The Accelerator Driven Sub-critical(ADS)system is a strategic plan to solve the nuclear waste problem for nuclear power plants in China.High-energy particle accelerators and colliders contain long strings of supercond...The Accelerator Driven Sub-critical(ADS)system is a strategic plan to solve the nuclear waste problem for nuclear power plants in China.High-energy particle accelerators and colliders contain long strings of superconducting devices,superconducting radio frequency cavities,and magnets,which may require cooling by 2 K superfluid helium(HeliumⅡ).2 K superfluid helium cryogenic system has become a research hot spot in the field of superconducting accelerators.In this study,the ADS Injector-I 2 K cryogenic system is examined in detail.The cryogenic system scheme design,key equipment,and technology design,such as the 2 K Joule–Thomson(J–T)heat exchanger and cryomodules CM1+CM2 design,are examined,in addition to the commissioning and operation of the cryogenic system.The ADS Injector-I 2 K cryogenic system is the first 100 W superfluid helium system designed and built independently in China.The ADS proton beam reached 10 Me V at 10 m A in July 2016 and 10 Me V at 2 m A in continuous mode in January 2017 and has been operated reliably for over 15,000 h,proving that the design of ADS Injector-I 2 K cryogenic system,the key equipment,and technology research are reasonable,reliable,and meet the requirements.The research into key technologies provides valuable engineering experience that can be helpful for future projects such as CI-ADS(China Initiative Accelerator-Driven System),SHINE(Shanghai High Repetition Rate XFEL and Extreme Light Facility),PAPS(Platform of Advanced Photon Source Technology),and CEPC(Circular Electron-Positron Collider),thereby developing national expertise in the field of superfluid helium cryogenic systems.展开更多
A 16-pole superconducting multipole wiggler with a large gap of 68 mm was designed and fabricated to serve as a multipole wiggler for HEPS-TF.The wiggler consists of 16 pairs of NbTi superconducting coils with a perio...A 16-pole superconducting multipole wiggler with a large gap of 68 mm was designed and fabricated to serve as a multipole wiggler for HEPS-TF.The wiggler consists of 16 pairs of NbTi superconducting coils with a period length of 170 mm,and its maximum peak field is 2.6 Tesla.In magnet design,magnet poles were optimized.Furthermore,the Lorentz force on the coils and electromagnetic force between the upper and lower halves were computed and analyzed along with the stored energy and inductance at different currents.To enhance the critical current of the magnet coil,all the pole coils selected for the magnet exhibited excellent performance,and appropriate prestress derived from the coil force analysis was applied to the pole coils during magnet assembly.The entire magnet structure was immersed in 4.2-K liquid helium in the cryostat cooled solely by four two-stage cryocoolers,and the performance test of the superconducting wiggler was appropriately completed.Based on the measured results,the first and second field integrals on the axis of the superconducting wiggler were significantly improved at different field levels after the compensation of the corrector coils.Subsequently,the wiggler was successfully installed in the storage ring of BEPCII operation with beams.展开更多
The dispatching for monthly generation plan is to manage the congestion considering the security constrains of the power grid, where the monthly generation plan is the result of vary monthly power exchange, including ...The dispatching for monthly generation plan is to manage the congestion considering the security constrains of the power grid, where the monthly generation plan is the result of vary monthly power exchange, including long-term power contract, power exchange among provinces and generation constitution exchanges. The application of monthly security constrained dispatching is with significant meaning for the security and stability of power grid. This paper brings forward the purpose and contents of security dispatching and introduces the working procedure and mathematic models. At last, the practical example of the Anhui Province power grid is introduced to explain the models.展开更多
A 3W1 superconducting wiggler(SCW)with the pole gap of 68 mm was successfully tested and installed in a BEPC II storage ring in November,2019.The goal of zero liquid helium consumption was achieved,and the cryogenic s...A 3W1 superconducting wiggler(SCW)with the pole gap of 68 mm was successfully tested and installed in a BEPC II storage ring in November,2019.The goal of zero liquid helium consumption was achieved,and the cryogenic system exhibited a 12%residual cooling capacity(approximately 0.69 W@4.2 K).The 3W1-SCW was set to operate at 2.49 T and has been operating for more than seven months.Three instances of magnet quenching occurred during the normal operation.The evaporated helium gas can be recycled to the helium gas recycling system when the pressure in the helium tank is higher than the parameter value(the setpoint of the pressure value is 1.2 bara).The cryogenic system can be recovered within 4 h if sufficient liquid helium is available to inject into the cryostat.展开更多
Two 650 MHz single-cell superconducting radio-frequency(SRF)cavities used for the Circular Electron Positron Collider(CEPC)were studied to achieve a high accelerating gradient(E_(acc))and high intrinsic quality factor...Two 650 MHz single-cell superconducting radio-frequency(SRF)cavities used for the Circular Electron Positron Collider(CEPC)were studied to achieve a high accelerating gradient(E_(acc))and high intrinsic quality factor(Q_(0)).The 650 MHz single-cell cavities were subjected to a combination of buffered chemical polishing(BCP)and electropolishing(EP),and their E_(acc) exceeded40 MV/m.Such a high E_(acc) may result from the cold EP with more uniform removal.BCP is easy,cheap,and rough,whereas EP is complicated,expensive,and precise Therefore,the combination of BCP and EP investigated in this study is suitable for surface treatments of mass SRF cavities.Medium temperature(mid-T)furnace baking was also conducted,which demonstrated an ultrahigh Q_(0) of 8×10^(10) at 22 MV/m for both cavities,and an extremely low BCS resistance(R_(BCS))of~1.0 nΩwas achieved a2.0 K.展开更多
