A novel technique for reducing reverberation artifact in acoustic shadow imaging using nonlinear ultrasound interaction, called nonlinear acoustic shadow method, has been developed and experimentally studied. In this ...A novel technique for reducing reverberation artifact in acoustic shadow imaging using nonlinear ultrasound interaction, called nonlinear acoustic shadow method, has been developed and experimentally studied. In this technique, the conventional acoustic shadow method is modified by using the secondary wave generated by nonlinear interaction of two primary sound waves emitted from parametric array. Either conventional or nonlinear acoustic shadow imaging is carried out for aluminum square cylinder and the size of the shadow is compared. The result shows that the nonlinear acoustic shadow method reduces reverberation artifact inside the square cylinder and has better accuracy in the size measurement than conventional acoustic shadow method.展开更多
Semi-aquatic arthropods skate on water surfaces with synergetic actions of their legs. The sculling forward locomotion of water striders was observed and analyzed in situ to understand and reproduce the abovementioned...Semi-aquatic arthropods skate on water surfaces with synergetic actions of their legs. The sculling forward locomotion of water striders was observed and analyzed in situ to understand and reproduce the abovementioned feature. The bright-edged elliptical shadows of the six legs of a water strider were recorded to derive the supporting force distributions on legs. The propulsion principles of water striders were quantitatively disclosed. A typical sculling forward process was accomplished within approximately 0.15 s. Water striders lifted their heads slightly and supported their weight mainly by the two driving legs to increase the propulsion force and reduce the water resistance during the process. The normalized thrust-area ratio （defined as the ratio of the propulsion force to the projected area） was usually lower than 0.4 after sculling for approximately 0.08 s. The entire normal supporting force remained nearly constant during a stroke to reduce the mass center fluctuation in the normal direction. In addition, water striders could easily control the locomotion direction and speed through the light swinging of the two hind legs as rudders. These sculling principles might inspire sophisticated biomimetic wa- ter-walking robots with high propulsion efficiency in the future.展开更多
The Tongchang orefield is located in the central part of the Mianxian-Lueyang-Yangpingguan area that is celebrated as a 'gold triangle' area,at the juncture of the latitudinal tectonic zone of South Qinling,th...The Tongchang orefield is located in the central part of the Mianxian-Lueyang-Yangpingguan area that is celebrated as a 'gold triangle' area,at the juncture of the latitudinal tectonic zone of South Qinling,the Longmenshan Cathysian tectonic zone and the Sichuan-Yunnan longitudinal tectonic zone,where there are distributed Cu-Au polymetallic ore deposits(occurrences) including the Tongchang,Chenjiaba,Qinjiabian,Hongtushi,Yinshangou and Xiakouyi ore deposits(mineralization).Based on the "giant pressure shadow" structure put forward and demonstrated by numerical modeling of the tectonic stress field and the static photoelasticity experiments on the basis of tectonic ore-controlling laws in the orefield,tectonic metallogenesis driven by orefield tectonic stress has been discussed in terms of its geological setting,orefield geomechanics,and tectonic stress field.It is thought that the dynamic evolution model of the tectonic stress field controls the whole process of formation of the polymetallic ore deposits(mineralization) in the orefield,as well as the deformation field.As a result,it controls the emplacement of rockbodies and the transformation of ore-source bodies,and provides both the channel-ways for ore-forming fluids and ore-hosting space.Furthermore,it controls the migration potential field of fluids and,thereafter,its flow direction,rate and volume;the tectonic stress field also controls the energy field and hence controls the position of occurrence of ore deposits and their scale.The method of tectonic stress field has been applied to ore prognosis in the orefield.The rules of magmatic emplacement and metallogenic fluid migrating and concentrating under the control of the structural stress field were expounded,hence providing the theoretical basis for the prognosis of concealed ores.In addition,a number of important target areas have been defined.展开更多
