In this paper,promising but simple schemes are investigated to enhance the micro-bunching of relativistic electron beams for coherent harmonic generation(CHG)by using phase merging effects.In contrast to the standard ...In this paper,promising but simple schemes are investigated to enhance the micro-bunching of relativistic electron beams for coherent harmonic generation(CHG)by using phase merging effects.In contrast to the standard CHG scheme,two specially designed dispersion sections(DSs)are adopted with the DS-modulator–DS configuration.The phase space of the e beam is appropriately coupled in the first DS,and the electrons within one seed wavelength can merge to the same phase with a matched second DS.Micro-bunching of the e beam can thus be enhanced by a large margin with much higher-harmonic components.Taking e beams from laser wakefield accelerators(LWFAs)as an example,start-to-end simulations are performed to show the effectiveness and robustness of the proposed schemes with several configurations.The beam current can be optimized to several tens to hundreds of kiloamperes,and the radiation power reaches hundreds of megawatts in the extreme ultraviolet regime within a 3.5 m-long beamline.The proposed schemes offer new opportunities for future compact free-electron lasers driven by LWFAs and provides prospects for truly compact and widely applicable systems.展开更多
BACKGROUND:This study aimed to establish an eff ective nomogram to predict the survival of heat stroke(HS)based on risk factors.METHODS:This was a retrospective,observational multicenter cohort study.We analyzed patie...BACKGROUND:This study aimed to establish an eff ective nomogram to predict the survival of heat stroke(HS)based on risk factors.METHODS:This was a retrospective,observational multicenter cohort study.We analyzed patients diagnosed with HS,who were treated between May 1 and September 30,2018 at 15 tertiary hospitals from 11 cities in Northern China.RESULTS:Among the 175 patients,32 patients(18.29%)died before hospital discharge.After the univariate analysis,mechanical ventilation,initial mean arterial pressure<70 mmHg,maximum heart rate,lab results on day 1(white blood cell count,alanine aminotransferase,creatinine),and Glasgow admission prediction score were included in multivariate analysis.Multivariate Cox regression showed that invasive ventilation,initial mean arterial pressure<70 mmHg(1 mmHg=0.133 kPa),and Glasgow admission prediction score were independent risk factors for HS.The nomogram was established for predicting 7-d and 14-d survival in the training cohort.The nomogram exhibited a concordance index(C-index)of 0.880(95%confidence interval[95%CI]0.831-0.930)by bootstrapping validation(B=1,000).Furthermore,the nomogram performed better when predicting 14-d survival,compared to 7-d survival.The prognostic index cut-off value was set at 2.085,according to the operating characteristic curve for overall survival prediction.The model showed good calibration ability in the internal and external validation datasets.CONCLUSION:A novel nomogram,integrated with prognostic factors,was proposed;it was highly predictive of the survival in HS patients.展开更多
为探究现代工艺酿造的浓香型白酒不同馏分中各风味组分以及对应酒精度的馏出特性和相关性,以机械化酿造的34个不同馏分的浓香型原酒为研究对象,采用液液萃取-气相色谱-质谱联用(liquid-liquid-extraction gas chromatography-mass,LLE-G...为探究现代工艺酿造的浓香型白酒不同馏分中各风味组分以及对应酒精度的馏出特性和相关性,以机械化酿造的34个不同馏分的浓香型原酒为研究对象,采用液液萃取-气相色谱-质谱联用(liquid-liquid-extraction gas chromatography-mass,LLE-GC-MS)对样品风味物质进行定性定量分析,结合感官品评分析结果,进行了层次聚类热图分析,Pearson相关性分析以及正交偏最小二乘判别分析(orthogonal projections to latent structures-discriminant analysis,OPLS-DA),建立了不同馏分酒精度变化的数学模型:C t=73.373-0.012e 0.007t,其中决定系数以及均方根误差均为0.997,表示模型拟合的效果非常好。通过总结馏出规律,可以很好地把34个馏分分为4个大类,其中馏分0~2为酒头,馏分3~12为头段酒,馏分13~26为中段酒,馏分27~33为酒尾。16种主要风味物质按照相关性分成了A、B两个大类,且2个类别之间存在着显著的负相关,A类物质随着馏分的馏出,含量逐渐降低,B类物质的趋势则完全相反。感官评定结果显示,头段酒的综合评价最好,酯香浓郁,窖香突出,糟味明显,口感谐调,而没有明显的尾味。该研究分别基于风味物质和酒精度建立了不同时间段馏分的分类模型,为浓香型白酒现代工艺的量质摘酒、分段摘酒提供了参考依据。展开更多