One of the most important devices for the High Energy Photon Source Test Facility project,the 2.6 T 32-pole 3W1 superconducting wiggler,was designed by the Institute of High Energy Physics(IHEP);its magnetic gap is 68...One of the most important devices for the High Energy Photon Source Test Facility project,the 2.6 T 32-pole 3W1 superconducting wiggler,was designed by the Institute of High Energy Physics(IHEP);its magnetic gap is 68 mm,and its storage energy is 286 kJ.It will be installed at the storage ring of the Beijing Electron Positron Collider Upgrade Project at the IHEP to replace the old permanent wiggler.The primary purpose of the cryostat is to create a safe and reliable system and realize long-term operation with zero liquid helium consumption.To maintain liquid helium temperature,four identical two-stage cryocoolers are placed symmetrically at the wiggler ends.The cryostat has only one 60 K thermal shield,which is used to reduce the heat load to the liquid helium vessel.The cryostat has several novel features,including a suspension system with little heat leakage that is self-centered during cooling of the cryostat,a special copper liner and high-efficiency condensers,three pairs of binary current leads,and three-level safety design.The cryogenic system has been cooled three times,and the residual cooling capacity is approximately 0.41 W at 4.2 K without current.展开更多
The 10-MeV Accelerator-Driven Subcritical(ADS)system Injector-I test stand at the Institute of High Energy Physics(IHEP)is a testing facility dedicated to demonstrating the feasibility of the spoke-based super-conduct...The 10-MeV Accelerator-Driven Subcritical(ADS)system Injector-I test stand at the Institute of High Energy Physics(IHEP)is a testing facility dedicated to demonstrating the feasibility of the spoke-based super-conducting(SC)linear accelerator(linac)for the ADS project in China.The injector adopted a four-vane copper structure radio frequency quadrupole(RFQ)with an output energy of 3.2 MeV and an SC section accommodating 14 β_(g)=0.12 single spoke cavities,14 SC solenoids,and 14 cold beam position monitors(BPMs).A 10-MeV pulsed beam with a beam current of 10 mA and a 2-mA continuous wave(CW)beam were successfully shooting through.The commissioning results confirmed the feasibility of using a 325-MHz spoke-type cavity for accelerating the proton beam in the low β and medium β sections.This paper describes the results achieved,the difficulties encountered,and the experiences obtained during commissioning.展开更多
The aim of this experiment was to analyze the leaf volatiles of crabapple (Malus sp.) individuals at different aphid’s resistance, to ascertain the particular ingredients which has lure or aversion effects on aphid, ...The aim of this experiment was to analyze the leaf volatiles of crabapple (Malus sp.) individuals at different aphid’s resistance, to ascertain the particular ingredients which has lure or aversion effects on aphid, and to provide reference for finding out a simple method to control effectively aphids. Volatiles of leaves from twenty-one different crabapple individuals were evaluated with the method of head space-solid phase micro-extraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS). Volatiles profiles of them were then compared. There are one hundred eighty-six kinds of volatiles were detected with varied contents found in different individuals. And all plants contain eight kinds of common components: 3-Hexen-1-ol, acetate, (Z)-, 4-Hexen-1-ol, (Z)-, n-Decanal, n-Tetradecane, .alpha.-Farnesene, Diethyl Phthalate, Oxime-, methoxy-phenyl- and Dibenzofuran-, wherein the relative content of higher have 3-Hexen-1-ol, acetate, (Z)- and 4-Hexen-1-ol, (Z)-. Specific volatile substances in high resistance plants contain 3-Hexenal, (Z)- and 2-Hexenal, (E)-. Leaf volatiles differ in twenty-one crabapple individuals. High resistance plants specific volatile substances contains 3-Hexenal, (Z)-, 2-Hexenal, (E)- and other small molecular volatile substances, and no-resistance plants all have .beta.-Farnesene.展开更多
Bioethanol, as a clean and renewable fuel, has gained increasing attention due to its major environmental benefits. Pervaporation(PV) is a promising and competitive technique for the recovery of ethanol from bioethano...Bioethanol, as a clean and renewable fuel, has gained increasing attention due to its major environmental benefits. Pervaporation(PV) is a promising and competitive technique for the recovery of ethanol from bioethanol fermentation systems due to the advantages of environmental friendliness, low energy consumption and easy coupling with fermentation process. The main challenge for the industrial application of ethanol perm-selective membranes is to break the trade-off effect between permeability and selectivity. As membrane is the heart of the pervaporation separation process, this article attempts to provide a comprehensive survey on the breakthroughs of ethanol perm-selective PV membranes from the perspectives of tailoring membrane materials to enhance PV separation performance. The research and development of polymeric and organic/inorganic hybrid membranes are reviewed to explore the fundamental structure-property-performance relationships. It is found that mixed matrix membranes with welldesigned membrane structures offer the hope of better control overphysi-/chemical microenvironment and cavity/pore size as well as size distribution, which may provide both high permeability and membrane selectivity to break the trade-off effect. The tentative perspective on the possible future directions of ethanol perm-selective membranes is also briefly discussed, which may provide some insights in developing a new generation of high-performance PV membranes for ethanol recovery.展开更多
