Temperature dependence of microscopic properties in diblock copolymer films has been investigated by dissipative particle dynamics simulations. Results show the relation between mean-square bond length (MSBL) and sy...Temperature dependence of microscopic properties in diblock copolymer films has been investigated by dissipative particle dynamics simulations. Results show the relation between mean-square bond length (MSBL) and system temperature can be described as a quadratic curve. The root-mean-square radius of gyration (RMSGR) and end-end distance (RMSED) increase gradually as the temperature rises and composition fraction changes from 0.1 to 0.5, in which the effect of the former is primary. Especially, the relation between RMSGR and temperature is nearly linear in the confinement-introduced direction. Density distribution of each component in the films can be controlled and adjusted effectively by its interaction with other components and boundaries. Moreover, the changes of system temperature and composition fraction can both affect the density distributions to a certain extent.展开更多
We tested and modified the quasi-analytical algorithm (QAA) using 57 groups of field data collected in the spring of 2003 in the Yellow Sea and East China Sea. The QAA performs well in deriving total absorption coeffi...We tested and modified the quasi-analytical algorithm (QAA) using 57 groups of field data collected in the spring of 2003 in the Yellow Sea and East China Sea. The QAA performs well in deriving total absorption coefficients of typical coastal waters. The average percentage difference (APD) is in a range of 13.9%–38.5% for the total absorption coefficient (13.9% at 440 nm), and differences in particle backscattering coefficient bbp(λ) are less than 50% (in the case of the updated QAA). To obtain improved results, we modified the QAA by adjusting the empirical relationships. The modified algorithm is then applied to the field data to test its performance. The APDs were 44.7%–46.6% for bbp(λ) and 9.9%–32.8% (9.9% at 555 nm) for the total absorption coefficient. This indicates that the modified QAA derives better results. We also used the modified model to derive phytoplankton pigment absorption (aph) and detritus and CDOM absorption (adg) coefficients. The APDs for aph and adg at 440 nm are 37.1% and 19.8%. In this paper, we discuss error sources using the measured dataset. More independent field data can improve this algorithm and derive better results.展开更多
Effects of spherical quasi-crystal contained in Mg-Zn-Y-Mn master alloy on the microstructure and as-cast mechanical properties of ZA155 high zinc magnesium alloy have been investigated by means of optical microscopy,...Effects of spherical quasi-crystal contained in Mg-Zn-Y-Mn master alloy on the microstructure and as-cast mechanical properties of ZA155 high zinc magnesium alloy have been investigated by means of optical microscopy,XRD,SEM,EDS,tensile test,impact test and hardness test.Experimental results show that the addition of spherical quasi-crystal contained in the Mg-Zn-Y-Mn master alloy into the ZA155 high zinc magnesium alloy resulted in grain refinement of the matrix,changing the morphologies of φ-Al2Mg5Zn2 phase and τ-Mg32(Al,Zn)49 phase from continuous net-like structures to discontinuous strip-like structure and blocky one,respectively.In the present research,the best comprehensive mechanical properties of reinforced ZA155 high zinc magnesium alloy has been obtained when 5.0wt% spherical quasi-crystal was introduced from the Mg-Zn-Y-Mn master alloy into the target alloy system.In such case,the room-temperature tensile strength reached 207 MPa,about 23% higher than that of the base alloy;the impact toughness peaked at 5.5 J/cm2,about 40% higher than that of the base alloy;and the elevated-temperature tensile strength reached 203 MPa,indicating improved heat resistance.展开更多
We investigate the dielectric properties of multi-walled carbon nanotubes(MWCNTs) and graphite filling in SiO2 with the filling concentration of 2-20 wt.% in the frequency range of 10 ^2-10^ 7 Hz.MWCNTs and graphite...We investigate the dielectric properties of multi-walled carbon nanotubes(MWCNTs) and graphite filling in SiO2 with the filling concentration of 2-20 wt.% in the frequency range of 10 ^2-10^ 7 Hz.MWCNTs and graphite have general electrical properties and percolation phenomena owing to their quasi-structure made up of graphene layers.Both permittivity ε and conductivity σ exhibit jumps around the percolation threshold.Variations of dielectric properties of the composites are in agreement with the percolation theory.All the percolation phenomena are determined by hopping and migrating electrons,which are attributed to the special electronic transport mechanism of the fillers in the composites.However,the twin-percolation phenomenon exists when the concentration of MWCNTs is between 5-10 wt.% and 15-20 wt.% in the MWCNTs/SiO2 composites,while in the graphite/SiO2 composites,there is only one percolation phenomenon in the graphite concentration of 10-15 wt.%.The unique twin-percolation phenomenon of MWCNTs/SiO2 is described and attributed to the electronic transfer mechanism,especially the network effect of MWCNTs in the composites.The network formation plays an essential role in determining the second percolation threshold of MWCNTs/SiO2.展开更多
