In space,surface tension plays an important role and liquid behaviour is much different from that on the ground.The static capillary surfaces in the annular space between two coaxial cones under microgravity are studi...In space,surface tension plays an important role and liquid behaviour is much different from that on the ground.The static capillary surfaces in the annular space between two coaxial cones under microgravity are studied in this paper.Theoretical expressions of the capillary surfaces are derived and a procedure is developed to predict the capillary surfaces based on the expressions.By considering various liquid contact angles,liquid volumes,and container geometries,numerical simulation with the volume of fluid method is carried out and microgravity experiments in Beijing Drop Tower are performed.The numerical and experimental results are in good agreement with theoretical predictions.Furthermore,capillary surfaces in an annulus with constant cross-section and in a spherical tank with a central column are also discussed.z3 will decrease obviously with the increase of the liquid contact angle.The theoretical models and findings will be great helpful for liquid management in space and the evaluation of propellant residue.展开更多
Field emission electric propulsion(FEEP) thrusters possess excellent characteristics, such as high specific impulse, low power requirements, compact size and precise pointing capabilities,making them ideal propulsion ...Field emission electric propulsion(FEEP) thrusters possess excellent characteristics, such as high specific impulse, low power requirements, compact size and precise pointing capabilities,making them ideal propulsion devices for micro-nano satellites. However, the detection of certain aspects, such as the evolution process of the liquid cone and the physical quantities at the cone apex, proves challenging due to the minute size of the needle tip and the vacuum environment in which they operate. Consequently, this paper introduces a computational fluid dynamics(CFD) model to gain insight into the formation process of the liquid cone on the tip apex of indium FEEP. The CFD model is based on electrohydrodynamic(EHD) equations and the volume of fluid(VOF) method. The entire cone formation process can be divided into three stages, and the time-dependent characteristics of the physical quantities at the cone apex are investigated. The influences of film thickness, apex radius size and applied voltage are compared.The results indicate a gradual increase in the values of electrostatic stress and surface tension stress at the cone apex over an initial period, followed by a rapid escalation within a short duration.Apex configurations featuring a small radius, thick film and high voltage exhibit a propensity for liquid cone formation, and the cone growth time decreases as the film thickness increases.Moreover, some unstable behavior is observed during the cone formation process.展开更多
The present paper examines the temperature-dependent viscosity and thermal conductivity of a micropolar silver(Ag)−Magnesium oxide(MgO)hybrid nanofluid made of silver and magnesium oxide over a rotating vertical cone,...The present paper examines the temperature-dependent viscosity and thermal conductivity of a micropolar silver(Ag)−Magnesium oxide(MgO)hybrid nanofluid made of silver and magnesium oxide over a rotating vertical cone,with the influence of transverse magnetic field and thermal radiation.The physical flow problem has been modeled with coupled partial differential equations.We apply similarity transformations to the nondimensionalized equations,and the resulting nonlinear differential equations are solved using overlapping grid multidomain spectral quasilinearization method.The flow behavior for the fluid is scrutinized under the impact of diverse physical constraints,which are illustrated graphically.The results of the skin friction coefficient and Nusselt number varying different flow parameters are presented in the form of a table.It is observed that the main flow of the hybrid nanofluid,nano particle fraction of silver and Magnesium/water,enhances compared to the mono-nano fluid MgO as the coupling number increases.The application of studies like this can be found in the atomization process of liquids such as centrifugal pumps,viscometers,rotors,fans.展开更多
