Purpose For the High Energy Photon Source(HEPS),a green-field fourth-generation storage ring light source,the prelimi-nary design report(PDR)was completed in 2018,when the accelerator physics design had been basically...Purpose For the High Energy Photon Source(HEPS),a green-field fourth-generation storage ring light source,the prelimi-nary design report(PDR)was completed in 2018,when the accelerator physics design had been basically finished.During the subsequent hardware and engineering design of the HEPS storage ring based on the PDR design,a few problems and challenges emerged,calling for modifications of the lattice.Method In this paper,we will introduce the background and reasons for the modifications and present the linear optics and simulation results for the nonlinear performance of the modified lattice of the HEPS storage ring.Result and conclusion The modified lattice satisfies the requirements from hardware and engineering design.展开更多
In recent years,a new generation of storage ring-based light sources,known as diffraction-limited storage rings(DLSRs),whose emittance approaches the diffraction limit for the range of X-ray wavelengths of interest to...In recent years,a new generation of storage ring-based light sources,known as diffraction-limited storage rings(DLSRs),whose emittance approaches the diffraction limit for the range of X-ray wavelengths of interest to the scientific community,has garnered significant attention worldwide.Researchers have begun to design and build DLSRs.Among various DLSR proposals,the hybrid multibend achromat(H-MBA)lattice enables sextupole strengths to be maintained at a reasonable level when minimizing the emittance;hence,it has been adopted in many DLSR designs.Based on the H-7BA lattice,the design of the Advanced Photon Source Upgrade Project(APS-U)can effectively reduce emittance by replacing six quadrupoles with anti-bends.Herein,we discuss the feasibility of designing an APS-U-type H-MBA lattice for the Southern Advanced Photon Source,a mid-energy DLSR light source with ultralow emittance that has been proposed to be built adjacent to the China Spallation Neutron Source.Both linear and nonlinear dynamics are optimized to obtain a detailed design of this type of lattice.The emittance is minimized,while a sufficiently large dynamic aperture(DA)and momentum acceptance(MA)are maintained.A design comprising 36 APS-U type H-7BAs,with an energy of 3 GeV and a circumference of 972 m,is achieved.The horizontal natural emittance is 20 pm·rad,with a horizontal DA of 5.8 mm,a vertical DA of 4.5 mm,and an MA of 4%,as well as a long longitudinal damping time of 120 ms.Subsequently,a few modifications are performed based on the APS-U-type lattice to reduce the maximum value of damping time from 120 to 44 ms while maintaining other performance parameters at the same level.展开更多
Variations in vegetation are closely related to climate change, but understanding of their characteristics and causes remains limited. As a typical semi-humid and semi-arid cold plateau region, it is important to unde...Variations in vegetation are closely related to climate change, but understanding of their characteristics and causes remains limited. As a typical semi-humid and semi-arid cold plateau region, it is important to understand the knowledge of long term Normalized Difference Vegetation Index(NDVI) variations and find the potential causes in the source region of the Yangtze River. Based on four tree-ring width chronologies, the regional mean NDVI for July and August spanning the period 1665–2013 was reconstructed using a regression model, and it explained 43.9% of the total variance during the period 1981–2013. In decadal, the reconstructed NDVI showed eight growth stages(1754–1764, 1766–1783, 1794–1811, 1828–1838, 1843–1855, 1862–1873, 1897–1909, and 1932–1945)and four degradation stages(1679–1698, 1726–1753, 1910–1923, and 1988–2000). And based on wavelet analysis, significant cycles of2–3 yr and 3–8 yr were identified. In additional, there was a significant positive correlation between the NDVI and the Palmer Drought Severity Index(PDSI) during the past 349 yr, and they were mainly in phase. However, according to the results of correlation analysis between different grades of drought/wet and NDVI, there was significant asymmetry in extreme drought years and extreme wet years. In extreme drought years, NDVI was positively correlated with PDSI, and in extreme wet years they were negatively correlated.展开更多
合肥光源储存环控制系统是一个基于EPICS(Experiment Physics and Industrial Control System)的分布式控制系统,本文首先描述其硬件结构、软件设计,然后重点介绍束流慢加速、束流闭轨校正、机器状态在线查询、数据存档及历史数据查询...合肥光源储存环控制系统是一个基于EPICS(Experiment Physics and Industrial Control System)的分布式控制系统,本文首先描述其硬件结构、软件设计,然后重点介绍束流慢加速、束流闭轨校正、机器状态在线查询、数据存档及历史数据查询等应用软件的开发。运行结果表明,合肥光源储存环控制系统很好地满足了机器运行和机器研究的需要。展开更多
