Repeating airgun sources are eco-friendly sources for monitoring the changes in the physical properties of subsurface mediums,but their signals decay quickly and are buried in the noises soon after traveling short dis...Repeating airgun sources are eco-friendly sources for monitoring the changes in the physical properties of subsurface mediums,but their signals decay quickly and are buried in the noises soon after traveling short distances.Stacking waveforms from different airgun shots recorded by a single seismic station(shot stacking)is the most popular technique to detect weak signals from noisy backgrounds,and has been widely used to process the data of Fixed Airgun Signal Transmission Stations(FASTS)in China.However,shot stacking sacrifices the time resolution in monitoring to recover a qualified airgun signal by stacking many shots at distance stations,and also suffers from persistent local noises.In this paper,we carried out several small-aperture seismic array experiments around the Binchuan FAST Station(BCFASTS)in Yunnan Province,China,and applied the array technique to improve airgun signal detection.The results show that seismic array processing combining with shot stacking can suppress seismic noises more efficiently,and provide better signal-to-noise ratio(SNR)and coherent airgun signals with less airgun shots.This work suggests that the array technique is a feasible and promising tool in FAST to increase the time resolution and reduce noise interference on routine monitoring.展开更多
Purpose A new rotating coil measurement system based on the coordinate measurement machine(CMM)is developed for measuring high-gradient small-aperture quadrupole magnet in the Test Facility of High Energy Photon Sourc...Purpose A new rotating coil measurement system based on the coordinate measurement machine(CMM)is developed for measuring high-gradient small-aperture quadrupole magnet in the Test Facility of High Energy Photon Source(HEPS-TF).Methods The CMMand two groups of Newport translate stages are combined to align the rotating coil relative to the magnet mechanical center.A high precision ceramic skeleton with bucked coil is made as a measurement sensor.The integrated field gradient,harmonics,magnetic center offset and excitation curve of a high-gradient small-aperture quadrupole prototype magnet are measured.Results The rotating coil is aligned to the magnet mechanical center within 10μm.The reproducibility of higher harmonics is within 0.2×10–4.The repeatability of the magnet center in horizontal direction is under 1.5μm,while that in vertical direction is less than 2.5μm in different days.The architecture of the measurement system,the measuring procedure and some primary results of the quadrupole prototype magnet are illustrated in this paper.Conclusion A rotating coil measurement system based on CMM has been well developed,and the collimation efficiency and precision are improved.The harmonic changes caused by iron fingers are measured by the measurement system.The difference between the measurement result and the OPERA-3D simulation result is less than 0.5×10–4.The performance of this measurement system can meet the magnet measurement requirements of HEPS-TF.展开更多
Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a p...Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a promising treatment for Parkinson’s disease.However,transplanted cells can be injured by mechanical damage during handling and by changes in the transplantation niche.Here,we developed a one-step biomanufacturing platform that uses small-aperture gelatin microcarriers to produce beads carrying midbrain dopaminergic progenitor cells.These beads allow midbrain dopaminergic progenitor cell differentiation and cryopreservation without digestion,effectively maintaining axonal integrity in vitro.Importantly,midbrain dopaminergic progenitor cell bead grafts showed increased survival and only mild immunoreactivity in vivo compared with suspended midbrain dopaminergic progenitor cell grafts.Overall,our findings show that these midbrain dopaminergic progenitor cell beads enhance the effectiveness of neuronal cell transplantation.展开更多
The equations of the reflector contours and the radiation patterns of the shaped dual-reflector antenna have been derived, and the methods of designing the antenna are also intro-duced briefly. The calculated and meas...The equations of the reflector contours and the radiation patterns of the shaped dual-reflector antenna have been derived, and the methods of designing the antenna are also intro-duced briefly. The calculated and measured results suggest that this new type of antennahas the advantages of low VSWR (voltage standing-wave ratio), low sidelobe, and high gain.Therefore it opens a bright prospect for the improvement of mid-and small-aperture anten-na performance, and gives the possibility for the realization of the 1990s new standard spec-ified by CCIR (International Radio Consultative Committee) on mid-and small-aperture an-tenna for satellite-communication earth stations.展开更多
基金jointly sponsored by National Natural Science Foundation of China(41574050,41674058)
文摘Repeating airgun sources are eco-friendly sources for monitoring the changes in the physical properties of subsurface mediums,but their signals decay quickly and are buried in the noises soon after traveling short distances.Stacking waveforms from different airgun shots recorded by a single seismic station(shot stacking)is the most popular technique to detect weak signals from noisy backgrounds,and has been widely used to process the data of Fixed Airgun Signal Transmission Stations(FASTS)in China.However,shot stacking sacrifices the time resolution in monitoring to recover a qualified airgun signal by stacking many shots at distance stations,and also suffers from persistent local noises.In this paper,we carried out several small-aperture seismic array experiments around the Binchuan FAST Station(BCFASTS)in Yunnan Province,China,and applied the array technique to improve airgun signal detection.The results show that seismic array processing combining with shot stacking can suppress seismic noises more efficiently,and provide better signal-to-noise ratio(SNR)and coherent airgun signals with less airgun shots.This work suggests that the array technique is a feasible and promising tool in FAST to increase the time resolution and reduce noise interference on routine monitoring.