Pinus is an economically and ecologically important genus whose members are dominant components globally in low-latitude mountainous and mid-latitude temperate forests.Pinus species richness is currently concentrated ...Pinus is an economically and ecologically important genus whose members are dominant components globally in low-latitude mountainous and mid-latitude temperate forests.Pinus species richness is currently concentrated in subtropical mid-low latitudes of the Northern Hemisphere,differing from the latitudinal diversity gradient mostly recognized in woody angiosperms.How the present pattern was developing in Earth's past is still poorly studied,particularly in eastern Asia.Here,a new fossil species,Pinus shengxianica sp.nov.is described based on a fossil seed cone from the Late Miocene Shengxian Formation in Zhejiang,southeast China.A co-occurring cone is recognized as a known fossil species,Pinus speciosa Li.Extensive comparison of extant and fossil members of Pinus suggests P.shengxianica shares a striking cone similarity to Pinus merkusii and Pinus latteri(subsection Pinus)from tropical Southeast Asia in having annular bulges around the umbo on the apophysis.The morphological resemblance indicates these two extant low-latitude pines probably possess a close affinity with the present newly-discovered P.shengxianica and originated from East Asian mid-low latitude ancestors during this generic re-diversification in the Miocene.This scenario is consistent with the evolutionary trajectory reflected by the pine fossil history and molecular data,marking the Miocene as a key period for the origin and evolution of most extant pines globally.The co-occurrences of diverse conifers and broadleaved angiosperms preferring diverse niches demonstrate Late Miocene eastern Zhejiang was one of the hot spots for coniferophyte diversity and hosted a needled-broadleaved mixed forest with complex vegetation structure and an altitudinal zonation.展开更多
As the reproductive organ of the endangered species Fokienia hodginsii,the size of the cones is a constraint on the reproductive renewal of the population.In this study,the molecular basis of the influence of cone siz...As the reproductive organ of the endangered species Fokienia hodginsii,the size of the cones is a constraint on the reproductive renewal of the population.In this study,the molecular basis of the influence of cone size on F.hodginsii was elucidated by comparing the phenotype,biochemistry,and transcriptome of two cultivars of F.hodginsii(‘FJ431’and‘FJ415’).The two cultivars differed significantly in cone size,with FJ431 having a significantly larger cone size and weight than FJ415,1.32 and 1.90 times that of FJ415,respectively.RNA-Seq analysis of both cultivars retrieved 75,940 genes whose approximate functions were classified as the pathway of response to endogenous stimulus and response to hormone and showed significant differences in the auxin-activated signaling pathway,particularly the MAPK signaling pathway-plant.Furthermore,the endogenous IAA content was significantly higher in FJ431 than in FJ415,and 1.58 and 1.29 times more IAA was present in immature and mature cones,respectively.Moreover,exogenous IAA treatment significantly induced the expression of the MAPK pathway-related gene TRINITY_DN10564_c0_g1 and significantly inhibited the expression of the MAPK pathwayrelated gene TRINITY_DN17056_c0_g1.Our work suggests that IAA can affect the cone size of F.hodginsii,most probably through the MAPK pathway.This has high theoretical and practical significance for the improvement of genetic breeding and the further cultivation of quality germplasm resources of F.hodginsii.展开更多
In this research, we explore the properties and applications of the mapping cone and its variant, the pinched mapping cone. The mapping cone is a construction that arises naturally in algebraic topology and is used to...In this research, we explore the properties and applications of the mapping cone and its variant, the pinched mapping cone. The mapping cone is a construction that arises naturally in algebraic topology and is used to study the homotopy type of spaces. It has several key properties, including its homotopy equivalence to the cofiber of a continuous map, and its ability to compute homotopy groups using the long exact sequence associated with the cofiber. We also provide an overview of the properties and applications of the mapping cone and the pinched mapping cone in algebraic topology. This work highlights the importance of these constructions in the study of homotopy theory and the calculation of homotopy groups. The study also points to the potential for further research in this area which includes the study of higher homotopy groups and the applications of these constructions to other areas of mathematics.展开更多
