In the space plasma environment, primary discharge may occur on the solar array and evolve into a destructive sustained arc, which threatens the safe operation of the spacecraft. Based on the plasma expansion fluid th...In the space plasma environment, primary discharge may occur on the solar array and evolve into a destructive sustained arc, which threatens the safe operation of the spacecraft. Based on the plasma expansion fluid theory, a new multicomponent plasma expansion model is proposed in this study, which takes into account the effects of ion species, ion number, initial discharge current, and Low Earth Orbit(LEO) plasma environment. The expansion simulation of single-component and multicomponent ions is carried out respectively, and the variations of plasma number density, expansion distance, and speed during the expansion process are obtained.Compared with the experimental results, the evolution of propagation distance and speed is closed and the error is within a reasonable range, which verifies the validity and rationality of the model. The propagation characteristics of the primary discharge on the solar array surface and the influence of the initial value on the maximum propagation distance and the propagation current peaks are investigated. This study can provide important theoretical support for the propagation and evolution of the primary discharge and the key behavior of the transition to secondary discharge on spacecraft solar array.展开更多
With the increasing penetration of wind and solar energies,the accompanying uncertainty that propagates in the system places higher requirements on the expansion planning of power systems.A source-grid-load-storage co...With the increasing penetration of wind and solar energies,the accompanying uncertainty that propagates in the system places higher requirements on the expansion planning of power systems.A source-grid-load-storage coordinated expansion planning model based on stochastic programming was proposed to suppress the impact of wind and solar energy fluctuations.Multiple types of system components,including demand response service entities,converter stations,DC transmission systems,cascade hydropower stations,and other traditional components,have been extensively modeled.Moreover,energy storage systems are considered to improve the accommodation level of renewable energy and alleviate the influence of intermittence.Demand-response service entities from the load side are used to reduce and move the demand during peak load periods.The uncertainties in wind,solar energy,and loads were simulated using stochastic programming.Finally,the effectiveness of the proposed model is verified through numerical simulations.展开更多
Historically,streamer-to-leader transition studies mainly focused on the rod-plane gap and low altitude analysis,with limited attention paid to the sphere-plane gap at high altitude analysis.In this work,sphere-plane ...Historically,streamer-to-leader transition studies mainly focused on the rod-plane gap and low altitude analysis,with limited attention paid to the sphere-plane gap at high altitude analysis.In this work,sphere-plane gap discharge tests were carried out under the gap distance of 5 m at the Qinghai Ultra High Voltage(UHV)test base at an altitude of 2200 m.The experiments measured the physical parameters such as the discharge current,electric field intensity and instantaneous optical power.The duration of the dark period and the critical charge of streamer-toleader transition were obtained at high altitude.Based on radial thermal expansion of the streamer stem,we established a modified streamer-to-leader transition model of the sphere-plane gap discharge at high altitude,and calculated the stem temperature,stem radii and the duration of streamer-to-leader transition.Compared with the measured duration of sphere-plane electrode discharge at an altitude of 2200 m,the error rate of the modified model was 0.94%,while the classical model was 6.97%,demonstrating the effectiveness of the modified model.From the comparisons and analysis,several suggestions are proposed to improve the numerical model for further quantitative investigations of the leader inception.展开更多
Background:With the expansion of urban areas,the remnants of forested areas play a crucial role in preserving biodiversity in urban environments.This study aimed to explore the impact of spatiotemporal urban expansion...Background:With the expansion of urban areas,the remnants of forested areas play a crucial role in preserving biodiversity in urban environments.This study aimed to explore the impact of spatiotemporal urban expansion on the networks of leaf traits in woody plants within remnant forest patches,thereby enhancing our understanding of plant adaptive strategies and contributing to the conservation of urban biodiversity.Methods:Our study examined woody plants within 120 sample plots across 15 remnant forest patches in Guiyang,China.We constructed leaf trait networks (LTNs) based on 26 anatomical,structural,and compositional leaf traits and assessed the effects of the spatiotemporal dynamics of urban expansion on these LTNs.Results and conclusions:Our results indicate that shrubs within these patches have greater average path lengths and diameters than trees.With increasing urban expansion intensity,we observed a rise in the edge density of the LTN-shrubs.Additionally,modularity within the networks of shrubs decreased as road density and urban expansion intensity increased,and increases in the average path length and average clustering coefficient for shrubs were observed with a rise in the composite terrain complexity index.Notably,patches subjected to‘leapfrog’expansion exhibited greater average patch length and diameter than those experiencing edge growth.Stomatal traits were found to have high degree centrality within these networks,signifying their substantial contribution to multiple functions.In urban remnant forests,shrubs bolster their resilience to variable environmental pressures by augmenting the complexity of their leaf trait networks.展开更多
