The dynamics of a solid spherical body in an oscillating liquid flow in a vertical axisymmetric channel of variable cross section is experimentally studied.It is shown that the oscillating liquid leads to the generati...The dynamics of a solid spherical body in an oscillating liquid flow in a vertical axisymmetric channel of variable cross section is experimentally studied.It is shown that the oscillating liquid leads to the generation of intense averaged flows in each of the channel segments.The intensity and direction of these flows depend on the dimensionless oscillating frequency.In the region of studied frequencies,the dynamics of the considered body is examined when the primary vortices emerging in the flow occupy the whole region in each segment.For a fixed frequency,an increase in the oscillation amplitude leads to a phase-inclusion holding effect,i.e.,the body occupies a quasi-stationary position in one of the cells of the vertical channel,while oscillating around its average position.It is also shown that the oscillating motion of a liquid column generates an averaged force acting on the body,the magnitude of which depends on the properties of the body and its position in the channel.The quasi-stationary position is determined by the relative density and size of the body,as well as the dimensionless frequency.The behavior of the body as a function of the amplitude and frequency of fluid oscillation and relative size is discussed in detail.Such findings may be used in the future to control the position of a phase inclusion and/or to strengthen mass transfer effects in a channel of variable cross section by means of fluid oscillations.展开更多
Alice Ridout and Susan Watkins offers a best perspective in their book Doris Lessing： Border Crossings, to contemplate Lessing’s writing. In her 57-year publishing career, Lessing always crosses the borders： as a f...Alice Ridout and Susan Watkins offers a best perspective in their book Doris Lessing： Border Crossings, to contemplate Lessing’s writing. In her 57-year publishing career, Lessing always crosses the borders： as a feminist or anti-feminist, as a science fiction writer or a realist who lost her way, as a Marxist or a reactionary, as a British writer or a postcolonial one. Lessing’s border-crossing not only lies in her different genres of writing or in different novels, but even in a single comparatively traditional novel. The Summer Before the Dark is a representative work of Lessing’s women portrayal transition from focusing on their outside world exploration to on their inner world seeking. This essay tries to look at the content and form of the novel, and to illustrate that Lessing’s border-crossing is also fulfilled in one single novel. She successfully crosses the border of convention and innovation： conventional in content, while innovative in form.展开更多
Population-based algorithms have been used in many real-world problems.Bat algorithm(BA)is one of the states of the art of these approaches.Because of the super bat,on the one hand,BA can converge quickly;on the other...Population-based algorithms have been used in many real-world problems.Bat algorithm(BA)is one of the states of the art of these approaches.Because of the super bat,on the one hand,BA can converge quickly;on the other hand,it is easy to fall into local optimum.Therefore,for typical BA algorithms,the ability of exploration and exploitation is not strong enough and it is hard to find a precise result.In this paper,we propose a novel bat algorithm based on cross boundary learning(CBL)and uniform explosion strategy(UES),namely BABLUE in short,to avoid the above contradiction and achieve both fast convergence and high quality.Different from previous opposition-based learning,the proposed CBL can expand the search area of population and then maintain the ability of global exploration in the process of fast convergence.In order to enhance the ability of local exploitation of the proposed algorithm,we propose UES,which can achieve almost the same search precise as that of firework explosion algorithm but consume less computation resource.BABLUE is tested with numerous experiments on unimodal,multimodal,one-dimensional,high-dimensional and discrete problems,and then compared with other typical intelligent optimization algorithms.The results show that the proposed algorithm outperforms other algorithms.展开更多
