We studied woodland vegetation in broad-leaved deciduous woodlands of Metema in northwestern Amhara regional state, Ethiopia Our objective was to describe plant species composition, diversity, re- generation status, a...We studied woodland vegetation in broad-leaved deciduous woodlands of Metema in northwestern Amhara regional state, Ethiopia Our objective was to describe plant species composition, diversity, re- generation status, and population structure by a selective approach with a systematic sampling design. A total of 74 quadrats (each for 25 m x 25 m, spaced at intervals of 150--200 m) were sampled along established tran- sect lines following the homogeneity of the vegetation. Vegetation data including cover-abundance, height, diameter at breast height (DBH), and numbers of seedlings and saplings of woody species were analyzed using Excel spreadsheet, Shannon Weiner diversity index, and PAST version 1.62. A total of 87 vascular plant species of 74 genera and 36 families were recorded. The dominant family was Fabaceae represented by 16 (18.39 %) species of 13 genera. Shannon Weiner diversity and evenness were 3.67 and 0.82, respectively, which showed that the area was en- dowed with rich floral diversity evenly distributed. The vegetation structure, as quantified by cumulative diameter class frequency distribution, plotted as an interrupted inverted-J- shape pattern with a sharp decrease in the 2nd diameter class. This indicated poor vegetation structure. The diameter classes frequency distributions of selected species plotted in four general patterns i.e., interrupted Inverted-J-shape, J-shape, Bell-shape and Irregular-shape. In conclusion, although the area showed high floral diversity and evenness, woody species including Sterculea setigera, Boswellia papyrifera, and Pterocarpus lucens showed lowest recruitment of seedlings and saplings.展开更多
This paper investigates theoretically the evolutions of the entanglement entropy of a system of two coupled-charge- qubits interacting with an LC-resonator. It is found that when the initial states of the two qubits a...This paper investigates theoretically the evolutions of the entanglement entropy of a system of two coupled-charge- qubits interacting with an LC-resonator. It is found that when the initial states of the two qubits are prepared in a given superposition excited state, the evolution of the von Neumann entropy of the system depends significantly on the coupling strength between the two Josephson charge qubits. With the variation of the coupling strength, the evolution of the entanglement entropy of the system forms some structures, especially the periodically bistable properties, which are the first discovered for such a system to our knowledge. It is found that the relative entropy entanglement of the system is also sensitive to the variation of the coupling strength between the two charge qubits, some novel 'collective oscillations' of the relative entropy are found for the system.展开更多
We offer a new understanding of the scientific world and the contents of the basic question of philosophy,which is based on an analysis of the phenomenon of the specific information in the various components of the st...We offer a new understanding of the scientific world and the contents of the basic question of philosophy,which is based on an analysis of the phenomenon of the specific information in the various components of the structure of reality.It is shown that,in addition to material objects,processes,and events,in the real world are also intangible objects,processes and conditions that are in its information content.So the basic question of philosophy is proposed to treat the relationship as a tangible and intangible component of reality.More succinctly it can be formulated as the ratio of matter and information.This allows you to point to some new challenges studying the phenomenon of information in various components of the structure of reality.展开更多
Since unmanned ground vehicles often encounter concave and convex obstacles in wild ground, a filtering algorithm using line structured light to detect these long distance obstacles is proposed. For the line structure...Since unmanned ground vehicles often encounter concave and convex obstacles in wild ground, a filtering algorithm using line structured light to detect these long distance obstacles is proposed. For the line structured light image, a ranked-order based adaptively extremum median (RAEM) filter algorithm on salt and pepper noise is presented. In the algorithm, firstly effective points and noise points in a filtering window are differentiated; then the gray values of noise points are replaced by the medium of gray values of the effective pixels, with the efficient points' gray values unchanged; in the end this algorithm is proved to be efficient by experiments. Experimental resuits demonstrate that the image blur, resulting into proposed algorithm can remove noise points effectively and minimize the protecting the edge information as much as possible.展开更多