Silicon is considered to be one of the most promising anode materials for lithium-ion batteries(LIBs),but its application is limited by the large volume expansion during alloying and dealloying.The constructing of a h...Silicon is considered to be one of the most promising anode materials for lithium-ion batteries(LIBs),but its application is limited by the large volume expansion during alloying and dealloying.The constructing of a high-performance solid electrolyte interface(SEI) film on the surface of the anode material is considered to be one of the effective strategies to mitigate volume expansion of silicon-based anode.In this study,an intermittent discharge strategy which helps to improve the utilization efficiency of electrolyte additive of lithium difluorobisoxalate phosphate(LiDFBOP) is proposed to construct a highly conductive and dense SEI film.The results of electrochemical and physical characterization and theoretical calculations show that the intermittent discharge in the voltage range from open circuit voltage(OCV) to 1.8 V facilitates the diffusion of the soluble products,creates the conditions for the repeated direct contact between Si@C anode and LiDFBOP additive,increases the decomposition of LiDFBOP additive,and thus produces a uniform,dense and inorganics-rich(Li_(2)C_(2)O_(4),LiF and Li_(x)PO_yF_z) SEI film.Subsequently,this SEI film helps to ensure the even intercalation/de-intercalation of Li^(+) in the SEI film and the homogeneous diffusion of Li^(+) inside the Si particles,decreasing the internal stresses and anisotropic phase transitions,maintaining the integrity of Si particles,inhibiting the volume expansion and thu s improving the electrochemical performance of cells.This study not only improves the utilization efficiency of expensive additives through a simply and low-cost method,but also enriches the strategy to improve the electrochemical performance of Si@C anode through interfacial engineering.展开更多
The resolution by Chen and Sun of divergent Chapman-Enskog expansion problem will not only build a unified foundation for non-equilibrium dynamics modeling at all Mach number and Knudsen number, but also shed light to...The resolution by Chen and Sun of divergent Chapman-Enskog expansion problem will not only build a unified foundation for non-equilibrium dynamics modeling at all Mach number and Knudsen number, but also shed light to a large class of difficult theoretical problems involving divergent expansion on strong nonlinearity.展开更多
Aim To determine the stress on wall of the spherical cavity while the spherical cavity expanding in concrete. Methods In Eulerian coordinate, the dimensionless radial stress equations were derived for the sphericall...Aim To determine the stress on wall of the spherical cavity while the spherical cavity expanding in concrete. Methods In Eulerian coordinate, the dimensionless radial stress equations were derived for the spherically symmetric, cavity expansion problem in plastic and elastic region of concrete by means of the similarity transformation. In the equations, Mohr Coulomb yield criterion was used.Results The dimensionless radial stress profiles were obtained. The relation between the dimensionless radial stress and the locked volumetric strain was analysed.Conclusion The test results show that the relative error between the model, which is applied in the closed form penetration equations that are developed, and the test data is less than 15.8%.展开更多
In this article,the authors obtain an inequality of homogeneous expansion for f,where f is a quasi-convex mapping(including quasi-convex mapping of type A and quasi-convex mapping of type B)defined on the open unit po...In this article,the authors obtain an inequality of homogeneous expansion for f,where f is a quasi-convex mapping(including quasi-convex mapping of type A and quasi-convex mapping of type B)defined on the open unit polydisk in C n .Meanwhile,the authors also investigate its application.展开更多
In this article, first, a sufficient condition for a starlike mapping of order a f（x） defined on the unit ball in a complex Banach space is given. Second, the sharp estimate of the third homogeneous expansion for f ...In this article, first, a sufficient condition for a starlike mapping of order a f（x） defined on the unit ball in a complex Banach space is given. Second, the sharp estimate of the third homogeneous expansion for f is established as well, where f（z） = （f1（z）, f2（z）,..., fn（z））＇ is a starlike mapping of order a or a normalized biholomorphic starlike mapping defined on the unit polydisk in Cn, and D2fk（0）（z2） /2i= zk（∑l=1^b akzzl）, k = 2t l=1 k = 1, 2,..., n. Our result states that the Bieberbaeh conjecture in several complex variables （the case of the third homogeneous expansion for starlike mappings of order α and biholomorphic starlike mappings） is partly proved.展开更多
