The China Spallation Neutron Source (CSNS) is the first accelerator-based pulsed neutron source in China. Its accelerators are made up of an 80 MeV H- linac, a Rapid Cycling Synchrotron (RCS) and two beam transport li...The China Spallation Neutron Source (CSNS) is the first accelerator-based pulsed neutron source in China. Its accelerators are made up of an 80 MeV H- linac, a Rapid Cycling Synchrotron (RCS) and two beam transport lines. RCS accumulates and accelerates protons to the design energy of 1.6 GeV, and extracts high energy beam to strike the target. The overview of RCS is presented, and the key problems of the physics design are discussed. The two beam transport lines, from linac to RCS and from RCS to the target, are also introduced.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
The low anodic oxidation potential severely suppresses the output voltage(≤0.6 V)of MXene-based symmetrical aqueous microsupercapacitors(MSA-MSCs)employing acidic electrolytes.Herein,a surface terminals reconstructio...The low anodic oxidation potential severely suppresses the output voltage(≤0.6 V)of MXene-based symmetrical aqueous microsupercapacitors(MSA-MSCs)employing acidic electrolytes.Herein,a surface terminals reconstruction mechanism on cathode of MSA-MSCs adopting aqueous neutral electrolyte(1 M Na_(2)SO_(4))is first revealed by systematical electrochemical experiments and in/ex-situ spectral analysis,which indicates that:the-O terminals on Ti3C2Tx flakes of cathode can combine with intercalated Na+cations during charging process to reconstruct into-ONa units to(i)inhibit the splitting reaction of adjacent water molecules,decreasing cathodic hydrogen evolution potential,more significantly,(ii)lower the potential of zero voltage(P0V)between the symmetrical electrodes to avoid anode oxidation,enabling full use of the unexploited potential range of cathode.Thus,the output voltage of the MSA-MSCs tremendously expanded from 0.6 V in acidic polyacrylamide(PAM)/1 M H_(2)SO_(4)hydrogel electrolyte to 1.5 V in neutral polyacrylamide/1 M Na2SO4 hydrogel electrolyte,boosting the corresponding areal energy density from 9.9 to 34.6μW·h·cm^(-2).The demonstrated deep insight on the surface terminals reconstruction mechanism for synchronously modulating the P0V between symmetrical electrodes and hydrogen evolution potential on cathode provides critical guidance for widening the cell voltage of MSA-MSCs with safer and more inexpensive neutral electrolytes.展开更多
To satisfy the ever-increasing bandwidth demand of modern data centers, researchers have proposed hybrid Data Center Networks(DCNs), which employ high-bandwidth Optical Circuit Switches(OCSs) to compensate for Electri...To satisfy the ever-increasing bandwidth demand of modern data centers, researchers have proposed hybrid Data Center Networks(DCNs), which employ high-bandwidth Optical Circuit Switches(OCSs) to compensate for Electrical Packet Switches(EPS). Existing designs, such as Helios and c-Through, mainly focus on reconfiguring optical devices to meet the estimated traffic requirements. However, these designs face two major challenges in their OCS-based networks, namely, the complex control mechanism and cabling problems. To solve these challenges, we propose TIO, a hybrid DCN that employs Visible Light Communication(VLC) instead of wired OCS design to connect racks. TIO integrates the wireless VLC-based Jellyfish and wired EPS-based Fat Tree seamlessly and combines the opposite and complementary characteristics, including wireless VLC direct connection and wired electrical packet switching, random graph, and Clos topology properties. To further exploit the merits of TIO, we design a hybrid routing scheme and congestion-aware flow scheduling method. Comprehensive evaluations indicate that TIO outperforms the Jellyfish and Fat Tree in both topology properties and network performance, and the flow scheduling method also evidently improves performance.展开更多
Visible-Light Communication(VLC) has the potential to provide dense and fast connectivity at low cost. In this paper we propose SFNet, a novel VLC-enabled hybrid data center network that extends the design of wireless...Visible-Light Communication(VLC) has the potential to provide dense and fast connectivity at low cost. In this paper we propose SFNet, a novel VLC-enabled hybrid data center network that extends the design of wireless Data Center Networks(DCNs) into three further dimensions:(1) fully wireless at the inter-rack level;(2) no need for a centralized control mechanism on wireless links;and(3) no need for any infrastructure-level alterations to data centers. Previous proposals typically cannot realize these three rationales simultaneously. To achieve this vision,the proposed SFNet augments fat-tree by organizing all racks into a wireless small-world network via VLC links. The use of VLC links eliminates hierarchical switches and cables in the wireless network, and thus reduces hardware investment and maintenance costs. To fully exploit the benefits of the topology of SFNet, we further propose its topology design and optimization method, routing scheme, and online flow scheduling algorithm. Comprehensive experiments indicate that SFNet exhibits good topological properties and network performance.展开更多