Corrosion is one of the important structural integrity concerns of aging aircraft, and it is estimated that a significant portion of airframe maintenance budgets is directed towards corrosion-related problems for both...Corrosion is one of the important structural integrity concerns of aging aircraft, and it is estimated that a significant portion of airframe maintenance budgets is directed towards corrosion-related problems for both military and commercial aircraft. In order to better understand how environmental factors influence the corrosion damage initiation and propagation on aircraft structure and to predict pre-corrosion test pieces of fatigue life and structural integrity of an effective approach, this paper uses the cellular automaton (CA) method to character the effect of electrolyte concentrations, dissolution probabilities, and temperature on the corrosion damage of a metal structure exposed to an aggressive environment, and the procedure for applying the local rules between the cells of the CA to simulate the corrosion damage evolution is formulated. The simulation results show that the different electrolyte concentrations, dissolution probabilities and temperature, the laws of the dissolution current with time are investigated and they obey the time power function.展开更多
The crystal structure of 2-(2-pyridyl) benzimidazole was determined by single- crystal X-ray diffraction at 193(2) K. It crystallizes in orthorhombic system, space group Pbca with unit cell constants a = 10.6204(7), b...The crystal structure of 2-(2-pyridyl) benzimidazole was determined by single- crystal X-ray diffraction at 193(2) K. It crystallizes in orthorhombic system, space group Pbca with unit cell constants a = 10.6204(7), b = 10.1407(4), c = 18.6327(8) , Z = 8, V = 2006.7(2) 3, Dc = 1.292 g/cm3, F(000) = 816 and m(MoK) = 0.081 mm-1. The structure was refined to R = 0.0317 and wR = 0.0454 for 795 observed reflections with I > 2s(I). In the solid state, it has an emission maximum at 369 nm, while in solution (DMSO), the maximum excitation is at 372 nm. Quantum chemistry calculation was performed by the method of density functional theory. Theoretical results show that atom N is the reactive site when coordinating with a metal, and the electronic structure of the title compound presents excellent carrier transport properties.展开更多
In this article, we study the initial boundary value problem of generalized Pochhammer-Chree equation utt-uxx-uxxt-uxxtt=f(u)xx,x∈Ω,t〉0,u(x,0)=u0(x),ut(x,0)=u1(x),x∈Ω,u(0,t)=u(1,t)=0,t≥0, where Ω...In this article, we study the initial boundary value problem of generalized Pochhammer-Chree equation utt-uxx-uxxt-uxxtt=f(u)xx,x∈Ω,t〉0,u(x,0)=u0(x),ut(x,0)=u1(x),x∈Ω,u(0,t)=u(1,t)=0,t≥0, where Ω = (0, 1). First, we obtain the existence of local Wkp solutions. Then, we prove that, if f(s) ∈ Ck+1(R) is nondecreasing, f(0) = 0 and |f(u)| ≤ C1|u|∫0uf(s)ds + C2, u0(x),u1(x) ∈ WkP(Ω) ∩ W01,P(Ω), k≥ 1, 1 〈 p≤ ∞, then for any T 〉 0 the problem admits a unique solution u(x, t) ∈ W2,∞(0, T; WkP(Ω) ∩ W01,P(Ω)). Finally, the finite time blow-up of solutions and global Wkp solution of generalized IMBo equations are discussed.展开更多
A wide range of techniques has been developed to image biological samples at high spatial and temporal resolution.In this paper,we report recent results from deep-UV confocal fAuorescence microscopy to image inherent ...A wide range of techniques has been developed to image biological samples at high spatial and temporal resolution.In this paper,we report recent results from deep-UV confocal fAuorescence microscopy to image inherent emission from fuorophores such as tryptophan,and structured ilumination microscopy(SIM)of biological materials.One motivation for developing deep-UV fhuorescence imaging and SIM is to provide methods to complement our measurements in the emerging field of X-ray coherent diffractive imaging.展开更多
