first appearance datum of Nv. w. eowaageni therefore is an ideal mark defining the IOB.
基金Supported by National Natural Science Foundation of China under Grant No.10801027Fok Ying Tong Education Foundation under Grant No.121003
文摘In this paper,we define lower-dimensional volumes of spin manifolds with boundary.We compute thelower-dimensional volume Vol^((2,2)) for 5-dimensional and 6-dimensional spin manifolds with boundary and we also getthe Kastler-Kalau-Walze type theorem in this case.
基金NSAF(Grant Nos.U1530402 and U1930401)National Natural Science Foundation of China(NSFC,Grant No.17N1051-0213)+2 种基金the National Science Foundation-Earth Sciences(EAR-1128799)the Department of Energy-Geosciences(DE-FG02-94ER14466)HPCAT operations are supported by DOE-NNSA’s Office of Experimental Sciences.APS is supported by DOEBES,under contract No.DE-AC02-06CH11357.
文摘The pyrite-type FeO_(2)and FeO_(2)H were synthesized at the pressure-temperature conditions relevant to Earth’s deep lower mantle.Through the water-iron reaction,the pyrite-phase is a good candidate to explain the chemical heterogeneities and seismological anomalies at the bottom of the mantle.The solid solution of pyrite-type FeO_(2)and FeO_(2)H,namely the FeO_(2)Hx(0≤x≤1),is particularly interesting and introduces puzzling chemical states for both the O and H atoms in the deep mantle.While the role of H in the FeO_(2)–FeO_(2)H system has been primarily investigated,discrepancies remain.In this work,we summarize recent progress on the pyrite-phase,including FeO_(2),FeO_(2)H,and FeO_(2)Hx,which is critical for understanding the water cycling,redox equilibria,and compositional heterogenicities in the deep lower mantle.
基金the State Basic Research Development Program (Grant No.G1999043604) the National Natural Science Foundation of China (Grant No. 50239040).
文摘Based on the clarifications of the deterioration characteristics of the lower Yellow River (LYR), the influence of river deterioration on flood discharging capacity is studied through theoretical derivation and analysis of field data. This study indicates that response of flood discharging capacity to river deterioration is nonlinear. Sediment depositions in the main channel cause the reductions of dominant discharge and thus the increase of initial flood stage. Reductions in the channel width result in the increases of the rising rate of flood stage and the decrease of flood discharging capacity.
基金Supported by the National Key Research and Development Program of China(Nos.2016YFC1401404,2017YFA0604102)the National Natural Science Foundation of China(Nos.41506015,41576013)+1 种基金the Zhejiang Provincial Natural Science Foundation(No.LY16D060001)the Open Research Fund of the State Key Laboratory of Estuarine and Coastal Research(No.SKLEC-KF201406)
文摘Oceanic turbulence plays an important role in coastal flow. However, as the effect of an uneven lower boundary on the adjacent turbulence is still not well understood, we explore the mechanics of nearshore turbulence with a turbulence-resolving numerical model known as a large-eddy-simulation model for an idealized scenario in a coastal region for which the lower boundary is a solid sinusoidal wave. The numerical simulation demonstrates how the mechanical energy of the current is transferred into local turbulence mixing, and shows the changes in turbulent intensity over the continuous phase change of the lower topography. The strongest turbulent kinetic energy is concentrated above the trough of the wavy surface. The turbulence mixing is mainly generated by the shear forces; the magnitude of shear production has a local maximum over the crest of the seabed topography, and there is an asymmetry in the shear production between the leeward and windward slopes. The numerical results are consistent with results from laboratory experiments. Our analysis provides an important insight into the mechanism of turbulent kinetic energy production and development.
文摘This paper presents new existence results for singular discrete boundary value problems. In particular our nonlinearity may be singular in its dependent variable and is allowed to change sign.