The compact and reliable ultraviolet[UV]source has attracted remarkable attention for its potential use in optical measurement systems,high-density optical storage,and biomedical applications.We demonstrate ultraviole...The compact and reliable ultraviolet[UV]source has attracted remarkable attention for its potential use in optical measurement systems,high-density optical storage,and biomedical applications.We demonstrate ultraviolet generation by frequency doubling in a lithium-tantalate-on-insulator[LTOI]microdisk via modal phase matching.The 50-μm-diameter microdisk was milled by a focused ion beam[FIB]and followed by chemo-mechanical polishing[CMP]to smooth the disk surface and edge,and the Q-factor reaches 2.74×10~5in the visible band.On-chip UV coherent light with a wavelength of384.3 nm was achieved,which shows great promise for using LTOIs in integrated ultraviolet source platforms.展开更多
Purpose In recent years,with the further development of superconducting technology,superconducting devices have been applied in particle accelerators and synchrotron radiation light source devices.As a new type of hea...Purpose In recent years,with the further development of superconducting technology,superconducting devices have been applied in particle accelerators and synchrotron radiation light source devices.As a new type of heat transfer structure,helium cryogenic oscillating heat pipe can be used to balance local hot spots in superconductors and improve heat transfer performance.Methods In this paper,a two-dimensional two-turns helium cryogenic oscillating heat pipe model is established.The flow performance of helium cryogenic oscillating heat pipe was analyzed by CFD simulation.Results and conclusion The results show that the development of flow pattern in the helium cryogenic oscillating heat pipe first forms bubble flow under the heating of the evaporation section,and then gradually forms slug flow and annular flow.The process consists of initial stage,transition stage and running stage.In the running stage,the effective thermal conductivity of COHP oscillates around 15,000 W/(m·K).展开更多
Lithium niobate is a material that exhibits outstanding electro-optic,nonlinear optical,acousto-optic,piezoelectric,photorefractive,and pyroelectric properties.A thin-film lithium niobate photonic crystal can confine ...Lithium niobate is a material that exhibits outstanding electro-optic,nonlinear optical,acousto-optic,piezoelectric,photorefractive,and pyroelectric properties.A thin-film lithium niobate photonic crystal can confine light in the sub-wavelength scale,which is beneficial to the integration of the lithium niobate on-chip device.The commercialization of the lithium niobate on insulator gives birth to the emergence of high-quality lithium niobate photonic crystals.In order to provide guidance to the research of lithium niobate photonic crystal devices,recent progress about fabrication,characterization,and applications of the thin-film lithium niobate photonic crystal is reviewed.The performance parameters of the different devices are compared.展开更多
Purpose The accelerator-driven subcritical system(ADS)is the internationally recognized key technology of nuclear waste problem treatment,of which superconducting proton linac is an important part.With the support of ...Purpose The accelerator-driven subcritical system(ADS)is the internationally recognized key technology of nuclear waste problem treatment,of which superconducting proton linac is an important part.With the support of the strategic science and technology pilot project of the Chinese Academy of Sciences,the Institute of High Energy Physics of the Chinese Academy of Sciences took the lead in the research of 325 MHz superconducting proton linac,which is called ADS Injector I.The superconducting accelerator part of ADS Injector I mainly consists of 14 spoke-type superconducting cavities withβ0.12.At the same time,the research work of various cavities with differentβvalues and different frequencies is also carried out to lay the technical and technological foundation for ADS main accelerator.The only way to determine whether the superconducting cavity can reach the design target and whether it can be installed into the cryostat is the vertical test at cryogenic.As the only way to test the microwave performance of the superconducting cavity at low temperature,the vertical test can accurately test the acceleration gradient Eacc and the corresponding quality factor Q0 of the superconducting cavity.The design and construction of the superconducting cavity vertical test facility is based on the practical needs of the pilot project and the long-term development of the superconducting accelerator.Methods This paper mainly introduces the design and construction of the cryogenic vertical test system for the superconducting cavity of ADS Injector I,including the system scheme design,process design,heat load analysis,2 K superfluid helium obtaining method,system commissioning and operation,etc.Results and Conclusion The static heat leakage at 2 K of the 2 K superfluid helium vertical test system of ADS Injector I is 1.624W,which has reached the international advanced level.The 2 K superfluid helium vertical test system of ADS Injector I after constructed not only meets the test requirements of ADS pilot project,but also conducts 4 K and 2 K vertical tests for other different types of superconducting cavities and relevant cryogenic experiments.展开更多