An analysis is presented to study the dual nature of solutions for the forced convective boundary layer flow and heat transfer in a cross flow with viscous dissipation terms in the energy equation. The governing equat...An analysis is presented to study the dual nature of solutions for the forced convective boundary layer flow and heat transfer in a cross flow with viscous dissipation terms in the energy equation. The governing equations are transformed into a set of three self-similar ordinary differential equations by similarity transformations. These equations are solved numerically using the very efficient shooting method. This study reveals that the dual solutions of the transformed similarity equations for velocity and temperature distributions exist for certain values of the moving parameter, Prandtl number, and Eckert numbers. The reverse heat flux is observed for larger Eckert numbers; that is, heat absorption at the wall occurs.展开更多
This paper reports study focusing on the effects of sloping bottom on the deep cross-equatorial boundary current, and discusses model and laboratory experiment results showing that the southward that the southward int...This paper reports study focusing on the effects of sloping bottom on the deep cross-equatorial boundary current, and discusses model and laboratory experiment results showing that the southward that the southward intrusion distance and flow speed of the western boundary current depend on the bottom slope variation rate,the difference between and and are the current thickness at eastward edge and westward edge, respectively), and the net mass transport.展开更多
GHANA＇S discovery of oil on its border with Cote d＇Ivoire is testing the long-standing relationship between the two nations. The long running dispute over oil has led to Cote d＇Ivoire＇s Director General of Hydroca...GHANA＇S discovery of oil on its border with Cote d＇Ivoire is testing the long-standing relationship between the two nations. The long running dispute over oil has led to Cote d＇Ivoire＇s Director General of Hydrocarbons and Petroci unveiling a new maritime border with Ghana in November 2011, that includes some of the massive oil wealth in the western region, Ghana＇s Jubilee oil fields, as reported by Upstream, a global oil and gas publication.展开更多
跨界团队在企业等创新主体开展颠覆性创新活动中发挥重要作用,而运用机器学习方法识别其网络特征与颠覆性创新绩效之间殊途同归的组态路径是一个亟待解决的重要问题。本文基于Incopat专利检索平台无人机领域139999条专利数据,采用社区...跨界团队在企业等创新主体开展颠覆性创新活动中发挥重要作用,而运用机器学习方法识别其网络特征与颠覆性创新绩效之间殊途同归的组态路径是一个亟待解决的重要问题。本文基于Incopat专利检索平台无人机领域139999条专利数据,采用社区发现算法在专利发明人合作关系数据中识别185个跨界团队,依据社会网络理论遴选跨界团队网络特征变量,利用k-means聚类算法对跨界团队进行类型划分,并运用决策树CART(classification and regression trees)算法挖掘不同类型跨界团队网络特征对其颠覆性创新绩效的影响。研究结果表明,①跨界团队共有二元合作、类完全合作和复杂合作3种合作类型,不同跨界团队类型对颠覆性创新绩效影响具有差异性,即类完全合作团队高颠覆性创新绩效占比最高,二元合作团队高颠覆性创新绩效占比最低;②合作强度具有普适性,它是影响不同跨界团队形成不同水平颠覆性创新绩效的核心因素;③合作强度正向影响二元合作团队颠覆性创新绩效,类完全合作团队的颠覆性创新绩效受聚集系数、合作强度与团队规模的共同影响,而对于合作强度较高的复杂合作团队而言,保持较低的网络密度有利于其提升颠覆性创新绩效。展开更多
文摘The dynamics of a solid spherical body in an oscillating liquid flow in a vertical axisymmetric channel of variable cross section is experimentally studied.It is shown that the oscillating liquid leads to the generation of intense averaged flows in each of the channel segments.The intensity and direction of these flows depend on the dimensionless oscillating frequency.In the region of studied frequencies,the dynamics of the considered body is examined when the primary vortices emerging in the flow occupy the whole region in each segment.For a fixed frequency,an increase in the oscillation amplitude leads to a phase-inclusion holding effect,i.e.,the body occupies a quasi-stationary position in one of the cells of the vertical channel,while oscillating around its average position.It is also shown that the oscillating motion of a liquid column generates an averaged force acting on the body,the magnitude of which depends on the properties of the body and its position in the channel.The quasi-stationary position is determined by the relative density and size of the body,as well as the dimensionless frequency.The behavior of the body as a function of the amplitude and frequency of fluid oscillation and relative size is discussed in detail.Such findings may be used in the future to control the position of a phase inclusion and/or to strengthen mass transfer effects in a channel of variable cross section by means of fluid oscillations.
