An ensemble prediction model of solar proton events （SPEs）, combining the information of solar flares and coronal mass ejections （CMEs）, is built. In this model, solar flares are parameterized by the peak flux, th...An ensemble prediction model of solar proton events （SPEs）, combining the information of solar flares and coronal mass ejections （CMEs）, is built. In this model, solar flares are parameterized by the peak flux, the duration and the longitude. In addition, CMEs are parameterized by the width, the speed and the measurement position angle. The importance of each parameter for the occurrence of SPEs is estimated by the information gain ratio. We find that the CME width and speed are more informative than the flare’s peak flux and duration. As the physical mechanism of SPEs is not very clear, a hidden naive Bayes approach, which is a probability-based calculation method from the field of machine learning, is used to build the prediction model from the observational data. As is known, SPEs originate from solar flares and/or shock waves associated with CMEs. Hence, we first build two base prediction models using the properties of solar flares and CMEs, respectively. Then the outputs of these models are combined to generate the ensemble prediction model of SPEs. The ensemble prediction model incorporating the complementary information of solar flares and CMEs achieves better performance than each base prediction model taken separately.展开更多
A statistical analysis is made on the correlation between solar proton events with energies >10Mev and solar radio bursts during the four-year period from 1997 November to 2000 November. We examine 28 solar proton ...A statistical analysis is made on the correlation between solar proton events with energies >10Mev and solar radio bursts during the four-year period from 1997 November to 2000 November. We examine 28 solar proton events and their corresponding solar radio bursts at 15400, 8800, 4995, 2695, 1415, 606, 410 and 245 MHz. The statistical result shows that there is a close association between solar proton events and ≥3 solar radio bursts occurring at several frequencies, one or two days before. In particular, it is noteworthy that proton events occurring in pairs within the same month are preceded 1-2 days by individual radio bursts and most of the radio bursts of solar flares occur at all eight frequencies. Those 245 MHz radio bursts associated with proton events have intense peak fluxes (up to 67000 sfu). Solar proton events are preceded 1 or 2 days by≥ 3 radio bursts at several frequencies and proton events occurring in pairs within the same month are preceded 1 or 2 days by some individual radio bursts. These correlations may be used for providing short-term or medium-term prediction of solar proton events.展开更多
This paper presents a comparative analysis on the two Solar Proton Events(SPE),which occurred on 14 July 2000(Bastille Day)and 28 October 2003(28OCT03)respectively.It is found that although the peak flux of the latter...This paper presents a comparative analysis on the two Solar Proton Events(SPE),which occurred on 14 July 2000(Bastille Day)and 28 October 2003(28OCT03)respectively.It is found that although the peak flux of the latter seemed to be greater than that of the former based on geostationary observations,the maximum intensities of the energetic protons(>10 MeV and 30 MeV)during the Bastille Day event were all higher than those of the 28OCT03 event according to the interplanetary observations.Further analysis indicated that the quantity of the seed particles,which could be accelerated to the energies exceeding 10 and 30 MeV by the Coronal Mass Ejection(CME)-driven shock on 14 July 2000,was far larger than that of the 28OCT03 event.In the Bastille Day case,when the CME approached to the height around 14 R⊙,the CME-driven shock would reach its maximum capacity in accelerating the solar en-ergetic protons(>100 MeV).In contrast,on 28 October 2003,when CME approached to the height about 58R⊙,the CME-driven shock reached its highest potential in accelerating the solar energetic protons of the same category.At this moment,the peak flux(>100 MeV)was about 155 pfu,which was much lower than 355 pfu measured on 14 July 2000.This demonstrated that in the Bastille Day event,the quantity of the seed particles,which could be accelerated to the energy beyond 100 MeV,was significantly larger than its counterpart in the 28OCT03 case.Therefore,the peak flux of an SPE event depends not only on the interplanetary intensity of the solar energetic particles,but also on the velocity of the associated CME-driven shock,and the quantity of the seed particles as well as on the interplanetary magnetic en-vironment.This paper also reveals that the magnetic sheath associated with ICME on 28 October 2003 captured a large number of solar energetic protons,including those having energy greater than 100 MeV.展开更多
Existing standards show a clear discrepancy in the specification of the maximum proton energy for qualified ground-based evaluation of single-event effects,which can range from 180 to 500 MeV. This work finds that the...Existing standards show a clear discrepancy in the specification of the maximum proton energy for qualified ground-based evaluation of single-event effects,which can range from 180 to 500 MeV. This work finds that the threshold linear energy transfer of a tested device is a critical parameter for determining the maximum proton energy. The inner mechanisms are further revealed. Highenergy deposition events(>10 MeV) in sensitive volumes are attributed to the interaction between protons and the tungsten vias in the metallization layers.展开更多
