Using V2O3 and MoO3 powders as precursors,a novel preparation method,i.e.,the so-called inorganic solgel,is developed to synthesize Mo^6+-doped vanadium dioxide(VO2) thin films.The structure,valence state,phase transi...Using V2O3 and MoO3 powders as precursors,a novel preparation method,i.e.,the so-called inorganic solgel,is developed to synthesize Mo^6+-doped vanadium dioxide(VO2) thin films.The structure,valence state,phase transition temperature and magnitude of resistivity change are characterized by x-ray diffraction,x-ray photoelectron spectroscopy and the four-point equipment.The results show that the main chemical composition of doped thin films was VO2,the sturcture of MoO3 in doped thin films did not change,and the phase transition temperature of doped thin films was obviously lowered with the increasing MoO3 doped concentration,but the magnitude of resistivity change was also decreased.However.so long as MoO3 doped concentration was not more than 5wt%.,the magnitude of resistivity change of doped thin films still reached more 2 orders.The analysis show that MoO3 dissolved in crystal structure of VO2 formed the donor defect MOv^x and then reduced the forbidden band width,which lowered the phase transition temperature,Consequently it was widened applications of the VO2 thin films.展开更多
A new method to eliminate the oil whip online is put forward by use ofpassive electromagnetic damper. The damper works contactless and with DC current. Neither sensor norclosed loop control is needed. The dynamic equa...A new method to eliminate the oil whip online is put forward by use ofpassive electromagnetic damper. The damper works contactless and with DC current. Neither sensor norclosed loop control is needed. The dynamic equations of rotor-bearing system are built up bycombining d'Alemdert principle with Rize way, and the nonlinear oil film forces based on unsteadyshort bearing model are coupled to system. Such nonlinear equations are numerically solved byNewmark integration method. The calculated results show that the bifurcation behavior of the systemcan be. changed and the oil whip of the rotor may be well damped by external damping. Thebifurcation diagrams also show that the subharmonic vibration amplitude decreases in motion and thespeed at which the system losses its stability increases obviously by exerting external damping.Then experiments are carried out to demonstrate this phenomenon. It is observed that the complextrajectories of the journal motion are disappeared and the rotor-bearing system became stable whenthe power of passive electromagnetic damper is turned on. The experiments have good repeatability.展开更多
The physiological mechanism of maintaining the green colour of pak choy leaves (Brassicarapa var chinensis) with heat-shock treatment was studied. Chlorophyll in the outerleaves of pak choy degraded rapidly during sto...The physiological mechanism of maintaining the green colour of pak choy leaves (Brassicarapa var chinensis) with heat-shock treatment was studied. Chlorophyll in the outerleaves of pak choy degraded rapidly during storage at ambient temperature (20±2℃), aslight yellow appeared. Heat-shock treatment (46-50℃) had a mild effect on maintainingthe green colour of outer leaves. Normal chlorophyll degradation was associated with abinding of chlorophyll with chlorophyll-binding-protein preceding chlorophyll breakdown.Heat-shock treatment was found to reduce the binding-capacity between chlorophyll-binding-protein and chlorophyll. In the chlorophyll degradation pathway, pheide dioxygenasewas synthesized during leaf senescence which was considered to be a key enzyme inchlorophyll degradation. Activity of this enzyme was reduced following heat-shocktreatment, which might explain the observed reduction in chlorophyll breakdown. Twogroups of heat-shock proteins were detected in treated leaves, the first group containingproteins from 54KDa to 74Kda, and the second group contained proteins from 15KDa to29KDa. Heat-shock treatment was also found to retard the decline of glucose and fructose(the main energy substrates) of outer leaves.展开更多
Catalytic decomposition of methylene chloride in air below 300℃ was studied. Sulfated titania was very effective in converting 959ppm methylene chloride selectively to CO, C02 and HCl. Complete decomposition of methy...Catalytic decomposition of methylene chloride in air below 300℃ was studied. Sulfated titania was very effective in converting 959ppm methylene chloride selectively to CO, C02 and HCl. Complete decomposition of methylene chloride was achieved at low temperature (275℃ ). It was found that the acidic property of catalyst was a determinant factor for the catalytic activity. The presence of water vapor in the feed stream remarkably reduced the catalytic activity, which could be due to the blockage of acidic sites on the surface of catalyst by water molecules. A bifunctional catalyst comprising copper oxide was developed to improve the selectivity of catalytic oxidation , which indicated that copper oxide can promote the deep oxidation of methylene chloride. The crystal form of TiO2 imposes an important influence upon the catalytic oxidation.展开更多
In order to solve excessive insertion loss and low on/off ratio in quantum well reflection-type waveguide optical switches, a novel InGaAs/InAlAs coupled quantum well structure is proposed. In the case of low applied ...In order to solve excessive insertion loss and low on/off ratio in quantum well reflection-type waveguide optical switches, a novel InGaAs/InAlAs coupled quantum well structure is proposed. In the case of low applied electric field （F=19 kV/cm） and low absorption loss （ et ~ 61.2 cm-1）, a large negative field-induced refractive index change （ A n=-0.0134） is obtained in the novel coupled quantum well structure at the operating wavelength （ 2 =1550 rim）. The value is larger by over one to two order of maL, nitude comoared to that in a rectanaular ouantum well （ROW） on the above same work conditions.展开更多