The visible light communication (VLC) has the potential to provide dense and fast connectivity at low cost. In this paper, we propose a novel VLC enabled Wireless Small-World Data Center (WSWDC). It employs VLC links ...The visible light communication (VLC) has the potential to provide dense and fast connectivity at low cost. In this paper, we propose a novel VLC enabled Wireless Small-World Data Center (WSWDC). It employs VLC links to achieve a fully wireless data center network (DCN) across racks for the first time. The using of VLC links eliminates hierarchical switches and inter-rack cables, and thus reducing hardware investment, as well as maintenance cost. More precisely, to simplify the configuration and control operations, we propose three DCN design rationales:(1) fully-wireless, all inter-rack links are wireless;(2) easy-deployable, it is not necessary to change the existing infrastructure inside data center;(3) plug-and-play, no extra centralized control operations are required. Previous proposals, however, cannot achieve the three rationales simultaneously. To this end, we first use regular VLC links to interconnect racks as a regular grid DCN and optimize the rack placement to shorten the average path length and the network diameter. To further exploiting the benefits of VLC links, a few random VLC links are carefully introduced to update the wireless grid DCN as a wireless small-world DCN. To avoid the potential interference among VLC links, we deploy VLC transceivers at different heights on the top of each rack. In this way, VLC links would not interfere with others at each height level. Moreover, we design a greedy but efficient routing method for any pair of racks using their identifiers as inputs. Comprehensive evaluation results indicate that our WSWDC exhibits good topological properties and network performance.展开更多
Multicast transfer can efficiently save the bandwidth consumption and reduce the load on the source node than a series of independent unicast transfers.Nowadays,many applications employ the content replica strategy to...Multicast transfer can efficiently save the bandwidth consumption and reduce the load on the source node than a series of independent unicast transfers.Nowadays,many applications employ the content replica strategy to improve the robustness and efficiency;hence each file and its replicas are usually distributed among multiple sources.In such scenarios,the traditional deterministic multicast develops into the Uncertain multicast,which has more flexibility in the source selection.In this paper,we focus on building and maintaining a minimal cost forest(MCF)for any uncertain multicast,whose group members(source nodes and destination nodes)may join or leave after constructing a MCF.We formulate this dynamic minimal cost forest(DMCF)problem as a mixed integer programming model.We then design three dedicated methods to approximate the optimal solution.Among them,our a-MCF aims to efficiently construct an MCF for any given uncertain multicast,without dynamic behaviors of multicast group members.The d-MCF method motivates to slightly update the existing MCF via local modifications once appearing a dynamic behavior.It can achieve the balance between the minimal cost and the minimal modifications to the existing forest.The last r-MCF is a supplement method to the d-MCF method,since many rounds of local modifications maymake the resultant forest far away from the optimal forest.Accordingly,our r-MCF method monitors the accumulated degradation and triggers the rearrangement process to reconstruct an new MCF when necessary.The comprehensive evaluation results demonstrate that our methods can well tackle the proposed DMCF problem.展开更多
文摘The China Spallation Neutron Source (CSNS) is the first accelerator-based pulsed neutron source in China. Its accelerators are made up of an 80 MeV H- linac, a Rapid Cycling Synchrotron (RCS) and two beam transport lines. RCS accumulates and accelerates protons to the design energy of 1.6 GeV, and extracts high energy beam to strike the target. The overview of RCS is presented, and the key problems of the physics design are discussed. The two beam transport lines, from linac to RCS and from RCS to the target, are also introduced.
