The development of late comers in the new normal state is a practical and urgent issue to be tackled by underdeveloped areas of China in current situation.The development strategy of late comers is economic developmen...The development of late comers in the new normal state is a practical and urgent issue to be tackled by underdeveloped areas of China in current situation.The development strategy of late comers is economic development strategy different from economically developed areas.Five element strategic analysis model(ECSRE) stresses intrinsic features of things,which is favorable for making clear weakness of late comers and suitable for southeast Chongqing.With the aid of the ECSRE,on the basis of analyzing resources and external conditions,this paper made an in-depth analysis on late comer strategy for southeast Chongqing from the perspective of industry pattern attribute,development stages,individual characters and thinking pattern of decision-makers.It stresses regional cooperation,unified restriction,dislocation characteristics,institutional simulation and innovation and improving policy system,to stimulate strengths of late comers,so as to promote long-term rapid and sustainable development of folk custom eco-tourism in southeast Chongqing.展开更多
真空开关的分闸速度是影响开关电弧形态及其使用性能的重要因素。为满足高精度分析的需求,提出运用数字图像处理技术从真空开关运动序列图像中精确跟踪触头位置,进而计算触头运动速度的检测方法。该文首先利用Solidworks软件建立真空开...真空开关的分闸速度是影响开关电弧形态及其使用性能的重要因素。为满足高精度分析的需求,提出运用数字图像处理技术从真空开关运动序列图像中精确跟踪触头位置,进而计算触头运动速度的检测方法。该文首先利用Solidworks软件建立真空开关触头模型,并以设定速度模拟分闸过程,获得了分闸过程动触头的运动序列图像。运用Harris角点检测算法提取序列图像中触头角点,然后用SSD(sum of square differences)角点匹配算法对相邻序列图像中所检测到的角点进行匹配,并从中筛选精确匹配角点,再以匹配的像素角点为初始值,计算亚像素精度角点,从而实现了动触头位置的亚像素级精度跟踪。计算相邻帧图像动触头的位移,该位移与相邻帧图像时间间隔的比值即为动触头的瞬时速度。结果表明:亚像素角点检测技术可实现动触头位置跟踪及其分闸速度计算,且相对误差≤4.7%,最高精度可达0.34%。该方法能够实现真空开关分闸速度的高精度检测,为后续分析分闸速度与电弧形态的关系奠定了基础。展开更多
The three-dimensional finite element method is used to solve the problem of the quarter-elliptical comer crack of the bolt-hole in mechanical joints being subjected to remote tension. The square-root stress singularit...The three-dimensional finite element method is used to solve the problem of the quarter-elliptical comer crack of the bolt-hole in mechanical joints being subjected to remote tension. The square-root stress singularity around the corner crack front is simulated using the collapsed 20-node quarter point singular elements. The contact interaction between the bolt and the hole boundary is considered in the finite element analysis. The stress intensity factors （SIFs） along the crack front are evaluated by using the displacement correlation technique. The effects of the amount of clearance between the hole and the bolt on the SIFs are investigated. The numerical results indicate that the SIF for mode I decrease with the decreases in clearance, and in the cases of clearance being present, the corner crack is in a mix-mode, even if mode I loading is dominant.展开更多
基金Supported by Key Project for Social Sciences of Chongqing Municipal Education Commission(14SK005),Project CK2013B26 and Project CK2015Z11
文摘The development of late comers in the new normal state is a practical and urgent issue to be tackled by underdeveloped areas of China in current situation.The development strategy of late comers is economic development strategy different from economically developed areas.Five element strategic analysis model(ECSRE) stresses intrinsic features of things,which is favorable for making clear weakness of late comers and suitable for southeast Chongqing.With the aid of the ECSRE,on the basis of analyzing resources and external conditions,this paper made an in-depth analysis on late comer strategy for southeast Chongqing from the perspective of industry pattern attribute,development stages,individual characters and thinking pattern of decision-makers.It stresses regional cooperation,unified restriction,dislocation characteristics,institutional simulation and innovation and improving policy system,to stimulate strengths of late comers,so as to promote long-term rapid and sustainable development of folk custom eco-tourism in southeast Chongqing.
基金Supposed by the National Natural Science Foundation of China under Grant No.60575019(国家自然科学基金)the National High-Tech Research and Development Plan of China under Grant No.2006AA01Z116(国家高技术研究发展计划(863))
文摘真空开关的分闸速度是影响开关电弧形态及其使用性能的重要因素。为满足高精度分析的需求,提出运用数字图像处理技术从真空开关运动序列图像中精确跟踪触头位置,进而计算触头运动速度的检测方法。该文首先利用Solidworks软件建立真空开关触头模型,并以设定速度模拟分闸过程,获得了分闸过程动触头的运动序列图像。运用Harris角点检测算法提取序列图像中触头角点,然后用SSD(sum of square differences)角点匹配算法对相邻序列图像中所检测到的角点进行匹配,并从中筛选精确匹配角点,再以匹配的像素角点为初始值,计算亚像素精度角点,从而实现了动触头位置的亚像素级精度跟踪。计算相邻帧图像动触头的位移,该位移与相邻帧图像时间间隔的比值即为动触头的瞬时速度。结果表明:亚像素角点检测技术可实现动触头位置跟踪及其分闸速度计算,且相对误差≤4.7%,最高精度可达0.34%。该方法能够实现真空开关分闸速度的高精度检测,为后续分析分闸速度与电弧形态的关系奠定了基础。
基金National Natural Science Foundation of China (10272036)
文摘The three-dimensional finite element method is used to solve the problem of the quarter-elliptical comer crack of the bolt-hole in mechanical joints being subjected to remote tension. The square-root stress singularity around the corner crack front is simulated using the collapsed 20-node quarter point singular elements. The contact interaction between the bolt and the hole boundary is considered in the finite element analysis. The stress intensity factors （SIFs） along the crack front are evaluated by using the displacement correlation technique. The effects of the amount of clearance between the hole and the bolt on the SIFs are investigated. The numerical results indicate that the SIF for mode I decrease with the decreases in clearance, and in the cases of clearance being present, the corner crack is in a mix-mode, even if mode I loading is dominant.