Single-event effects(SEEs)induced by mediumenergy protons in a 28 nm system-on-chip(SoC)were investigated at the China Institute of Atomic Energy.An on-chip memory block was irradiated with 90 MeV and 70 MeV protons,r...Single-event effects(SEEs)induced by mediumenergy protons in a 28 nm system-on-chip(SoC)were investigated at the China Institute of Atomic Energy.An on-chip memory block was irradiated with 90 MeV and 70 MeV protons,respectively.Single-bit upset and multicell upset events were observed,and an uppermost number of nine upset cells were discovered in the 90 MeV proton irradiation test.The results indicate that the SEE sensitivities of the 28 nm SoC to the 90 MeV and 70 MeV protons were similar.Cosmic Ray Effects on Micro-Electronics Monte Carlo simulations were analyzed,and it demonstrates that protons can induce effects in a 28 nm SoC if their energies are greater than 1.4 MeV and that the lowest corresponding linear energy transfer was 0.142 MeV cm^2 mg^-1.The similarities and discrepancies of the SEEs induced by the 90 MeV and 70 MeV protons were analyzed.展开更多
Geant4 Monte Carlo simulation results of the single event upset(SEU)induced by protons with energy ranging from 0.3 MeV to 1 GeV are reported.The SEU cross section for planar and three-dimensional(3D)die-stacked SRAM ...Geant4 Monte Carlo simulation results of the single event upset(SEU)induced by protons with energy ranging from 0.3 MeV to 1 GeV are reported.The SEU cross section for planar and three-dimensional(3D)die-stacked SRAM are calculated.The results show that the SEU cross sections of the planar device and the 3D device are different from each other under low energy proton direct ionization mechanism,but almost the same for the high energy proton.Besides,the multi-bit upset(MBU)ratio and pattern are presented and analyzed.The results indicate that the MBU ratio of the 3D die-stacked device is higher than that of the planar device,and the MBU patterns are more complicated.Finally,the on-orbit upset rate for the 3D die-stacked device and the planar device are calculated by SPACE RADIATION software.The calculation results indicate that no matter what the orbital parameters and shielding conditions are,the on-orbit upset rate of planar device is higher than that of 3D die-stacked device.展开更多
This paper presents a simulation study of the impact of energy straggle on a proton-induced single event upset （SEU） test in a commercial 65-nm static random access memory cell. The simulation results indicate that ...This paper presents a simulation study of the impact of energy straggle on a proton-induced single event upset （SEU） test in a commercial 65-nm static random access memory cell. The simulation results indicate that the SEU cross sections for low energy protons are significantly underestimated due to the use of degraders in the SEU test. In contrast, using degraders in a high energy proton test may cause the overestimation of the SEU cross sections. The results are confirmed by the experimental data and the impact of energy straggle on the SEU cross section needs to be taken into account when conducting a proton-induced SEU test in a nanodevice using degraders.展开更多
This paper presents an investigation into the impact of proton-induced alteration of carrier lifetime on the singleevent transient(SET) caused by heavy ions in silicon–germanium heterojunction bipolar transistor(SiGe...This paper presents an investigation into the impact of proton-induced alteration of carrier lifetime on the singleevent transient(SET) caused by heavy ions in silicon–germanium heterojunction bipolar transistor(SiGe HBT).The ioninduced current transients and integrated charge collections under different proton fluences are obtained based on technology computer-aided design(TCAD) simulation.The results indicate that the impact of carrier lifetime alteration is determined by the dominating charge collection mechanism at the ion incident position and only the long-time diffusion process is affected.With a proton fluence of 5 × 1013 cm-2, almost no change is found in the transient feature, and the charge collection of events happened in the region enclosed by deep trench isolation(DTI), where prompt funneling collection is the dominating mechanism.Meanwhile, for the events happening outside DTI where diffusion dominates the collection process, the peak value and the duration of the ion-induced current transient both decrease with increasing proton fluence, leading to a great decrease in charge collection.展开更多