We propose a novel approach for generating a high-density,spatially periodic narrow electron beam comb(EBC)from a plasma grating induced by the interference of two intense laser pulses in subcritical-density plasma.We...We propose a novel approach for generating a high-density,spatially periodic narrow electron beam comb(EBC)from a plasma grating induced by the interference of two intense laser pulses in subcritical-density plasma.We employ particle-in-cell(PIC)simulations to investigate the effects of cross-propagating laser pulses with specific angles overlapping in a subcritical plasma.This overlap results in the formation of a transverse standing wave,leading to a spatially periodic high-density modulation known as a plasma grating.The electron density peak within the grating can reach several times the background plasma density.The charge imbalance between electrons and ions in the electron density peaks causes mutual repulsion among the electrons,resulting in Coulomb expansion and acceleration of the electrons.As a result,some electrons expand into vacuum,forming a periodic narrow EBC with an individual beam width in the nanoscale range.To further explore the formation of the nanoscale EBC,we conduct additional PIC simulations to study the dependence on various laser parameters.Overall,our proposed method offers a promising and controlled approach to generate tunable narrow EBCs with high density.展开更多
Due to the advantages of comfort and safety,high-speed trains are gradually becoming the mainstream public transport in China.Since the operating speed and mileage of high-speed trains have achieved rapid growth,it is...Due to the advantages of comfort and safety,high-speed trains are gradually becoming the mainstream public transport in China.Since the operating speed and mileage of high-speed trains have achieved rapid growth,it is more and more urgent to ensure their reliability and safety.As an important component in the bogies of highspeed trains,the health state of the bearing directly affects the operational safety of the trains.It is therefore necessary to diagnoze the faults of bearings in the bogies of high-speed trains as early as possible.In this paper,the bearing fault diagnostic methods for high-speed trains have been systematically summarized with their challenges and perspectives.First,it briefly introduces the structure of bearings in the bogies as well as the fault characteristic frequencies.Then,a brief review of the research on vibration-based signal processing methods and machine learning methods has been provided.Finally,the challenges and future developments of vibrationbased bearing fault diagnostic methods for high-speed trains have been analyzed.展开更多
Background:This study aims to explore the significance of serum amylase levels in patients with organophosphorus pesticide(OP)poisoning and to provide a new perspective for evaluating the severity and prognosis of OP ...Background:This study aims to explore the significance of serum amylase levels in patients with organophosphorus pesticide(OP)poisoning and to provide a new perspective for evaluating the severity and prognosis of OP poisoning.Methods:The clinical data of 67 patients with acute OP poisoning,who had been treated in the emergency department of the General Hospital of Ningxia Medical University between September 2020 and August 2022,were retrospectively analyzed.Using Spearman rank correlation,serum amylase levels during admission and severity of poisoning correlated with discharge outcomes.Based on serum amylase levels,receiver operating characteristic curves were plotted to predict the severity and mortality of patients who experience organophosphate poisoning.The optimal threshold serum amylase level at admission was determined based on the maximum Youden index.Results:Using Spearman rank correlation analysis,serum amylase levels at admission positively correlated with the severity of poisoning and discharge outcomes,but the degree of correlation was weak(r_(s):0.344;0.264;P<0.05).The patients’serum amylase levels at admission had receiver operating characteristic area under the curve values of 0.726 and 0.735 to predict the degree of severe poisoning