Power transformers play a vital role in power transmission systems from the energy source to the consumption center.In situ diagnostics of the performance of power transformers provides a variety of benefits to ensure...Power transformers play a vital role in power transmission systems from the energy source to the consumption center.In situ diagnostics of the performance of power transformers provides a variety of benefits to ensure reliable electricity transmission.Immunity to electromagnetic interference,high sensitivity,high insulation as well as small dimensions of optical sensing make it very attractive for applications in power transformer monitoring.This paper presents a critical review of various diagnostic methods for power transformers such as partial discharge,dissolved gases,temperature and other important sensing,and optical detection.The advantages and disadvantages of different monitoring methods are carefully discussed and assessed.Finally,the existing technical barriers and future prospects of optical monitoring methods for power transformers are presented.展开更多
The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 3...The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.展开更多
Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei.As a future high energy nuclear physics project,an Electron-ion collider in China(EicC)...Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei.As a future high energy nuclear physics project,an Electron-ion collider in China(EicC)has been proposed.It will be constructed based on an upgraded heavy-ion accelerator,High Intensity heavy-ion Accelerator Facility(HIAF)which is currently under construction,together with a new electron ring.The proposed collider will provide highly polarized electrons(with a po-larization of 80%)and protons(with a polarization of 70%)with variable center of mass energies from 15 to 20 GeV and the luminosity of(2–3)×1033 cm^(−2)·s^(−1).Polarized deuterons and Helium-3,as well as unpolarized ion beams from Carbon to Uranium,will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region,including 3D tomography of nucleon;the partonic structure of nuclei and the parton interaction with the nuclear environment;the exotic states,especially those with heavy flavor quark contents.In addition,issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC.In order to achieve the above-mentioned physics goals,a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe.The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States.The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.展开更多
轻子散射实验是探索核子与原子核结构的理想工具。中国电子离子对撞机(Electron Ion Collider in China,EicC)建议书设想在已开建的强流重离子加速器装置(High Intensity heavy ion Accelerator Facility,HIAF)的基础上,升级质子束流为2...轻子散射实验是探索核子与原子核结构的理想工具。中国电子离子对撞机(Electron Ion Collider in China,EicC)建议书设想在已开建的强流重离子加速器装置(High Intensity heavy ion Accelerator Facility,HIAF)的基础上,升级质子束流为20 GeV的极化束流,并建造2.8~5 GeV极化电子束流,从而实现质心系能量为15~20 GeV的双极化电子-离子对撞。EicC设计的亮度为(2~4)×10^33cm^-2·s^-1,质子束流极化率达到70%,电子束流极化率达到80%。该装置除了能提供极化轻离子束流(例如:氦-3)外,也可产生非极化重离子束流(碳-12~铀-238)。EicC将聚焦核子海夸克部分子结构、原子核物质结构与性质、奇特强子态三个方面的物理研究。高亮度、高精度的对撞机有助于精确地测量核子结构函数并对核子进行三维成像,揭示强相互作用的动力学规律;原子核部分子分布包括核子短程关联以及原子核介质效应同样是该提案的重要科学目标;EicC能区接近重味夸克产生阈值,在研究重味强子谱方面拥有低背景的独特优势,有助于发现研究新的奇特强子态。质子质量起源问题也可以通过重味矢量介子的产生来研究。为了完成上述物理目标,我们将利用最先进的探测器技术建造接近全立体角覆盖的EicC对撞机谱仪。在准备EicC白皮书的过程中,我们得到世界各国专家的支持。EicC的物理与已有的实验和美国即将建设的EIC中的物理项目相互补充。EicC的建成及运行有望引领前沿的中高能核物理研究,使我国在加速器和探测器先进技术等领域实现跨越式发展,为我国核物理与强子物理以及相关科学领域提供大型综合实验平台与人才培养基地。展开更多
To achieve the Paris Agreement,China pledged to become“Carbon Neutral”by the 2060s.In addition to massive decarbonization,this would require significant changes in ecosystems toward negative CO_(2)emissions.The abil...To achieve the Paris Agreement,China pledged to become“Carbon Neutral”by the 2060s.In addition to massive decarbonization,this would require significant changes in ecosystems toward negative CO_(2)emissions.The ability of coastal blue carbon ecosystems(BCEs),including mangrove,salt marsh,and seagrass meadows,to sequester large amounts of CO_(2)makes their conservation and restoration an important“nature-based solution(NbS)”for climate adaptation and mitigation.In this review,we examine how BCEs in China can contribute to climate mitigation.On the national scale,the BCEs in China store up to 118 Tg C across a total area of 1,440,377 