In this paper the authors give a definite meaning to any formal trigonometrical series and generalize it to all abstract Hilbert space. Then in the case L-2(-infinity + infinity) they discussed extensively the general...In this paper the authors give a definite meaning to any formal trigonometrical series and generalize it to all abstract Hilbert space. Then in the case L-2(-infinity + infinity) they discussed extensively the generalized expansion problem by Hermite functions, and applied to a non-strictly nonlinear hyperbolic system.展开更多
This paper considers a capacity expansion problem with budget constraint. Suppose each edge in the network has two attributes: capacity and the degree of difficulty. The difficulty degree of a tree T is the maximum. d...This paper considers a capacity expansion problem with budget constraint. Suppose each edge in the network has two attributes: capacity and the degree of difficulty. The difficulty degree of a tree T is the maximum. degree of difficulty of all edges in the tree and the cost for coping with the difficulty in a tree is a nondecreasing function about the difficulty degree of the tree. The authors need to increase capacities of some edges so that there is a spanning tree whose capacity can be increased to the maximum extent, meanwhile the total cost for increasing capacity as well as overcoming the difficulty in the spanning tree does not exceed a given budget D*. Suppose the cost for increasing capacity on each edge is a linear function about the increment of capacity, they transform this problem into solving some hybrid parametric spanning tree problems([1]) and propose a strongly polynomial algorithm.展开更多
The super-cell plane wave expansion method is employed to calculate band structures for the design of a siliconbased one-dimensional phononic crystal plate with large absolute forbidden bands. In this method, a low im...The super-cell plane wave expansion method is employed to calculate band structures for the design of a siliconbased one-dimensional phononic crystal plate with large absolute forbidden bands. In this method, a low impedance medium is introduced to replace the free stress boundary, which largely reduces the computational complexity. The dependence of band gaps on structural parameters is investigated in detail. To prove the validity of the super-cell plane wave expansion, the transmitted power spectra of the Lamb wave are calculated by using a finite element method. With the detailed computation, the band-gap of a one-dimensional plate can be designed as required with appropriate structural parameters, which provides a guide to the fabrication of a Lamb wave phononic crystal.展开更多
Materials with the formula Yb2-xAlxMo3O12 （x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 0.9, 1.0, 1.1, 1.3, 1.5, and 1.8） were synthesized and their structures, phase transitions, and hygroscopicity investigated using X-ray po...Materials with the formula Yb2-xAlxMo3O12 （x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 0.9, 1.0, 1.1, 1.3, 1.5, and 1.8） were synthesized and their structures, phase transitions, and hygroscopicity investigated using X-ray powder diffraction, Raman spectroscopy, and thermal analysis. It is shown that Yb2-xAlxMo3012 solid solutions crystallize in a single monoclinic phase for 1.7 〈 x 〈 2.0 and in a single orthorhombic phase for 0.0 〈 x 〈 0,4, and exhibit the characteristics of both monoclinic and orthorhombic structures outside these compositional ranges. The monoclinic to orthorhonlbic phase transition temperature of A12Mo3012 can be reduced by partial substitution of A13＋ by Yb3＋, and the Yb2-zAlxMo3012 （0.0 〈 x 〈 2.0） materials are hydrated at room temperature and contain two kinds of water species. One of these interacts strongly with and hinders the motions of the polyhedra, while the other does not. The partial substitution of A13＋ for Yb3＋ in Yb2Mo3012 decreases its hygroscopicity, and the linear thermal expansion coefficients after complete removal of water species are measured to be -9.1 x 10-6/K, -5.5 x 10-6/K, 5.74 x 10-6/K, and 9.5 x 10 6/K for Ybl.sAlo.2（MoO4）3, Yb1.6Alo.4（MoO4）3, Ybo.4All.6（Mo04）3, and Ybo.2Al1.8（MoO4）3, respectively.展开更多
This paper deals with the bending problem of rectangular plates with two opposite edges simply supported. It is proved that there exists no normed symplectic orthogonal eigenfunction system for the associated infinite...This paper deals with the bending problem of rectangular plates with two opposite edges simply supported. It is proved that there exists no normed symplectic orthogonal eigenfunction system for the associated infinite-dimensional Hamiltonian operator H and that the two block operators belonging to Hamiltonian operator H possess two normed symplectic orthogonal eigenfunction systems in some space. It is demonstrated by using the properties of the block operators that the above bending problem can be solved by the symplectic eigenfunction expansion theorem, thereby obtaining analytical solutions of rectangular plates with two opposite edges simply supported and the other two edges supported in any manner.展开更多
Based on a first order nonlinear ordinary differential equation with at most a sixth-degree nonlinear term which is extended from a type of elliptic equation, and by converting it into a new expansion form, this paper...Based on a first order nonlinear ordinary differential equation with at most a sixth-degree nonlinear term which is extended from a type of elliptic equation, and by converting it into a new expansion form, this paper proposes a new algebraic method to construct exact solutions for nonlinear evolution equations. Being concise and straightforward, the method is applied to modified Benjamin-Bona-Mahony （mBBM） model, and some new exact solutions to the system are obtained. The algorithm is of important significance in exploring exact solutions for other nonlinear evolution equations.展开更多