and death,respectively.Based on the maximum Youden index,the optimal threshold of serum amylase were 97.8 and 194.1 U/L when the degree of poisoning was severe and the discharge outcome of patients was died.In comparison to patients with serum amylase levels≤194.1 U/L at admission,the OR values of death in patients with serum amylase levels>194.1 U/L at admission was 15.944(95%CI:1.825-139.274).Conclusion:Serum amylase levels in patients with organophosphate poisoning correlate with the degree of poisoning and discharge outcomes.Higher serum amylase level was a risk factor for organophosphorus poisoning death.展开更多
Fault diagnosis technology has been widely applied and is an important part of ensuring the safe operation of mechanical equipment.In response to the problem of frequent faults in rolling bearings,this paper designs a...Fault diagnosis technology has been widely applied and is an important part of ensuring the safe operation of mechanical equipment.In response to the problem of frequent faults in rolling bearings,this paper designs a rolling bearing fault diagnosis method based on convolutional capsule network(CCN).More specifically,the original vibration signal is converted into a two-dimensional time–frequency image using continuous wavelet transform(CWT),and the feature extraction is performed on the two-dimensional time–frequency image using the convolution layer at the front end of the network,and the extracted features are input into the capsule network.The capsule network converts the extracted features into vector neurons,and the dynamic routing algorithm is used to achieve feature transfer and output the results of fault diagnosis.Two different datasets are used to compare with other traditional deep learning models to verify the fault diagnosis capability of the method.The results show that the CCN has good diagnostic capability under different working conditions,even in the presence of noise and insufficient samples,compared to other models.This method contributes to the safe and reliable operation of mechanical equipment and is suitable for other rotating scenarios.展开更多
针对软件定义网络(Software Defined Network,SDN)的负载均衡问题,为使网络的资源分配更加合理,防止网络拥塞,设计了一种基于Q-学习的负载均衡(Q-learning Load Balance,QLLB)算法,可根据网络环境自行作出决策,避免网络拥塞,实现网络资...针对软件定义网络(Software Defined Network,SDN)的负载均衡问题,为使网络的资源分配更加合理,防止网络拥塞,设计了一种基于Q-学习的负载均衡(Q-learning Load Balance,QLLB)算法,可根据网络环境自行作出决策,避免网络拥塞,实现网络资源的合理分配。与最短路径算法Dijkstra、蚁群算法进行的性能对比结果表明,QLLB算法有效实现了负载均衡,使得各个链路的带宽利用率更加平均,吞吐量分别提升了约8%和2%,可有效提升网络性能。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12388102,12225411,12105353,11991072,and 12174410)the CAS Project for Young Scientists in Basic Research(Grant No.YSBR060)+1 种基金the Program of Shanghai Academic Research Leader(Grant No.22XD1424200)the State Key Laboratory Program of the Chinese Ministry of Science and Technology and CAS Youth Innovation Promotion Association(Y201952 and 2022242).
文摘In this paper,promising but simple schemes are investigated to enhance the micro-bunching of relativistic electron beams for coherent harmonic generation(CHG)by using phase merging effects.In contrast to the standard CHG scheme,two specially designed dispersion sections(DSs)are adopted with the DS-modulator–DS configuration.The phase space of the e beam is appropriately coupled in the first DS,and the electrons within one seed wavelength can merge to the same phase with a matched second DS.Micro-bunching of the e beam can thus be enhanced by a large margin with much higher-harmonic components.Taking e beams from laser wakefield accelerators(LWFAs)as an example,start-to-end simulations are performed to show the effectiveness and robustness of the proposed schemes with several configurations.The beam current can be optimized to several tens to hundreds of kiloamperes,and the radiation power reaches hundreds of megawatts in the extreme ultraviolet regime within a 3.5 m-long beamline.The proposed schemes offer new opportunities for future compact free-electron lasers driven by LWFAs and provides prospects for truly compact and widely applicable systems.