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.
基金the National Natural Science Foundation of China(No.51871001)Excellent Youth Fund of Anhui Province(No.2108085Y17)+2 种基金Innovation and Entrepreneurship Support Plan of Anhui Province for Returned Personnels Studying Abroad(No.2022LCX001)Project supported by the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices(No.KF202212)Hundred-Talent Program of Anhui Province.
文摘The low anodic oxidation potential severely suppresses the output voltage(≤0.6 V)of MXene-based symmetrical aqueous microsupercapacitors(MSA-MSCs)employing acidic electrolytes.Herein,a surface terminals reconstruction mechanism on cathode of MSA-MSCs adopting aqueous neutral electrolyte(1 M Na_(2)SO_(4))is first revealed by systematical electrochemical experiments and in/ex-situ spectral analysis,which indicates that:the-O terminals on Ti3C2Tx flakes of cathode can combine with intercalated Na+cations during charging process to reconstruct into-ONa units to(i)inhibit the splitting reaction of adjacent water molecules,decreasing cathodic hydrogen evolution potential,more significantly,(ii)lower the potential of zero voltage(P0V)between the symmetrical electrodes to avoid anode oxidation,enabling full use of the unexploited potential range of cathode.Thus,the output voltage of the MSA-MSCs tremendously expanded from 0.6 V in acidic polyacrylamide(PAM)/1 M H_(2)SO_(4)hydrogel electrolyte to 1.5 V in neutral polyacrylamide/1 M Na2SO4 hydrogel electrolyte,boosting the corresponding areal energy density from 9.9 to 34.6μW·h·cm^(-2).The demonstrated deep insight on the surface terminals reconstruction mechanism for synchronously modulating the P0V between symmetrical electrodes and hydrogen evolution potential on cathode provides critical guidance for widening the cell voltage of MSA-MSCs with safer and more inexpensive neutral electrolytes.
基金partially supported by the National Natural Science Foundation for Outstanding Excellent Young Scholars of China(No.61422214)the National Natural Science Foundation of China(No.61772544)+3 种基金the National Key Basic Research and Development(973)Program of China(No.2014CB347800)the Hunan Provincial Natural Science Fund for Distinguished Young Scholars(No.2016JJ1002)the Guangxi Cooperative Innovation Center of Cloud Computing and Big Data(Nos.YD16507 and YD17X11)the NUDT Research Plan(No.ZK17-03-50)
文摘To satisfy the ever-increasing bandwidth demand of modern data centers, researchers have proposed hybrid Data Center Networks(DCNs), which employ high-bandwidth Optical Circuit Switches(OCSs) to compensate for Electrical Packet Switches(EPS). Existing designs, such as Helios and c-Through, mainly focus on reconfiguring optical devices to meet the estimated traffic requirements. However, these designs face two major challenges in their OCS-based networks, namely, the complex control mechanism and cabling problems. To solve these challenges, we propose TIO, a hybrid DCN that employs Visible Light Communication(VLC) instead of wired OCS design to connect racks. TIO integrates the wireless VLC-based Jellyfish and wired EPS-based Fat Tree seamlessly and combines the opposite and complementary characteristics, including wireless VLC direct connection and wired electrical packet switching, random graph, and Clos topology properties. To further exploit the merits of TIO, we design a hybrid routing scheme and congestion-aware flow scheduling method. Comprehensive evaluations indicate that TIO outperforms the Jellyfish and Fat Tree in both topology properties and network performance, and the flow scheduling method also evidently improves performance.