Recently the （G′/G）-expansion method was proposed to find the traveling wave solutions of nonlinear evolution equations. This paper shows that the （G′/G）-expansion method is a special form of the truncated Pain...Recently the （G′/G）-expansion method was proposed to find the traveling wave solutions of nonlinear evolution equations. This paper shows that the （G′/G）-expansion method is a special form of the truncated Painlev＇e expansion method by introducing an intermediate expansion method. Then the generalized （G′/G）-（G/G′） expansion method is naturally derived from the standpoint of the nonstandard truncated Painlev＇e expansion. The application of the generalized method to the mKdV equation shows that it extends the range of exact solutions obtained by using the （ G′/ G）-expansion method.展开更多
In this study,we propose a method for estimating the amount of expansion that occurs in subsea pipelines,which could be applied in the design of robust structures that transport oil and gas from offshore wells.We begi...In this study,we propose a method for estimating the amount of expansion that occurs in subsea pipelines,which could be applied in the design of robust structures that transport oil and gas from offshore wells.We begin with a literature review and general discussion of existing estimation methods and terminologies with respect to subsea pipelines.Due to the effects of high pressure and high temperature,the production of fluid from offshore wells is typically caused by physical deformation of subsea structures,e.g.,expansion and contraction during the transportation process.In severe cases,vertical and lateral buckling occurs,which causes a significant negative impact on structural safety,and which is related to on-bottom stability,free-span,structural collapse,and many other factors.In addition,these factors may affect the production rate with respect to flow assurance,wax,and hydration,to name a few.In this study,we developed a simple and efficient method for generating a reliable pipe expansion design in the early stage,which can lead to savings in both cost and computation time.As such,in this paper,we propose an applicable diagram,which we call the standard dimensionless ratio(SDR)versus virtual anchor length(LA)diagram,that utilizes an efficient procedure for estimating subsea pipeline expansion based on applied reliable scenarios.With this user guideline,offshore pipeline structural designers can reliably determine the amount of subsea pipeline expansion and the obtained results will also be useful for the installation,design,and maintenance of the subsea pipeline.展开更多
β-eucryptite powders are prepared by the sol-gel method through using tetraethoxysilane lithium nitrate and aluminum isopropoxide as starting materials. β-eucryptite ceramics are prepared by spark plasma sintering. ...β-eucryptite powders are prepared by the sol-gel method through using tetraethoxysilane lithium nitrate and aluminum isopropoxide as starting materials. β-eucryptite ceramics are prepared by spark plasma sintering. The effects of sintering temperature on the negative thermal expansion properties of the β-eucryptite are investigated by x-ray diffraction（XRD）, scanning electron microscopy, and thermal expansion test. The XRD results exhibit no change in the crystal structure of the sample prepared by different sintering processes. The negative thermal expansion properties increase with the increase of the sintering temperature. The coefficient of thermal expansion of β-eucryptite ceramics sintered at 1100℃ is calculated to be -4.93 × 10^（-6）℃^（-1）. Crystallization behaviors of the ceramics may play an important role in the increase of negative thermal expansion of β-eucryptite. High sintering temperature could improve the crystallization behaviors of the ceramics and reduce the residue glass phase, which can improve the negative thermal expansion properties of β-eucryptite ceramics.展开更多
Comparing with the resin bolt, the hydraulic expansion bolt has different anchoring mechanism and application advantage. According to the working mechanism of the hydraulic expansion bolt, its anchoring force is expre...Comparing with the resin bolt, the hydraulic expansion bolt has different anchoring mechanism and application advantage. According to the working mechanism of the hydraulic expansion bolt, its anchoring force is expressed in four forms including support anchoring force, tension anchoring force, expansion anchoring force and tangent anchoring force, and their values can be obtained on the basis of each calculation formula. Among them, the expansion anchoring force, which is the unique anchoring force of the hydraulic expansion bolt, can provide confining pressure to increase the strength of rock. Aiming at solving the problem of stability control in the soft rock roadway in Jinbaotun Coal Mine which has a double layer of 40 U-type sheds and cannot provide enough resistance support to control floor heave, the study reveals the mechanism of floor heave in the soft rock roadway, and designs the reasonable support parameters of the hydraulic expansion bolts. The observed results of floor convergence indicate that the hydraulic expansion bolts can prevent the development and flow of the plastic zone in the floor rock to control floor heave. Research results enrich the control technology in the soft rock roadway.展开更多
基金supported by National Natural Science Foundation of China (Nos. 51937004 and 51977002)sponsored by Beijing Nova Program (No. 20220484153)。