文摘Purpose A new rotating coil measurement system based on the coordinate measurement machine(CMM)is developed for measuring high-gradient small-aperture quadrupole magnet in the Test Facility of High Energy Photon Source(HEPS-TF).Methods The CMMand two groups of Newport translate stages are combined to align the rotating coil relative to the magnet mechanical center.A high precision ceramic skeleton with bucked coil is made as a measurement sensor.The integrated field gradient,harmonics,magnetic center offset and excitation curve of a high-gradient small-aperture quadrupole prototype magnet are measured.Results The rotating coil is aligned to the magnet mechanical center within 10μm.The reproducibility of higher harmonics is within 0.2×10–4.The repeatability of the magnet center in horizontal direction is under 1.5μm,while that in vertical direction is less than 2.5μm in different days.The architecture of the measurement system,the measuring procedure and some primary results of the quadrupole prototype magnet are illustrated in this paper.Conclusion A rotating coil measurement system based on CMM has been well developed,and the collimation efficiency and precision are improved.The harmonic changes caused by iron fingers are measured by the measurement system.The difference between the measurement result and the OPERA-3D simulation result is less than 0.5×10–4.The performance of this measurement system can meet the magnet measurement requirements of HEPS-TF.
基金supported by the National Key Research and Development Program of China,Nos.2017YFE0122900(to BH),2019YFA0110800(to WL),2019YFA0903802(to YW),2021YFA1101604(to LW),2018YFA0108502(to LF),and 2020YFA0804003(to JW)the National Natural Science Foundation of China,Nos.31621004(to WL,BH)and 31970821(to YW)+1 种基金CAS Project for Young Scientists in Basic Research,No.YSBR-041(to YW)Joint Funds of the National Natural Science Foundation of China,No.U21A20396(to BH)。
文摘Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a promising treatment for Parkinson’s disease.However,transplanted cells can be injured by mechanical damage during handling and by changes in the transplantation niche.Here,we developed a one-step biomanufacturing platform that uses small-aperture gelatin microcarriers to produce beads carrying midbrain dopaminergic progenitor cells.These beads allow midbrain dopaminergic progenitor cell differentiation and cryopreservation without digestion,effectively maintaining axonal integrity in vitro.Importantly,midbrain dopaminergic progenitor cell bead grafts showed increased survival and only mild immunoreactivity in vivo compared with suspended midbrain dopaminergic progenitor cell grafts.Overall,our findings show that these midbrain dopaminergic progenitor cell beads enhance the effectiveness of neuronal cell transplantation.
文摘The equations of the reflector contours and the radiation patterns of the shaped dual-reflector antenna have been derived, and the methods of designing the antenna are also intro-duced briefly. The calculated and measured results suggest that this new type of antennahas the advantages of low VSWR (voltage standing-wave ratio), low sidelobe, and high gain.Therefore it opens a bright prospect for the improvement of mid-and small-aperture anten-na performance, and gives the possibility for the realization of the 1990s new standard spec-ified by CCIR (International Radio Consultative Committee) on mid-and small-aperture an-tenna for satellite-communication earth stations.