A mixed organic(4-phenylbutylamine, 4-PBA) and inorganic(cesium, Cs) cations are used to deposit quasi-two-dimensional layered perovskites. This layered perovskites exhibit good film coverage as twodimensional per...A mixed organic(4-phenylbutylamine, 4-PBA) and inorganic(cesium, Cs) cations are used to deposit quasi-two-dimensional layered perovskites. This layered perovskites exhibit good film coverage as twodimensional perovskites and high emission performance close to three-dimensional organic–inorganic hybrid perovskites. Light-emitting diodes(LEDs) are fabricated by using solution process based on the quasi-two-dimensional layered perovskites. The perovskite LEDs exhibit a sky-blue emission with electroluminescence peak at 491 nm and a low turn on voltage at 2.9 V. The maximum external quantum efficiency reaches 0.015% at brightness of 186 cd/m^2.展开更多
Topological photonics have led to robust optical behavior of optical devices, which has alleviated the influence of manufacturing defects and perturbations on the device performance. Meanwhile, temporal coupled-mode t...Topological photonics have led to robust optical behavior of optical devices, which has alleviated the influence of manufacturing defects and perturbations on the device performance. Meanwhile, temporal coupled-mode theory(t-CMT) has been developed and applied widely. However, the t-CMT of cascaded coupled cavities(CCC) system and its corresponding high-order filter has yet to be established. Here, the t-CMT of CCC system is established based on the existing t-CMT. By combining the CCC with topological waveguides, a versatile design scheme of high-order nonreciprocal add-drop filter(HONAF) is proposed. The relationship between the coupling effect of cavities and transmission and the filtering performance of HONAF is analyzed quantitatively. Then, a method to improve the transmission efficiency and quality factor of the filter is given. The proposed HONAF is based on the combination of gyromagnetic photonic crystals and decagonal Penrose-type photonic quasicrystals. The transmission and filtering performance of the HONAF are numerically analyzed, which verifies the consistency between theoretical prediction and numerical simulation. The established t-CMT of CCC system can be widely used in coupled resonator optical waveguides and their related systems. The proposed HONAF with excellent performance can also be applied to wavelength division multiplexing/demultiplexing systems.展开更多
Laser communication using photons should consider not only the transmission environment’s effects,but also the performance of the single-photon detector used and the photon number distribution.Photon communication ba...Laser communication using photons should consider not only the transmission environment’s effects,but also the performance of the single-photon detector used and the photon number distribution.Photon communication based on the superconducting nanowire single-photon detector(SNSPD)is a new technology that addresses the current sensitivity limitations at the level of single photons in deep space communication.The communication’s bit error rate(BER)is limited by dark noise in the space environment and the photon number distribution with a traditional single-pixel SNSPD,which is unable to resolve the photon number distribution.In this work,an enhanced photon communication method was proposed based on the photon number resolving function of four-pixel array SNSPDs.A simulated picture transmission was carried out,and the error rate in this counting mode can be reduced by 2 orders of magnitude when compared with classical optical communication.However,in the communication mode using photon-enhanced counting,the four-pixel response amplitude for counting was found to restrain the communication rate,and this counting mode is extremely dependent on the incident light intensity through experiments,which limits the sensitivity and speed of the SNSPD array’s performance advantage.Therefore,a BER theoretical calculation model for laser communication was presented using the Bayesian estimation algorithm in order to analyze the selection of counting methods for information acquisition under different light intensities and to make better use of the SNSPD array’s high sensitivity and speed and thus to obtain a lower BER.The counting method and theoretical model proposed in this work refer to array SNSPDs in the deep space field.展开更多
The blockchain,with its key characteristics of decentralization,persistence,anonymity,and auditability,has become a solution to overcome the overdependence and lack of trust for a traditional public key infrastructure...The blockchain,with its key characteristics of decentralization,persistence,anonymity,and auditability,has become a solution to overcome the overdependence and lack of trust for a traditional public key infrastructure on third-party institutions.Because of these characteristics,the blockchain is suitable for solving certain open problems in the service-oriented social network,where the unreliability of submitted reviews of service vendors can cause serious security problems.To solve the unreliability problems of submitted reviews,this paper first proposes a blockchain-based identity authentication scheme and a new trusted service evaluation model by introducing the scheme into a service evaluation model.The new trusted service evaluation model consists of the blockchain-based identity authentication scheme,evaluation submission module,and evaluation publicity module.In the proposed evaluation model,only users who have successfully been authenticated can submit reviews to service vendors.The registration and authentication records of users’identity and the reviews for service vendors are all stored in the blockchain network.The security analysis shows that this model can ensure the credibility of users’reviews for service vendors,and other users can obtain credible reviews of service vendors via the review publicity module.The experimental results also show that the proposed model has a lower review submission delay than other models.展开更多