文摘Alice Ridout and Susan Watkins offers a best perspective in their book Doris Lessing： Border Crossings, to contemplate Lessing’s writing. In her 57-year publishing career, Lessing always crosses the borders： as a feminist or anti-feminist, as a science fiction writer or a realist who lost her way, as a Marxist or a reactionary, as a British writer or a postcolonial one. Lessing’s border-crossing not only lies in her different genres of writing or in different novels, but even in a single comparatively traditional novel. The Summer Before the Dark is a representative work of Lessing’s women portrayal transition from focusing on their outside world exploration to on their inner world seeking. This essay tries to look at the content and form of the novel, and to illustrate that Lessing’s border-crossing is also fulfilled in one single novel. She successfully crosses the border of convention and innovation： conventional in content, while innovative in form.
基金Supported by the National Natural Science Foundation of China(61472289)the Open Project Program of the State Key Laboratory of Digital Manufacturing Equipment and Technology(DMETKF2017016)
文摘Population-based algorithms have been used in many real-world problems.Bat algorithm(BA)is one of the states of the art of these approaches.Because of the super bat,on the one hand,BA can converge quickly;on the other hand,it is easy to fall into local optimum.Therefore,for typical BA algorithms,the ability of exploration and exploitation is not strong enough and it is hard to find a precise result.In this paper,we propose a novel bat algorithm based on cross boundary learning(CBL)and uniform explosion strategy(UES),namely BABLUE in short,to avoid the above contradiction and achieve both fast convergence and high quality.Different from previous opposition-based learning,the proposed CBL can expand the search area of population and then maintain the ability of global exploration in the process of fast convergence.In order to enhance the ability of local exploitation of the proposed algorithm,we propose UES,which can achieve almost the same search precise as that of firework explosion algorithm but consume less computation resource.BABLUE is tested with numerous experiments on unimodal,multimodal,one-dimensional,high-dimensional and discrete problems,and then compared with other typical intelligent optimization algorithms.The results show that the proposed algorithm outperforms other algorithms.
文摘An analysis is presented to study the dual nature of solutions for the forced convective boundary layer flow and heat transfer in a cross flow with viscous dissipation terms in the energy equation. The governing equations are transformed into a set of three self-similar ordinary differential equations by similarity transformations. These equations are solved numerically using the very efficient shooting method. This study reveals that the dual solutions of the transformed similarity equations for velocity and temperature distributions exist for certain values of the moving parameter, Prandtl number, and Eckert numbers. The reverse heat flux is observed for larger Eckert numbers; that is, heat absorption at the wall occurs.
文摘This paper reports study focusing on the effects of sloping bottom on the deep cross-equatorial boundary current, and discusses model and laboratory experiment results showing that the southward that the southward intrusion distance and flow speed of the western boundary current depend on the bottom slope variation rate,the difference between and and are the current thickness at eastward edge and westward edge, respectively), and the net mass transport.
文摘GHANA＇S discovery of oil on its border with Cote d＇Ivoire is testing the long-standing relationship between the two nations. The long running dispute over oil has led to Cote d＇Ivoire＇s Director General of Hydrocarbons and Petroci unveiling a new maritime border with Ghana in November 2011, that includes some of the massive oil wealth in the western region, Ghana＇s Jubilee oil fields, as reported by Upstream, a global oil and gas publication.
文摘跨界团队在企业等创新主体开展颠覆性创新活动中发挥重要作用,而运用机器学习方法识别其网络特征与颠覆性创新绩效之间殊途同归的组态路径是一个亟待解决的重要问题。本文基于Incopat专利检索平台无人机领域139999条专利数据,采用社区发现算法在专利发明人合作关系数据中识别185个跨界团队,依据社会网络理论遴选跨界团队网络特征变量,利用k-means聚类算法对跨界团队进行类型划分,并运用决策树CART(classification and regression trees)算法挖掘不同类型跨界团队网络特征对其颠覆性创新绩效的影响。研究结果表明,①跨界团队共有二元合作、类完全合作和复杂合作3种合作类型,不同跨界团队类型对颠覆性创新绩效影响具有差异性,即类完全合作团队高颠覆性创新绩效占比最高,二元合作团队高颠覆性创新绩效占比最低;②合作强度具有普适性,它是影响不同跨界团队形成不同水平颠覆性创新绩效的核心因素;③合作强度正向影响二元合作团队颠覆性创新绩效,类完全合作团队的颠覆性创新绩效受聚集系数、合作强度与团队规模的共同影响,而对于合作强度较高的复杂合作团队而言,保持较低的网络密度有利于其提升颠覆性创新绩效。
