The periodic impact force induced by tip-sample contact in a tapping mode atomic force microscope （AFM） gives rise to the non-harmonic response of a micro-cantilever. These non-harmonic signals contain the full char...The periodic impact force induced by tip-sample contact in a tapping mode atomic force microscope （AFM） gives rise to the non-harmonic response of a micro-cantilever. These non-harmonic signals contain the full characteristics of tip-sample interaction. A complete theoretical model describing the dynamical behaviour of tip-sample system was developed in this paper. An analytic formula was introduced to describe the relationship between time-varying tip-sample impact force and tip motion. The theoretical analysis and numerical results both show that the timevarying tip-sample impact force can be reconstructed by recording tip motion. This allows for the reconstruction of the characteristics of the tip-sample force, like contact time and maximum contact force. It can also explain the ability of AFM higher harmonics imaging in mapping stiffness and surface energy variations.展开更多
Here a new scheme for mode filtering is proposed. Based on the ponderomotive force effect,propagation of the microwave dual-mode through a plasma-filled metallic rectangular waveguide is investigated. To excite the TE...Here a new scheme for mode filtering is proposed. Based on the ponderomotive force effect,propagation of the microwave dual-mode through a plasma-filled metallic rectangular waveguide is investigated. To excite the TE_（20） mode in a rectangular waveguide, the existence of fundamental modes is unavoidable. To filter the destructive mode（TE_（10））, the waveguide is filled with a collisional plasma. Based on the coupling effect, the energy of this destructive TE_（10） mode is transferred to the TE_（20） mode. The proposed structure acts like a mode convertor. The TE_（10） mode become more attenuated and instead the TE_（20） mode is amplified. The plasma filled rectangular waveguide acts as a mode filtering tool.展开更多
To investigated the hemostatic ability of the S and F1-10 methods in clinical and ex vivo studies. METHODSThe hemostatic abilities of the two methods were analyzed retrospectively in all six gastric endoscopic submuco...To investigated the hemostatic ability of the S and F1-10 methods in clinical and ex vivo studies. METHODSThe hemostatic abilities of the two methods were analyzed retrospectively in all six gastric endoscopic submucosal dissection cases. The treated vessel diameter, compressed vessel frequency, and bleeding frequency after cutting the vessels were noted by the recorded videos. The coagulation mechanism of the two power settings was evaluated using the data recording program and histological examination on macro- and microscopic levels in the ex vivo experiments using porcine tissues. RESULTSF1-10 method showed a significantly better hemostatic ability for vessels ≥ 2 mm in diameter and a trend of overall better coagulation effect, evaluated by the bleeding rate after cutting the vessels. F1-10 method could sustain electrical current longer and effectively coagulate the tissue wider and deeper than the S method in the porcine model. CONCLUSIONF1-10 method is suggested to achieve a stronger hemostatic effect than the S method in clinical procedures and ex vivo models.展开更多
The empirical analyses on agricultural industrialization pattern and local animal husbandry in northwestern areas show that the industrialization development of husbandry in northwestern areas faces international and ...The empirical analyses on agricultural industrialization pattern and local animal husbandry in northwestern areas show that the industrialization development of husbandry in northwestern areas faces international and national competitive pressures. The survival ability and competitive ability are the key points of husbandry industrialization. The paper, having a lamb fattening professional cooperatives in Hainan sub-prefecture of Qinghai Province as the example, introduces the general conditions of the establishment and development of cooperatives and points out the advantages and disadvantages of husbandry in Qinghai Province. The paper analyzes the competitive advantages of Hongyuan Lamb Fattening Cooperatives through five forces mode of Michael Port, putting forward countermeasures and upgrading the competitiveness of Hongyuan Lamb Fattening Competitive.展开更多
