[Objective]This study was to reveal the essence of mechanism about how the alien invasive plants spread.[Method]Species niche and material/energy flow were used as basic research indicators to analyze the intrinsic me...[Objective]This study was to reveal the essence of mechanism about how the alien invasive plants spread.[Method]Species niche and material/energy flow were used as basic research indicators to analyze the intrinsic mechanism of alien plants invasion.[Result]Most of the invasive plants have not been explicitly defined and their effective control methods not brought forward.[Conclusion]Overrun of alien invasive plants depends on whether the niche of a species could be continuously met at spatial level.Based on this we put forward corresponding control measures,proposed an assumption to establish a cylinder-network model and discussed the definition of alien invasive plants.展开更多
Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dyna...Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dynamic behaviours of debris flows with differences in volumes, concentrations(solid volume fraction), and travel distances after interception by a uniform flexible net barrier. A high-speed camera was used to monitor the whole test process, and their dynamic behaviours were recorded. A preliminary computational framework on energy conversion is proposed according to the deposition mechanisms and outflow of debris flow under the effects of the flexible net barrier. The experimental results show that the dynamic interaction process between a debris flow and the flexible net barrier can be divided into two stages:(a) the two-phase impact of the leading edge of the debris flow with the net and(b) collision and friction between the body of the debris flow and intercepted debris material. The approach velocity of a debris flow decreases sharply(a maximum of 63%) after the interception by the net barrier, and the mass ratio of the debris material being intercepted and the kinetic energy ratio of the debris material being absorbed by the net barrier are close due to the limited interception efficiency of the flexible net barrier, which is believed to be related to the flexibility. The energy ratio of outflow is relative small despite the large permeability of the flexible net barrier.展开更多
The energy of interaction between DNA strands in promoters is of great functional importance. Visualization of the energy of DNA strands distribution in promoter sequences was achieved. The separation of promoters in ...The energy of interaction between DNA strands in promoters is of great functional importance. Visualization of the energy of DNA strands distribution in promoter sequences was achieved. The separation of promoters in groups by their energetic properties enables evaluation of the dependence of promoter strength on the energetic properties. The analysis of groups (clusters) of promoters distributed by the energy of DNA strands interaction in ?55, ?35, ?10 and +6 sequences indicates their connection with the transcriptional activity.展开更多
A gun, with its explosive energy, can accelerate a bullet, with mass m, from zero velocity. After a bullet is shot into a wall, the wall receives energy, which is converted from explosive to kinetic energy of the ball...A gun, with its explosive energy, can accelerate a bullet, with mass m, from zero velocity. After a bullet is shot into a wall, the wall receives energy, which is converted from explosive to kinetic energy of the ball, and then, to heat and/or deformation energy of the wall. When a person carries this gun in a moving vehicle, and shoots at a wall, the observer witnesses the bullet gain kinetic energy compared with the original scenario. From where is the additional energy derived？ Is the explosive energy of the gunpowder a frame-of-reference-dependent quantity？ Does it concern the theory of relativity by Albert Einstein？ In this article, the additional energy e is defined as the mutual energy of relative motion, which is a flame-of-reference-dependent energy, and thus, may be transferred from one reference frame to another.展开更多
We determine explicitly the exact transcendental bound states energies equation for a one-dimensional harmonic oscillator perturbed by a single and a double point interactions via Green's function techniques using...We determine explicitly the exact transcendental bound states energies equation for a one-dimensional harmonic oscillator perturbed by a single and a double point interactions via Green's function techniques using both momentum and position space representations. The even and odd solutions of the problem are discussed. The corresponding limiting cases are recovered. For the harmonic oscillator with a point interaction in more than one dimension,divergent series appear. We use to remove this divergence an exponential regulator and we obtain a transcendental equation for the energy bound states. The results obtained here are consistent with other investigations using different methods.展开更多
基金Supported by Joint Research Fund from National Natural Science Foundation of China(NSFC)-Yunnan Province(U0933601)Students Research Fund from Southwest Forestry University(1001)~~
文摘[Objective]This study was to reveal the essence of mechanism about how the alien invasive plants spread.[Method]Species niche and material/energy flow were used as basic research indicators to analyze the intrinsic mechanism of alien plants invasion.[Result]Most of the invasive plants have not been explicitly defined and their effective control methods not brought forward.[Conclusion]Overrun of alien invasive plants depends on whether the niche of a species could be continuously met at spatial level.Based on this we put forward corresponding control measures,proposed an assumption to establish a cylinder-network model and discussed the definition of alien invasive plants.
基金supported by the National Natural Science Foundation of China (51639007)the Youth Science and Technology Fund of Sichuan Province (2016JQ0011)the Science and Technology Fund of Chengdu Water Authority (14H1055).
文摘Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dynamic behaviours of debris flows with differences in volumes, concentrations(solid volume fraction), and travel distances after interception by a uniform flexible net barrier. A high-speed camera was used to monitor the whole test process, and their dynamic behaviours were recorded. A preliminary computational framework on energy conversion is proposed according to the deposition mechanisms and outflow of debris flow under the effects of the flexible net barrier. The experimental results show that the dynamic interaction process between a debris flow and the flexible net barrier can be divided into two stages:(a) the two-phase impact of the leading edge of the debris flow with the net and(b) collision and friction between the body of the debris flow and intercepted debris material. The approach velocity of a debris flow decreases sharply(a maximum of 63%) after the interception by the net barrier, and the mass ratio of the debris material being intercepted and the kinetic energy ratio of the debris material being absorbed by the net barrier are close due to the limited interception efficiency of the flexible net barrier, which is believed to be related to the flexibility. The energy ratio of outflow is relative small despite the large permeability of the flexible net barrier.
文摘The energy of interaction between DNA strands in promoters is of great functional importance. Visualization of the energy of DNA strands distribution in promoter sequences was achieved. The separation of promoters in groups by their energetic properties enables evaluation of the dependence of promoter strength on the energetic properties. The analysis of groups (clusters) of promoters distributed by the energy of DNA strands interaction in ?55, ?35, ?10 and +6 sequences indicates their connection with the transcriptional activity.
文摘A gun, with its explosive energy, can accelerate a bullet, with mass m, from zero velocity. After a bullet is shot into a wall, the wall receives energy, which is converted from explosive to kinetic energy of the ball, and then, to heat and/or deformation energy of the wall. When a person carries this gun in a moving vehicle, and shoots at a wall, the observer witnesses the bullet gain kinetic energy compared with the original scenario. From where is the additional energy derived？ Is the explosive energy of the gunpowder a frame-of-reference-dependent quantity？ Does it concern the theory of relativity by Albert Einstein？ In this article, the additional energy e is defined as the mutual energy of relative motion, which is a flame-of-reference-dependent energy, and thus, may be transferred from one reference frame to another.
基金Supported by the Algerian Ministry of Higher Education and Scientific Research under the CNEPRU project No.D01720140001
文摘We determine explicitly the exact transcendental bound states energies equation for a one-dimensional harmonic oscillator perturbed by a single and a double point interactions via Green's function techniques using both momentum and position space representations. The even and odd solutions of the problem are discussed. The corresponding limiting cases are recovered. For the harmonic oscillator with a point interaction in more than one dimension,divergent series appear. We use to remove this divergence an exponential regulator and we obtain a transcendental equation for the energy bound states. The results obtained here are consistent with other investigations using different methods.
