柔性运行技术通过主动柔性运行控制技术、功率随动驱动技术、井下工况与系统自身运行状态识别诊断技术、优化变轨控制技术,实现了抽油机非匀速举升,改变了抽油机所固有的光杆速度模式,优化了井下抽汲过程,弥补了四连杆机构本性带来的固...柔性运行技术通过主动柔性运行控制技术、功率随动驱动技术、井下工况与系统自身运行状态识别诊断技术、优化变轨控制技术,实现了抽油机非匀速举升,改变了抽油机所固有的光杆速度模式,优化了井下抽汲过程,弥补了四连杆机构本性带来的固有缺陷,在不对抽油机结构进行任何改动的情况下,达到提高井下效率、确保系统按需运行、降低设备损耗率和机采单耗的目的。该技术对抽油机井的沉没度无特殊要求,对抽油机的平衡状况要求严格,平衡状况越好,应用效果越好。现场应用实现日耗电降低30.7 k Wh,功率因数提高0.64,有功节电率13.75%的节能效果。展开更多
The structure and principle of the GMM actuator and the new nozzle flapper valve with the GMA were presented. Based on the axis-symmetric FEM model of the GMA driving magnetic field was computed. And the field distrib...The structure and principle of the GMM actuator and the new nozzle flapper valve with the GMA were presented. Based on the axis-symmetric FEM model of the GMA driving magnetic field was computed. And the field distribution for different input currents and variant curves of magnetic flux density along the axis were determined by using FEM. Magnetic flux density of the GMM actuator was practically measured under different input currents. The experiment of output displacement and frequency response of the GMM actuator was carried out under typical working conditions. The experiment results show that the GMA for nozzle flapper servo valve has bigger output displacement and quick response speed. And theoretical basis was presented to further introduce the GMA nozzle flapper valve into two stage electro-hydraulic servooo valve.展开更多
Thermal vibration of single-layered graphene sheets (SLGSs) is investigated using plate model together with the law of equi-partition of energy and the molecular dynamics (MD) method based on the condensed-phase Optim...Thermal vibration of single-layered graphene sheets (SLGSs) is investigated using plate model together with the law of equi-partition of energy and the molecular dynamics (MD) method based on the condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies (COMPASS) force field.The in-plane stiffness and Poisson ratio of SLGSs are calculated by stretching SLGSs.The effective thickness of SLGSs is obtained by the MD simulations for the thermal vibration of SLGSs through the natural frequency.The root-mean-squared (RMS) amplitudes for SLGSs of differing temperatures and boundary conditions are calculated by the MD,and are compared with the results calculated by the thin plate model together with the law of equi-partition of energy.At the center of SLGSs,the thin plate theory can predict the MD results reasonably well.For the difference of bonding structure of the edge atoms,the deviation between the MD results and plate theory becomes more readily apparent near the edges of SLGSs.展开更多
We study tile local linear estimator for tile drift coefficient of stochastic differential equations driven by α-stable Levy motions observed at discrete instants. Under regular conditions, we derive the weak consis-...We study tile local linear estimator for tile drift coefficient of stochastic differential equations driven by α-stable Levy motions observed at discrete instants. Under regular conditions, we derive the weak consis- tency and central limit theorem of the estimator. Compared with Nadaraya-Watson estimator, the local linear estimator has a bias reduction whether the kernel function is symmetric or not under different schemes. A silnu- lation study demonstrates that the local linear estimator performs better than Nadaraya-Watson estimator, especially on the boundary.展开更多
文摘柔性运行技术通过主动柔性运行控制技术、功率随动驱动技术、井下工况与系统自身运行状态识别诊断技术、优化变轨控制技术,实现了抽油机非匀速举升,改变了抽油机所固有的光杆速度模式,优化了井下抽汲过程,弥补了四连杆机构本性带来的固有缺陷,在不对抽油机结构进行任何改动的情况下,达到提高井下效率、确保系统按需运行、降低设备损耗率和机采单耗的目的。该技术对抽油机井的沉没度无特殊要求,对抽油机的平衡状况要求严格,平衡状况越好,应用效果越好。现场应用实现日耗电降低30.7 k Wh,功率因数提高0.64,有功节电率13.75%的节能效果。
文摘The structure and principle of the GMM actuator and the new nozzle flapper valve with the GMA were presented. Based on the axis-symmetric FEM model of the GMA driving magnetic field was computed. And the field distribution for different input currents and variant curves of magnetic flux density along the axis were determined by using FEM. Magnetic flux density of the GMM actuator was practically measured under different input currents. The experiment of output displacement and frequency response of the GMM actuator was carried out under typical working conditions. The experiment results show that the GMA for nozzle flapper servo valve has bigger output displacement and quick response speed. And theoretical basis was presented to further introduce the GMA nozzle flapper valve into two stage electro-hydraulic servooo valve.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11072108)the Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 201028)+1 种基金Program for New Century Excellent Talents in University (Grant No. NCET-11-0832)the Foundation of Nanjing University Aeronautics and Astronautics
文摘Thermal vibration of single-layered graphene sheets (SLGSs) is investigated using plate model together with the law of equi-partition of energy and the molecular dynamics (MD) method based on the condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies (COMPASS) force field.The in-plane stiffness and Poisson ratio of SLGSs are calculated by stretching SLGSs.The effective thickness of SLGSs is obtained by the MD simulations for the thermal vibration of SLGSs through the natural frequency.The root-mean-squared (RMS) amplitudes for SLGSs of differing temperatures and boundary conditions are calculated by the MD,and are compared with the results calculated by the thin plate model together with the law of equi-partition of energy.At the center of SLGSs,the thin plate theory can predict the MD results reasonably well.For the difference of bonding structure of the edge atoms,the deviation between the MD results and plate theory becomes more readily apparent near the edges of SLGSs.
基金supported by National Natural Science Foundation of China(Grant Nos.11171303 and 11071213)the Specialized Research Fund for the Doctor Program of Higher Education(Grant No.20090101110020)
文摘We study tile local linear estimator for tile drift coefficient of stochastic differential equations driven by α-stable Levy motions observed at discrete instants. Under regular conditions, we derive the weak consis- tency and central limit theorem of the estimator. Compared with Nadaraya-Watson estimator, the local linear estimator has a bias reduction whether the kernel function is symmetric or not under different schemes. A silnu- lation study demonstrates that the local linear estimator performs better than Nadaraya-Watson estimator, especially on the boundary.