ha,including over 75%as unvegetated tidal flats.The annual sedimental C burial of these BCEs reaches up to 2.06 Tg C year^(−1),of which most occurs in salt marshes and tidal flats.The lateral C flux of mangroves and salt marshes contributes to 1.17 Tg C year^(−1)along the Chinese coastline.Conservation and restoration of BCEs benefit climate change mitigation and provide other ecological services with a value of$32,000 ha^(−1)year^(−1).The potential practices and technologies that can be implemented in China to improve BCE C sequestration,including their constraints and feasibility,are also outlined.Future directions are suggested to improve blue carbon estimates on aerial extent,carbon stocks,sequestration,and mitigation potential.Restoring and preserving BCEs would be a cost-effective step to achieve Carbon Neutral by 2060 in China despite various barriers that should be removed.展开更多
Spartina alterniflora has rapidly and extensively encroached on China's coastline over the past decades.Among the coastal areas invaded by S.alterniflora,at most 93%are mudflats.However,the effect of S.alterniflor...Spartina alterniflora has rapidly and extensively encroached on China's coastline over the past decades.Among the coastal areas invaded by S.alterniflora,at most 93%are mudflats.However,the effect of S.alterniflora invasion on soil organic carbon(SOC)stocks of coastal mudflats has not been systematically studied on a national scale.Here,we quantified the nationwide changes in SOC stocks in coastal mudflats associated with S.alterniflora invasion between 1990 and 2020.We found that S.alterniflora invasion significantly enhanced SOC stocks in coastal China.Nonetheless,the benefit of S.alterniflora invasion of coastal SOC stock may be weakened by continuing human intervention.We found that S.alterniflora invading mudflats added 2.3 Tg SOC stocks to China's coastal blue carbon,while 1.78 Tg SOC stocks were lost mainly due to human activities,resulted in a net SOC stock gain of 0.52 Tg C.These findings overturned the traditionally thought that S.alterniflora invasion would reduce ecosystem services by highlighting that the historical invasion of S.alterniflora has broadly and consistently enhanced blue carbon stock in coastal China.展开更多
Stable triggering of acquisition devices is critical to accurately measure electromagnetic transients,especially for very fast transient overvoltages(VFTOs).A highly stable and lowcos t self-trigger method for transie...Stable triggering of acquisition devices is critical to accurately measure electromagnetic transients,especially for very fast transient overvoltages(VFTOs).A highly stable and lowcos t self-trigger method for transient measurement is proposed.An integrated low-voltage arm module was developed to synchronously realise the triggering and VFTO measurement.The trigger branch was developed using a high-pass filter.This component obtained the high-frequency component of the VFTO to trigger the oscilloscope.The trigger branch was integrated with the measurement branch through an impedance converter.An attenuator was implemented before the impedance converter to avoid overvoltage damage to the chip.The circuit parameters of the attenuator were optimised to alleviate the disturbance of the measurement branch.The calibration results demonstrated that the±1 dB bandwidth of the measurement branch in this system ranged from 11.8 Hz to 105 MHz.The low cutoff frequency of the trigger branch was 710 Hz.The VFTO waveforms generated by the operation of a disconnector in a real 252 kV gas insulated switchgear were measured using the proposed system.The test results verified that the self-trigger measurement system can provide stable trigger signals and accurately measure the VFTO waveforms.展开更多
