The results of a commissioning experiment on the SILEX-Ⅱlaser facility(formerly known as CAEP-PW)are reported.SILEX-Ⅱis a complete optical parametric chirped-pulse amplification laser facility.The peak power reached...The results of a commissioning experiment on the SILEX-Ⅱlaser facility(formerly known as CAEP-PW)are reported.SILEX-Ⅱis a complete optical parametric chirped-pulse amplification laser facility.The peak power reached about 1 PWin a 30 fs pulse duration during the experiment.The laser contrast was better than 1010 at 20 ps ahead of the main pulse.In the basic laser foil target interaction,a set of experimental data were collected,including spatially resolved x-ray emission,the image of the coherent transition radiation,the harmonic spectra in the direction of reflection,the energy spectra and beam profile of accelerated protons,hot-electron spectra,and transmitted laser energy fraction and spatial distribution.The experimental results show that the laser intensity reached 531020 W/cm^(2) within a 5.8μm focus(FWHM).Significant laser transmission did not occur when the thickness of theCHfoil was equal to or greater than 50 nm.The maximum energy of the accelerated protons in the target normal direction was roughly unchanged when the target thickness varied between 50 nm and 15μm.The maximum proton energy via the target normal sheath field acceleration mechanism was about 21 MeV.We expect the on-target laser intensity to reach 10^(22) W/cm^(2) in the near future,after optimization of the laser focus and upgrade of the laser power to 3 PW.展开更多
Molten salt pebble bed reactor is one of the sixth-generation Ⅳ reactor types. To investigate the mechanical behavior of the fuel pebbles in the core, a visualization experiment facility of pebble bed(VEFPB) is desig...Molten salt pebble bed reactor is one of the sixth-generation Ⅳ reactor types. To investigate the mechanical behavior of the fuel pebbles in the core, a visualization experiment facility of pebble bed(VEFPB) is designed. To obtain a uniform flow field of the core and analyze the influence of the flow field on the structure of the pebble bed, computational fluid dynamics software Fluent is used to simulate the flow field distribution of the core of VEFPB. The simulation results show that the disturbance at the bottom of the pebble bed is proportional to the flow velocity of the inlet pipe, and the flow velocity close to the inlet side is more significant than that in other parts; the design of the cylinder bottom plate with holes of different sizes can effectively reduce the flow velocity and the disturbance at the bottom of the pebble bed. In addition,according to the velocity contours of the core of VEFPB, it is observed that the flow field distribution of the core is considerably uniform except at the bottom of the pebble bed. This ensures the stability of the pebble bed and verifies the rationality of the design of VEFPB. This study provides the technical support and reference for the flow field analysis of the core of molten salt pebble bed reactor.展开更多
Shock-timing experiments are indispensable to inertial confinement fusion mainly because the timing of multiple shock waves is crucial to understanding the processes of laser irradiation of targets. Investigations int...Shock-timing experiments are indispensable to inertial confinement fusion mainly because the timing of multiple shock waves is crucial to understanding the processes of laser irradiation of targets. Investigations into shock waves driven by a two-step radiation pulse in polystyrene（CH） capsule targets are experimentally conducted at the Shen Guang Ⅱ laser facility. Differing from the traditional shock-timing implementation in which one shock wave could catch up with another one in solid CH, in this experiment, the second shock front in a rarefaction CH layer is observed through velocity interferometry. This second shock could also be made to converge with rarefaction waves within only a few micrometers of the CH capsule by designing the two-shock coalescence time. A shock-timing diagnostic technique to tune the multi-shock convergence in the CH capsule can thereby be achieved.The experimental results in the CH layer are quasi-quantitatively interpreted using streamlines simulated with the Multi-1 D program. The experimental results are expected to offer important information for target structure and laser pulse design, both of which are important for realizing inertial confinement fusion.展开更多
