The interaction between regular waves and an oscillating wave energy converter(WEC)in front of a vertical seawall is investigated using a 2D analytical model.A three-degree of freedom(DOF)WEC and a WEC hinged to the s...The interaction between regular waves and an oscillating wave energy converter(WEC)in front of a vertical seawall is investigated using a 2D analytical model.A three-degree of freedom(DOF)WEC and a WEC hinged to the seawall(constrained to pitch mode)are considered to examine the influence of the DOF of the WEC on the wave energy extraction performance.Results show that the piston-mode water resonance in the gap and the coupled WEC and water column resonant motion significantly influence the wave energy extraction efficiency.At low frequency,the case with a 3-DOF WEC has a broader high-efficiency bandwidth than that with a heaving WEC.However,3-DOF WEC exhibits worse performance at high frequencies.The frequency response of the wave energy capture width ratio(CWR)for the pitching WEC case shows a trimodal trend under the specified conditions.It showcases the best overall wave energy extraction performance in terms of the high-efficiency bandwidth.Furthermore,a parametric study indicates that the gap distance between the WEC and the seawall has tremendous effects on the CWR of both cases.As the position of the hinge point of the pitching WEC changes,the CWR at the low and high frequencies shows opposite trends.展开更多
Tailoring multiple degrees-of-freedom(DoFs)to achieve high-dimensional laser field is crucial for advancing optical technologies.While recent advancements have demonstrated the ability to manipulate a limited number o...Tailoring multiple degrees-of-freedom(DoFs)to achieve high-dimensional laser field is crucial for advancing optical technologies.While recent advancements have demonstrated the ability to manipulate a limited number of DoFs,most existing methods rely on bulky optical components or intricate systems that employ time-consuming iterative methods and,most critically,the on-demand tailoring of multiple DoFs simultaneously through a compact,single element—remains underexplored.In this study,we propose an intelligent hybrid strategy that enables the simultaneous and customizable manipulation of six DoFs:wave vector,initial phase,spatial mode,amplitude,orbital angular momentum(OAM)and spin angular momentum(SAM).Our approach advances in phase-only property,which facilitates tailoring strategy experimentally demonstrated on a compact metasurface.A fabricated sample is tailored to realize arbitrary manipulation across six DoFs,constructing a 288-dimensional space.Notably,since the OAM eigenstates constitute an infinite dimensional Hilbert space,this proposal can be further extended to even higher dimensions.Proof-of-principle experiments confirm the effectiveness in manipulation capability and dimensionality.We envision that this powerful tailoring ability offers immense potential for multifunctional photonic devices across both classical and quantum scenarios and such compactness extending the dimensional capabilities for integration on-chip requirements.展开更多
A new technology of offshore oil rod pumping production is developed for offshore heavy oil recovery. A new type of miniature hydraulic pumping unit with long-stroke, low pumping speed and compact structure is designe...A new technology of offshore oil rod pumping production is developed for offshore heavy oil recovery. A new type of miniature hydraulic pumping unit with long-stroke, low pumping speed and compact structure is designed based on the spatial characteristics of offshore platforms. By combining the strengths of sinusoidal velocity curve and trapezoidal velocity curve, a kinematical model of the acceleration, the velocity and displacement of the pumping unit＇s hanging point is established. The results show that the pumping unit has good kinematic characteristics of smooth motion and small dynamic load. The multi-degree-of-freedom dynamic model of the single-well pumping unit is established. The first and second order natural frequencies of the sucker rod string subsystem and the pumping unit subsystem are studied. The results show that the first and the second order natural frequencies among the pumping rod string, pumping unit-platform subsystem and the dynamic excitation have differences over 5 times from each other, indicating that resonance phenomenon will not appear during the operation and the dynamic requirements for field use are met in the system.展开更多
A new cascade control program was proposed based on modified internal model control to handle stable,unstable and integrating processes with time delay.The program had totally four controllers of which the secondary l...A new cascade control program was proposed based on modified internal model control to handle stable,unstable and integrating processes with time delay.The program had totally four controllers of which the secondary loop had two controllers and the primary loop had two controllers.The two secondary loop controllers were designed using IMC technique.They were decoupled completely and could be adjusted independently,which avoided the undesirable influence on performance of the primary controllers.The main controller in the primary loop was devised as a PID using the method of minimum sensitivity,which could guarantee not only the nominal performance but also the robust stability of the system.A setpoint filter was added in the primary loop to improve the tracking performance.All the controllers of the two closed-loops were designed analytically,and could be adjusted and optimized by single parameter respectively.Simulations were carried out on three various processes with time delay,and the results show that the proposed method can provide a better performance of both set-point tracking and disturbance rejection and robustness against parameters perturbation.展开更多