文摘Visible-Light Communication(VLC) has the potential to provide dense and fast connectivity at low cost. In this paper we propose SFNet, a novel VLC-enabled hybrid data center network that extends the design of wireless Data Center Networks(DCNs) into three further dimensions:(1) fully wireless at the inter-rack level;(2) no need for a centralized control mechanism on wireless links;and(3) no need for any infrastructure-level alterations to data centers. Previous proposals typically cannot realize these three rationales simultaneously. To achieve this vision,the proposed SFNet augments fat-tree by organizing all racks into a wireless small-world network via VLC links. The use of VLC links eliminates hierarchical switches and cables in the wireless network, and thus reduces hardware investment and maintenance costs. To fully exploit the benefits of the topology of SFNet, we further propose its topology design and optimization method, routing scheme, and online flow scheduling algorithm. Comprehensive experiments indicate that SFNet exhibits good topological properties and network performance.
基金This work was partially supported by the National Natural Science Foundation for Outstanding Excellent young scholars of China (61422214)the National Natural Science Foundation of China (Grant No. 61772544)+2 种基金National Basic Research Program (973 program)(2014CB347800)the Hunan Provincial Natural Science Fund for Distinguished Young Scholars (2016JJ1002)the Guangxi Cooperative Innovation Center of cloud computing and Big Data (YD16507 and YD17X11).
文摘The visible light communication (VLC) has the potential to provide dense and fast connectivity at low cost. In this paper, we propose a novel VLC enabled Wireless Small-World Data Center (WSWDC). It employs VLC links to achieve a fully wireless data center network (DCN) across racks for the first time. The using of VLC links eliminates hierarchical switches and inter-rack cables, and thus reducing hardware investment, as well as maintenance cost. More precisely, to simplify the configuration and control operations, we propose three DCN design rationales:(1) fully-wireless, all inter-rack links are wireless;(2) easy-deployable, it is not necessary to change the existing infrastructure inside data center;(3) plug-and-play, no extra centralized control operations are required. Previous proposals, however, cannot achieve the three rationales simultaneously. To this end, we first use regular VLC links to interconnect racks as a regular grid DCN and optimize the rack placement to shorten the average path length and the network diameter. To further exploiting the benefits of VLC links, a few random VLC links are carefully introduced to update the wireless grid DCN as a wireless small-world DCN. To avoid the potential interference among VLC links, we deploy VLC transceivers at different heights on the top of each rack. In this way, VLC links would not interfere with others at each height level. Moreover, we design a greedy but efficient routing method for any pair of racks using their identifiers as inputs. Comprehensive evaluation results indicate that our WSWDC exhibits good topological properties and network performance.
文摘Multicast transfer can efficiently save the bandwidth consumption and reduce the load on the source node than a series of independent unicast transfers.Nowadays,many applications employ the content replica strategy to improve the robustness and efficiency;hence each file and its replicas are usually distributed among multiple sources.In such scenarios,the traditional deterministic multicast develops into the Uncertain multicast,which has more flexibility in the source selection.In this paper,we focus on building and maintaining a minimal cost forest(MCF)for any uncertain multicast,whose group members(source nodes and destination nodes)may join or leave after constructing a MCF.We formulate this dynamic minimal cost forest(DMCF)problem as a mixed integer programming model.We then design three dedicated methods to approximate the optimal solution.Among them,our a-MCF aims to efficiently construct an MCF for any given uncertain multicast,without dynamic behaviors of multicast group members.The d-MCF method motivates to slightly update the existing MCF via local modifications once appearing a dynamic behavior.It can achieve the balance between the minimal cost and the minimal modifications to the existing forest.The last r-MCF is a supplement method to the d-MCF method,since many rounds of local modifications maymake the resultant forest far away from the optimal forest.Accordingly,our r-MCF method monitors the accumulated degradation and triggers the rearrangement process to reconstruct an new MCF when necessary.The comprehensive evaluation results demonstrate that our methods can well tackle the proposed DMCF problem.