文摘In the space plasma environment, primary discharge may occur on the solar array and evolve into a destructive sustained arc, which threatens the safe operation of the spacecraft. Based on the plasma expansion fluid theory, a new multicomponent plasma expansion model is proposed in this study, which takes into account the effects of ion species, ion number, initial discharge current, and Low Earth Orbit(LEO) plasma environment. The expansion simulation of single-component and multicomponent ions is carried out respectively, and the variations of plasma number density, expansion distance, and speed during the expansion process are obtained.Compared with the experimental results, the evolution of propagation distance and speed is closed and the error is within a reasonable range, which verifies the validity and rationality of the model. The propagation characteristics of the primary discharge on the solar array surface and the influence of the initial value on the maximum propagation distance and the propagation current peaks are investigated. This study can provide important theoretical support for the propagation and evolution of the primary discharge and the key behavior of the transition to secondary discharge on spacecraft solar array.
基金supported by Science and Technology Project of SGCC(SGSW0000FZGHBJS2200070)。
文摘With the increasing penetration of wind and solar energies,the accompanying uncertainty that propagates in the system places higher requirements on the expansion planning of power systems.A source-grid-load-storage coordinated expansion planning model based on stochastic programming was proposed to suppress the impact of wind and solar energy fluctuations.Multiple types of system components,including demand response service entities,converter stations,DC transmission systems,cascade hydropower stations,and other traditional components,have been extensively modeled.Moreover,energy storage systems are considered to improve the accommodation level of renewable energy and alleviate the influence of intermittence.Demand-response service entities from the load side are used to reduce and move the demand during peak load periods.The uncertainties in wind,solar energy,and loads were simulated using stochastic programming.Finally,the effectiveness of the proposed model is verified through numerical simulations.
基金supported by National Natural Science Foundation of China(Scientific Funds for Young Scientists)(No.52007064)。
文摘Historically,streamer-to-leader transition studies mainly focused on the rod-plane gap and low altitude analysis,with limited attention paid to the sphere-plane gap at high altitude analysis.In this work,sphere-plane gap discharge tests were carried out under the gap distance of 5 m at the Qinghai Ultra High Voltage(UHV)test base at an altitude of 2200 m.The experiments measured the physical parameters such as the discharge current,electric field intensity and instantaneous optical power.The duration of the dark period and the critical charge of streamer-toleader transition were obtained at high altitude.Based on radial thermal expansion of the streamer stem,we established a modified streamer-to-leader transition model of the sphere-plane gap discharge at high altitude,and calculated the stem temperature,stem radii and the duration of streamer-to-leader transition.Compared with the measured duration of sphere-plane electrode discharge at an altitude of 2200 m,the error rate of the modified model was 0.94%,while the classical model was 6.97%,demonstrating the effectiveness of the modified model.From the comparisons and analysis,several suggestions are proposed to improve the numerical model for further quantitative investigations of the leader inception.
基金funded by the National Natural Science Foundation of China (No.32360418)the Guizhou Provincial Basic Research Program (Natural Science)(No.QianKeHeJiChu-ZK[2024]YiBan022)。
文摘Background:With the expansion of urban areas,the remnants of forested areas play a crucial role in preserving biodiversity in urban environments.This study aimed to explore the impact of spatiotemporal urban expansion on the networks of leaf traits in woody plants within remnant forest patches,thereby enhancing our understanding of plant adaptive strategies and contributing to the conservation of urban biodiversity.Methods:Our study examined woody plants within 120 sample plots across 15 remnant forest patches in Guiyang,China.We constructed leaf trait networks (LTNs) based on 26 anatomical,structural,and compositional leaf traits and assessed the effects of the spatiotemporal dynamics of urban expansion on these LTNs.Results and conclusions:Our results indicate that shrubs within these patches have greater average path lengths and diameters than trees.With increasing urban expansion intensity,we observed a rise in the edge density of the LTN-shrubs.Additionally,modularity within the networks of shrubs decreased as road density and urban expansion intensity increased,and increases in the average path length and average clustering coefficient for shrubs were observed with a rise in the composite terrain complexity index.Notably,patches subjected to‘leapfrog’expansion exhibited greater average patch length and diameter than those experiencing edge growth.Stomatal traits were found to have high degree centrality within these networks,signifying their substantial contribution to multiple functions.In urban remnant forests,shrubs bolster their resilience to variable environmental pressures by augmenting the complexity of their leaf trait networks.