In order to obtain the reasonable undrained shear strength Su for geotechnical analyses of bridge foundations in Yangtze River floodplain clayey soils, a site-specific study is conducted using the imported piezocone p...In order to obtain the reasonable undrained shear strength Su for geotechnical analyses of bridge foundations in Yangtze River floodplain clayey soils, a site-specific study is conducted using the imported piezocone penetration test (CPTu) with dissipation phases at the Fourth Nanjing Yangtze River Bridge construction sites. Taking the values of Su from laboratory tests as references, several existing Su-predicted methods based on CPTu are compared and evaluated. To verify the presented cone factor Nk, additional test sites are selected and examined. The results show that the values of cone factors such as Nkt, Nke, and Nau, depend on the shear test mode and disturbance. Generally, the values of Nke show more scattering than those of Nkt and N△u. For the stratified and layered sediments of the Yangtze River floodplain, it is recommended using the net cone resistance qT to estimate Su and the preliminary cone factor values Nkt are from 7 to 16, with an average of 11. It is also confirmed that the CPTu test, as a new technique in site characterization, can present reasonable parameters for bridge foundations.展开更多
Cone penetration testing (CPT) is an extensively utilized and cost effective tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic cone into penetrable soils and recordi...Cone penetration testing (CPT) is an extensively utilized and cost effective tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic cone into penetrable soils and recording the resistance to the cone tip (q<sub>c</sub> value). The measured q<sub>c</sub> values (after correction for the pore water pressure) are utilized to estimate soil type and associated soil properties based predominantly on empirical correlations. The most common cone tips have associated areas of 10 cm<sup>2</sup> and 15 cm<sup>2</sup>. Investigators also utilized significantly larger cone tips (33 cm<sup>2</sup> and 40 cm<sup>2</sup>) so that gravelly soils can be penetrated. Small cone tips (2 cm<sup>2</sup> and 5 cm<sup>2</sup>) are utilized for shallow soil investigations. The cone tip resistance measured at a particular depth is affected by the values above and below the depth of interest which results in a smoothing or blurring of the true bearing values. Extensive work has been carried out in mathematically modelling the smoothing function which results in the blurred cone bearing measurements. This paper outlines a technique which facilitates estimating the dominant parameters of the cone smoothing function from processing real cone bearing data sets. This cone calibration technique is referred to as the so-called CPSPE algorithm. The mathematical details of the CPSPE algorithm are outlined in this paper along with the results from a challenging test bed simulation.展开更多
The author gives a dual characterization of solid cones in locally convex spaces. From this the author obtains some criteria for judging convex cones to be solid in various kinds of locally convex spaces. Using a gene...The author gives a dual characterization of solid cones in locally convex spaces. From this the author obtains some criteria for judging convex cones to be solid in various kinds of locally convex spaces. Using a general expression of the interior of a solid cone, the author obtains a number of necessary and sufficient conditions for convex cones to be solid in the framework of Banach spaces. In particular, the author gives a dual relationship between solid cones and generalized sharp cones. The related known results are improved and extended.展开更多
A multicriterion clustering model with cone dominated structure is established and the concept of cone-efficient clustering is put forward. The properties of cone-efficient clustering are disscussed, and a method to s...A multicriterion clustering model with cone dominated structure is established and the concept of cone-efficient clustering is put forward. The properties of cone-efficient clustering are disscussed, and a method to solve multicriterion clustering is put forward.The model of Ref.[3] is a special case of that proposed in this paper.展开更多
Novel headstand pyrocarbon cones (HPCs) with hollow structure were developed on the surfaces of pyrocarbon layers of the carbon/carbon (C/C) composites at 650-750 °C by the electromagnetic-field-assisted chem...Novel headstand pyrocarbon cones (HPCs) with hollow structure were developed on the surfaces of pyrocarbon layers of the carbon/carbon (C/C) composites at 650-750 °C by the electromagnetic-field-assisted chemical vapor deposition in the absence of catalysts. The fine microstructures of the HPCs were characterized by high-resolution transmission electron microscopy. The results show that the textural features of the HPCs directly transfer from turbostratic structure in roots to a well-ordered high texture in stems. And the degree of high texture ordering decreases gradually from the stem to the tail of the HPCs. The formation mechanism of the HPCs was inferred as the comprehensive effect of polarization induction on electromagnetic fields and particle-filler property under disruptive discharge.展开更多
基金supported by the China Manned Space Engineering Program(Fluid Physics Experimental Rack and the Priority Research Program of Space Station)the Natural Science Foundation Project(Grant No.12032020).