文摘The Accelerator Driven Sub-critical(ADS)system is a strategic plan to solve the nuclear waste problem for nuclear power plants in China.High-energy particle accelerators and colliders contain long strings of superconducting devices,superconducting radio frequency cavities,and magnets,which may require cooling by 2 K superfluid helium(HeliumⅡ).2 K superfluid helium cryogenic system has become a research hot spot in the field of superconducting accelerators.In this study,the ADS Injector-I 2 K cryogenic system is examined in detail.The cryogenic system scheme design,key equipment,and technology design,such as the 2 K Joule–Thomson(J–T)heat exchanger and cryomodules CM1+CM2 design,are examined,in addition to the commissioning and operation of the cryogenic system.The ADS Injector-I 2 K cryogenic system is the first 100 W superfluid helium system designed and built independently in China.The ADS proton beam reached 10 Me V at 10 m A in July 2016 and 10 Me V at 2 m A in continuous mode in January 2017 and has been operated reliably for over 15,000 h,proving that the design of ADS Injector-I 2 K cryogenic system,the key equipment,and technology research are reasonable,reliable,and meet the requirements.The research into key technologies provides valuable engineering experience that can be helpful for future projects such as CI-ADS(China Initiative Accelerator-Driven System),SHINE(Shanghai High Repetition Rate XFEL and Extreme Light Facility),PAPS(Platform of Advanced Photon Source Technology),and CEPC(Circular Electron-Positron Collider),thereby developing national expertise in the field of superfluid helium cryogenic systems.
文摘A 16-pole superconducting multipole wiggler with a large gap of 68 mm was designed and fabricated to serve as a multipole wiggler for HEPS-TF.The wiggler consists of 16 pairs of NbTi superconducting coils with a period length of 170 mm,and its maximum peak field is 2.6 Tesla.In magnet design,magnet poles were optimized.Furthermore,the Lorentz force on the coils and electromagnetic force between the upper and lower halves were computed and analyzed along with the stored energy and inductance at different currents.To enhance the critical current of the magnet coil,all the pole coils selected for the magnet exhibited excellent performance,and appropriate prestress derived from the coil force analysis was applied to the pole coils during magnet assembly.The entire magnet structure was immersed in 4.2-K liquid helium in the cryostat cooled solely by four two-stage cryocoolers,and the performance test of the superconducting wiggler was appropriately completed.Based on the measured results,the first and second field integrals on the axis of the superconducting wiggler were significantly improved at different field levels after the compensation of the corrector coils.Subsequently,the wiggler was successfully installed in the storage ring of BEPCII operation with beams.
文摘The dispatching for monthly generation plan is to manage the congestion considering the security constrains of the power grid, where the monthly generation plan is the result of vary monthly power exchange, including long-term power contract, power exchange among provinces and generation constitution exchanges. The application of monthly security constrained dispatching is with significant meaning for the security and stability of power grid. This paper brings forward the purpose and contents of security dispatching and introduces the working procedure and mathematic models. At last, the practical example of the Anhui Province power grid is introduced to explain the models.
基金supported in part by the High Energy Photon Source Test Facility and the Key Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences
文摘A 3W1 superconducting wiggler(SCW)with the pole gap of 68 mm was successfully tested and installed in a BEPC II storage ring in November,2019.The goal of zero liquid helium consumption was achieved,and the cryogenic system exhibited a 12%residual cooling capacity(approximately 0.69 W@4.2 K).The 3W1-SCW was set to operate at 2.49 T and has been operating for more than seven months.Three instances of magnet quenching occurred during the normal operation.The evaporated helium gas can be recycled to the helium gas recycling system when the pressure in the helium tank is higher than the parameter value(the setpoint of the pressure value is 1.2 bara).The cryogenic system can be recovered within 4 h if sufficient liquid helium is available to inject into the cryostat.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB25000000)the National Natural Science Foundation of China(No.12075270)the Platform of Advanced Photon Source Technology R&D。
文摘Two 650 MHz single-cell superconducting radio-frequency(SRF)cavities used for the Circular Electron Positron Collider(CEPC)were studied to achieve a high accelerating gradient(E_(acc))and high intrinsic quality factor(Q_(0)).The 650 MHz single-cell cavities were subjected to a combination of buffered chemical polishing(BCP)and electropolishing(EP),and their E_(acc) exceeded40 MV/m.Such a high E_(acc) may result from the cold EP with more uniform removal.BCP is easy,cheap,and rough,whereas EP is complicated,expensive,and precise Therefore,the combination of BCP and EP investigated in this study is suitable for surface treatments of mass SRF cavities.Medium temperature(mid-T)furnace baking was also conducted,which demonstrated an ultrahigh Q_(0) of 8×10^(10) at 22 MV/m for both cavities,and an extremely low BCS resistance(R_(BCS))of~1.0 nΩwas achieved a2.0 K.