Background: Hand hygiene (HH) compliance of healthcare workers (HCWs) remains suboptimal despite standard multimodal promotion, and evidence for the effectiveness of novel interventions is urgently needed. Aim: Improv...Background: Hand hygiene (HH) compliance of healthcare workers (HCWs) remains suboptimal despite standard multimodal promotion, and evidence for the effectiveness of novel interventions is urgently needed. Aim: Improve HCWs’ HH compliance toward minimizing healthcare associated infection (HCAI) risk in Wadi Al Dawasir Hospital (WDH), central Kingdom of Saudi Arabia (KSA). Methodology: A quasi experimental approach was adopted to achieve study aim. The HCWs’ behavior of HH during the duration between 2015 and 2016 was evaluated before and after a HH educational plan based on the World Health Organization (WHO) “Multimodal HH Improvement Strategy” (MMHHIS). The HCWs’ compliance in response to HH indications represented by the WHO’s “My 5-Moments for HH” and the type of HH action taken, whether hand washing (HW) or hand-rubbing (HR) were analyzed. Results: The number of opportunities observed of HH performance accounted 230 in 2015 (pre-education), and 237 in 2016 (post-education). The HCWs’ HH compliance rate in the pre-education phase did not vary by the 5-moment indications [χ2(df 4) = 0.01, p = 0.98]. Conversely, the compliance rate after HH education was higher than non-compliance across all 5-moment indication opportunities (ranged between 57.0% up to 88.9%) [χ2(df 1) = 18.25, p rd and 4th 5-moment indications (“after body fluid exposure” and “after patient contact,” respectively) were met with a significant HH improvement [χ2(df 1) = 8.98, p = 0.003;and χ2(df 1) = 16.3, p −4.38, p = 0.001). Only physicians and nurses showed a significant “within-profession” improvement in HH compliance after education, compared to that before education (Z = −3.51, p = 0.001, Z = −2.48, p = 0.013, respectively). Conclusions: Applying a HH education plan based on standardized multimodal HH strategy proved effective in improving the HH compliance of the hospital’s staff. An ongoing observation policy within a HH-resourceful environment assures a sustainable and sound HCWs’ HH behavior.展开更多
This paper presents the main results obtained during a decade of scientific activities in the Meuse/Haute-Marne Underground Research Laboratory （URL） located on the eastern boundary of the Paris Basin, in the Callov...This paper presents the main results obtained during a decade of scientific activities in the Meuse/Haute-Marne Underground Research Laboratory （URL） located on the eastern boundary of the Paris Basin, in the Callovo-Oxfordian clay rock formation. The URL was built in the framework of ANDRA＇s research program into the feasibility of a reversible deep geological disposal of high-level and intermediate-level long-lived radioactive （HL, ILLL） waste. Its underground drifts have been used to study a 160-million-year old clay layer. The 2006 Planning Act adopted this disposal concept as the reference solution for the long-term management of HL and ILLL radioactive waste. Today, research is continuing into the design and sitting of the disposal facility which could be commissioned by 2025 if its license is granted in 2016. Through these programs, the laboratory will help ANDRA develop a concrete approach with a view to proposing suitable architectures and management methods for a deep disposal facility, to allow by 2016 the decision for the start of the construction of the shafts and drifts of the new disposal facility.展开更多
Water hammer phenomenon involves the transformation of kinetic energy in pressure energy, this transformation occurs as the fluid conditions change inside the pipe in quite a short time. Industry requires to affront f...Water hammer phenomenon involves the transformation of kinetic energy in pressure energy, this transformation occurs as the fluid conditions change inside the pipe in quite a short time. Industry requires to affront frequent flow interruptions in pipe systems due to the closing of valves or stopping of pumping equipment. This phenomenon can initiate serious damages like destruction of the pipe system involving leakage of the working fluid to the environment. If the system operates in a fragile environment, as in cold regions, concern about the consequences of leakage increases due to the variation of physical properties of fluid as well as the pipe material as a function of the temperature. Water hammer effects can be controlled focusing efforts on reducing the pressure increment that takes place once the phenomenon is presented. Some methods try to reduce the time of closure or the rate of change before the closure using special valves, others install additional elements to absorb the pressure surge and dissipate energy, others install relief valves to release the pressure, and others try to split the problem is smaller sections by installing check valves with dashpot or non-return valves. Splitting the pipeline into shorter sections is often used to help preventing the pipeline length of water falling back after a pump stops. In this paper the numerical results of maximum and minimum pressure values at both ends of a closed section are compared to experimental data. The numerical results follow the experimental trends.展开更多