基金Department of Education of Gansu Province: Industrial Support Plan Project (2022CYZC-23)National Natural Science Foundation of China (22269012)Gansu Key Research and Development Program (23YFGA0053)。
文摘Silicon is considered to be one of the most promising anode materials for lithium-ion batteries(LIBs),but its application is limited by the large volume expansion during alloying and dealloying.The constructing of a high-performance solid electrolyte interface(SEI) film on the surface of the anode material is considered to be one of the effective strategies to mitigate volume expansion of silicon-based anode.In this study,an intermittent discharge strategy which helps to improve the utilization efficiency of electrolyte additive of lithium difluorobisoxalate phosphate(LiDFBOP) is proposed to construct a highly conductive and dense SEI film.The results of electrochemical and physical characterization and theoretical calculations show that the intermittent discharge in the voltage range from open circuit voltage(OCV) to 1.8 V facilitates the diffusion of the soluble products,creates the conditions for the repeated direct contact between Si@C anode and LiDFBOP additive,increases the decomposition of LiDFBOP additive,and thus produces a uniform,dense and inorganics-rich(Li_(2)C_(2)O_(4),LiF and Li_(x)PO_yF_z) SEI film.Subsequently,this SEI film helps to ensure the even intercalation/de-intercalation of Li^(+) in the SEI film and the homogeneous diffusion of Li^(+) inside the Si particles,decreasing the internal stresses and anisotropic phase transitions,maintaining the integrity of Si particles,inhibiting the volume expansion and thu s improving the electrochemical performance of cells.This study not only improves the utilization efficiency of expensive additives through a simply and low-cost method,but also enriches the strategy to improve the electrochemical performance of Si@C anode through interfacial engineering.
文摘The resolution by Chen and Sun of divergent Chapman-Enskog expansion problem will not only build a unified foundation for non-equilibrium dynamics modeling at all Mach number and Knudsen number, but also shed light to a large class of difficult theoretical problems involving divergent expansion on strong nonlinearity.
文摘Aim To determine the stress on wall of the spherical cavity while the spherical cavity expanding in concrete. Methods In Eulerian coordinate, the dimensionless radial stress equations were derived for the spherically symmetric, cavity expansion problem in plastic and elastic region of concrete by means of the similarity transformation. In the equations, Mohr Coulomb yield criterion was used.Results The dimensionless radial stress profiles were obtained. The relation between the dimensionless radial stress and the locked volumetric strain was analysed.Conclusion The test results show that the relative error between the model, which is applied in the closed form penetration equations that are developed, and the test data is less than 15.8%.
基金Sponsored by National Natural Science Foundation of China under grant No.10571164Specialized Research Fund for the Doctoral Program of Higher Education under grant No.20050358052Guangdong Natural Science Foundation under grant No.06301315
文摘In this article,the authors obtain an inequality of homogeneous expansion for f,where f is a quasi-convex mapping(including quasi-convex mapping of type A and quasi-convex mapping of type B)defined on the open unit polydisk in C n .Meanwhile,the authors also investigate its application.
基金Project supported by National Natural Science Foundation of China(10971063,11061015)Major Program of Zhejiang Provincial Natural Science Foundation of China(D7080080)Guangdong Natural Science Foundation(06301315)
文摘In this article, first, a sufficient condition for a starlike mapping of order a f（x） defined on the unit ball in a complex Banach space is given. Second, the sharp estimate of the third homogeneous expansion for f is established as well, where f（z） = （f1（z）, f2（z）,..., fn（z））＇ is a starlike mapping of order a or a normalized biholomorphic starlike mapping defined on the unit polydisk in Cn, and D2fk（0）（z2） /2i= zk（∑l=1^b akzzl）, k = 2t l=1 k = 1, 2,..., n. Our result states that the Bieberbaeh conjecture in several complex variables （the case of the third homogeneous expansion for starlike mappings of order α and biholomorphic starlike mappings） is partly proved.