We predict proton single event effect(SEE)error rates for the VATA160 ASIC chip on the Dark Matter Particle Explorer(DAMPE) to evaluate its radiation tolerance.Lacking proton test facilities,we built a Monte Carlo sim...We predict proton single event effect(SEE)error rates for the VATA160 ASIC chip on the Dark Matter Particle Explorer(DAMPE) to evaluate its radiation tolerance.Lacking proton test facilities,we built a Monte Carlo simulation tool named PRESTAGE to calculate the proton SEE cross-sections.PRESTAGE is based on the particle transport toolkit Geant4.It adopts a location-dependent strategy to derive the SEE sensitivity of the device from heavy-ion test data,which have been measured at the HI-13 tandem accelerator of the China Institute of Atomic Energy and the heavy-ion research facility in Lanzhou.The AP-8,SOLPRO,and August 1972 worst-case models are used to predict the average and peak proton fluxes on the DAMPE orbit.Calculation results show that the averaged proton SEE error rate for the VATA160 chip is approximately 2.17×10^(-5)/device/day.Worst-case error rates for the Van Allen belts and solar energetic particle events are 1-3 orders of magnitude higher than the averaged error rate.展开更多
AIM:To evaluate the efficacy,safety and influential factors of proton pump inhibitor(PPI)treatment for non-erosive reflux disease(NERD).METHODS:PubMed,MEDLINE,EMBASE and the Cochrane Library were searched up to April ...AIM:To evaluate the efficacy,safety and influential factors of proton pump inhibitor(PPI)treatment for non-erosive reflux disease(NERD).METHODS:PubMed,MEDLINE,EMBASE and the Cochrane Library were searched up to April 2013 to identify eligible randomized controlled trials(RCTs)that probed into the efficacy,safety and influential factors of PPI treatment for NERD.The rates of symptomatic relief and adverse events were measured as the outcomes.After RCT selection,assessment and data collection,the pooled RRs and 95%CI were calculated.This meta-analysis was performed using the Stata 12.0 software(Stata Corporation,College Station,Texas,United States).The level of evidence was estimated by the Grading of Recommendations Assessment,Development and Evaluation system.RESULTS:Seventeen RCTs including 6072 patients met the inclusion criteria.The results of the metaanalysis showed that PPI treatment was significantly superior to H2receptor antagonists(H2RA)treatment(RR=1.629,95%CI:1.422-1.867,P=0.000)and placebo(RR=1.903,95%CI:1.573-2.302,P=0.000)for the symptomatic relief of NERD.However,there were no obvious differences between PPI and H2RA(RR=0.928,95%CI:0.776-1.110,P=0.414)or PPI and the placebo(RR=1.000,95%CI:0.896-1.116,P=0.997)regarding the rate of adverse events.The overall rate of symptomatic relief of PPI against NERD was 51.4%(95%CI:0.433-0.595,P=0.000),and relief was influenced by hiatal hernia(P=0.030).The adverse rate of PPI against NERD was 21.0%(95%CI:0.152-0.208,P=0.000),and was affected by hiatal hernia(P=0.081)and drinking(P=0.053).CONCLUSION:PPI overmatched H2RA on symptomatic relief rate but not on adverse rate for NERD.Its relief rate and adverse rate were influenced by hiatal hernia and drinking.展开更多
基金supported by the Young Researcher Grant of National Astronomical Observatories, Chinese Academy of Sciences, the National Basic Research Program of China (973 Program, Grant No. 2011CB811406)the National Natural Science Foundation of China (Grant Nos. 10733020, 10921303, 11003026 and 11078010)
文摘An ensemble prediction model of solar proton events （SPEs）, combining the information of solar flares and coronal mass ejections （CMEs）, is built. In this model, solar flares are parameterized by the peak flux, the duration and the longitude. In addition, CMEs are parameterized by the width, the speed and the measurement position angle. The importance of each parameter for the occurrence of SPEs is estimated by the information gain ratio. We find that the CME width and speed are more informative than the flare’s peak flux and duration. As the physical mechanism of SPEs is not very clear, a hidden naive Bayes approach, which is a probability-based calculation method from the field of machine learning, is used to build the prediction model from the observational data. As is known, SPEs originate from solar flares and/or shock waves associated with CMEs. Hence, we first build two base prediction models using the properties of solar flares and CMEs, respectively. Then the outputs of these models are combined to generate the ensemble prediction model of SPEs. The ensemble prediction model incorporating the complementary information of solar flares and CMEs achieves better performance than each base prediction model taken separately.
文摘A statistical analysis is made on the correlation between solar proton events with energies >10Mev and solar radio bursts during the four-year period from 1997 November to 2000 November. We examine 28 solar proton events and their corresponding solar radio bursts at 15400, 8800, 4995, 2695, 1415, 606, 410 and 245 MHz. The statistical result shows that there is a close association between solar proton events and ≥3 solar radio bursts occurring at several frequencies, one or two days before. In particular, it is noteworthy that proton events occurring in pairs within the same month are preceded 1-2 days by individual radio bursts and most of the radio bursts of solar flares occur at all eight frequencies. Those 245 MHz radio bursts associated with proton events have intense peak fluxes (up to 67000 sfu). Solar proton events are preceded 1 or 2 days by≥ 3 radio bursts at several frequencies and proton events occurring in pairs within the same month are preceded 1 or 2 days by some individual radio bursts. These correlations may be used for providing short-term or medium-term prediction of solar proton events.