文摘In space,surface tension plays an important role and liquid behaviour is much different from that on the ground.The static capillary surfaces in the annular space between two coaxial cones under microgravity are studied in this paper.Theoretical expressions of the capillary surfaces are derived and a procedure is developed to predict the capillary surfaces based on the expressions.By considering various liquid contact angles,liquid volumes,and container geometries,numerical simulation with the volume of fluid method is carried out and microgravity experiments in Beijing Drop Tower are performed.The numerical and experimental results are in good agreement with theoretical predictions.Furthermore,capillary surfaces in an annulus with constant cross-section and in a spherical tank with a central column are also discussed.z3 will decrease obviously with the increase of the liquid contact angle.The theoretical models and findings will be great helpful for liquid management in space and the evaluation of propellant residue.
基金supported by National Natural Science Foundation of China(No.52075334)。
文摘Field emission electric propulsion(FEEP) thrusters possess excellent characteristics, such as high specific impulse, low power requirements, compact size and precise pointing capabilities,making them ideal propulsion devices for micro-nano satellites. However, the detection of certain aspects, such as the evolution process of the liquid cone and the physical quantities at the cone apex, proves challenging due to the minute size of the needle tip and the vacuum environment in which they operate. Consequently, this paper introduces a computational fluid dynamics(CFD) model to gain insight into the formation process of the liquid cone on the tip apex of indium FEEP. The CFD model is based on electrohydrodynamic(EHD) equations and the volume of fluid(VOF) method. The entire cone formation process can be divided into three stages, and the time-dependent characteristics of the physical quantities at the cone apex are investigated. The influences of film thickness, apex radius size and applied voltage are compared.The results indicate a gradual increase in the values of electrostatic stress and surface tension stress at the cone apex over an initial period, followed by a rapid escalation within a short duration.Apex configurations featuring a small radius, thick film and high voltage exhibit a propensity for liquid cone formation, and the cone growth time decreases as the film thickness increases.Moreover, some unstable behavior is observed during the cone formation process.
文摘The present paper examines the temperature-dependent viscosity and thermal conductivity of a micropolar silver(Ag)−Magnesium oxide(MgO)hybrid nanofluid made of silver and magnesium oxide over a rotating vertical cone,with the influence of transverse magnetic field and thermal radiation.The physical flow problem has been modeled with coupled partial differential equations.We apply similarity transformations to the nondimensionalized equations,and the resulting nonlinear differential equations are solved using overlapping grid multidomain spectral quasilinearization method.The flow behavior for the fluid is scrutinized under the impact of diverse physical constraints,which are illustrated graphically.The results of the skin friction coefficient and Nusselt number varying different flow parameters are presented in the form of a table.It is observed that the main flow of the hybrid nanofluid,nano particle fraction of silver and Magnesium/water,enhances compared to the mono-nano fluid MgO as the coupling number increases.The application of studies like this can be found in the atomization process of liquids such as centrifugal pumps,viscometers,rotors,fans.
基金This work was funded in part by the National Natural Science Foundation of China(No.41872017)the Foundation of State Key Laboratory of Palaeobiology and Stratigraphy(Nanjing Institute of Geology and Palaeontology,CAS)(Nos.193113 and 183125)+1 种基金the Fundamental Research Funds for the Central Universities,CHD(Nos.300102272206,300102271402 and 300102271403)the Undergraduate Innovation and Entrepreneurship Project(No.S202210710194).