文摘In this paper the authors give a definite meaning to any formal trigonometrical series and generalize it to all abstract Hilbert space. Then in the case L-2(-infinity + infinity) they discussed extensively the generalized expansion problem by Hermite functions, and applied to a non-strictly nonlinear hyperbolic system.
基金the partial support of National Natural ScienceFoundation (Grant 70071011 .)
文摘This paper considers a capacity expansion problem with budget constraint. Suppose each edge in the network has two attributes: capacity and the degree of difficulty. The difficulty degree of a tree T is the maximum. degree of difficulty of all edges in the tree and the cost for coping with the difficulty in a tree is a nondecreasing function about the difficulty degree of the tree. The authors need to increase capacities of some edges so that there is a spanning tree whose capacity can be increased to the maximum extent, meanwhile the total cost for increasing capacity as well as overcoming the difficulty in the spanning tree does not exceed a given budget D*. Suppose the cost for increasing capacity on each edge is a linear function about the increment of capacity, they transform this problem into solving some hybrid parametric spanning tree problems([1]) and propose a strongly polynomial algorithm.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10874086 and 10834009)the National Basic Research Program of China (Grant No. 2010CB327803)
文摘The super-cell plane wave expansion method is employed to calculate band structures for the design of a siliconbased one-dimensional phononic crystal plate with large absolute forbidden bands. In this method, a low impedance medium is introduced to replace the free stress boundary, which largely reduces the computational complexity. The dependence of band gaps on structural parameters is investigated in detail. To prove the validity of the super-cell plane wave expansion, the transmitted power spectra of the Lamb wave are calculated by using a finite element method. With the detailed computation, the band-gap of a one-dimensional plate can be designed as required with appropriate structural parameters, which provides a guide to the fabrication of a Lamb wave phononic crystal.
基金supported by the National Natural Science Foundation of China (Grant No. 10974183)
文摘Materials with the formula Yb2-xAlxMo3O12 （x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 0.9, 1.0, 1.1, 1.3, 1.5, and 1.8） were synthesized and their structures, phase transitions, and hygroscopicity investigated using X-ray powder diffraction, Raman spectroscopy, and thermal analysis. It is shown that Yb2-xAlxMo3012 solid solutions crystallize in a single monoclinic phase for 1.7 〈 x 〈 2.0 and in a single orthorhombic phase for 0.0 〈 x 〈 0,4, and exhibit the characteristics of both monoclinic and orthorhombic structures outside these compositional ranges. The monoclinic to orthorhonlbic phase transition temperature of A12Mo3012 can be reduced by partial substitution of A13＋ by Yb3＋, and the Yb2-zAlxMo3012 （0.0 〈 x 〈 2.0） materials are hydrated at room temperature and contain two kinds of water species. One of these interacts strongly with and hinders the motions of the polyhedra, while the other does not. The partial substitution of A13＋ for Yb3＋ in Yb2Mo3012 decreases its hygroscopicity, and the linear thermal expansion coefficients after complete removal of water species are measured to be -9.1 x 10-6/K, -5.5 x 10-6/K, 5.74 x 10-6/K, and 9.5 x 10 6/K for Ybl.sAlo.2（MoO4）3, Yb1.6Alo.4（MoO4）3, Ybo.4All.6（Mo04）3, and Ybo.2Al1.8（MoO4）3, respectively.
基金supported by the National Natural Science Foundation of China(Grant No 10562002)the Natural Science Foundation of Inner Mongolia,China(Grants No 200508010103 and 200711020106)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No 20070126002)
文摘This paper deals with the bending problem of rectangular plates with two opposite edges simply supported. It is proved that there exists no normed symplectic orthogonal eigenfunction system for the associated infinite-dimensional Hamiltonian operator H and that the two block operators belonging to Hamiltonian operator H possess two normed symplectic orthogonal eigenfunction systems in some space. It is demonstrated by using the properties of the block operators that the above bending problem can be solved by the symplectic eigenfunction expansion theorem, thereby obtaining analytical solutions of rectangular plates with two opposite edges simply supported and the other two edges supported in any manner.
基金Project supported by the Science and Technology Foundation of Guizhou Province,China (Grant No 20072009)
文摘Based on a first order nonlinear ordinary differential equation with at most a sixth-degree nonlinear term which is extended from a type of elliptic equation, and by converting it into a new expansion form, this paper proposes a new algebraic method to construct exact solutions for nonlinear evolution equations. Being concise and straightforward, the method is applied to modified Benjamin-Bona-Mahony （mBBM） model, and some new exact solutions to the system are obtained. The algorithm is of important significance in exploring exact solutions for other nonlinear evolution equations.