基金Supported by the National Natural Science Foundation of China(Grant Nos.10373017&5067702)
文摘This paper presents a comparative analysis on the two Solar Proton Events(SPE),which occurred on 14 July 2000(Bastille Day)and 28 October 2003(28OCT03)respectively.It is found that although the peak flux of the latter seemed to be greater than that of the former based on geostationary observations,the maximum intensities of the energetic protons(>10 MeV and 30 MeV)during the Bastille Day event were all higher than those of the 28OCT03 event according to the interplanetary observations.Further analysis indicated that the quantity of the seed particles,which could be accelerated to the energies exceeding 10 and 30 MeV by the Coronal Mass Ejection(CME)-driven shock on 14 July 2000,was far larger than that of the 28OCT03 event.In the Bastille Day case,when the CME approached to the height around 14 R⊙,the CME-driven shock would reach its maximum capacity in accelerating the solar en-ergetic protons(>100 MeV).In contrast,on 28 October 2003,when CME approached to the height about 58R⊙,the CME-driven shock reached its highest potential in accelerating the solar energetic protons of the same category.At this moment,the peak flux(>100 MeV)was about 155 pfu,which was much lower than 355 pfu measured on 14 July 2000.This demonstrated that in the Bastille Day event,the quantity of the seed particles,which could be accelerated to the energy beyond 100 MeV,was significantly larger than its counterpart in the 28OCT03 case.Therefore,the peak flux of an SPE event depends not only on the interplanetary intensity of the solar energetic particles,but also on the velocity of the associated CME-driven shock,and the quantity of the seed particles as well as on the interplanetary magnetic en-vironment.This paper also reveals that the magnetic sheath associated with ICME on 28 October 2003 captured a large number of solar energetic protons,including those having energy greater than 100 MeV.
基金supported by the National Natural Science Foundation of China(No.11505033)the Science and Technology Research Project of Guangdong,China(Nos.2015B090901048 and 2017B090901068)the Science and Technology Plan Project of Guangzhou,China(No.201707010186)
文摘Existing standards show a clear discrepancy in the specification of the maximum proton energy for qualified ground-based evaluation of single-event effects,which can range from 180 to 500 MeV. This work finds that the threshold linear energy transfer of a tested device is a critical parameter for determining the maximum proton energy. The inner mechanisms are further revealed. Highenergy deposition events(>10 MeV) in sensitive volumes are attributed to the interaction between protons and the tungsten vias in the metallization layers.
基金supported by the National Natural Science Foundation of China(Grant Nos.11575138,11835006,11690040,and 11690043)
文摘Single-event effects(SEEs)induced by mediumenergy protons in a 28 nm system-on-chip(SoC)were investigated at the China Institute of Atomic Energy.An on-chip memory block was irradiated with 90 MeV and 70 MeV protons,respectively.Single-bit upset and multicell upset events were observed,and an uppermost number of nine upset cells were discovered in the 90 MeV proton irradiation test.The results indicate that the SEE sensitivities of the 28 nm SoC to the 90 MeV and 70 MeV protons were similar.Cosmic Ray Effects on Micro-Electronics Monte Carlo simulations were analyzed,and it demonstrates that protons can induce effects in a 28 nm SoC if their energies are greater than 1.4 MeV and that the lowest corresponding linear energy transfer was 0.142 MeV cm^2 mg^-1.The similarities and discrepancies of the SEEs induced by the 90 MeV and 70 MeV protons were analyzed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11690041 and 11675233)the Fund from the Science and Technology on Analog Integrated Circuit Laboratory,China(Grant No.JCKY2019210C054).
文摘Geant4 Monte Carlo simulation results of the single event upset(SEU)induced by protons with energy ranging from 0.3 MeV to 1 GeV are reported.The SEU cross section for planar and three-dimensional(3D)die-stacked SRAM are calculated.The results show that the SEU cross sections of the planar device and the 3D device are different from each other under low energy proton direct ionization mechanism,but almost the same for the high energy proton.Besides,the multi-bit upset(MBU)ratio and pattern are presented and analyzed.The results indicate that the MBU ratio of the 3D die-stacked device is higher than that of the planar device,and the MBU patterns are more complicated.Finally,the on-orbit upset rate for the 3D die-stacked device and the planar device are calculated by SPACE RADIATION software.The calculation results indicate that no matter what the orbital parameters and shielding conditions are,the on-orbit upset rate of planar device is higher than that of 3D die-stacked device.