Multi-hop reasoning for incomplete Knowledge Graphs(KGs)demonstrates excellent interpretability with decent performance.Reinforcement Learning(RL)based approaches formulate multi-hop reasoning as a typical sequential ...Multi-hop reasoning for incomplete Knowledge Graphs(KGs)demonstrates excellent interpretability with decent performance.Reinforcement Learning(RL)based approaches formulate multi-hop reasoning as a typical sequential decision problem.An intractable shortcoming of multi-hop reasoning with RL is that sparse reward signals make performance unstable.Current mainstream methods apply heuristic reward functions to counter this challenge.However,the inaccurate rewards caused by heuristic functions guide the agent to improper inference paths and unrelated object entities.To this end,we propose a novel adaptive Inverse Reinforcement Learning(IRL)framework for multi-hop reasoning,called AInvR.(1)To counter the missing and spurious paths,we replace the heuristic rule rewards with an adaptive rule reward learning mechanism based on agent’s inference trajectories;(2)to alleviate the impact of over-rewarded object entities misled by inaccurate reward shaping and rules,we propose an adaptive negative hit reward learning mechanism based on agent’s sampling strategy;(3)to further explore diverse paths and mitigate the influence of missing facts,we design a reward dropout mechanism to randomly mask and perturb reward parameters for the reward learning process.Experimental results on several benchmark knowledge graphs demonstrate that our method is more effective than existing multi-hop approaches.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:51677070,51807088State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources,Grant/Award Number:LAPS19010+4 种基金Beijing Natural Science Foundation,Grant/Award Number:3182036CAST,Grant/Award Number:YESS20160004Fok Ying‐Tong Education Foundation for Young Teachers in the Higher Education Institutions of China,Grant/Award Number:161053China Scholarship Council(CSC)Fundamental Research Funds for the Central Universities,Grant/Award Number:2019MS006。
文摘Power transformers play a vital role in power transmission systems from the energy source to the consumption center.In situ diagnostics of the performance of power transformers provides a variety of benefits to ensure reliable electricity transmission.Immunity to electromagnetic interference,high sensitivity,high insulation as well as small dimensions of optical sensing make it very attractive for applications in power transformer monitoring.This paper presents a critical review of various diagnostic methods for power transformers such as partial discharge,dissolved gases,temperature and other important sensing,and optical detection.The advantages and disadvantages of different monitoring methods are carefully discussed and assessed.Finally,the existing technical barriers and future prospects of optical monitoring methods for power transformers are presented.
基金support from diverse funding sources,including the National Key Program for S&T Research and Development of the Ministry of Science and Technology(MOST),Yifang Wang's Science Studio of the Ten Thousand Talents Project,the CAS Key Foreign Cooperation Grant,the National Natural Science Foundation of China(NSFC)Beijing Municipal Science&Technology Commission,the CAS Focused Science Grant,the IHEP Innovation Grant,the CAS Lead Special Training Programthe CAS Center for Excellence in Particle Physics,the CAS International Partnership Program,and the CAS/SAFEA International Partnership Program for Creative Research Teams.
文摘The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.
文摘Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei.As a future high energy nuclear physics project,an Electron-ion collider in China(EicC)has been proposed.It will be constructed based on an upgraded heavy-ion accelerator,High Intensity heavy-ion Accelerator Facility(HIAF)which is currently under construction,together with a new electron ring.The proposed collider will provide highly polarized electrons(with a po-larization of 80%)and protons(with a polarization of 70%)with variable center of mass energies from 15 to 20 GeV and the luminosity of(2–3)×1033 cm^(−2)·s^(−1).Polarized deuterons and Helium-3,as well as unpolarized ion beams from Carbon to Uranium,will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region,including 3D tomography of nucleon;the partonic structure of nuclei and the parton interaction with the nuclear environment;the exotic states,especially those with heavy flavor quark contents.In addition,issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC.In order to achieve the above-mentioned physics goals,a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe.The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States.The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.
