目的采用静息态脑功能磁共振成像低频振幅(amplitude of low-frequency fluctuation,ALFF)分析法比较髓海不足型与肝肾亏虚型阿尔茨海默病(Alzheimer’s disease,AD)患者的脑功能区活动存在的差异,以期为AD患者的中医辨证分型和同病异...目的采用静息态脑功能磁共振成像低频振幅(amplitude of low-frequency fluctuation,ALFF)分析法比较髓海不足型与肝肾亏虚型阿尔茨海默病(Alzheimer’s disease,AD)患者的脑功能区活动存在的差异,以期为AD患者的中医辨证分型和同病异治提供影像学证据。方法选取2018年11月至2021年4月于浙江省立同德医院就诊的AD患者60例,其中髓海不足组29例,肝肾亏虚组31例,选取同期年龄相对应的健康老年人36例纳入对照组。对三组受试者分别行静息态脑功能磁共振成像扫描,应用ALFF分析法对比三组受试者脑区的ALFF值差异。结果与对照组比较,髓海不足组患者的右小脑后部、左前扣带回、右前扣带回ALFF值升高(P<0.05),肝肾亏虚组患者的右侧岛叶、左侧岛叶ALFF值升高(P<0.05)。与髓海不足组比较,肝肾亏虚组患者的右小脑后部ALFF值降低(P<0.05)。结论静息态脑功能磁共振成像ALFF分析法可为AD患者的中医辨证分型和同病异治提供影像学证据。展开更多
The estimation of the external quality factor is important for designing coupling devices for the cavities.A new representation of the external quality factor calculations for single-cell cavity coupled to a coaxial t...The estimation of the external quality factor is important for designing coupling devices for the cavities.A new representation of the external quality factor calculations for single-cell cavity coupled to a coaxial transmission line is derived based on analytic analysis and numeric analysis with the help of 3D electromagnetic code,and verified with experimental measurements at room temperature.In logarithmic scale the results for the external quality factor were quasi-linear over the limited range,and the simulated and measured data could be used and extrapolated to the superconducting case.For the unpolished 1.5 GHz 3rd harmonic superconducting cavity,the discrepancy between the evaluation value and measurement result is less than 25% within an acceptable deviation.展开更多
In this paper we report the design and realization of beam trip diagnostic system at Shanghai Synchrotron Radiation Facility (SSRF). The system can find out the first fault signal in the key operation signals related ...In this paper we report the design and realization of beam trip diagnostic system at Shanghai Synchrotron Radiation Facility (SSRF). The system can find out the first fault signal in the key operation signals related to the RF system by analyzing the time sequence, also it can decide which trips occurs first among the three superconducting RF stations. All the states of monitored signals in a time period ahead and behind beam trip are recorded. The results are compared with those from other diagnostic tools at SSRF. The work is of help in improving reliability of the superconducting RF system and stability of the storage ring operation.展开更多
In this paper,higher order modes(HOMs) and loss factor of a new type of 500-MHz superconducting cavity is studied,by simulating its broadband HOMs damping at different positions of the ferrite HOM-absorber and differe...In this paper,higher order modes(HOMs) and loss factor of a new type of 500-MHz superconducting cavity is studied,by simulating its broadband HOMs damping at different positions of the ferrite HOM-absorber and different lengths of the ferrite.The results show that the impedance and Q value of the HOMs in transverse and longitudinal modes could be greatly reduced.The HOM longitudinal impedance could be damped to meet the requirement of SSRF beam instability threshold.The calculated loss factor of the new SC cavity was compared with cavities at SSRF.It was estimated that the HOM absorber could absorb a total power of 3.16 kW at 4-mm beam bunch length.展开更多
In the superconducting RF module, the dissipation power of the niobium cavity is an important parameter. In the Superconducting radio frequency (SRF) module's acceptance test at Shanghai Synchrotron Radiation Faci...In the superconducting RF module, the dissipation power of the niobium cavity is an important parameter. In the Superconducting radio frequency (SRF) module's acceptance test at Shanghai Synchrotron Radiation Facility (SSRF), the Venturi tube is used to measure the quality factor of SRF cavity at 4.2 K. During the test, the venturi tube is be calibrated by increasing heat load with internal heater. In this paper, the horizontal test principle and venturi effect are briefly introduced. The authors find out a correct way to calibrate the venturi tubes, the calibration results are presented here. From the calibration results, one can deduce the static loss of each module, the source of static loss is also analyzed.展开更多
