The frictional properties of micro bearings have strong influence on the performance of the whole system because of tiny scale of micro-electromechanical system (MEMS). To develop micro bearings with low friction,it i...The frictional properties of micro bearings have strong influence on the performance of the whole system because of tiny scale of micro-electromechanical system (MEMS). To develop micro bearings with low friction,it is important to evaluate the friction behaviors on the micro bearing. The testing system and the principle to evaluate the tribological performance of micromachining work-pieces under the load of mill Newton scale is introduced in paper "A new approach to measure the friction coefficient of micro journal bearings" of Yao et al,. But as the tribological force is faint in micro scale, the measured force is influenced a lot by the testing error. As the equation of that of Yao’s paper is very sensitive to the measured force, the tested result is influenced remarkably by testing error. So it is hard to get precision result. To solve this problem, the test system with new compensation method is introduced to precisely evaluate tribological performance under mill scale. The new metrology method is developed by means of the error compensation from two sets of testing data. The data are the force collected respectively when the friction counterparts rotate in CW(clockwise) and CCW(counter-clockwise) direction. So we deduce the equation of friction coefficient respctively on the condition of journal running in CCW and CW direction. As condition of measuring those two friciton coefficients are alike except the running direction of journal, and then the friction coefficient should be the same because this difference of direction has no influence on the fricition coefficients. Considering this, we unite the both equation, make the data measured in different subtract each other in the equation, and then a new equation can be gotten. This new equation enhances the metrology precision of friction coefficient theoretically thanks to the counteracting of error values in the equation. Using this method we testing the friction of high speed steel journal with hard alloy bearing. The result shows the new compensation method has better precision and repetition than CW and CCW method thanks to the error resistance.展开更多
为实现双碳目标,激励传统机组向灵活调节资源过渡,保障传统机组提供辅助服务获得收益,亟需设计科学有效的转动惯量辅助服务补偿机制。首先,总结归纳了中国当前的转动惯量补偿机制并提取了其中的关键要素,以此为基础设计了一个政府激励...为实现双碳目标,激励传统机组向灵活调节资源过渡,保障传统机组提供辅助服务获得收益,亟需设计科学有效的转动惯量辅助服务补偿机制。首先,总结归纳了中国当前的转动惯量补偿机制并提取了其中的关键要素,以此为基础设计了一个政府激励与发电商决策相协调的转动惯量补偿机制。然后,提出确定发电机组转动惯量最优补偿系数的主从博弈模型。其中上层代表政府机构,旨在通过发电商的惯量支撑表现来设定最佳补偿,维持电力系统总惯量在一定水平内。下层代表发电商的决策行为,在政府设定的补偿系数下,试图使总生产成本最小化。最后,主从博弈优化模型被重新表述为混合整数线性规划(mixed integer linear programming,MILP)模型并由现成的MILP求解器求解。通过算例依次进行转动惯量补偿系数的灵敏度分析、效果分析和大系统适应性分析,验证了所提方法的有效性和实际应用能力。展开更多
To obtain frequency-temperature compensation in a sapphire loaded cavity for hydrogen maser, a dielectric named SrTiO3 is employed whose temperature coefficient of permittivity is opposite to that of sapphire. Based o...To obtain frequency-temperature compensation in a sapphire loaded cavity for hydrogen maser, a dielectric named SrTiO3 is employed whose temperature coefficient of permittivity is opposite to that of sapphire. Based on theoretical analysis and computer simulation, a TE011 mode of a sapphire loaded cavity associated with two small rings of SrTiO3 with different thickness is solved, and the useful parameters that influence the temperature coefficient of cavity are calculated. Finally an experiment is brought forward and its results are very close to the computing results. When the thickness of SiTiO3 dielectric is 7 mm and the diameter is 17 mm in configuration b, the temperature coefficient of cavity is decreased from -58.8 kHz/K to -8.2 kHz/K and the quality factor is 40248.展开更多
文摘The frictional properties of micro bearings have strong influence on the performance of the whole system because of tiny scale of micro-electromechanical system (MEMS). To develop micro bearings with low friction,it is important to evaluate the friction behaviors on the micro bearing. The testing system and the principle to evaluate the tribological performance of micromachining work-pieces under the load of mill Newton scale is introduced in paper "A new approach to measure the friction coefficient of micro journal bearings" of Yao et al,. But as the tribological force is faint in micro scale, the measured force is influenced a lot by the testing error. As the equation of that of Yao’s paper is very sensitive to the measured force, the tested result is influenced remarkably by testing error. So it is hard to get precision result. To solve this problem, the test system with new compensation method is introduced to precisely evaluate tribological performance under mill scale. The new metrology method is developed by means of the error compensation from two sets of testing data. The data are the force collected respectively when the friction counterparts rotate in CW(clockwise) and CCW(counter-clockwise) direction. So we deduce the equation of friction coefficient respctively on the condition of journal running in CCW and CW direction. As condition of measuring those two friciton coefficients are alike except the running direction of journal, and then the friction coefficient should be the same because this difference of direction has no influence on the fricition coefficients. Considering this, we unite the both equation, make the data measured in different subtract each other in the equation, and then a new equation can be gotten. This new equation enhances the metrology precision of friction coefficient theoretically thanks to the counteracting of error values in the equation. Using this method we testing the friction of high speed steel journal with hard alloy bearing. The result shows the new compensation method has better precision and repetition than CW and CCW method thanks to the error resistance.
文摘为实现双碳目标,激励传统机组向灵活调节资源过渡,保障传统机组提供辅助服务获得收益,亟需设计科学有效的转动惯量辅助服务补偿机制。首先,总结归纳了中国当前的转动惯量补偿机制并提取了其中的关键要素,以此为基础设计了一个政府激励与发电商决策相协调的转动惯量补偿机制。然后,提出确定发电机组转动惯量最优补偿系数的主从博弈模型。其中上层代表政府机构,旨在通过发电商的惯量支撑表现来设定最佳补偿,维持电力系统总惯量在一定水平内。下层代表发电商的决策行为,在政府设定的补偿系数下,试图使总生产成本最小化。最后,主从博弈优化模型被重新表述为混合整数线性规划(mixed integer linear programming,MILP)模型并由现成的MILP求解器求解。通过算例依次进行转动惯量补偿系数的灵敏度分析、效果分析和大系统适应性分析,验证了所提方法的有效性和实际应用能力。
文摘To obtain frequency-temperature compensation in a sapphire loaded cavity for hydrogen maser, a dielectric named SrTiO3 is employed whose temperature coefficient of permittivity is opposite to that of sapphire. Based on theoretical analysis and computer simulation, a TE011 mode of a sapphire loaded cavity associated with two small rings of SrTiO3 with different thickness is solved, and the useful parameters that influence the temperature coefficient of cavity are calculated. Finally an experiment is brought forward and its results are very close to the computing results. When the thickness of SiTiO3 dielectric is 7 mm and the diameter is 17 mm in configuration b, the temperature coefficient of cavity is decreased from -58.8 kHz/K to -8.2 kHz/K and the quality factor is 40248.