Following the previous relevant works [1]-[3], a scaling analysis is performed to derive a set of scaling criteria which were thought to be suitable for reproducing the major thermal-hydraulic phenomena in a scaled-do...Following the previous relevant works [1]-[3], a scaling analysis is performed to derive a set of scaling criteria which were thought to be suitable for reproducing the major thermal-hydraulic phenomena in a scaled-down CANDU moderator tank similar to that in a prototype power plant during a full power steady state condition. The objective of building a scaled-down moderator tank is to generate the experimental data necessary to validate the computer codes which are used to analyze the accident analysis of CANDU-6 plants. The major variables of interests in this paper are moderator flow velocity and temperature of the moderator which is D2O inside the moderator tank during a steady state and transient conditions. The reason is that the local subcooling of the moderator is found to be a critical parameter determining whether the stable film boiling can sustain on the outer surface of the calandria tube if the contact of overheated pressure tube and cold calandria tube should occur due to pressure tube ballooning during LBLOCA with ECC injection failure [4]. The key phenomena involved include the inlet jet development and impingement, buoyancy force driven by the moderator temperature gradient caused by non-uniform direct heating of the moderator, and the pressure drop due to viscous friction of the flow across the calandria tube array. In this paper, the previous researches are reviewed, some concerns or potential problems associated with them implied by comparing CFD analyses results between the CANDU-6 moderator tank and 1/4 scaled-down test facility are described, and as a way to examine the assumption of the scaling analysis is true an order-of-magnitude analyses are performed. Based on the results of these analyses the assumption of neglecting ?and ?terms cannot be justified for the power of 0.5 MW and 1.566 MW for the 1/4 scaled-down facility. Further investigation is thought to be necessary to confirm this result, i.e. if the scaling of the previous work1 is justifiable by some other independent analyses.展开更多
The high voltage Padova test facility(HVPTF)is an experiment set in Padova,Italy,operating in the framework of the Neutral Beam Test Facility project of the International Thermonuclear Experimental Reactor(ITER).One o...The high voltage Padova test facility(HVPTF)is an experiment set in Padova,Italy,operating in the framework of the Neutral Beam Test Facility project of the International Thermonuclear Experimental Reactor(ITER).One of the purposes of HVPTF is to study the phenomenology of discharge events occurring between electrodes at high voltage differences over long vacuum gaps,which is crucial in the development of the neutral beam injector foreseen for ITER.The facility hosts a cylindrical vacuum vessel with stable pressure control,where two electrodes of different possible geometries can be mounted.Two independent power supplies allow for total voltage differences up to 800 kVDC with adjustable gap widths up to 250 mm.Among the diagnostics,a gas electron multiplier(GEM)detector is installed for acquisition of x-ray emission on a radial line of sight of the vessel.This paper presents a study of the experimental sessions featuring stainless-steel needle-plane electrodes.The analysis is based on the GEM data,in relation to the information on current and voltage of the two power supplies.The events are characterised in terms of both temporal and spatial evolution,providing sequential emission profiles with spatial resolution of tens of millimetres on timescales of the order of hundreds of nanoseconds.展开更多
The optimization method of a mathematical model and connected-pipe experimental technique for a test in altitude test facility (ATF) of a liquid fuel ramjet engine was researched.The optimization of the simple mathema...The optimization method of a mathematical model and connected-pipe experimental technique for a test in altitude test facility (ATF) of a liquid fuel ramjet engine was researched.The optimization of the simple mathematical model was divided into two steps.Firstly,using the test engine's geometry configuration size data,a preliminary adjustment was done.Secondly,using experimental test data,the components' experiential coefficients were modified appropriately.Emphasis was laid on the simulation technique of flight condition and parameters measurement method.The experimental technique was applied to a ramjet ATF test successfully.The comparison results show that the optimized-model has higher precision and the nozzle gross thrust difference drops from 12% to about 4%.展开更多
基金This work was supported by the National Key Program for S&T Research and Development(Grant No.2018YFA0404804)the Science Challenge Project(Grant No.TZ2016005)the National Natural Science Foundation of China(Grant No.11805181).