We present a faithful and efficient hyperentanglement purification protocol(hyper-EPP)for nonlocal two-photon systems in spatial-polarization-time-bin hyperentangled Bell states.As the single-photon detectors can dete...We present a faithful and efficient hyperentanglement purification protocol(hyper-EPP)for nonlocal two-photon systems in spatial-polarization-time-bin hyperentangled Bell states.As the single-photon detectors can detect and herald the undesirable properties caused by side leakage and finite coupling strength,the parity-check gates and swap gates of our hyper-EPP in the spatial,polarization and time-bin mode degrees of freedom(DoFs)work faithfully.The qubit-flip errors in photon systems in three DoFs can be corrected effectively with the faithful parity-check gates and the photon pairs can be reused to distill high-fidelity ones by introducing the faithful swap gates,which greatly increases the efficiency of our hyper-EPP.Further,the maximal hyperentanglement can be obtained in principle by operating multiple rounds of the hyper-EPP.展开更多
Hyperentangled Bell states analysis(HBSA)is an essential building block for certain hyper-parallel quantum information processing.We propose a complete and deterministic HBSA scheme encoded in spatial and polarization...Hyperentangled Bell states analysis(HBSA)is an essential building block for certain hyper-parallel quantum information processing.We propose a complete and deterministic HBSA scheme encoded in spatial and polarization degrees of freedom(DOFs)of two-photon system assisted by a fixed frequency-based entanglement and a time interval DOF.The parity information the spatial-based and polarization-based hyper-entanglement can be distinguished by the distinct time intervals of the photon pairs,and the phase information can be distinguished by the detection signature.Compared with previous schemes,the number of the auxiliary entanglements is reduced from two to one by introducing time interval DOF.Moreover,the additional frequency and time interval DOFs suffer less from the collective channel noise.展开更多
基金supported by the Key R&D Program of Shandong Province,China(No.2021ZLGX04)the National Natural Science Foundation of China(No.52171284)。
文摘The interaction between regular waves and an oscillating wave energy converter(WEC)in front of a vertical seawall is investigated using a 2D analytical model.A three-degree of freedom(DOF)WEC and a WEC hinged to the seawall(constrained to pitch mode)are considered to examine the influence of the DOF of the WEC on the wave energy extraction performance.Results show that the piston-mode water resonance in the gap and the coupled WEC and water column resonant motion significantly influence the wave energy extraction efficiency.At low frequency,the case with a 3-DOF WEC has a broader high-efficiency bandwidth than that with a heaving WEC.However,3-DOF WEC exhibits worse performance at high frequencies.The frequency response of the wave energy capture width ratio(CWR)for the pitching WEC case shows a trimodal trend under the specified conditions.It showcases the best overall wave energy extraction performance in terms of the high-efficiency bandwidth.Furthermore,a parametric study indicates that the gap distance between the WEC and the seawall has tremendous effects on the CWR of both cases.As the position of the hinge point of the pitching WEC changes,the CWR at the low and high frequencies shows opposite trends.
基金supported by the National Key Research and Development Program of China(2022YFB3607700)National Natural Science Foundation of China(62350011,62375014)+1 种基金Beijing Natural Science Foundation(1232031)Special Fund for Basic Scientific Research of Central Universities of China(2024CX11002).
文摘Tailoring multiple degrees-of-freedom(DoFs)to achieve high-dimensional laser field is crucial for advancing optical technologies.While recent advancements have demonstrated the ability to manipulate a limited number of DoFs,most existing methods rely on bulky optical components or intricate systems that employ time-consuming iterative methods and,most critically,the on-demand tailoring of multiple DoFs simultaneously through a compact,single element—remains underexplored.In this study,we propose an intelligent hybrid strategy that enables the simultaneous and customizable manipulation of six DoFs:wave vector,initial phase,spatial mode,amplitude,orbital angular momentum(OAM)and spin angular momentum(SAM).Our approach advances in phase-only property,which facilitates tailoring strategy experimentally demonstrated on a compact metasurface.A fabricated sample is tailored to realize arbitrary manipulation across six DoFs,constructing a 288-dimensional space.Notably,since the OAM eigenstates constitute an infinite dimensional Hilbert space,this proposal can be further extended to even higher dimensions.Proof-of-principle experiments confirm the effectiveness in manipulation capability and dimensionality.We envision that this powerful tailoring ability offers immense potential for multifunctional photonic devices across both classical and quantum scenarios and such compactness extending the dimensional capabilities for integration on-chip requirements.