The mechanisms involved in the variability of Atlantic Meridional Overturning Circulation （AMOC） are studied using a 2000-yr control simulation of the coupled Fast Ocean-Atmosphere Model （FOAM）.This study identifi...The mechanisms involved in the variability of Atlantic Meridional Overturning Circulation （AMOC） are studied using a 2000-yr control simulation of the coupled Fast Ocean-Atmosphere Model （FOAM）.This study identifies a coupled mode between SST and surface heat flux in the North Atlantic at the decadal timescale,as well as a forcing mode of surface heat flux at the interannual timescale.The coupled mode is regulated by AMOC through meridional heat transport.The increase in surface heating in the North Atlantic weakens the AMOC approximately 10 yr later,and the weakened AMOC in turn decreases SST and sea surface salinity.The decreased SST results in an increase in surface heating in the North Atlantic,thus forming a positive feedback loop.Meanwhile,the weakened AMOC weakens northward heat transport and therefore lowers subsurface temperature approximately 19 yr later,which prevents the AMOC from weakening.In the forcing mode,the surface heat flux leads AMOC by approximately 4 yr.展开更多
The hydraulic force on the reversible pump turbine might cause serious problems（e.g., the abnormal stops due to large vibrations of the machine）, affecting the safe operations of the pumped energy storage power plan...The hydraulic force on the reversible pump turbine might cause serious problems（e.g., the abnormal stops due to large vibrations of the machine）, affecting the safe operations of the pumped energy storage power plants. In the present paper, the hydraulic force on the impeller of a model reversible pump turbine is quantitatively investigated through numerical simulations. It is found that both the amplitude of the force and its dominant components strongly depend on the operating conditions（e.g., the turbine mode, the runaway mode and the turbine brake mode） and the guide vane openings. For example, the axial force parallel with the shaft is prominent in the turbine mode while the force perpendicular to the shaft is the dominant near the runaway and the turbine brake modes. The physical origins of the hydraulic force are further revealed by the analysis of the fluid states inside the impeller.展开更多
In this paper the effects of temperature on the radial breathing modes （RBMs） and radial wave propaga- tion in multiwall carbon nanotubes （MWCNTs） are inves- tigated using a continuum model of multiple elastic iso...In this paper the effects of temperature on the radial breathing modes （RBMs） and radial wave propaga- tion in multiwall carbon nanotubes （MWCNTs） are inves- tigated using a continuum model of multiple elastic isotropic shells. The van der Waals forces between tubes are simulated as a nonlinear function of interlayer spacing of MWCNTs. The governing equations are solved using a finite element method. A wide range of innermost radius-to-thickness ratio of MWCNTs is considered to enhance the investigation. The presented solution is verified by comparing the results with those reported in the literature. The effects of temperature on the van der Waals interaction coefficient between layers of MWCNTs are examined. It is found that the variation of the van der Waals interaction coefficient at high temperature is sensible. Subsequently, variations of RBM frequencies and radial wave propagation in MWCNTs with temperatures up to 1 600 K are illustrated. It is shown that the thick MWC- NTs are more sensible to temperature than the thin ones.展开更多
基金Project supported by the National High-Tech Research and Development Program of China (Grant No. 2007AA12Z128)
文摘The periodic impact force induced by tip-sample contact in a tapping mode atomic force microscope （AFM） gives rise to the non-harmonic response of a micro-cantilever. These non-harmonic signals contain the full characteristics of tip-sample interaction. A complete theoretical model describing the dynamical behaviour of tip-sample system was developed in this paper. An analytic formula was introduced to describe the relationship between time-varying tip-sample impact force and tip motion. The theoretical analysis and numerical results both show that the timevarying tip-sample impact force can be reconstructed by recording tip motion. This allows for the reconstruction of the characteristics of the tip-sample force, like contact time and maximum contact force. It can also explain the ability of AFM higher harmonics imaging in mapping stiffness and surface energy variations.
基金supported by Hormoz branch, Islamic Azad University, Iran, Hormoze Island grant
文摘Here a new scheme for mode filtering is proposed. Based on the ponderomotive force effect,propagation of the microwave dual-mode through a plasma-filled metallic rectangular waveguide is investigated. To excite the TE_（20） mode in a rectangular waveguide, the existence of fundamental modes is unavoidable. To filter the destructive mode（TE_（10））, the waveguide is filled with a collisional plasma. Based on the coupling effect, the energy of this destructive TE_（10） mode is transferred to the TE_（20） mode. The proposed structure acts like a mode convertor. The TE_（10） mode become more attenuated and instead the TE_（20） mode is amplified. The plasma filled rectangular waveguide acts as a mode filtering tool.