Multiturn coils is an effective transmitter for transient electromagnetic method(TEM) used in narrow space and complex terrain at presently. However, its high mutual inductance coupling and long turn-off time affect t...Multiturn coils is an effective transmitter for transient electromagnetic method(TEM) used in narrow space and complex terrain at presently. However, its high mutual inductance coupling and long turn-off time affect the quality of later data processing and interpretation. Compared with multiturn coils, the new conical source has low mutual inductance and short turn-off time. Based on the superposition principle, we use Hankel transform and numerical filtering method for forward modelling of the conical source field in the layered-media and explore TEM characteristics excited by this source. We apply improved damped least square inversion to integrated transient electromagnetic(TEM) data. We first invert the induced voltage into similar resistivity and apparent depth, and then use the inverted results as input parameters in the initial model and transform the apparent resistivity data into the frequency domain. Then, damped least square inversion is performed in the frequency domain using the initial model. Subsequently, we use automated model building to search for the extremes and inflection points in the resistivity–depth data that are treated as critical layer parameters. The inversion of theoretical and observed data suggests that the method modifies the resistivity and depth and yields a model of the underground layers.展开更多
基金supported by the High Energy Photon Source(HEPS),a major national science and technol-ogy infrastructurethe National Natural Science Foundation of China(No.11922512)+1 种基金Youth Inno-vation Promotion Association of Chinese Academy of Sciences(No.Y201904)Bureau of Frontier Sciences and Education of Chinese Academy of Sciences(No.QYZDJ-SSW-SLH001)
文摘Purpose For the High Energy Photon Source(HEPS),a green-field fourth-generation storage ring light source,the prelimi-nary design report(PDR)was completed in 2018,when the accelerator physics design had been basically finished.During the subsequent hardware and engineering design of the HEPS storage ring based on the PDR design,a few problems and challenges emerged,calling for modifications of the lattice.Method In this paper,we will introduce the background and reasons for the modifications and present the linear optics and simulation results for the nonlinear performance of the modified lattice of the HEPS storage ring.Result and conclusion The modified lattice satisfies the requirements from hardware and engineering design.
基金This work was supported by the National Natural Science Foundation of China(No.11922512)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.Y201904)the Guangdong Basic and Applied Basic Research Foundation—Guangdong Dongguan Joint Foundation(No.2019B1515120069).
文摘In recent years,a new generation of storage ring-based light sources,known as diffraction-limited storage rings(DLSRs),whose emittance approaches the diffraction limit for the range of X-ray wavelengths of interest to the scientific community,has garnered significant attention worldwide.Researchers have begun to design and build DLSRs.Among various DLSR proposals,the hybrid multibend achromat(H-MBA)lattice enables sextupole strengths to be maintained at a reasonable level when minimizing the emittance;hence,it has been adopted in many DLSR designs.Based on the H-7BA lattice,the design of the Advanced Photon Source Upgrade Project(APS-U)can effectively reduce emittance by replacing six quadrupoles with anti-bends.Herein,we discuss the feasibility of designing an APS-U-type H-MBA lattice for the Southern Advanced Photon Source,a mid-energy DLSR light source with ultralow emittance that has been proposed to be built adjacent to the China Spallation Neutron Source.Both linear and nonlinear dynamics are optimized to obtain a detailed design of this type of lattice.The emittance is minimized,while a sufficiently large dynamic aperture(DA)and momentum acceptance(MA)are maintained.A design comprising 36 APS-U type H-7BAs,with an energy of 3 GeV and a circumference of 972 m,is achieved.The horizontal natural emittance is 20 pm·rad,with a horizontal DA of 5.8 mm,a vertical DA of 4.5 mm,and an MA of 4%,as well as a long longitudinal damping time of 120 ms.Subsequently,a few modifications are performed based on the APS-U-type lattice to reduce the maximum value of damping time from 120 to 44 ms while maintaining other performance parameters at the same level.