基金supported by the High Energy Photon Source Test Facility(HEPS-TF)project。
文摘One of the most important devices for the High Energy Photon Source Test Facility project,the 2.6 T 32-pole 3W1 superconducting wiggler,was designed by the Institute of High Energy Physics(IHEP);its magnetic gap is 68 mm,and its storage energy is 286 kJ.It will be installed at the storage ring of the Beijing Electron Positron Collider Upgrade Project at the IHEP to replace the old permanent wiggler.The primary purpose of the cryostat is to create a safe and reliable system and realize long-term operation with zero liquid helium consumption.To maintain liquid helium temperature,four identical two-stage cryocoolers are placed symmetrically at the wiggler ends.The cryostat has only one 60 K thermal shield,which is used to reduce the heat load to the liquid helium vessel.The cryostat has several novel features,including a suspension system with little heat leakage that is self-centered during cooling of the cryostat,a special copper liner and high-efficiency condensers,three pairs of binary current leads,and three-level safety design.The cryogenic system has been cooled three times,and the residual cooling capacity is approximately 0.41 W at 4.2 K without current.
基金This work was supported by Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA03030201)the Key Laboratory of Particle Acceleration Physics and Technology Autonomous Foundation of CAS China(No.JSQ2017ZZ01).
文摘The 10-MeV Accelerator-Driven Subcritical(ADS)system Injector-I test stand at the Institute of High Energy Physics(IHEP)is a testing facility dedicated to demonstrating the feasibility of the spoke-based super-conducting(SC)linear accelerator(linac)for the ADS project in China.The injector adopted a four-vane copper structure radio frequency quadrupole(RFQ)with an output energy of 3.2 MeV and an SC section accommodating 14 β_(g)=0.12 single spoke cavities,14 SC solenoids,and 14 cold beam position monitors(BPMs).A 10-MeV pulsed beam with a beam current of 10 mA and a 2-mA continuous wave(CW)beam were successfully shooting through.The commissioning results confirmed the feasibility of using a 325-MHz spoke-type cavity for accelerating the proton beam in the low β and medium β sections.This paper describes the results achieved,the difficulties encountered,and the experiences obtained during commissioning.
文摘The aim of this experiment was to analyze the leaf volatiles of crabapple (Malus sp.) individuals at different aphid’s resistance, to ascertain the particular ingredients which has lure or aversion effects on aphid, and to provide reference for finding out a simple method to control effectively aphids. Volatiles of leaves from twenty-one different crabapple individuals were evaluated with the method of head space-solid phase micro-extraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS). Volatiles profiles of them were then compared. There are one hundred eighty-six kinds of volatiles were detected with varied contents found in different individuals. And all plants contain eight kinds of common components: 3-Hexen-1-ol, acetate, (Z)-, 4-Hexen-1-ol, (Z)-, n-Decanal, n-Tetradecane, .alpha.-Farnesene, Diethyl Phthalate, Oxime-, methoxy-phenyl- and Dibenzofuran-, wherein the relative content of higher have 3-Hexen-1-ol, acetate, (Z)- and 4-Hexen-1-ol, (Z)-. Specific volatile substances in high resistance plants contain 3-Hexenal, (Z)- and 2-Hexenal, (E)-. Leaf volatiles differ in twenty-one crabapple individuals. High resistance plants specific volatile substances contains 3-Hexenal, (Z)-, 2-Hexenal, (E)- and other small molecular volatile substances, and no-resistance plants all have .beta.-Farnesene.
基金financial support of Beijing Natural Science Foundation Commission-Beijing Municipal Education Commission Joint Foundation,China(KZ201910011012)National Natural Science Foundation of China(21736001,21776153,21206001)+1 种基金Open Research Fund Program of Key Laboratory of Cleaner Production and Integrated Resource Utilization of China National Light Industry(CP-2020-YB7)College Students Scientific Research and Undertaking Starting Action Project,China。
文摘Bioethanol, as a clean and renewable fuel, has gained increasing attention due to its major environmental benefits. Pervaporation(PV) is a promising and competitive technique for the recovery of ethanol from bioethanol fermentation systems due to the advantages of environmental friendliness, low energy consumption and easy coupling with fermentation process. The main challenge for the industrial application of ethanol perm-selective membranes is to break the trade-off effect between permeability and selectivity. As membrane is the heart of the pervaporation separation process, this article attempts to provide a comprehensive survey on the breakthroughs of ethanol perm-selective PV membranes from the perspectives of tailoring membrane materials to enhance PV separation performance. The research and development of polymeric and organic/inorganic hybrid membranes are reviewed to explore the fundamental structure-property-performance relationships. It is found that mixed matrix membranes with welldesigned membrane structures offer the hope of better control overphysi-/chemical microenvironment and cavity/pore size as well as size distribution, which may provide both high permeability and membrane selectivity to break the trade-off effect. The tentative perspective on the possible future directions of ethanol perm-selective membranes is also briefly discussed, which may provide some insights in developing a new generation of high-performance PV membranes for ethanol recovery.