Let X be a complex quasi Banach space and Φ:[0,∞)→[0,∞) an increasing convex function with Φ(0)=0 , lim t→∞Φ(t)=∞ and Φ∈Δ 2 . Then L * Φ(X) is a quasi Banach space with contin...Let X be a complex quasi Banach space and Φ:[0,∞)→[0,∞) an increasing convex function with Φ(0)=0 , lim t→∞Φ(t)=∞ and Φ∈Δ 2 . Then L * Φ(X) is a quasi Banach space with continuous quasi norm and L * Φ(X) has the ARNP if and only if X does.展开更多
The heat dissipated pad is made of composite mixing silicon or epoxy resin with thermal conductive inorganic fillers. The heat-dissipation material improves performance as the amount of thermal conductivity filler inc...The heat dissipated pad is made of composite mixing silicon or epoxy resin with thermal conductive inorganic fillers. The heat-dissipation material improves performance as the amount of thermal conductivity filler increases. However, the optimum recipe should be determined by considering the price and pad formability. In this study, high performance thermal pad is made of silicon resin mixed with Al2O3 as a thermally conductive filler. Since Al2O3 is low cost, it can use much filler. Al2O3 has improved slip-ability with organic coating on it to increase the viscosity of the slurry. The same process and the same recipe, could maximize the amount of the filler. As a result, the thermal conductivity is lower by 10%. But the viscosity is reduced by 60%, too. So form-ability is getting priority.展开更多
In this paper, the lattice parameter and bulk modulus of lithium(Li) at different pressures and temperatures are calculated by using the density functional theory method within the generalized gradient approximation(G...In this paper, the lattice parameter and bulk modulus of lithium(Li) at different pressures and temperatures are calculated by using the density functional theory method within the generalized gradient approximation(GGA).Through the quasi-harmonic Debye model, the thermodynamic properties of Li are predicted. The dependences of the normalized primitive cell volume V/V0 on pressure P, the variation of the thermal expansion coefficient α with pressure P and temperature T, as well as the dependences of the heat capacity Cv on pressure P and temperature T are obtained systematically in the ranges of 0~100 GPa and 0~2 000 K.展开更多
The rock mass in fault zones is frequently subjected to cyclic loading and unloading during deep resource exploitation and tunnel excavation.Research on the mechanical and hydraulic characteristics of fault rock durin...The rock mass in fault zones is frequently subjected to cyclic loading and unloading during deep resource exploitation and tunnel excavation.Research on the mechanical and hydraulic characteristics of fault rock during the cyclic loading and unloading is of great signifcance for revealing the formation mechanism of water-conducting pathways in fault and preventing water inrush disasters.In this study,the mechanical and seepage tests of fault rock under the multi-stage cyclic loading and unloading of axial compression were carried out by using the fuid–solid coupling triaxial experimental device.The hysteresis loop of the stress–strain curve,peak strain rate,secant Young's modulus,and permeability of fault rock were obtained,and the evolution law of the dissipated energy of fault rock with the cyclic number of load and unloading was discussed.The experimental results show that with an increase in the cyclic number of loading and unloading,several changes occur.The hysteresis loop of the stress–strain curve of the fault rock shifts towards higher levels of strain.Additionally,both the peak strain rate and the secant Young's modulus of the fault rock increase,resulting in an increase in the secant Young's modulus of the fault rock mass.However,the growth rate of the secant Young's modulus gradually slows down with the increase of cyclic number of loading and unloading.The permeability evolution of fault rock under the multi-stage cyclic loading and unloading of axial compression can be divided into three stages:steady increase stage,cyclic decrease stage,and rapid increase stage.Besides,the calculation model of dissipated energy of fault rock considering the efective stress was established.The calculation results show that the relationship between the dissipated energy of fault rock and the cyclic number of loading and unloading conforms to an exponential function.展开更多
This paper presents an experimental study to explore the compressive properties of fiber recycled aggregate concrete.A total of 75 specimens with the replacement rate of recycled coarse aggregate and fiber type were c...This paper presents an experimental study to explore the compressive properties of fiber recycled aggregate concrete.A total of 75 specimens with the replacement rate of recycled coarse aggregate and fiber type were conducted under a uniaxial compressive test.The failure modes,stress-strain whole curves,peak stress,peak strain,and energy dissipation capacity were systematically observed and revealed.Test results indicate that steel fiber has the best modification effect on energy dissipation capacity and the toughness index of recycled concrete,corresponding to the enhancement of 81.75% and 22.90% on average.The addition of polyvinyl