文摘目的采用静息态脑功能磁共振成像低频振幅(amplitude of low-frequency fluctuation,ALFF)分析法比较髓海不足型与肝肾亏虚型阿尔茨海默病(Alzheimer’s disease,AD)患者的脑功能区活动存在的差异,以期为AD患者的中医辨证分型和同病异治提供影像学证据。方法选取2018年11月至2021年4月于浙江省立同德医院就诊的AD患者60例,其中髓海不足组29例,肝肾亏虚组31例,选取同期年龄相对应的健康老年人36例纳入对照组。对三组受试者分别行静息态脑功能磁共振成像扫描,应用ALFF分析法对比三组受试者脑区的ALFF值差异。结果与对照组比较,髓海不足组患者的右小脑后部、左前扣带回、右前扣带回ALFF值升高(P<0.05),肝肾亏虚组患者的右侧岛叶、左侧岛叶ALFF值升高(P<0.05)。与髓海不足组比较,肝肾亏虚组患者的右小脑后部ALFF值降低(P<0.05)。结论静息态脑功能磁共振成像ALFF分析法可为AD患者的中医辨证分型和同病异治提供影像学证据。
基金Supported by project Science and Technology Commission of Shanghai Municipality (026505027, 036505011)
文摘The estimation of the external quality factor is important for designing coupling devices for the cavities.A new representation of the external quality factor calculations for single-cell cavity coupled to a coaxial transmission line is derived based on analytic analysis and numeric analysis with the help of 3D electromagnetic code,and verified with experimental measurements at room temperature.In logarithmic scale the results for the external quality factor were quasi-linear over the limited range,and the simulated and measured data could be used and extrapolated to the superconducting case.For the unpolished 1.5 GHz 3rd harmonic superconducting cavity,the discrepancy between the evaluation value and measurement result is less than 25% within an acceptable deviation.
文摘In this paper we report the design and realization of beam trip diagnostic system at Shanghai Synchrotron Radiation Facility (SSRF). The system can find out the first fault signal in the key operation signals related to the RF system by analyzing the time sequence, also it can decide which trips occurs first among the three superconducting RF stations. All the states of monitored signals in a time period ahead and behind beam trip are recorded. The results are compared with those from other diagnostic tools at SSRF. The work is of help in improving reliability of the superconducting RF system and stability of the storage ring operation.
文摘In this paper,higher order modes(HOMs) and loss factor of a new type of 500-MHz superconducting cavity is studied,by simulating its broadband HOMs damping at different positions of the ferrite HOM-absorber and different lengths of the ferrite.The results show that the impedance and Q value of the HOMs in transverse and longitudinal modes could be greatly reduced.The HOM longitudinal impedance could be damped to meet the requirement of SSRF beam instability threshold.The calculated loss factor of the new SC cavity was compared with cavities at SSRF.It was estimated that the HOM absorber could absorb a total power of 3.16 kW at 4-mm beam bunch length.
基金Supported by Shanghai Synchrotron Radiation Facility
文摘In the superconducting RF module, the dissipation power of the niobium cavity is an important parameter. In the Superconducting radio frequency (SRF) module's acceptance test at Shanghai Synchrotron Radiation Facility (SSRF), the Venturi tube is used to measure the quality factor of SRF cavity at 4.2 K. During the test, the venturi tube is be calibrated by increasing heat load with internal heater. In this paper, the horizontal test principle and venturi effect are briefly introduced. The authors find out a correct way to calibrate the venturi tubes, the calibration results are presented here. From the calibration results, one can deduce the static loss of each module, the source of static loss is also analyzed.