文摘BACKGROUND:This study aimed to establish an eff ective nomogram to predict the survival of heat stroke(HS)based on risk factors.METHODS:This was a retrospective,observational multicenter cohort study.We analyzed patients diagnosed with HS,who were treated between May 1 and September 30,2018 at 15 tertiary hospitals from 11 cities in Northern China.RESULTS:Among the 175 patients,32 patients(18.29%)died before hospital discharge.After the univariate analysis,mechanical ventilation,initial mean arterial pressure<70 mmHg,maximum heart rate,lab results on day 1(white blood cell count,alanine aminotransferase,creatinine),and Glasgow admission prediction score were included in multivariate analysis.Multivariate Cox regression showed that invasive ventilation,initial mean arterial pressure<70 mmHg(1 mmHg=0.133 kPa),and Glasgow admission prediction score were independent risk factors for HS.The nomogram was established for predicting 7-d and 14-d survival in the training cohort.The nomogram exhibited a concordance index(C-index)of 0.880(95%confidence interval[95%CI]0.831-0.930)by bootstrapping validation(B=1,000).Furthermore,the nomogram performed better when predicting 14-d survival,compared to 7-d survival.The prognostic index cut-off value was set at 2.085,according to the operating characteristic curve for overall survival prediction.The model showed good calibration ability in the internal and external validation datasets.CONCLUSION:A novel nomogram,integrated with prognostic factors,was proposed;it was highly predictive of the survival in HS patients.
文摘为探究现代工艺酿造的浓香型白酒不同馏分中各风味组分以及对应酒精度的馏出特性和相关性,以机械化酿造的34个不同馏分的浓香型原酒为研究对象,采用液液萃取-气相色谱-质谱联用(liquid-liquid-extraction gas chromatography-mass,LLE-GC-MS)对样品风味物质进行定性定量分析,结合感官品评分析结果,进行了层次聚类热图分析,Pearson相关性分析以及正交偏最小二乘判别分析(orthogonal projections to latent structures-discriminant analysis,OPLS-DA),建立了不同馏分酒精度变化的数学模型:C t=73.373-0.012e 0.007t,其中决定系数以及均方根误差均为0.997,表示模型拟合的效果非常好。通过总结馏出规律,可以很好地把34个馏分分为4个大类,其中馏分0~2为酒头,馏分3~12为头段酒,馏分13~26为中段酒,馏分27~33为酒尾。16种主要风味物质按照相关性分成了A、B两个大类,且2个类别之间存在着显著的负相关,A类物质随着馏分的馏出,含量逐渐降低,B类物质的趋势则完全相反。感官评定结果显示,头段酒的综合评价最好,酯香浓郁,窖香突出,糟味明显,口感谐调,而没有明显的尾味。该研究分别基于风味物质和酒精度建立了不同时间段馏分的分类模型,为浓香型白酒现代工艺的量质摘酒、分段摘酒提供了参考依据。
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.12174410,11991072,11991074,12225411,and 12105353)the CAS Project for Young Scientists in Basic Research(Grant No.YSBR060)the State Key Laboratory Program of the Chinese Ministry of Science and Technology,and the CAS Youth Innovation Promotion Association(Grant Nos.Y201952 and 2022242).
文摘We propose a novel approach for generating a high-density,spatially periodic narrow electron beam comb(EBC)from a plasma grating induced by the interference of two intense laser pulses in subcritical-density plasma.We employ particle-in-cell(PIC)simulations to investigate the effects of cross-propagating laser pulses with specific angles overlapping in a subcritical plasma.This overlap results in the formation of a transverse standing wave,leading to a spatially periodic high-density modulation known as a plasma grating.The electron density peak within the grating can reach several times the background plasma density.The charge imbalance between electrons and ions in the electron density peaks causes mutual repulsion among the electrons,resulting in Coulomb expansion and acceleration of the electrons.As a result,some electrons expand into vacuum,forming a periodic narrow EBC with an individual beam width in the nanoscale range.To further explore the formation of the nanoscale EBC,we conduct additional PIC simulations to study the dependence on various laser parameters.Overall,our proposed method offers a promising and controlled approach to generate tunable narrow EBCs with high density.
基金supported by the National Natural Science Foundation of China(52375078).