文摘Pinus is an economically and ecologically important genus whose members are dominant components globally in low-latitude mountainous and mid-latitude temperate forests.Pinus species richness is currently concentrated in subtropical mid-low latitudes of the Northern Hemisphere,differing from the latitudinal diversity gradient mostly recognized in woody angiosperms.How the present pattern was developing in Earth's past is still poorly studied,particularly in eastern Asia.Here,a new fossil species,Pinus shengxianica sp.nov.is described based on a fossil seed cone from the Late Miocene Shengxian Formation in Zhejiang,southeast China.A co-occurring cone is recognized as a known fossil species,Pinus speciosa Li.Extensive comparison of extant and fossil members of Pinus suggests P.shengxianica shares a striking cone similarity to Pinus merkusii and Pinus latteri(subsection Pinus)from tropical Southeast Asia in having annular bulges around the umbo on the apophysis.The morphological resemblance indicates these two extant low-latitude pines probably possess a close affinity with the present newly-discovered P.shengxianica and originated from East Asian mid-low latitude ancestors during this generic re-diversification in the Miocene.This scenario is consistent with the evolutionary trajectory reflected by the pine fossil history and molecular data,marking the Miocene as a key period for the origin and evolution of most extant pines globally.The co-occurrences of diverse conifers and broadleaved angiosperms preferring diverse niches demonstrate Late Miocene eastern Zhejiang was one of the hot spots for coniferophyte diversity and hosted a needled-broadleaved mixed forest with complex vegetation structure and an altitudinal zonation.
基金The“Eagle Program”of Fujian Province,funded by the Department of Human Resources and Social Security of Fujian ProvinceThe“Fujian Cypress 1st Generation Core Breeding Population Construction Research”(No.2021R1010004),funded by the Department of Science and Technology of Fujian Province.
文摘As the reproductive organ of the endangered species Fokienia hodginsii,the size of the cones is a constraint on the reproductive renewal of the population.In this study,the molecular basis of the influence of cone size on F.hodginsii was elucidated by comparing the phenotype,biochemistry,and transcriptome of two cultivars of F.hodginsii(‘FJ431’and‘FJ415’).The two cultivars differed significantly in cone size,with FJ431 having a significantly larger cone size and weight than FJ415,1.32 and 1.90 times that of FJ415,respectively.RNA-Seq analysis of both cultivars retrieved 75,940 genes whose approximate functions were classified as the pathway of response to endogenous stimulus and response to hormone and showed significant differences in the auxin-activated signaling pathway,particularly the MAPK signaling pathway-plant.Furthermore,the endogenous IAA content was significantly higher in FJ431 than in FJ415,and 1.58 and 1.29 times more IAA was present in immature and mature cones,respectively.Moreover,exogenous IAA treatment significantly induced the expression of the MAPK pathway-related gene TRINITY_DN10564_c0_g1 and significantly inhibited the expression of the MAPK pathwayrelated gene TRINITY_DN17056_c0_g1.Our work suggests that IAA can affect the cone size of F.hodginsii,most probably through the MAPK pathway.This has high theoretical and practical significance for the improvement of genetic breeding and the further cultivation of quality germplasm resources of F.hodginsii.
文摘In this research, we explore the properties and applications of the mapping cone and its variant, the pinched mapping cone. The mapping cone is a construction that arises naturally in algebraic topology and is used to study the homotopy type of spaces. It has several key properties, including its homotopy equivalence to the cofiber of a continuous map, and its ability to compute homotopy groups using the long exact sequence associated with the cofiber. We also provide an overview of the properties and applications of the mapping cone and the pinched mapping cone in algebraic topology. This work highlights the importance of these constructions in the study of homotopy theory and the calculation of homotopy groups. The study also points to the potential for further research in this area which includes the study of higher homotopy groups and the applications of these constructions to other areas of mathematics.