Shadow and variable illumination considerably influence the results of image understanding such as image segmentation, object tracking, and object recognition. The intrinsic image decomposition is to separate the refl...Shadow and variable illumination considerably influence the results of image understanding such as image segmentation, object tracking, and object recognition. The intrinsic image decomposition is to separate the reflectance and the illumination image from an observed image. The intrinsic image decomposition is very useful to remove shadows and then improve the performance of image understanding. In this paper, we present a new shadow removal method based on intrinsic image decomposition on a single color image using the Fisher Linear Discriminant (FLD). Under the assumptions-Lambertian surfaces, approximately Planckian lighting, and narrowband camera sensors, there exist an invariant image, which is 1-dimensional greyscale and independent of illuminant color and intensity. The Fisher Linear Discriminant is applied to create the invariant image. And further the shadows can be removed through the difference between invariant image and original color image. The experimental results on real data show good performance of this algorithm.展开更多
目的 Linear Programming的simplexmethod建模求最优解。方法应用simplexmethod.结果建立了LinearProgramming的数学模型并用simplexmethod求得了最优解.结论因为单纯形表反映了Linear Programming的所有信息,故用simplexmethod可简便...目的 Linear Programming的simplexmethod建模求最优解。方法应用simplexmethod.结果建立了LinearProgramming的数学模型并用simplexmethod求得了最优解.结论因为单纯形表反映了Linear Programming的所有信息,故用simplexmethod可简便地求得最优解.simplexmethod的基本思路是:先将Linear Programming用sim-plexmethod划为标准型,根据问题的标准型,进行初等行变换,将主元素列除主元素化为1外其余的元素均化为0,当基变量值全为非负时,问题就得到了最优解.展开更多
In this paper we show that an -stable diffeomorphism has the weak inverse shadowing property with respect to classes of continuous method and and some of the -stable diffeomorphisms have weak inverse shadowing propert...In this paper we show that an -stable diffeomorphism has the weak inverse shadowing property with respect to classes of continuous method and and some of the -stable diffeomorphisms have weak inverse shadowing property with respect to classes . In addition we study relation between minimality and weak inverse shadowing property with respect to class and relation between expansivity and inverse shadowing property with respect to class .展开更多
由于光伏阵列在局部阴影情况下输出功率呈多峰值状态,而传统最大功率点追踪(MPPT:Maximum Power Point Tracking)控制无法解决多峰问题,会陷入局部最优,影响光伏发电效率,为此,提出一种复合算法应用于光伏最大功率点追踪。该方法将麻雀...由于光伏阵列在局部阴影情况下输出功率呈多峰值状态,而传统最大功率点追踪(MPPT:Maximum Power Point Tracking)控制无法解决多峰问题,会陷入局部最优,影响光伏发电效率,为此,提出一种复合算法应用于光伏最大功率点追踪。该方法将麻雀算法的初始种群进行优化,结合反向学习策略,加强了算法的全局搜索能力。当搜索到光伏发电最大功率点附近转换成扰动观察法,利用其快速收敛的特性快速搜索至最大功率点。利用Simulink仿真与硬件实验,验证所提出复合算法的全局搜索能力和快速收敛能力,与麻雀算法、扰动观察法相对比,复合算法的准确性和快速性具有显著提升。展开更多
文摘A novel technique for reducing reverberation artifact in acoustic shadow imaging using nonlinear ultrasound interaction, called nonlinear acoustic shadow method, has been developed and experimentally studied. In this technique, the conventional acoustic shadow method is modified by using the secondary wave generated by nonlinear interaction of two primary sound waves emitted from parametric array. Either conventional or nonlinear acoustic shadow imaging is carried out for aluminum square cylinder and the size of the shadow is compared. The result shows that the nonlinear acoustic shadow method reduces reverberation artifact inside the square cylinder and has better accuracy in the size measurement than conventional acoustic shadow method.
基金This work is supported by the National Natural Science Foundation of China （Grant No. 51425502）.
文摘Semi-aquatic arthropods skate on water surfaces with synergetic actions of their legs. The sculling forward locomotion of water striders was observed and analyzed in situ to understand and reproduce the abovementioned feature. The bright-edged elliptical shadows of the six legs of a water strider were recorded to derive the supporting force distributions on legs. The propulsion principles of water striders were quantitatively disclosed. A typical sculling forward process was accomplished within approximately 0.15 s. Water striders lifted their heads slightly and supported their weight mainly by the two driving legs to increase the propulsion force and reduce the water resistance during the process. The normalized thrust-area ratio （defined as the ratio of the propulsion force to the projected area） was usually lower than 0.4 after sculling for approximately 0.08 s. The entire normal supporting force remained nearly constant during a stroke to reduce the mass center fluctuation in the normal direction. In addition, water striders could easily control the locomotion direction and speed through the light swinging of the two hind legs as rudders. These sculling principles might inspire sophisticated biomimetic wa- ter-walking robots with high propulsion efficiency in the future.