基金Under the auspices of the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(No.2019QZKK0103)National Natural Science Foundation of China(No.41772173,41405077)+1 种基金the Thousand Talents Program for High-end Innovation of Qinghai Provincethe Applied Basic Research Project of Qinghai Province(No.2019-zj-7045)。
文摘Variations in vegetation are closely related to climate change, but understanding of their characteristics and causes remains limited. As a typical semi-humid and semi-arid cold plateau region, it is important to understand the knowledge of long term Normalized Difference Vegetation Index(NDVI) variations and find the potential causes in the source region of the Yangtze River. Based on four tree-ring width chronologies, the regional mean NDVI for July and August spanning the period 1665–2013 was reconstructed using a regression model, and it explained 43.9% of the total variance during the period 1981–2013. In decadal, the reconstructed NDVI showed eight growth stages(1754–1764, 1766–1783, 1794–1811, 1828–1838, 1843–1855, 1862–1873, 1897–1909, and 1932–1945)and four degradation stages(1679–1698, 1726–1753, 1910–1923, and 1988–2000). And based on wavelet analysis, significant cycles of2–3 yr and 3–8 yr were identified. In additional, there was a significant positive correlation between the NDVI and the Palmer Drought Severity Index(PDSI) during the past 349 yr, and they were mainly in phase. However, according to the results of correlation analysis between different grades of drought/wet and NDVI, there was significant asymmetry in extreme drought years and extreme wet years. In extreme drought years, NDVI was positively correlated with PDSI, and in extreme wet years they were negatively correlated.
文摘合肥光源储存环控制系统是一个基于EPICS(Experiment Physics and Industrial Control System)的分布式控制系统,本文首先描述其硬件结构、软件设计,然后重点介绍束流慢加速、束流闭轨校正、机器状态在线查询、数据存档及历史数据查询等应用软件的开发。运行结果表明,合肥光源储存环控制系统很好地满足了机器运行和机器研究的需要。
基金supported by the National Natural Science Foundation of China(Nos.41564001,41674133,41572185,and 41604104)the Distinguished Young Talent Foundation of Jiangxi Province(No.20171BCB23068)
文摘Multiturn coils is an effective transmitter for transient electromagnetic method(TEM) used in narrow space and complex terrain at presently. However, its high mutual inductance coupling and long turn-off time affect the quality of later data processing and interpretation. Compared with multiturn coils, the new conical source has low mutual inductance and short turn-off time. Based on the superposition principle, we use Hankel transform and numerical filtering method for forward modelling of the conical source field in the layered-media and explore TEM characteristics excited by this source. We apply improved damped least square inversion to integrated transient electromagnetic(TEM) data. We first invert the induced voltage into similar resistivity and apparent depth, and then use the inverted results as input parameters in the initial model and transform the apparent resistivity data into the frequency domain. Then, damped least square inversion is performed in the frequency domain using the initial model. Subsequently, we use automated model building to search for the extremes and inflection points in the resistivity–depth data that are treated as critical layer parameters. The inversion of theoretical and observed data suggests that the method modifies the resistivity and depth and yields a model of the underground layers.