alcohol fiber can effectively improve the compressive strength and energy dissipation capacity of recycled aggregate concrete by 28.49% and 29.43% on average,respectively.The compressive strength and energy dissipation capacity of recycled aggregate concrete is increased by an average of 16.5% and 24.4% by incorporating carbon fiber.The energy dissipation capacity of recycled aggregate concrete is increased by an average of 13.5% with the incorporation of polypropylene fiber.However,the addition of carbon fiber results in a slight reduction of toughness by 16.97%,and the effect of polyvinyl alcohol fiber on the energy dissipation capacity is limited.Besides,with the increase in replacement rate,the compressive strength and the energy dissipation capacity of recycled coarse aggregate concrete with fiber decreased,and toughness first decreased and then increased.Finally,based on the analysis of test data,a segment-based stress-strain model of fiber recycled aggregate concrete was proposed,which shows good agreement with the test results.展开更多
Standards are a double edge sword and have come to be the main technical tariff and a window for market access to international trade. Standards are closely related to intellectual property, especially patents. The es...Standards are a double edge sword and have come to be the main technical tariff and a window for market access to international trade. Standards are closely related to intellectual property, especially patents. The essence of intellectual property in standardization lies in the fact that standards are a kind of quasi-public good, while patents are essentially private property. The absorption of patents into standards creates an opportunity for a patent holder to take advantage by making a profit. To prevent the abuse of patents in standards by the patent holder, SDOs (Standards Development Organizations) have to adjust the disclosure policies of the standards in patents.展开更多
An operator T is called k-quasi-*-A(n) operator, if T^(*k)|T^(1+n)|^(2/(1+n))T^k ≥T^(*k)|T~* |~2T^k , k ∈ Z, which is a generalization of quasi-*-A(n) operator. In this paper we prove some properties of k-quasi-*-A(...An operator T is called k-quasi-*-A(n) operator, if T^(*k)|T^(1+n)|^(2/(1+n))T^k ≥T^(*k)|T~* |~2T^k , k ∈ Z, which is a generalization of quasi-*-A(n) operator. In this paper we prove some properties of k-quasi-*-A(n) operator, such as, if T is a k-quasi-*-A(n) operator and N(T )■N(T~* ), then its point spectrum and joint point spectrum are identical. Using these results, we also prove that if T is a k-quasi-*-A(n) operator and N(T )■N(T ), then the spectral mapping theorem holds for the Weyl spectrum and for the essential approximate point spectrum.展开更多
基金Project supported by the Shanghai Leading Academic Discipline Project(Grant No.S30109)the Research and Development Special Fundation of Excellent Young Teachers of Universities in Shanghai,the Developmental Foundation of Scientific Technology of Shanghai Universitythe Innovation Foundation of Shanghai University
文摘Temperature dependence of microscopic properties in diblock copolymer films has been investigated by dissipative particle dynamics simulations. Results show the relation between mean-square bond length (MSBL) and system temperature can be described as a quadratic curve. The root-mean-square radius of gyration (RMSGR) and end-end distance (RMSED) increase gradually as the temperature rises and composition fraction changes from 0.1 to 0.5, in which the effect of the former is primary. Especially, the relation between RMSGR and temperature is nearly linear in the confinement-introduced direction. Density distribution of each component in the films can be controlled and adjusted effectively by its interaction with other components and boundaries. Moreover, the changes of system temperature and composition fraction can both affect the density distributions to a certain extent.
基金Supported by the National Natural Science Foundation of China (Nos.40706060,60802089)the National High Technology Research and Development Program of China (863 Program) (No.2007AA092102)the Dragon Project (No.5292)
文摘We tested and modified the quasi-analytical algorithm (QAA) using 57 groups of field data collected in the spring of 2003 in the Yellow Sea and East China Sea. The QAA performs well in deriving total absorption coefficients of typical coastal waters. The average percentage difference (APD) is in a range of 13.9%–38.5% for the total absorption coefficient (13.9% at 440 nm), and differences in particle backscattering coefficient bbp(λ) are less than 50% (in the case of the updated QAA). To obtain improved results, we modified the QAA by adjusting the empirical relationships. The modified algorithm is then applied to the field data to test its performance. The APDs were 44.7%–46.6% for bbp(λ) and 9.9%–32.8% (9.9% at 555 nm) for the total absorption coefficient. This indicates that the modified QAA derives better results. We also used the modified model to derive phytoplankton pigment absorption (aph) and detritus and CDOM absorption (adg) coefficients. The APDs for aph and adg at 440 nm are 37.1% and 19.8%. In this paper, we discuss error sources using the measured dataset. More independent field data can improve this algorithm and derive better results.