文摘轻子散射实验是探索核子与原子核结构的理想工具。中国电子离子对撞机(Electron Ion Collider in China,EicC)建议书设想在已开建的强流重离子加速器装置(High Intensity heavy ion Accelerator Facility,HIAF)的基础上,升级质子束流为20 GeV的极化束流,并建造2.8~5 GeV极化电子束流,从而实现质心系能量为15~20 GeV的双极化电子-离子对撞。EicC设计的亮度为(2~4)×10^33cm^-2·s^-1,质子束流极化率达到70%,电子束流极化率达到80%。该装置除了能提供极化轻离子束流(例如:氦-3)外,也可产生非极化重离子束流(碳-12~铀-238)。EicC将聚焦核子海夸克部分子结构、原子核物质结构与性质、奇特强子态三个方面的物理研究。高亮度、高精度的对撞机有助于精确地测量核子结构函数并对核子进行三维成像,揭示强相互作用的动力学规律;原子核部分子分布包括核子短程关联以及原子核介质效应同样是该提案的重要科学目标;EicC能区接近重味夸克产生阈值,在研究重味强子谱方面拥有低背景的独特优势,有助于发现研究新的奇特强子态。质子质量起源问题也可以通过重味矢量介子的产生来研究。为了完成上述物理目标,我们将利用最先进的探测器技术建造接近全立体角覆盖的EicC对撞机谱仪。在准备EicC白皮书的过程中,我们得到世界各国专家的支持。EicC的物理与已有的实验和美国即将建设的EIC中的物理项目相互补充。EicC的建成及运行有望引领前沿的中高能核物理研究,使我国在加速器和探测器先进技术等领域实现跨越式发展,为我国核物理与强子物理以及相关科学领域提供大型综合实验平台与人才培养基地。
基金CAS Project for Young Scientists in Basic Research(YSBR-037)ANSO collaborative research(ANSO-CR-KP-2022-11)+4 种基金National Natural Science Foundation of China(U2106209,42141003,42141016,and 32171594)Guangdong Basic and Applied Basic Research Foundation(2021B1515020011 and 2021B1212110004)CAS Youth Innovation Promotion Association(2021347)National Forestry and Grassland Administration Youth Talent Support Program(2020BJ003)R&D program of Guangdong Provincial Department of Science and Technology(2018B030324003).
文摘To achieve the Paris Agreement,China pledged to become“Carbon Neutral”by the 2060s.In addition to massive decarbonization,this would require significant changes in ecosystems toward negative CO_(2)emissions.The ability of coastal blue carbon ecosystems(BCEs),including mangrove,salt marsh,and seagrass meadows,to sequester large amounts of CO_(2)makes their conservation and restoration an important“nature-based solution(NbS)”for climate adaptation and mitigation.In this review,we examine how BCEs in China can contribute to climate mitigation.On the national scale,the BCEs in China store up to 118 Tg C across a total area of 1,440,377 ha,including over 75%as unvegetated tidal flats.The annual sedimental C burial of these BCEs reaches up to 2.06 Tg C year^(−1),of which most occurs in salt marshes and tidal flats.The lateral C flux of mangroves and salt marshes contributes to 1.17 Tg C year^(−1)along the Chinese coastline.Conservation and restoration of BCEs benefit climate change mitigation and provide other ecological services with a value of$32,000 ha^(−1)year^(−1).The potential practices and technologies that can be implemented in China to improve BCE C sequestration,including their constraints and feasibility,are also outlined.Future directions are suggested to improve blue carbon estimates on aerial extent,carbon stocks,sequestration,and mitigation potential.Restoring and preserving BCEs would be a cost-effective step to achieve Carbon Neutral by 2060 in China despite various barriers that should be removed.