文摘To investigated the hemostatic ability of the S and F1-10 methods in clinical and ex vivo studies. METHODSThe hemostatic abilities of the two methods were analyzed retrospectively in all six gastric endoscopic submucosal dissection cases. The treated vessel diameter, compressed vessel frequency, and bleeding frequency after cutting the vessels were noted by the recorded videos. The coagulation mechanism of the two power settings was evaluated using the data recording program and histological examination on macro- and microscopic levels in the ex vivo experiments using porcine tissues. RESULTSF1-10 method showed a significantly better hemostatic ability for vessels ≥ 2 mm in diameter and a trend of overall better coagulation effect, evaluated by the bleeding rate after cutting the vessels. F1-10 method could sustain electrical current longer and effectively coagulate the tissue wider and deeper than the S method in the porcine model. CONCLUSIONF1-10 method is suggested to achieve a stronger hemostatic effect than the S method in clinical procedures and ex vivo models.
基金Supported by Major Policy Research Project of Chinese Association for Science and Technology (2009ZCYJ20-A)
文摘The empirical analyses on agricultural industrialization pattern and local animal husbandry in northwestern areas show that the industrialization development of husbandry in northwestern areas faces international and national competitive pressures. The survival ability and competitive ability are the key points of husbandry industrialization. The paper, having a lamb fattening professional cooperatives in Hainan sub-prefecture of Qinghai Province as the example, introduces the general conditions of the establishment and development of cooperatives and points out the advantages and disadvantages of husbandry in Qinghai Province. The paper analyzes the competitive advantages of Hongyuan Lamb Fattening Cooperatives through five forces mode of Michael Port, putting forward countermeasures and upgrading the competitiveness of Hongyuan Lamb Fattening Competitive.
基金supported by the National Natural Science Foundation of China (No. 41176002)
文摘The mechanisms involved in the variability of Atlantic Meridional Overturning Circulation （AMOC） are studied using a 2000-yr control simulation of the coupled Fast Ocean-Atmosphere Model （FOAM）.This study identifies a coupled mode between SST and surface heat flux in the North Atlantic at the decadal timescale,as well as a forcing mode of surface heat flux at the interannual timescale.The coupled mode is regulated by AMOC through meridional heat transport.The increase in surface heating in the North Atlantic weakens the AMOC approximately 10 yr later,and the weakened AMOC in turn decreases SST and sea surface salinity.The decreased SST results in an increase in surface heating in the North Atlantic,thus forming a positive feedback loop.Meanwhile,the weakened AMOC weakens northward heat transport and therefore lowers subsurface temperature approximately 19 yr later,which prevents the AMOC from weakening.In the forcing mode,the surface heat flux leads AMOC by approximately 4 yr.
基金Project supported by the National Natural Science Foun-dation of China(Project No.51506051)
文摘The hydraulic force on the reversible pump turbine might cause serious problems（e.g., the abnormal stops due to large vibrations of the machine）, affecting the safe operations of the pumped energy storage power plants. In the present paper, the hydraulic force on the impeller of a model reversible pump turbine is quantitatively investigated through numerical simulations. It is found that both the amplitude of the force and its dominant components strongly depend on the operating conditions（e.g., the turbine mode, the runaway mode and the turbine brake mode） and the guide vane openings. For example, the axial force parallel with the shaft is prominent in the turbine mode while the force perpendicular to the shaft is the dominant near the runaway and the turbine brake modes. The physical origins of the hydraulic force are further revealed by the analysis of the fluid states inside the impeller.
文摘In this paper the effects of temperature on the radial breathing modes （RBMs） and radial wave propaga- tion in multiwall carbon nanotubes （MWCNTs） are inves- tigated using a continuum model of multiple elastic isotropic shells. The van der Waals forces between tubes are simulated as a nonlinear function of interlayer spacing of MWCNTs. The governing equations are solved using a finite element method. A wide range of innermost radius-to-thickness ratio of MWCNTs is considered to enhance the investigation. The presented solution is verified by comparing the results with those reported in the literature. The effects of temperature on the van der Waals interaction coefficient between layers of MWCNTs are examined. It is found that the variation of the van der Waals interaction coefficient at high temperature is sensible. Subsequently, variations of RBM frequencies and radial wave propagation in MWCNTs with temperatures up to 1 600 K are illustrated. It is shown that the thick MWC- NTs are more sensible to temperature than the thin ones.