基金Granted jointly by the Funds for Program for NCET in University (NCET-04-917)NSF (40863002)Project for the Distinguishing Discipline of KUST (2008)
文摘The Tongchang orefield is located in the central part of the Mianxian-Lueyang-Yangpingguan area that is celebrated as a 'gold triangle' area,at the juncture of the latitudinal tectonic zone of South Qinling,the Longmenshan Cathysian tectonic zone and the Sichuan-Yunnan longitudinal tectonic zone,where there are distributed Cu-Au polymetallic ore deposits(occurrences) including the Tongchang,Chenjiaba,Qinjiabian,Hongtushi,Yinshangou and Xiakouyi ore deposits(mineralization).Based on the "giant pressure shadow" structure put forward and demonstrated by numerical modeling of the tectonic stress field and the static photoelasticity experiments on the basis of tectonic ore-controlling laws in the orefield,tectonic metallogenesis driven by orefield tectonic stress has been discussed in terms of its geological setting,orefield geomechanics,and tectonic stress field.It is thought that the dynamic evolution model of the tectonic stress field controls the whole process of formation of the polymetallic ore deposits(mineralization) in the orefield,as well as the deformation field.As a result,it controls the emplacement of rockbodies and the transformation of ore-source bodies,and provides both the channel-ways for ore-forming fluids and ore-hosting space.Furthermore,it controls the migration potential field of fluids and,thereafter,its flow direction,rate and volume;the tectonic stress field also controls the energy field and hence controls the position of occurrence of ore deposits and their scale.The method of tectonic stress field has been applied to ore prognosis in the orefield.The rules of magmatic emplacement and metallogenic fluid migrating and concentrating under the control of the structural stress field were expounded,hence providing the theoretical basis for the prognosis of concealed ores.In addition,a number of important target areas have been defined.
文摘Shadow and variable illumination considerably influence the results of image understanding such as image segmentation, object tracking, and object recognition. The intrinsic image decomposition is to separate the reflectance and the illumination image from an observed image. The intrinsic image decomposition is very useful to remove shadows and then improve the performance of image understanding. In this paper, we present a new shadow removal method based on intrinsic image decomposition on a single color image using the Fisher Linear Discriminant (FLD). Under the assumptions-Lambertian surfaces, approximately Planckian lighting, and narrowband camera sensors, there exist an invariant image, which is 1-dimensional greyscale and independent of illuminant color and intensity. The Fisher Linear Discriminant is applied to create the invariant image. And further the shadows can be removed through the difference between invariant image and original color image. The experimental results on real data show good performance of this algorithm.
文摘目的 Linear Programming的simplexmethod建模求最优解。方法应用simplexmethod.结果建立了LinearProgramming的数学模型并用simplexmethod求得了最优解.结论因为单纯形表反映了Linear Programming的所有信息,故用simplexmethod可简便地求得最优解.simplexmethod的基本思路是:先将Linear Programming用sim-plexmethod划为标准型,根据问题的标准型,进行初等行变换,将主元素列除主元素化为1外其余的元素均化为0,当基变量值全为非负时,问题就得到了最优解.
文摘In this paper we show that an -stable diffeomorphism has the weak inverse shadowing property with respect to classes of continuous method and and some of the -stable diffeomorphisms have weak inverse shadowing property with respect to classes . In addition we study relation between minimality and weak inverse shadowing property with respect to class and relation between expansivity and inverse shadowing property with respect to class .
文摘由于光伏阵列在局部阴影情况下输出功率呈多峰值状态,而传统最大功率点追踪(MPPT:Maximum Power Point Tracking)控制无法解决多峰问题,会陷入局部最优,影响光伏发电效率,为此,提出一种复合算法应用于光伏最大功率点追踪。该方法将麻雀算法的初始种群进行优化,结合反向学习策略,加强了算法的全局搜索能力。当搜索到光伏发电最大功率点附近转换成扰动观察法,利用其快速收敛的特性快速搜索至最大功率点。利用Simulink仿真与硬件实验,验证所提出复合算法的全局搜索能力和快速收敛能力,与麻雀算法、扰动观察法相对比,复合算法的准确性和快速性具有显著提升。