A real-size experiment on 11 tubes was done to study the performance o f centrifugal concrete-filled steel tubes under bending and torsion. This pape r first introduces the relevant operating method,equipment,subjects...A real-size experiment on 11 tubes was done to study the performance o f centrifugal concrete-filled steel tubes under bending and torsion. This pape r first introduces the relevant operating method,equipment,subjects and process es. The factors that affect deformation and stiffness and the break mechanism un der different loading were studied. Experimental stress analysis showed that the values of practical critical stress of steel tubes accorded well with the MISES Yielding Rule. The correlative equation (on the bearing capacity of a structura l member under bending and torsion) deduced in this study may provide valuable reference for the design of this structural member.展开更多
In this work, the charge dynamics characteristics of injection, transport and decay in porous and non-porous polytetrafluoroethylene (PTFE) film electrets were investigated by means of corona charging, isothermal and ...In this work, the charge dynamics characteristics of injection, transport and decay in porous and non-porous polytetrafluoroethylene (PTFE) film electrets were investigated by means of corona charging, isothermal and thermal stimulating surface-potential decay measurements. The results showed that the initial surface potential, whether positively or negatively charging, is much higher in non-porous PTFE than in porous PTFE. For porous film the value of initial sur-face potentials increases with increase of film thickness. Higher charging temperature can remarkably improve charge stability. The charge dynamics are correlated to materials microstructure according to their scanning electron micrographs.For non-porous PTFE films, polarizability change of C-F bonds is the main origin of electret charges; but for porous PTFE film a large number of bulk and interface type traps are expected because of the greater area of interface and higher crys-tallinity.展开更多
In this paper, an important problem arising from conservation biology is considered. Namely, how does the introduced species affect the survival of a native endangered species through predation? By using Kamke compari...In this paper, an important problem arising from conservation biology is considered. Namely, how does the introduced species affect the survival of a native endangered species through predation? By using Kamke comparison theorem and some results in Cui and Chen’s paper (1998), some sufficient conditions that guarantee the permanence of the species and global stability of a unique positive periodic solution are obtained. Biological implication of these results are discussed. MR Subject Classification 34C25 - 92D25 Keywords ecological invasion - diffusion - permanence - predation global stability Supported by the Research Foundation of Education Department of Zhejiang Province (20038049).展开更多
The diffusion-based micro flow of a T-sensor with three inlets in whichvarious species are injected was simulated numerically. The results show that the Reynolds number isan important factor of affecting the efficienc...The diffusion-based micro flow of a T-sensor with three inlets in whichvarious species are injected was simulated numerically. The results show that the Reynolds number isan important factor of affecting the efficiency of diffusion. The smaller the channel width is, themore strongly the species diffuse. The velocity gradient across the channel width plays a key rolein the diffusion of species. The conclusions are helpful to the design of micro-fluidic devices andthe analysis of data collected from such devices.展开更多
文摘Using V2O3 and MoO3 powders as precursors,a novel preparation method,i.e.,the so-called inorganic solgel,is developed to synthesize Mo^6+-doped vanadium dioxide(VO2) thin films.The structure,valence state,phase transition temperature and magnitude of resistivity change are characterized by x-ray diffraction,x-ray photoelectron spectroscopy and the four-point equipment.The results show that the main chemical composition of doped thin films was VO2,the sturcture of MoO3 in doped thin films did not change,and the phase transition temperature of doped thin films was obviously lowered with the increasing MoO3 doped concentration,but the magnitude of resistivity change was also decreased.However.so long as MoO3 doped concentration was not more than 5wt%.,the magnitude of resistivity change of doped thin films still reached more 2 orders.The analysis show that MoO3 dissolved in crystal structure of VO2 formed the donor defect MOv^x and then reduced the forbidden band width,which lowered the phase transition temperature,Consequently it was widened applications of the VO2 thin films.
基金This project is supported by National Natural Science Foundation of China (No.50375140).
文摘A new method to eliminate the oil whip online is put forward by use ofpassive electromagnetic damper. The damper works contactless and with DC current. Neither sensor norclosed loop control is needed. The dynamic equations of rotor-bearing system are built up bycombining d'Alemdert principle with Rize way, and the nonlinear oil film forces based on unsteadyshort bearing model are coupled to system. Such nonlinear equations are numerically solved byNewmark integration method. The calculated results show that the bifurcation behavior of the systemcan be. changed and the oil whip of the rotor may be well damped by external damping. Thebifurcation diagrams also show that the subharmonic vibration amplitude decreases in motion and thespeed at which the system losses its stability increases obviously by exerting external damping.Then experiments are carried out to demonstrate this phenomenon. It is observed that the complextrajectories of the journal motion are disappeared and the rotor-bearing system became stable whenthe power of passive electromagnetic damper is turned on. The experiments have good repeatability.