基金supported by both the National Natural Science Foundation of China (No. 50571073)the Natural Science Foundation of Shanxi Province (No. 2009011028-3,20051052)
文摘Effects of spherical quasi-crystal contained in Mg-Zn-Y-Mn master alloy on the microstructure and as-cast mechanical properties of ZA155 high zinc magnesium alloy have been investigated by means of optical microscopy,XRD,SEM,EDS,tensile test,impact test and hardness test.Experimental results show that the addition of spherical quasi-crystal contained in the Mg-Zn-Y-Mn master alloy into the ZA155 high zinc magnesium alloy resulted in grain refinement of the matrix,changing the morphologies of φ-Al2Mg5Zn2 phase and τ-Mg32(Al,Zn)49 phase from continuous net-like structures to discontinuous strip-like structure and blocky one,respectively.In the present research,the best comprehensive mechanical properties of reinforced ZA155 high zinc magnesium alloy has been obtained when 5.0wt% spherical quasi-crystal was introduced from the Mg-Zn-Y-Mn master alloy into the target alloy system.In such case,the room-temperature tensile strength reached 207 MPa,about 23% higher than that of the base alloy;the impact toughness peaked at 5.5 J/cm2,about 40% higher than that of the base alloy;and the elevated-temperature tensile strength reached 203 MPa,indicating improved heat resistance.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 50972014,51072024,and 51132002)
文摘We investigate the dielectric properties of multi-walled carbon nanotubes(MWCNTs) and graphite filling in SiO2 with the filling concentration of 2-20 wt.% in the frequency range of 10 ^2-10^ 7 Hz.MWCNTs and graphite have general electrical properties and percolation phenomena owing to their quasi-structure made up of graphene layers.Both permittivity ε and conductivity σ exhibit jumps around the percolation threshold.Variations of dielectric properties of the composites are in agreement with the percolation theory.All the percolation phenomena are determined by hopping and migrating electrons,which are attributed to the special electronic transport mechanism of the fillers in the composites.However,the twin-percolation phenomenon exists when the concentration of MWCNTs is between 5-10 wt.% and 15-20 wt.% in the MWCNTs/SiO2 composites,while in the graphite/SiO2 composites,there is only one percolation phenomenon in the graphite concentration of 10-15 wt.%.The unique twin-percolation phenomenon of MWCNTs/SiO2 is described and attributed to the electronic transfer mechanism,especially the network effect of MWCNTs in the composites.The network formation plays an essential role in determining the second percolation threshold of MWCNTs/SiO2.
文摘Let X be a complex quasi Banach space and Φ:[0,∞)→[0,∞) an increasing convex function with Φ(0)=0 , lim t→∞Φ(t)=∞ and Φ∈Δ 2 . Then L * Φ(X) is a quasi Banach space with continuous quasi norm and L * Φ(X) has the ARNP if and only if X does.
文摘The heat dissipated pad is made of composite mixing silicon or epoxy resin with thermal conductive inorganic fillers. The heat-dissipation material improves performance as the amount of thermal conductivity filler increases. However, the optimum recipe should be determined by considering the price and pad formability. In this study, high performance thermal pad is made of silicon resin mixed with Al2O3 as a thermally conductive filler. Since Al2O3 is low cost, it can use much filler. Al2O3 has improved slip-ability with organic coating on it to increase the viscosity of the slurry. The same process and the same recipe, could maximize the amount of the filler. As a result, the thermal conductivity is lower by 10%. But the viscosity is reduced by 60%, too. So form-ability is getting priority.
文摘In this paper, the lattice parameter and bulk modulus of lithium(Li) at different pressures and temperatures are calculated by using the density functional theory method within the generalized gradient approximation(GGA).Through the quasi-harmonic Debye model, the thermodynamic properties of Li are predicted. The dependences of the normalized primitive cell volume V/V0 on pressure P, the variation of the thermal expansion coefficient α with pressure P and temperature T, as well as the dependences of the heat capacity Cv on pressure P and temperature T are obtained systematically in the ranges of 0~100 GPa and 0~2 000 K.