文摘The results of a commissioning experiment on the SILEX-Ⅱlaser facility(formerly known as CAEP-PW)are reported.SILEX-Ⅱis a complete optical parametric chirped-pulse amplification laser facility.The peak power reached about 1 PWin a 30 fs pulse duration during the experiment.The laser contrast was better than 1010 at 20 ps ahead of the main pulse.In the basic laser foil target interaction,a set of experimental data were collected,including spatially resolved x-ray emission,the image of the coherent transition radiation,the harmonic spectra in the direction of reflection,the energy spectra and beam profile of accelerated protons,hot-electron spectra,and transmitted laser energy fraction and spatial distribution.The experimental results show that the laser intensity reached 531020 W/cm^(2) within a 5.8μm focus(FWHM).Significant laser transmission did not occur when the thickness of theCHfoil was equal to or greater than 50 nm.The maximum energy of the accelerated protons in the target normal direction was roughly unchanged when the target thickness varied between 50 nm and 15μm.The maximum proton energy via the target normal sheath field acceleration mechanism was about 21 MeV.We expect the on-target laser intensity to reach 10^(22) W/cm^(2) in the near future,after optimization of the laser focus and upgrade of the laser power to 3 PW.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XD02010000)the Frontier Science Key Program of the Chinese Academy of Sciences(No.QYZDY-SSW-JSC016)
文摘Molten salt pebble bed reactor is one of the sixth-generation Ⅳ reactor types. To investigate the mechanical behavior of the fuel pebbles in the core, a visualization experiment facility of pebble bed(VEFPB) is designed. To obtain a uniform flow field of the core and analyze the influence of the flow field on the structure of the pebble bed, computational fluid dynamics software Fluent is used to simulate the flow field distribution of the core of VEFPB. The simulation results show that the disturbance at the bottom of the pebble bed is proportional to the flow velocity of the inlet pipe, and the flow velocity close to the inlet side is more significant than that in other parts; the design of the cylinder bottom plate with holes of different sizes can effectively reduce the flow velocity and the disturbance at the bottom of the pebble bed. In addition,according to the velocity contours of the core of VEFPB, it is observed that the flow field distribution of the core is considerably uniform except at the bottom of the pebble bed. This ensures the stability of the pebble bed and verifies the rationality of the design of VEFPB. This study provides the technical support and reference for the flow field analysis of the core of molten salt pebble bed reactor.
基金Supported by the Science and Technology on Plasma Physics Laboratory under Grant No 9140C6801021001
文摘Shock-timing experiments are indispensable to inertial confinement fusion mainly because the timing of multiple shock waves is crucial to understanding the processes of laser irradiation of targets. Investigations into shock waves driven by a two-step radiation pulse in polystyrene（CH） capsule targets are experimentally conducted at the Shen Guang Ⅱ laser facility. Differing from the traditional shock-timing implementation in which one shock wave could catch up with another one in solid CH, in this experiment, the second shock front in a rarefaction CH layer is observed through velocity interferometry. This second shock could also be made to converge with rarefaction waves within only a few micrometers of the CH capsule by designing the two-shock coalescence time. A shock-timing diagnostic technique to tune the multi-shock convergence in the CH capsule can thereby be achieved.The experimental results in the CH layer are quasi-quantitatively interpreted using streamlines simulated with the Multi-1 D program. The experimental results are expected to offer important information for target structure and laser pulse design, both of which are important for realizing inertial confinement fusion.
