Ellipse fitting is a useful tool to obtain the differential signal of two atom interference gravimeters. The quality standard of ellipse fitting should be the deviation between the true phase and the fitting phase of ...Ellipse fitting is a useful tool to obtain the differential signal of two atom interference gravimeters. The quality standard of ellipse fitting should be the deviation between the true phase and the fitting phase of the interference fringe. In this paper, we present a new algorithm to fit the ellipse. The algorithm is to minimize the differential noise of two interference gravimeters and obtain a more accurate value of the gravity gradient. We have theoretically derived the expression of the differential-mode noise and implemented the ellipse fitting in the program. This new algorithm is also compared with the classical methods.展开更多
In this paper,we present new bounds for the perimeter of an ellipse in terms of harmonic,geometric,arithmetic and quadratic means;these new bounds represent improvements upon some previously known results.
The enhanced cooling performance caused by ellipse-shaped tabs located at the outlet of the film cooling holes is conducted.Three covering ratios of ellipse-shaped tabs on film holes and four blowing ratios are studie...The enhanced cooling performance caused by ellipse-shaped tabs located at the outlet of the film cooling holes is conducted.Three covering ratios of ellipse-shaped tabs on film holes and four blowing ratios are studied.The results show that:(1)The heat transfer coefficient ratio is higher than that without tab,indicating that the mixing of mainstream and coolant jet provides a better coverage film on the cooling wall,but increases the local turbulence production which enhances the heat transfer coefficient;(2)When the ellipse-shaped tabs are located at the film hole outlet,there is a larger pressure drop with the ellipse tab relative to the no-tab case.Thus,the discharge coefficient with ellipse tab is lower than that without tab.展开更多
钻井液振动筛作为一级固相控制设备,常存在“筛堵”“筛糊”和“跑浆”等问题,而通过改变“力心”和质径积比值等参数来得到合理的变椭圆振动轨迹,可以较好解决这些问题。针对变椭圆轨迹振动筛的结构参数改变要求,研究其对振动轨迹和颗...钻井液振动筛作为一级固相控制设备,常存在“筛堵”“筛糊”和“跑浆”等问题,而通过改变“力心”和质径积比值等参数来得到合理的变椭圆振动轨迹,可以较好解决这些问题。针对变椭圆轨迹振动筛的结构参数改变要求,研究其对振动轨迹和颗粒行为的影响,并基于离散元法(Discrete Element Method)的耦合多体系统动力学(Dynamics of Multi-body System)研究方法,对变椭圆振动筛本体和物料颗粒进行联合分析求解;分析了变椭圆振动筛力心位置和偏心块质径积比值对振动轨迹、物料颗粒运移速度和透筛率的影响。结果表明:振动筛在力心与质心的距离在100~150 mm,偏心块质径积比值在10∶7左右,入料端最大椭圆倾角在60°~65°时,变椭圆振动筛可以达到较好的筛分性能。研究结论可为变椭圆振动筛的设计提供理论支持。展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFC0601602)the Fundamental Research Funds for the Central Universities,China(Grant Nos.2017FZA3005 and 2018FZA3005)
文摘Ellipse fitting is a useful tool to obtain the differential signal of two atom interference gravimeters. The quality standard of ellipse fitting should be the deviation between the true phase and the fitting phase of the interference fringe. In this paper, we present a new algorithm to fit the ellipse. The algorithm is to minimize the differential noise of two interference gravimeters and obtain a more accurate value of the gravity gradient. We have theoretically derived the expression of the differential-mode noise and implemented the ellipse fitting in the program. This new algorithm is also compared with the classical methods.
基金supported by the Natural Science Foundation of China(11971142)the Natural Science Foundation of Zhejiang Province(LY19A010012)。
文摘In this paper,we present new bounds for the perimeter of an ellipse in terms of harmonic,geometric,arithmetic and quadratic means;these new bounds represent improvements upon some previously known results.
基金supported by the Research Program of the National Natural Science Foundation of China(51276088)
文摘The enhanced cooling performance caused by ellipse-shaped tabs located at the outlet of the film cooling holes is conducted.Three covering ratios of ellipse-shaped tabs on film holes and four blowing ratios are studied.The results show that:(1)The heat transfer coefficient ratio is higher than that without tab,indicating that the mixing of mainstream and coolant jet provides a better coverage film on the cooling wall,but increases the local turbulence production which enhances the heat transfer coefficient;(2)When the ellipse-shaped tabs are located at the film hole outlet,there is a larger pressure drop with the ellipse tab relative to the no-tab case.Thus,the discharge coefficient with ellipse tab is lower than that without tab.
文摘钻井液振动筛作为一级固相控制设备,常存在“筛堵”“筛糊”和“跑浆”等问题,而通过改变“力心”和质径积比值等参数来得到合理的变椭圆振动轨迹,可以较好解决这些问题。针对变椭圆轨迹振动筛的结构参数改变要求,研究其对振动轨迹和颗粒行为的影响,并基于离散元法(Discrete Element Method)的耦合多体系统动力学(Dynamics of Multi-body System)研究方法,对变椭圆振动筛本体和物料颗粒进行联合分析求解;分析了变椭圆振动筛力心位置和偏心块质径积比值对振动轨迹、物料颗粒运移速度和透筛率的影响。结果表明:振动筛在力心与质心的距离在100~150 mm,偏心块质径积比值在10∶7左右,入料端最大椭圆倾角在60°~65°时,变椭圆振动筛可以达到较好的筛分性能。研究结论可为变椭圆振动筛的设计提供理论支持。