基金supported by the National Key R&D Program of China(No.2019YFB2203501)the National Natural Science Foundation of China(Nos.12134009 and 91950107)+1 种基金Shanghai Municipal Science and Technology Major Project(2019SHZDZX01-ZX06)SJTU(No.21X010200828)。
文摘The compact and reliable ultraviolet[UV]source has attracted remarkable attention for its potential use in optical measurement systems,high-density optical storage,and biomedical applications.We demonstrate ultraviolet generation by frequency doubling in a lithium-tantalate-on-insulator[LTOI]microdisk via modal phase matching.The 50-μm-diameter microdisk was milled by a focused ion beam[FIB]and followed by chemo-mechanical polishing[CMP]to smooth the disk surface and edge,and the Q-factor reaches 2.74×10~5in the visible band.On-chip UV coherent light with a wavelength of384.3 nm was achieved,which shows great promise for using LTOIs in integrated ultraviolet source platforms.
基金This work was supported by National Natural Science Foundation of China(No.11905233).
文摘Purpose In recent years,with the further development of superconducting technology,superconducting devices have been applied in particle accelerators and synchrotron radiation light source devices.As a new type of heat transfer structure,helium cryogenic oscillating heat pipe can be used to balance local hot spots in superconductors and improve heat transfer performance.Methods In this paper,a two-dimensional two-turns helium cryogenic oscillating heat pipe model is established.The flow performance of helium cryogenic oscillating heat pipe was analyzed by CFD simulation.Results and conclusion The results show that the development of flow pattern in the helium cryogenic oscillating heat pipe first forms bubble flow under the heating of the evaporation section,and then gradually forms slug flow and annular flow.The process consists of initial stage,transition stage and running stage.In the running stage,the effective thermal conductivity of COHP oscillates around 15,000 W/(m·K).
基金supported by the National Natural Science Foundation of China(Nos.91950107,and 12134009)the National Key R&D Program of China(No.2019YFB2203501)+1 种基金the Shanghai Municipal Science and Technology Major Project(No.2019SHZDZX01-ZX06)the SJTU(No.21X010200828)。
文摘Lithium niobate is a material that exhibits outstanding electro-optic,nonlinear optical,acousto-optic,piezoelectric,photorefractive,and pyroelectric properties.A thin-film lithium niobate photonic crystal can confine light in the sub-wavelength scale,which is beneficial to the integration of the lithium niobate on-chip device.The commercialization of the lithium niobate on insulator gives birth to the emergence of high-quality lithium niobate photonic crystals.In order to provide guidance to the research of lithium niobate photonic crystal devices,recent progress about fabrication,characterization,and applications of the thin-film lithium niobate photonic crystal is reviewed.The performance parameters of the different devices are compared.
文摘Purpose The accelerator-driven subcritical system(ADS)is the internationally recognized key technology of nuclear waste problem treatment,of which superconducting proton linac is an important part.With the support of the strategic science and technology pilot project of the Chinese Academy of Sciences,the Institute of High Energy Physics of the Chinese Academy of Sciences took the lead in the research of 325 MHz superconducting proton linac,which is called ADS Injector I.The superconducting accelerator part of ADS Injector I mainly consists of 14 spoke-type superconducting cavities withβ0.12.At the same time,the research work of various cavities with differentβvalues and different frequencies is also carried out to lay the technical and technological foundation for ADS main accelerator.The only way to determine whether the superconducting cavity can reach the design target and whether it can be installed into the cryostat is the vertical test at cryogenic.As the only way to test the microwave performance of the superconducting cavity at low temperature,the vertical test can accurately test the acceleration gradient Eacc and the corresponding quality factor Q0 of the superconducting cavity.The design and construction of the superconducting cavity vertical test facility is based on the practical needs of the pilot project and the long-term development of the superconducting accelerator.Methods This paper mainly introduces the design and construction of the cryogenic vertical test system for the superconducting cavity of ADS Injector I,including the system scheme design,process design,heat load analysis,2 K superfluid helium obtaining method,system commissioning and operation,etc.Results and Conclusion The static heat leakage at 2 K of the 2 K superfluid helium vertical test system of ADS Injector I is 1.624W,which has reached the international advanced level.The 2 K superfluid helium vertical test system of ADS Injector I after constructed not only meets the test requirements of ADS pilot project,but also conducts 4 K and 2 K vertical tests for other different types of superconducting cavities and relevant cryogenic experiments.
基金supported by the Key R&D program of Guangzhou(202007020004)the Natural Science Foundation of Guangdong Province(2018A0303130146)+1 种基金the Project of Science and Technology of Guangzhou(201904010171)the Open Fund of State Key Laboratory of Luminescent Materials and Devices(2023-skllmd-05).