文摘Background: Hand hygiene (HH) compliance of healthcare workers (HCWs) remains suboptimal despite standard multimodal promotion, and evidence for the effectiveness of novel interventions is urgently needed. Aim: Improve HCWs’ HH compliance toward minimizing healthcare associated infection (HCAI) risk in Wadi Al Dawasir Hospital (WDH), central Kingdom of Saudi Arabia (KSA). Methodology: A quasi experimental approach was adopted to achieve study aim. The HCWs’ behavior of HH during the duration between 2015 and 2016 was evaluated before and after a HH educational plan based on the World Health Organization (WHO) “Multimodal HH Improvement Strategy” (MMHHIS). The HCWs’ compliance in response to HH indications represented by the WHO’s “My 5-Moments for HH” and the type of HH action taken, whether hand washing (HW) or hand-rubbing (HR) were analyzed. Results: The number of opportunities observed of HH performance accounted 230 in 2015 (pre-education), and 237 in 2016 (post-education). The HCWs’ HH compliance rate in the pre-education phase did not vary by the 5-moment indications [χ2(df 4) = 0.01, p = 0.98]. Conversely, the compliance rate after HH education was higher than non-compliance across all 5-moment indication opportunities (ranged between 57.0% up to 88.9%) [χ2(df 1) = 18.25, p rd and 4th 5-moment indications (“after body fluid exposure” and “after patient contact,” respectively) were met with a significant HH improvement [χ2(df 1) = 8.98, p = 0.003;and χ2(df 1) = 16.3, p −4.38, p = 0.001). Only physicians and nurses showed a significant “within-profession” improvement in HH compliance after education, compared to that before education (Z = −3.51, p = 0.001, Z = −2.48, p = 0.013, respectively). Conclusions: Applying a HH education plan based on standardized multimodal HH strategy proved effective in improving the HH compliance of the hospital’s staff. An ongoing observation policy within a HH-resourceful environment assures a sustainable and sound HCWs’ HH behavior.
文摘This paper presents the main results obtained during a decade of scientific activities in the Meuse/Haute-Marne Underground Research Laboratory （URL） located on the eastern boundary of the Paris Basin, in the Callovo-Oxfordian clay rock formation. The URL was built in the framework of ANDRA＇s research program into the feasibility of a reversible deep geological disposal of high-level and intermediate-level long-lived radioactive （HL, ILLL） waste. Its underground drifts have been used to study a 160-million-year old clay layer. The 2006 Planning Act adopted this disposal concept as the reference solution for the long-term management of HL and ILLL radioactive waste. Today, research is continuing into the design and sitting of the disposal facility which could be commissioned by 2025 if its license is granted in 2016. Through these programs, the laboratory will help ANDRA develop a concrete approach with a view to proposing suitable architectures and management methods for a deep disposal facility, to allow by 2016 the decision for the start of the construction of the shafts and drifts of the new disposal facility.