基金The National Natural Science Foundation of China(No.40702047)
文摘In order to obtain the reasonable undrained shear strength Su for geotechnical analyses of bridge foundations in Yangtze River floodplain clayey soils, a site-specific study is conducted using the imported piezocone penetration test (CPTu) with dissipation phases at the Fourth Nanjing Yangtze River Bridge construction sites. Taking the values of Su from laboratory tests as references, several existing Su-predicted methods based on CPTu are compared and evaluated. To verify the presented cone factor Nk, additional test sites are selected and examined. The results show that the values of cone factors such as Nkt, Nke, and Nau, depend on the shear test mode and disturbance. Generally, the values of Nke show more scattering than those of Nkt and N△u. For the stratified and layered sediments of the Yangtze River floodplain, it is recommended using the net cone resistance qT to estimate Su and the preliminary cone factor values Nkt are from 7 to 16, with an average of 11. It is also confirmed that the CPTu test, as a new technique in site characterization, can present reasonable parameters for bridge foundations.
文摘Cone penetration testing (CPT) is an extensively utilized and cost effective tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic cone into penetrable soils and recording the resistance to the cone tip (q<sub>c</sub> value). The measured q<sub>c</sub> values (after correction for the pore water pressure) are utilized to estimate soil type and associated soil properties based predominantly on empirical correlations. The most common cone tips have associated areas of 10 cm<sup>2</sup> and 15 cm<sup>2</sup>. Investigators also utilized significantly larger cone tips (33 cm<sup>2</sup> and 40 cm<sup>2</sup>) so that gravelly soils can be penetrated. Small cone tips (2 cm<sup>2</sup> and 5 cm<sup>2</sup>) are utilized for shallow soil investigations. The cone tip resistance measured at a particular depth is affected by the values above and below the depth of interest which results in a smoothing or blurring of the true bearing values. Extensive work has been carried out in mathematically modelling the smoothing function which results in the blurred cone bearing measurements. This paper outlines a technique which facilitates estimating the dominant parameters of the cone smoothing function from processing real cone bearing data sets. This cone calibration technique is referred to as the so-called CPSPE algorithm. The mathematical details of the CPSPE algorithm are outlined in this paper along with the results from a challenging test bed simulation.
基金the National Natural Science Foundation of China(10571035)
文摘The author gives a dual characterization of solid cones in locally convex spaces. From this the author obtains some criteria for judging convex cones to be solid in various kinds of locally convex spaces. Using a general expression of the interior of a solid cone, the author obtains a number of necessary and sufficient conditions for convex cones to be solid in the framework of Banach spaces. In particular, the author gives a dual relationship between solid cones and generalized sharp cones. The related known results are improved and extended.
文摘A multicriterion clustering model with cone dominated structure is established and the concept of cone-efficient clustering is put forward. The properties of cone-efficient clustering are disscussed, and a method to solve multicriterion clustering is put forward.The model of Ref.[3] is a special case of that proposed in this paper.
基金Project (2011CB605801) supported by the National Basic Research Program of ChinaProject (2011M500127) supported by the China Postdoctoral Science Foundation+1 种基金Projects (50802115, 51102089) supported by the National Natural Science Foundation of ChinaProject supported by the Postdoctoral Fund of the Central South University, China
文摘Novel headstand pyrocarbon cones (HPCs) with hollow structure were developed on the surfaces of pyrocarbon layers of the carbon/carbon (C/C) composites at 650-750 °C by the electromagnetic-field-assisted chemical vapor deposition in the absence of catalysts. The fine microstructures of the HPCs were characterized by high-resolution transmission electron microscopy. The results show that the textural features of the HPCs directly transfer from turbostratic structure in roots to a well-ordered high texture in stems. And the degree of high texture ordering decreases gradually from the stem to the tail of the HPCs. The formation mechanism of the HPCs was inferred as the comprehensive effect of polarization induction on electromagnetic fields and particle-filler property under disruptive discharge.