文摘Due to the advantages of comfort and safety,high-speed trains are gradually becoming the mainstream public transport in China.Since the operating speed and mileage of high-speed trains have achieved rapid growth,it is more and more urgent to ensure their reliability and safety.As an important component in the bogies of highspeed trains,the health state of the bearing directly affects the operational safety of the trains.It is therefore necessary to diagnoze the faults of bearings in the bogies of high-speed trains as early as possible.In this paper,the bearing fault diagnostic methods for high-speed trains have been systematically summarized with their challenges and perspectives.First,it briefly introduces the structure of bearings in the bogies as well as the fault characteristic frequencies.Then,a brief review of the research on vibration-based signal processing methods and machine learning methods has been provided.Finally,the challenges and future developments of vibrationbased bearing fault diagnostic methods for high-speed trains have been analyzed.
基金Ningxia Medical University General Hospital’s Ethics Committee(Ethics Number:KYLL-2022-1243).
文摘Background:This study aims to explore the significance of serum amylase levels in patients with organophosphorus pesticide(OP)poisoning and to provide a new perspective for evaluating the severity and prognosis of OP poisoning.Methods:The clinical data of 67 patients with acute OP poisoning,who had been treated in the emergency department of the General Hospital of Ningxia Medical University between September 2020 and August 2022,were retrospectively analyzed.Using Spearman rank correlation,serum amylase levels during admission and severity of poisoning correlated with discharge outcomes.Based on serum amylase levels,receiver operating characteristic curves were plotted to predict the severity and mortality of patients who experience organophosphate poisoning.The optimal threshold serum amylase level at admission was determined based on the maximum Youden index.Results:Using Spearman rank correlation analysis,serum amylase levels at admission positively correlated with the severity of poisoning and discharge outcomes,but the degree of correlation was weak(r_(s):0.344;0.264;P<0.05).The patients’serum amylase levels at admission had receiver operating characteristic area under the curve values of 0.726 and 0.735 to predict the degree of severe poisoning and death,respectively.Based on the maximum Youden index,the optimal threshold of serum amylase were 97.8 and 194.1 U/L when the degree of poisoning was severe and the discharge outcome of patients was died.In comparison to patients with serum amylase levels≤194.1 U/L at admission,the OR values of death in patients with serum amylase levels>194.1 U/L at admission was 15.944(95%CI:1.825-139.274).Conclusion:Serum amylase levels in patients with organophosphate poisoning correlate with the degree of poisoning and discharge outcomes.Higher serum amylase level was a risk factor for organophosphorus poisoning death.
基金Science and Technology Planning Project of Inner Mongolia of China under contract number 2021GG0346.
文摘Fault diagnosis technology has been widely applied and is an important part of ensuring the safe operation of mechanical equipment.In response to the problem of frequent faults in rolling bearings,this paper designs a rolling bearing fault diagnosis method based on convolutional capsule network(CCN).More specifically,the original vibration signal is converted into a two-dimensional time–frequency image using continuous wavelet transform(CWT),and the feature extraction is performed on the two-dimensional time–frequency image using the convolution layer at the front end of the network,and the extracted features are input into the capsule network.The capsule network converts the extracted features into vector neurons,and the dynamic routing algorithm is used to achieve feature transfer and output the results of fault diagnosis.Two different datasets are used to compare with other traditional deep learning models to verify the fault diagnosis capability of the method.The results show that the CCN has good diagnostic capability under different working conditions,even in the presence of noise and insufficient samples,compared to other models.This method contributes to the safe and reliable operation of mechanical equipment and is suitable for other rotating scenarios.
文摘针对软件定义网络(Software Defined Network,SDN)的负载均衡问题,为使网络的资源分配更加合理,防止网络拥塞,设计了一种基于Q-学习的负载均衡(Q-learning Load Balance,QLLB)算法,可根据网络环境自行作出决策,避免网络拥塞,实现网络资源的合理分配。与最短路径算法Dijkstra、蚁群算法进行的性能对比结果表明,QLLB算法有效实现了负载均衡,使得各个链路的带宽利用率更加平均,吞吐量分别提升了约8%和2%,可有效提升网络性能。