基金Project supported by the National Key Basic Research Project of China (Grant No. 2004CB318000)the National Natural Science Foundation of China (Grant No. 10771072)
文摘Recently the （G′/G）-expansion method was proposed to find the traveling wave solutions of nonlinear evolution equations. This paper shows that the （G′/G）-expansion method is a special form of the truncated Painlev＇e expansion method by introducing an intermediate expansion method. Then the generalized （G′/G）-（G/G′） expansion method is naturally derived from the standpoint of the nonstandard truncated Painlev＇e expansion. The application of the generalized method to the mKdV equation shows that it extends the range of exact solutions obtained by using the （ G′/ G）-expansion method.
基金Supported by the Technology Innovation Program(Grant No.:10053121 and 10051279) funded by the Ministry of Trade,Industry&Energy(MI,Korea)
文摘In this study,we propose a method for estimating the amount of expansion that occurs in subsea pipelines,which could be applied in the design of robust structures that transport oil and gas from offshore wells.We begin with a literature review and general discussion of existing estimation methods and terminologies with respect to subsea pipelines.Due to the effects of high pressure and high temperature,the production of fluid from offshore wells is typically caused by physical deformation of subsea structures,e.g.,expansion and contraction during the transportation process.In severe cases,vertical and lateral buckling occurs,which causes a significant negative impact on structural safety,and which is related to on-bottom stability,free-span,structural collapse,and many other factors.In addition,these factors may affect the production rate with respect to flow assurance,wax,and hydration,to name a few.In this study,we developed a simple and efficient method for generating a reliable pipe expansion design in the early stage,which can lead to savings in both cost and computation time.As such,in this paper,we propose an applicable diagram,which we call the standard dimensionless ratio(SDR)versus virtual anchor length(LA)diagram,that utilizes an efficient procedure for estimating subsea pipeline expansion based on applied reliable scenarios.With this user guideline,offshore pipeline structural designers can reliably determine the amount of subsea pipeline expansion and the obtained results will also be useful for the installation,design,and maintenance of the subsea pipeline.
基金Project supported by the Programs for Tackling Key Problems in Science and Technology,Henan Province,China(Grant Nos.172102210103,182102310895,182102210031,and 182102311079)the Doctoral Program of Henan Institute of Engineering,China(Grant Nos.D2016015 and D2016016)the Nationallevel College Students Innovative Entrepreneurial Training Plan Program,China(Grant No.201611517041)
文摘β-eucryptite powders are prepared by the sol-gel method through using tetraethoxysilane lithium nitrate and aluminum isopropoxide as starting materials. β-eucryptite ceramics are prepared by spark plasma sintering. The effects of sintering temperature on the negative thermal expansion properties of the β-eucryptite are investigated by x-ray diffraction（XRD）, scanning electron microscopy, and thermal expansion test. The XRD results exhibit no change in the crystal structure of the sample prepared by different sintering processes. The negative thermal expansion properties increase with the increase of the sintering temperature. The coefficient of thermal expansion of β-eucryptite ceramics sintered at 1100℃ is calculated to be -4.93 × 10^（-6）℃^（-1）. Crystallization behaviors of the ceramics may play an important role in the increase of negative thermal expansion of β-eucryptite. High sintering temperature could improve the crystallization behaviors of the ceramics and reduce the residue glass phase, which can improve the negative thermal expansion properties of β-eucryptite ceramics.
基金support by the National Natural Science Foundation of China (No.51174195)the Fundamental Research Funds for the Central Universities of China (No.2010QNA31)
文摘Comparing with the resin bolt, the hydraulic expansion bolt has different anchoring mechanism and application advantage. According to the working mechanism of the hydraulic expansion bolt, its anchoring force is expressed in four forms including support anchoring force, tension anchoring force, expansion anchoring force and tangent anchoring force, and their values can be obtained on the basis of each calculation formula. Among them, the expansion anchoring force, which is the unique anchoring force of the hydraulic expansion bolt, can provide confining pressure to increase the strength of rock. Aiming at solving the problem of stability control in the soft rock roadway in Jinbaotun Coal Mine which has a double layer of 40 U-type sheds and cannot provide enough resistance support to control floor heave, the study reveals the mechanism of floor heave in the soft rock roadway, and designs the reasonable support parameters of the hydraulic expansion bolts. The observed results of floor convergence indicate that the hydraulic expansion bolts can prevent the development and flow of the plastic zone in the floor rock to control floor heave. Research results enrich the control technology in the soft rock roadway.