基金supported by the National Science Fund for Excellent Young researchers of Science China(52122404)the National Natural Science Foundation of China(41977238).
文摘The rock mass in fault zones is frequently subjected to cyclic loading and unloading during deep resource exploitation and tunnel excavation.Research on the mechanical and hydraulic characteristics of fault rock during the cyclic loading and unloading is of great signifcance for revealing the formation mechanism of water-conducting pathways in fault and preventing water inrush disasters.In this study,the mechanical and seepage tests of fault rock under the multi-stage cyclic loading and unloading of axial compression were carried out by using the fuid–solid coupling triaxial experimental device.The hysteresis loop of the stress–strain curve,peak strain rate,secant Young's modulus,and permeability of fault rock were obtained,and the evolution law of the dissipated energy of fault rock with the cyclic number of load and unloading was discussed.The experimental results show that with an increase in the cyclic number of loading and unloading,several changes occur.The hysteresis loop of the stress–strain curve of the fault rock shifts towards higher levels of strain.Additionally,both the peak strain rate and the secant Young's modulus of the fault rock increase,resulting in an increase in the secant Young's modulus of the fault rock mass.However,the growth rate of the secant Young's modulus gradually slows down with the increase of cyclic number of loading and unloading.The permeability evolution of fault rock under the multi-stage cyclic loading and unloading of axial compression can be divided into three stages:steady increase stage,cyclic decrease stage,and rapid increase stage.Besides,the calculation model of dissipated energy of fault rock considering the efective stress was established.The calculation results show that the relationship between the dissipated energy of fault rock and the cyclic number of loading and unloading conforms to an exponential function.
基金supported by the Postdoctoral Science Foundation of China(2021M693854)the Doctoral Foundation of Guangxi University of Science and Technology(No.18Z09)Bagui Scholar Program sponsored from the People’s Government of Guangxi Zhuang Autonomous Region(No.2019(79)).
文摘This paper presents an experimental study to explore the compressive properties of fiber recycled aggregate concrete.A total of 75 specimens with the replacement rate of recycled coarse aggregate and fiber type were conducted under a uniaxial compressive test.The failure modes,stress-strain whole curves,peak stress,peak strain,and energy dissipation capacity were systematically observed and revealed.Test results indicate that steel fiber has the best modification effect on energy dissipation capacity and the toughness index of recycled concrete,corresponding to the enhancement of 81.75% and 22.90% on average.The addition of polyvinyl alcohol fiber can effectively improve the compressive strength and energy dissipation capacity of recycled aggregate concrete by 28.49% and 29.43% on average,respectively.The compressive strength and energy dissipation capacity of recycled aggregate concrete is increased by an average of 16.5% and 24.4% by incorporating carbon fiber.The energy dissipation capacity of recycled aggregate concrete is increased by an average of 13.5% with the incorporation of polypropylene fiber.However,the addition of carbon fiber results in a slight reduction of toughness by 16.97%,and the effect of polyvinyl alcohol fiber on the energy dissipation capacity is limited.Besides,with the increase in replacement rate,the compressive strength and the energy dissipation capacity of recycled coarse aggregate concrete with fiber decreased,and toughness first decreased and then increased.Finally,based on the analysis of test data,a segment-based stress-strain model of fiber recycled aggregate concrete was proposed,which shows good agreement with the test results.
文摘Standards are a double edge sword and have come to be the main technical tariff and a window for market access to international trade. Standards are closely related to intellectual property, especially patents. The essence of intellectual property in standardization lies in the fact that standards are a kind of quasi-public good, while patents are essentially private property. The absorption of patents into standards creates an opportunity for a patent holder to take advantage by making a profit. To prevent the abuse of patents in standards by the patent holder, SDOs (Standards Development Organizations) have to adjust the disclosure policies of the standards in patents.
基金Supported by the Natural Science Foundation of the Department of Education of Henan Province(12B110025, 102300410012)
文摘An operator T is called k-quasi-*-A(n) operator, if T^(*k)|T^(1+n)|^(2/(1+n))T^k ≥T^(*k)|T~* |~2T^k , k ∈ Z, which is a generalization of quasi-*-A(n) operator. In this paper we prove some properties of k-quasi-*-A(n) operator, such as, if T is a k-quasi-*-A(n) operator and N(T )■N(T~* ), then its point spectrum and joint point spectrum are identical. Using these results, we also prove that if T is a k-quasi-*-A(n) operator and N(T )■N(T ), then the spectral mapping theorem holds for the Weyl spectrum and for the essential approximate point spectrum.