Sound propagation in a wedge-shaped waveguide with perfectly reflecting boundaries is one of the few range- dependent problems with an analytical solution, and hence provides an ideal benchmark for a full two-way solu...Sound propagation in a wedge-shaped waveguide with perfectly reflecting boundaries is one of the few range- dependent problems with an analytical solution, and hence provides an ideal benchmark for a full two-way solution to the wave equation. An analytical solution for the sound propagation in an ideal wedge with a pressure-release bottom was presented by Buckingham and Tolstoy [Buckingham and Tolstoy 1990 J. Acoust. Soc. Am. 87 1511]. The ideal wedge problem with a rigid bottom is also of great importance in underwater acoustics. We present an analytical solution to the ideal wedge problem with a perfectly reflecting bottom, either rigid or pressure-release, which may be used to provide a means for investigating the sound field in depth-varying channels, and to establish the accuracy of numerical propagation models. Closed-form expressions for coupling matrices are also provided for the ideal waveguides characterized by a ho- mogeneous water column bounded by perfectly reflecting boundaries. A comparison between the analytical solution and the numerical solution recently proposed by Luo et al. [Luo W Y, Yang C M and Zhang R H 2012 Chin. Phys. Lett. 29 014302] is also presented, through which the accuracy of this numerical model is illustrated.展开更多
This paper investigates the dynamical properties of nonstationary solutions in one-dimensional two-component Bose-Einstein condensates. It gives three kinds of stationary solutions to this model and develops a general...This paper investigates the dynamical properties of nonstationary solutions in one-dimensional two-component Bose-Einstein condensates. It gives three kinds of stationary solutions to this model and develops a general method of constructing nonstationary solutions. It obtains the unique features about general evolution and soliton evolution of nonstationary solutions in this model.展开更多
In this paper, we investigate the periodic wave solutions and solitary wave solutions of a (2+1)-dimensional Korteweg-de Vries (KDV) equation</span><span style="font-size:10pt;font-family:"">...In this paper, we investigate the periodic wave solutions and solitary wave solutions of a (2+1)-dimensional Korteweg-de Vries (KDV) equation</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">by applying Jacobi elliptic function expansion method. Abundant types of Jacobi elliptic function solutions are obtained by choosing different </span><span style="font-size:10.0pt;font-family:"">coefficient</span><span style="font-size:10.0pt;font-family:"">s</span><span style="font-size:10pt;font-family:""> <i>p</i>, <i>q</i> and <i>r</i> in the</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">elliptic equation. Then these solutions are</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">coupled into an auxiliary equation</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">and substituted into the (2+1)-dimensional KDV equation. As <span>a result,</span></span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">a large number of complex Jacobi elliptic function solutions are ob</span><span style="font-size:10pt;font-family:"">tained, and many of them have not been found in other documents. As</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10.0pt;font-family:""><span></span></span><span style="font-size:10pt;font-family:"">, some complex solitary solutions are also obtained correspondingly.</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">These solutions that we obtained in this paper will be helpful to understand the physics of the (2+1)-dimensional KDV equation.展开更多
文摘We studied woodland vegetation in broad-leaved deciduous woodlands of Metema in northwestern Amhara regional state, Ethiopia Our objective was to describe plant species composition, diversity, re- generation status, and population structure by a selective approach with a systematic sampling design. A total of 74 quadrats (each for 25 m x 25 m, spaced at intervals of 150--200 m) were sampled along established tran- sect lines following the homogeneity of the vegetation. Vegetation data including cover-abundance, height, diameter at breast height (DBH), and numbers of seedlings and saplings of woody species were analyzed using Excel spreadsheet, Shannon Weiner diversity index, and PAST version 1.62. A total of 87 vascular plant species of 74 genera and 36 families were recorded. The dominant family was Fabaceae represented by 16 (18.39 %) species of 13 genera. Shannon Weiner diversity and evenness were 3.67 and 0.82, respectively, which showed that the area was en- dowed with rich floral diversity evenly distributed. The vegetation structure, as quantified by cumulative diameter class frequency distribution, plotted as an interrupted inverted-J- shape pattern with a sharp decrease in the 2nd diameter class. This indicated poor vegetation structure. The diameter classes frequency distributions of selected species plotted in four general patterns i.e., interrupted Inverted-J-shape, J-shape, Bell-shape and Irregular-shape. In conclusion, although the area showed high floral diversity and evenness, woody species including Sterculea setigera, Boswellia papyrifera, and Pterocarpus lucens showed lowest recruitment of seedlings and saplings.