基金financially supported by the National Basic Research Program of China-Fundamental Studies of Perovskite Solar Cells (No. 2015CB932200)the Natural Science Foundation of [6_TD$IF]Jiangsu Province, China (Nos. BK20131413, BK20140952, BM2012010)+3 种基金the National Natural Science Foundation of China (Nos. 11474164, 61405091)the National 973 Program of China (No. 2015CB654901)the Jiangsu Specially-Appointed Professor programthe Synergetic Innovation Center for Organic Electronics and Information Displays
文摘A mixed organic(4-phenylbutylamine, 4-PBA) and inorganic(cesium, Cs) cations are used to deposit quasi-two-dimensional layered perovskites. This layered perovskites exhibit good film coverage as twodimensional perovskites and high emission performance close to three-dimensional organic–inorganic hybrid perovskites. Light-emitting diodes(LEDs) are fabricated by using solution process based on the quasi-two-dimensional layered perovskites. The perovskite LEDs exhibit a sky-blue emission with electroluminescence peak at 491 nm and a low turn on voltage at 2.9 V. The maximum external quantum efficiency reaches 0.015% at brightness of 186 cd/m^2.
基金supported by the National Key R&D Program of China (2017YFA0304002)the National Natural Science Foundation of China (12033002, 61571217, 61521001, 61801206 and 11227904)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the Jiangsu Provincial Key Laboratory of Advanced Manipulating Technique of Electromagnetic Waves
基金supported by the National Natural Science Foundation of China(Grant Nos.61405058,and 62075059)the Natural Science Foundation of Hunan Province(Grant Nos.2017JJ2048,and 2020JJ4161)the Fundamental Research Funds for the Central Universities(Grant No.531118040112)。
文摘Topological photonics have led to robust optical behavior of optical devices, which has alleviated the influence of manufacturing defects and perturbations on the device performance. Meanwhile, temporal coupled-mode theory(t-CMT) has been developed and applied widely. However, the t-CMT of cascaded coupled cavities(CCC) system and its corresponding high-order filter has yet to be established. Here, the t-CMT of CCC system is established based on the existing t-CMT. By combining the CCC with topological waveguides, a versatile design scheme of high-order nonreciprocal add-drop filter(HONAF) is proposed. The relationship between the coupling effect of cavities and transmission and the filtering performance of HONAF is analyzed quantitatively. Then, a method to improve the transmission efficiency and quality factor of the filter is given. The proposed HONAF is based on the combination of gyromagnetic photonic crystals and decagonal Penrose-type photonic quasicrystals. The transmission and filtering performance of the HONAF are numerically analyzed, which verifies the consistency between theoretical prediction and numerical simulation. The established t-CMT of CCC system can be widely used in coupled resonator optical waveguides and their related systems. The proposed HONAF with excellent performance can also be applied to wavelength division multiplexing/demultiplexing systems.
基金National Key Research and Development Program of China(2017YFA0304002)National Natural Science Foundation of China(61571217,61521001,61801206,11227904)+1 种基金Priority Academic Program Development of Jiangsu Higher Education InstitutionsNanjing University。
文摘Laser communication using photons should consider not only the transmission environment’s effects,but also the performance of the single-photon detector used and the photon number distribution.Photon communication based on the superconducting nanowire single-photon detector(SNSPD)is a new technology that addresses the current sensitivity limitations at the level of single photons in deep space communication.The communication’s bit error rate(BER)is limited by dark noise in the space environment and the photon number distribution with a traditional single-pixel SNSPD,which is unable to resolve the photon number distribution.In this work,an enhanced photon communication method was proposed based on the photon number resolving function of four-pixel array SNSPDs.A simulated picture transmission was carried out,and the error rate in this counting mode can be reduced by 2 orders of magnitude when compared with classical optical communication.However,in the communication mode using photon-enhanced counting,the four-pixel response amplitude for counting was found to restrain the communication rate,and this counting mode is extremely dependent on the incident light intensity through experiments,which limits the sensitivity and speed of the SNSPD array’s performance advantage.Therefore,a BER theoretical calculation model for laser communication was presented using the Bayesian estimation algorithm in order to analyze the selection of counting methods for information acquisition under different light intensities and to make better use of the SNSPD array’s high sensitivity and speed and thus to obtain a lower BER.The counting method and theoretical model proposed in this work refer to array SNSPDs in the deep space field.
文摘The blockchain,with its key characteristics of decentralization,persistence,anonymity,and auditability,has become a solution to overcome the overdependence and lack of trust for a traditional public key infrastructure on third-party institutions.Because of these characteristics,the blockchain is suitable for solving certain open problems in the service-oriented social network,where the unreliability of submitted reviews of service vendors can cause serious security problems.To solve the unreliability problems of submitted reviews,this paper first proposes a blockchain-based identity authentication scheme and a new trusted service evaluation model by introducing the scheme into a service evaluation model.The new trusted service evaluation model consists of the blockchain-based identity authentication scheme,evaluation submission module,and evaluation publicity module.In the proposed evaluation model,only users who have successfully been authenticated can submit reviews to service vendors.The registration and authentication records of users’identity and the reviews for service vendors are all stored in the blockchain network.The security analysis shows that this model can ensure the credibility of users’reviews for service vendors,and other users can obtain credible reviews of service vendors via the review publicity module.The experimental results also show that the proposed model has a lower review submission delay than other models.