文摘The physiological mechanism of maintaining the green colour of pak choy leaves (Brassicarapa var chinensis) with heat-shock treatment was studied. Chlorophyll in the outerleaves of pak choy degraded rapidly during storage at ambient temperature (20±2℃), aslight yellow appeared. Heat-shock treatment (46-50℃) had a mild effect on maintainingthe green colour of outer leaves. Normal chlorophyll degradation was associated with abinding of chlorophyll with chlorophyll-binding-protein preceding chlorophyll breakdown.Heat-shock treatment was found to reduce the binding-capacity between chlorophyll-binding-protein and chlorophyll. In the chlorophyll degradation pathway, pheide dioxygenasewas synthesized during leaf senescence which was considered to be a key enzyme inchlorophyll degradation. Activity of this enzyme was reduced following heat-shocktreatment, which might explain the observed reduction in chlorophyll breakdown. Twogroups of heat-shock proteins were detected in treated leaves, the first group containingproteins from 54KDa to 74Kda, and the second group contained proteins from 15KDa to29KDa. Heat-shock treatment was also found to retard the decline of glucose and fructose(the main energy substrates) of outer leaves.
文摘Catalytic decomposition of methylene chloride in air below 300℃ was studied. Sulfated titania was very effective in converting 959ppm methylene chloride selectively to CO, C02 and HCl. Complete decomposition of methylene chloride was achieved at low temperature (275℃ ). It was found that the acidic property of catalyst was a determinant factor for the catalytic activity. The presence of water vapor in the feed stream remarkably reduced the catalytic activity, which could be due to the blockage of acidic sites on the surface of catalyst by water molecules. A bifunctional catalyst comprising copper oxide was developed to improve the selectivity of catalytic oxidation , which indicated that copper oxide can promote the deep oxidation of methylene chloride. The crystal form of TiO2 imposes an important influence upon the catalytic oxidation.
基金Supported by the National Natural Science Foundation of China under Grant No. 60277034 and 60436020
文摘In order to solve excessive insertion loss and low on/off ratio in quantum well reflection-type waveguide optical switches, a novel InGaAs/InAlAs coupled quantum well structure is proposed. In the case of low applied electric field （F=19 kV/cm） and low absorption loss （ et ~ 61.2 cm-1）, a large negative field-induced refractive index change （ A n=-0.0134） is obtained in the novel coupled quantum well structure at the operating wavelength （ 2 =1550 rim）. The value is larger by over one to two order of maL, nitude comoared to that in a rectanaular ouantum well （ROW） on the above same work conditions.
文摘A real-size experiment on 11 tubes was done to study the performance o f centrifugal concrete-filled steel tubes under bending and torsion. This pape r first introduces the relevant operating method,equipment,subjects and process es. The factors that affect deformation and stiffness and the break mechanism un der different loading were studied. Experimental stress analysis showed that the values of practical critical stress of steel tubes accorded well with the MISES Yielding Rule. The correlative equation (on the bearing capacity of a structura l member under bending and torsion) deduced in this study may provide valuable reference for the design of this structural member.
文摘In this work, the charge dynamics characteristics of injection, transport and decay in porous and non-porous polytetrafluoroethylene (PTFE) film electrets were investigated by means of corona charging, isothermal and thermal stimulating surface-potential decay measurements. The results showed that the initial surface potential, whether positively or negatively charging, is much higher in non-porous PTFE than in porous PTFE. For porous film the value of initial sur-face potentials increases with increase of film thickness. Higher charging temperature can remarkably improve charge stability. The charge dynamics are correlated to materials microstructure according to their scanning electron micrographs.For non-porous PTFE films, polarizability change of C-F bonds is the main origin of electret charges; but for porous PTFE film a large number of bulk and interface type traps are expected because of the greater area of interface and higher crys-tallinity.
基金Supported by the Research Foundation of Education Department of Zhejiang Province( 2 0 0 380 4 9)
文摘In this paper, an important problem arising from conservation biology is considered. Namely, how does the introduced species affect the survival of a native endangered species through predation? By using Kamke comparison theorem and some results in Cui and Chen’s paper (1998), some sufficient conditions that guarantee the permanence of the species and global stability of a unique positive periodic solution are obtained. Biological implication of these results are discussed. MR Subject Classification 34C25 - 92D25 Keywords ecological invasion - diffusion - permanence - predation global stability Supported by the Research Foundation of Education Department of Zhejiang Province (20038049).
文摘The diffusion-based micro flow of a T-sensor with three inlets in whichvarious species are injected was simulated numerically. The results show that the Reynolds number isan important factor of affecting the efficiency of diffusion. The smaller the channel width is, themore strongly the species diffuse. The velocity gradient across the channel width plays a key rolein the diffusion of species. The conclusions are helpful to the design of micro-fluidic devices andthe analysis of data collected from such devices.