基金financially supported by the National Natural Science Foundation of China(Grant No.51174224)the National Science and Technology Major Projects of Oil and Gas(Grant Nos.2016ZX05066 and 2016ZX05042)the Natural Science Foundation of Shandong Province(Grant No.ZR2014El015)
文摘A new technology of offshore oil rod pumping production is developed for offshore heavy oil recovery. A new type of miniature hydraulic pumping unit with long-stroke, low pumping speed and compact structure is designed based on the spatial characteristics of offshore platforms. By combining the strengths of sinusoidal velocity curve and trapezoidal velocity curve, a kinematical model of the acceleration, the velocity and displacement of the pumping unit＇s hanging point is established. The results show that the pumping unit has good kinematic characteristics of smooth motion and small dynamic load. The multi-degree-of-freedom dynamic model of the single-well pumping unit is established. The first and second order natural frequencies of the sucker rod string subsystem and the pumping unit subsystem are studied. The results show that the first and the second order natural frequencies among the pumping rod string, pumping unit-platform subsystem and the dynamic excitation have differences over 5 times from each other, indicating that resonance phenomenon will not appear during the operation and the dynamic requirements for field use are met in the system.
基金Project(J11LG02) supported by the Science and Technology Funds of Education Department of Shandong Province,China
文摘A new cascade control program was proposed based on modified internal model control to handle stable,unstable and integrating processes with time delay.The program had totally four controllers of which the secondary loop had two controllers and the primary loop had two controllers.The two secondary loop controllers were designed using IMC technique.They were decoupled completely and could be adjusted independently,which avoided the undesirable influence on performance of the primary controllers.The main controller in the primary loop was devised as a PID using the method of minimum sensitivity,which could guarantee not only the nominal performance but also the robust stability of the system.A setpoint filter was added in the primary loop to improve the tracking performance.All the controllers of the two closed-loops were designed analytically,and could be adjusted and optimized by single parameter respectively.Simulations were carried out on three various processes with time delay,and the results show that the proposed method can provide a better performance of both set-point tracking and disturbance rejection and robustness against parameters perturbation.
基金Project supported by the National Natural Science Foundation of China(Grant No.61901420 and 11604226)the Shanxi Province Science Foundation for Youths(Grant No.201901D211235)+1 种基金the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(Grant No.2019L0507)the Program of Beijing Municipal Commission of Education of China(Grant Nos.CIT&TCD201904080 and KM201810028005)。
文摘We present a faithful and efficient hyperentanglement purification protocol(hyper-EPP)for nonlocal two-photon systems in spatial-polarization-time-bin hyperentangled Bell states.As the single-photon detectors can detect and herald the undesirable properties caused by side leakage and finite coupling strength,the parity-check gates and swap gates of our hyper-EPP in the spatial,polarization and time-bin mode degrees of freedom(DoFs)work faithfully.The qubit-flip errors in photon systems in three DoFs can be corrected effectively with the faithful parity-check gates and the photon pairs can be reused to distill high-fidelity ones by introducing the faithful swap gates,which greatly increases the efficiency of our hyper-EPP.Further,the maximal hyperentanglement can be obtained in principle by operating multiple rounds of the hyper-EPP.
基金This work was supported by the National Natural Science Foundation of China under Grant No.11604012the Fundamental Research Funds for the Central Universities under Grant No.FRF-TP-19-011A3+2 种基金the National Natural Science Foundation of China under Contract 61901420the Shanxi Province Science Foundation for Youths under Contract No.201901D211235the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi under Contract No.2019L0507。
文摘Hyperentangled Bell states analysis(HBSA)is an essential building block for certain hyper-parallel quantum information processing.We propose a complete and deterministic HBSA scheme encoded in spatial and polarization degrees of freedom(DOFs)of two-photon system assisted by a fixed frequency-based entanglement and a time interval DOF.The parity information the spatial-based and polarization-based hyper-entanglement can be distinguished by the distinct time intervals of the photon pairs,and the phase information can be distinguished by the detection signature.Compared with previous schemes,the number of the auxiliary entanglements is reduced from two to one by introducing time interval DOF.Moreover,the additional frequency and time interval DOFs suffer less from the collective channel noise.