基金supported by the CAS Project for Young Scientists in Basic Research(YSBR-037)the National Key R&D Program of China(2023YFE0113100,2023YFF1304500,2021YFC3100400)+8 种基金the National Natural Science Foundation of China(U2106209,32171594,32301398,42007230)Guangdong Basic and Applied Basic Research Foundation(2021B1515020011)the CAS Youth Innovation Promotion Association(2021347)the National Forestry and Grassland Administration Youth Talent Support Program(2020BJ003)ANSO collaborative research(ANSO-CR-KP-202211)Guangdong Key Research Program(2022B1111230001)Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(SML2023SP218)Guangdong Provincial Key Laboratory of Applied Botany,South China Botanical Garden(2023B1212060046)the MOST Ocean Negative Carbon Emissions project。
文摘Spartina alterniflora has rapidly and extensively encroached on China's coastline over the past decades.Among the coastal areas invaded by S.alterniflora,at most 93%are mudflats.However,the effect of S.alterniflora invasion on soil organic carbon(SOC)stocks of coastal mudflats has not been systematically studied on a national scale.Here,we quantified the nationwide changes in SOC stocks in coastal mudflats associated with S.alterniflora invasion between 1990 and 2020.We found that S.alterniflora invasion significantly enhanced SOC stocks in coastal China.Nonetheless,the benefit of S.alterniflora invasion of coastal SOC stock may be weakened by continuing human intervention.We found that S.alterniflora invading mudflats added 2.3 Tg SOC stocks to China's coastal blue carbon,while 1.78 Tg SOC stocks were lost mainly due to human activities,resulted in a net SOC stock gain of 0.52 Tg C.These findings overturned the traditionally thought that S.alterniflora invasion would reduce ecosystem services by highlighting that the historical invasion of S.alterniflora has broadly and consistently enhanced blue carbon stock in coastal China.
基金National Key R&D Program of China,Grant/Award Number:2017YFB0903800Open Fund of State Key Laboratory of Power Grid Environmental Protection,Grant/Award Number:GYW51202201427。
文摘Stable triggering of acquisition devices is critical to accurately measure electromagnetic transients,especially for very fast transient overvoltages(VFTOs).A highly stable and lowcos t self-trigger method for transient measurement is proposed.An integrated low-voltage arm module was developed to synchronously realise the triggering and VFTO measurement.The trigger branch was developed using a high-pass filter.This component obtained the high-frequency component of the VFTO to trigger the oscilloscope.The trigger branch was integrated with the measurement branch through an impedance converter.An attenuator was implemented before the impedance converter to avoid overvoltage damage to the chip.The circuit parameters of the attenuator were optimised to alleviate the disturbance of the measurement branch.The calibration results demonstrated that the±1 dB bandwidth of the measurement branch in this system ranged from 11.8 Hz to 105 MHz.The low cutoff frequency of the trigger branch was 710 Hz.The VFTO waveforms generated by the operation of a disconnector in a real 252 kV gas insulated switchgear were measured using the proposed system.The test results verified that the self-trigger measurement system can provide stable trigger signals and accurately measure the VFTO waveforms.
基金This work was supported by the National Natural Science Foundation of China(No.U19A2059)。
文摘Multi-hop reasoning for incomplete Knowledge Graphs(KGs)demonstrates excellent interpretability with decent performance.Reinforcement Learning(RL)based approaches formulate multi-hop reasoning as a typical sequential decision problem.An intractable shortcoming of multi-hop reasoning with RL is that sparse reward signals make performance unstable.Current mainstream methods apply heuristic reward functions to counter this challenge.However,the inaccurate rewards caused by heuristic functions guide the agent to improper inference paths and unrelated object entities.To this end,we propose a novel adaptive Inverse Reinforcement Learning(IRL)framework for multi-hop reasoning,called AInvR.(1)To counter the missing and spurious paths,we replace the heuristic rule rewards with an adaptive rule reward learning mechanism based on agent’s inference trajectories;(2)to alleviate the impact of over-rewarded object entities misled by inaccurate reward shaping and rules,we propose an adaptive negative hit reward learning mechanism based on agent’s sampling strategy;(3)to further explore diverse paths and mitigate the influence of missing facts,we design a reward dropout mechanism to randomly mask and perturb reward parameters for the reward learning process.Experimental results on several benchmark knowledge graphs demonstrate that our method is more effective than existing multi-hop approaches.