基金Project supported by the China "State 973 Project" (Grant No.2006CB921606)the Natural Science Foundation of HubeiProvince of Chinathe Innovation Fund of Huazhong University of Science and Technology (2010)
文摘This paper investigates theoretically the evolutions of the entanglement entropy of a system of two coupled-charge- qubits interacting with an LC-resonator. It is found that when the initial states of the two qubits are prepared in a given superposition excited state, the evolution of the von Neumann entropy of the system depends significantly on the coupling strength between the two Josephson charge qubits. With the variation of the coupling strength, the evolution of the entanglement entropy of the system forms some structures, especially the periodically bistable properties, which are the first discovered for such a system to our knowledge. It is found that the relative entropy entanglement of the system is also sensitive to the variation of the coupling strength between the two charge qubits, some novel 'collective oscillations' of the relative entropy are found for the system.
文摘We offer a new understanding of the scientific world and the contents of the basic question of philosophy,which is based on an analysis of the phenomenon of the specific information in the various components of the structure of reality.It is shown that,in addition to material objects,processes,and events,in the real world are also intangible objects,processes and conditions that are in its information content.So the basic question of philosophy is proposed to treat the relationship as a tangible and intangible component of reality.More succinctly it can be formulated as the ratio of matter and information.This allows you to point to some new challenges studying the phenomenon of information in various components of the structure of reality.
基金Supported by the National Natural Science Foundation of China(61273346)the National Defense Key Fundamental Research Program of China(A20130010)the Program for the Fundamental Research of Beijing Institute of Technology(2016CX02010)
文摘Since unmanned ground vehicles often encounter concave and convex obstacles in wild ground, a filtering algorithm using line structured light to detect these long distance obstacles is proposed. For the line structured light image, a ranked-order based adaptively extremum median (RAEM) filter algorithm on salt and pepper noise is presented. In the algorithm, firstly effective points and noise points in a filtering window are differentiated; then the gray values of noise points are replaced by the medium of gray values of the effective pixels, with the efficient points' gray values unchanged; in the end this algorithm is proved to be efficient by experiments. Experimental resuits demonstrate that the image blur, resulting into proposed algorithm can remove noise points effectively and minimize the protecting the edge information as much as possible.
基金supported by the National Natural Science Foundation of China (10962007)Key Project of Chinese Ministry of Education (209136)Ningxia Natural Science Foundation of China (NZ1027)
文摘Corrosion is one of the important structural integrity concerns of aging aircraft, and it is estimated that a significant portion of airframe maintenance budgets is directed towards corrosion-related problems for both military and commercial aircraft. In order to better understand how environmental factors influence the corrosion damage initiation and propagation on aircraft structure and to predict pre-corrosion test pieces of fatigue life and structural integrity of an effective approach, this paper uses the cellular automaton (CA) method to character the effect of electrolyte concentrations, dissolution probabilities, and temperature on the corrosion damage of a metal structure exposed to an aggressive environment, and the procedure for applying the local rules between the cells of the CA to simulate the corrosion damage evolution is formulated. The simulation results show that the different electrolyte concentrations, dissolution probabilities and temperature, the laws of the dissolution current with time are investigated and they obey the time power function.
基金The report was supported by the funds of Ministry of Education Scientific and Technical Committee in Jilin province (20005511) and NENU Testing Fund [2001]3
文摘The crystal structure of 2-(2-pyridyl) benzimidazole was determined by single- crystal X-ray diffraction at 193(2) K. It crystallizes in orthorhombic system, space group Pbca with unit cell constants a = 10.6204(7), b = 10.1407(4), c = 18.6327(8) , Z = 8, V = 2006.7(2) 3, Dc = 1.292 g/cm3, F(000) = 816 and m(MoK) = 0.081 mm-1. The structure was refined to R = 0.0317 and wR = 0.0454 for 795 observed reflections with I > 2s(I). In the solid state, it has an emission maximum at 369 nm, while in solution (DMSO), the maximum excitation is at 372 nm. Quantum chemistry calculation was performed by the method of density functional theory. Theoretical results show that atom N is the reactive site when coordinating with a metal, and the electronic structure of the title compound presents excellent carrier transport properties.