文摘Water hammer phenomenon involves the transformation of kinetic energy in pressure energy, this transformation occurs as the fluid conditions change inside the pipe in quite a short time. Industry requires to affront frequent flow interruptions in pipe systems due to the closing of valves or stopping of pumping equipment. This phenomenon can initiate serious damages like destruction of the pipe system involving leakage of the working fluid to the environment. If the system operates in a fragile environment, as in cold regions, concern about the consequences of leakage increases due to the variation of physical properties of fluid as well as the pipe material as a function of the temperature. Water hammer effects can be controlled focusing efforts on reducing the pressure increment that takes place once the phenomenon is presented. Some methods try to reduce the time of closure or the rate of change before the closure using special valves, others install additional elements to absorb the pressure surge and dissipate energy, others install relief valves to release the pressure, and others try to split the problem is smaller sections by installing check valves with dashpot or non-return valves. Splitting the pipeline into shorter sections is often used to help preventing the pipeline length of water falling back after a pump stops. In this paper the numerical results of maximum and minimum pressure values at both ends of a closed section are compared to experimental data. The numerical results follow the experimental trends.
文摘Following the previous relevant works [1]-[3], a scaling analysis is performed to derive a set of scaling criteria which were thought to be suitable for reproducing the major thermal-hydraulic phenomena in a scaled-down CANDU moderator tank similar to that in a prototype power plant during a full power steady state condition. The objective of building a scaled-down moderator tank is to generate the experimental data necessary to validate the computer codes which are used to analyze the accident analysis of CANDU-6 plants. The major variables of interests in this paper are moderator flow velocity and temperature of the moderator which is D2O inside the moderator tank during a steady state and transient conditions. The reason is that the local subcooling of the moderator is found to be a critical parameter determining whether the stable film boiling can sustain on the outer surface of the calandria tube if the contact of overheated pressure tube and cold calandria tube should occur due to pressure tube ballooning during LBLOCA with ECC injection failure [4]. The key phenomena involved include the inlet jet development and impingement, buoyancy force driven by the moderator temperature gradient caused by non-uniform direct heating of the moderator, and the pressure drop due to viscous friction of the flow across the calandria tube array. In this paper, the previous researches are reviewed, some concerns or potential problems associated with them implied by comparing CFD analyses results between the CANDU-6 moderator tank and 1/4 scaled-down test facility are described, and as a way to examine the assumption of the scaling analysis is true an order-of-magnitude analyses are performed. Based on the results of these analyses the assumption of neglecting ?and ?terms cannot be justified for the power of 0.5 MW and 1.566 MW for the 1/4 scaled-down facility. Further investigation is thought to be necessary to confirm this result, i.e. if the scaling of the previous work1 is justifiable by some other independent analyses.
文摘The high voltage Padova test facility(HVPTF)is an experiment set in Padova,Italy,operating in the framework of the Neutral Beam Test Facility project of the International Thermonuclear Experimental Reactor(ITER).One of the purposes of HVPTF is to study the phenomenology of discharge events occurring between electrodes at high voltage differences over long vacuum gaps,which is crucial in the development of the neutral beam injector foreseen for ITER.The facility hosts a cylindrical vacuum vessel with stable pressure control,where two electrodes of different possible geometries can be mounted.Two independent power supplies allow for total voltage differences up to 800 kVDC with adjustable gap widths up to 250 mm.Among the diagnostics,a gas electron multiplier(GEM)detector is installed for acquisition of x-ray emission on a radial line of sight of the vessel.This paper presents a study of the experimental sessions featuring stainless-steel needle-plane electrodes.The analysis is based on the GEM data,in relation to the information on current and voltage of the two power supplies.The events are characterised in terms of both temporal and spatial evolution,providing sequential emission profiles with spatial resolution of tens of millimetres on timescales of the order of hundreds of nanoseconds.
文摘The optimization method of a mathematical model and connected-pipe experimental technique for a test in altitude test facility (ATF) of a liquid fuel ramjet engine was researched.The optimization of the simple mathematical model was divided into two steps.Firstly,using the test engine's geometry configuration size data,a preliminary adjustment was done.Secondly,using experimental test data,the components' experiential coefficients were modified appropriately.Emphasis was laid on the simulation technique of flight condition and parameters measurement method.The experimental technique was applied to a ramjet ATF test successfully.The comparison results show that the optimized-model has higher precision and the nozzle gross thrust difference drops from 12% to about 4%.