基金supported by the National Natural Science Foundation of China(Grant Nos.11690041 and 11675233)
文摘This paper presents a simulation study of the impact of energy straggle on a proton-induced single event upset （SEU） test in a commercial 65-nm static random access memory cell. The simulation results indicate that the SEU cross sections for low energy protons are significantly underestimated due to the use of degraders in the SEU test. In contrast, using degraders in a high energy proton test may cause the overestimation of the SEU cross sections. The results are confirmed by the experimental data and the impact of energy straggle on the SEU cross section needs to be taken into account when conducting a proton-induced SEU test in a nanodevice using degraders.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11775167,61574171,11575138,and 11835006)
文摘This paper presents an investigation into the impact of proton-induced alteration of carrier lifetime on the singleevent transient(SET) caused by heavy ions in silicon–germanium heterojunction bipolar transistor(SiGe HBT).The ioninduced current transients and integrated charge collections under different proton fluences are obtained based on technology computer-aided design(TCAD) simulation.The results indicate that the impact of carrier lifetime alteration is determined by the dominating charge collection mechanism at the ion incident position and only the long-time diffusion process is affected.With a proton fluence of 5 × 1013 cm-2, almost no change is found in the transient feature, and the charge collection of events happened in the region enclosed by deep trench isolation(DTI), where prompt funneling collection is the dominating mechanism.Meanwhile, for the events happening outside DTI where diffusion dominates the collection process, the peak value and the duration of the ion-induced current transient both decrease with increasing proton fluence, leading to a great decrease in charge collection.
基金supported by the National Natural Science Foundation of China(Nos.11179003,10975164,10805062,and 11005134)
文摘We predict proton single event effect(SEE)error rates for the VATA160 ASIC chip on the Dark Matter Particle Explorer(DAMPE) to evaluate its radiation tolerance.Lacking proton test facilities,we built a Monte Carlo simulation tool named PRESTAGE to calculate the proton SEE cross-sections.PRESTAGE is based on the particle transport toolkit Geant4.It adopts a location-dependent strategy to derive the SEE sensitivity of the device from heavy-ion test data,which have been measured at the HI-13 tandem accelerator of the China Institute of Atomic Energy and the heavy-ion research facility in Lanzhou.The AP-8,SOLPRO,and August 1972 worst-case models are used to predict the average and peak proton fluxes on the DAMPE orbit.Calculation results show that the averaged proton SEE error rate for the VATA160 chip is approximately 2.17×10^(-5)/device/day.Worst-case error rates for the Van Allen belts and solar energetic particle events are 1-3 orders of magnitude higher than the averaged error rate.
文摘AIM:To evaluate the efficacy,safety and influential factors of proton pump inhibitor(PPI)treatment for non-erosive reflux disease(NERD).METHODS:PubMed,MEDLINE,EMBASE and the Cochrane Library were searched up to April 2013 to identify eligible randomized controlled trials(RCTs)that probed into the efficacy,safety and influential factors of PPI treatment for NERD.The rates of symptomatic relief and adverse events were measured as the outcomes.After RCT selection,assessment and data collection,the pooled RRs and 95%CI were calculated.This meta-analysis was performed using the Stata 12.0 software(Stata Corporation,College Station,Texas,United States).The level of evidence was estimated by the Grading of Recommendations Assessment,Development and Evaluation system.RESULTS:Seventeen RCTs including 6072 patients met the inclusion criteria.The results of the metaanalysis showed that PPI treatment was significantly superior to H2receptor antagonists(H2RA)treatment(RR=1.629,95%CI:1.422-1.867,P=0.000)and placebo(RR=1.903,95%CI:1.573-2.302,P=0.000)for the symptomatic relief of NERD.However,there were no obvious differences between PPI and H2RA(RR=0.928,95%CI:0.776-1.110,P=0.414)or PPI and the placebo(RR=1.000,95%CI:0.896-1.116,P=0.997)regarding the rate of adverse events.The overall rate of symptomatic relief of PPI against NERD was 51.4%(95%CI:0.433-0.595,P=0.000),and relief was influenced by hiatal hernia(P=0.030).The adverse rate of PPI against NERD was 21.0%(95%CI:0.152-0.208,P=0.000),and was affected by hiatal hernia(P=0.081)and drinking(P=0.053).CONCLUSION:PPI overmatched H2RA on symptomatic relief rate but not on adverse rate for NERD.Its relief rate and adverse rate were influenced by hiatal hernia and drinking.