基金supported by National Natural Science Foundation of China(10871055,10926149)Natural Science Foundation of Heilongjiang Province (A2007-02+2 种基金A200810)Science and Technology Foundation of Education Office of Heilongjiang Province(11541276)Foundational Science Founda-tion of Harbin Engineering University
文摘In this article, we study the initial boundary value problem of generalized Pochhammer-Chree equation utt-uxx-uxxt-uxxtt=f(u)xx,x∈Ω,t〉0,u(x,0)=u0(x),ut(x,0)=u1(x),x∈Ω,u(0,t)=u(1,t)=0,t≥0, where Ω = (0, 1). First, we obtain the existence of local Wkp solutions. Then, we prove that, if f(s) ∈ Ck+1(R) is nondecreasing, f(0) = 0 and |f(u)| ≤ C1|u|∫0uf(s)ds + C2, u0(x),u1(x) ∈ WkP(Ω) ∩ W01,P(Ω), k≥ 1, 1 〈 p≤ ∞, then for any T 〉 0 the problem admits a unique solution u(x, t) ∈ W2,∞(0, T; WkP(Ω) ∩ W01,P(Ω)). Finally, the finite time blow-up of solutions and global Wkp solution of generalized IMBo equations are discussed.
基金We acknowledge the support of the Australian Research Council for the Center of Excellence for Coherent X-ray Science(CE0561787).
文摘A wide range of techniques has been developed to image biological samples at high spatial and temporal resolution.In this paper,we report recent results from deep-UV confocal fAuorescence microscopy to image inherent emission from fuorophores such as tryptophan,and structured ilumination microscopy(SIM)of biological materials.One motivation for developing deep-UV fhuorescence imaging and SIM is to provide methods to complement our measurements in the emerging field of X-ray coherent diffractive imaging.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11125420 and 10734100)the Knowledge Innovation Program of the Chinese Academy of Sciences
文摘Sound propagation in a wedge-shaped waveguide with perfectly reflecting boundaries is one of the few range- dependent problems with an analytical solution, and hence provides an ideal benchmark for a full two-way solution to the wave equation. An analytical solution for the sound propagation in an ideal wedge with a pressure-release bottom was presented by Buckingham and Tolstoy [Buckingham and Tolstoy 1990 J. Acoust. Soc. Am. 87 1511]. The ideal wedge problem with a rigid bottom is also of great importance in underwater acoustics. We present an analytical solution to the ideal wedge problem with a perfectly reflecting bottom, either rigid or pressure-release, which may be used to provide a means for investigating the sound field in depth-varying channels, and to establish the accuracy of numerical propagation models. Closed-form expressions for coupling matrices are also provided for the ideal waveguides characterized by a ho- mogeneous water column bounded by perfectly reflecting boundaries. A comparison between the analytical solution and the numerical solution recently proposed by Luo et al. [Luo W Y, Yang C M and Zhang R H 2012 Chin. Phys. Lett. 29 014302] is also presented, through which the accuracy of this numerical model is illustrated.
基金supported by the National Natural Science Foundation of China (Grant No. 1057411)the Foundation for Researching Group by Beijing Normal Universitythe Foundation for Outstanding Doctoral Dissertation by Beijing Normal University
文摘This paper investigates the dynamical properties of nonstationary solutions in one-dimensional two-component Bose-Einstein condensates. It gives three kinds of stationary solutions to this model and develops a general method of constructing nonstationary solutions. It obtains the unique features about general evolution and soliton evolution of nonstationary solutions in this model.
文摘In this paper, we investigate the periodic wave solutions and solitary wave solutions of a (2+1)-dimensional Korteweg-de Vries (KDV) equation</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">by applying Jacobi elliptic function expansion method. Abundant types of Jacobi elliptic function solutions are obtained by choosing different </span><span style="font-size:10.0pt;font-family:"">coefficient</span><span style="font-size:10.0pt;font-family:"">s</span><span style="font-size:10pt;font-family:""> <i>p</i>, <i>q</i> and <i>r</i> in the</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">elliptic equation. Then these solutions are</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">coupled into an auxiliary equation</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">and substituted into the (2+1)-dimensional KDV equation. As <span>a result,</span></span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">a large number of complex Jacobi elliptic function solutions are ob</span><span style="font-size:10pt;font-family:"">tained, and many of them have not been found in other documents. As</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10.0pt;font-family:""><span></span></span><span style="font-size:10pt;font-family:"">, some complex solitary solutions are also obtained correspondingly.</span><span style="font-size:10pt;font-family:""> </span><span style="font-size:10pt;font-family:"">These solutions that we obtained in this paper will be helpful to understand the physics of the (2+1)-dimensional KDV equation.