Multi-radar signal separation is a critical process in modern reconnaissance systems. However, the complicated battlefield is typically confronted with increasing electronic equipment and complex radar waveforms. The ...Multi-radar signal separation is a critical process in modern reconnaissance systems. However, the complicated battlefield is typically confronted with increasing electronic equipment and complex radar waveforms. The intercepted signal is difficult to separate with conventional parameters because of severe overlapping in both time and frequency domains. On the contrary, time-frequency analysis maps the 1D signal into a 2D time-frequency plane, which provides a better insight into the signal than traditional methods. Particularly, the parameterized time-frequency analysis (PTFA) shows great potential in processing such non stationary signals. Five procedures for the PTFA are proposed to separate the overlapped multi-radar signal, including initiation, instantaneous frequency estimation with PTFA, signal demodulation, signal separation with adaptive filter and signal recovery. The proposed method is verified with both simulated and real signals, which shows good performance in the application on multi-radar signal separation.展开更多
An ensemble prediction system based on the GRAPES model, using multi-physics, is used to discuss the influence of different physical processes in numerical models on forecast of heavy rainfall in South China in the an...An ensemble prediction system based on the GRAPES model, using multi-physics, is used to discuss the influence of different physical processes in numerical models on forecast of heavy rainfall in South China in the annually first raining season(AFRS). Pattern, magnitude and area of precipitation, evolution of synoptic situation, as well as apparent heat source and apparent moisture sink between different ensemble members are comparatively analyzed. The choice of parameterization scheme for land-surface processes gives rise to the largest influence on the precipitation prediction. The influences of cumulus-convection and cloud-microphysics processes are mainly focused on heavy rainfall;the use of cumulus-convection parameterization tends to produce large-area and light rainfall. Change in parameterization schemes for land-surface and cumulus-convection processes both will cause prominent change in forecast of both dynamic and thermodynamic variables, while change in cloud-microphysics processes show primary impact on dynamic variables. Comparing simplified Arakawa-Schubert and Kain-Fritsch with Betts-Miller-Janjic schemes, SLAB with NOAH schemes, as well as both WRF single moment 6-class and NCEP 3-class with simplified explicit schemes of phase-mixed cloud and precipitation shows that the former predicts stronger low-level jets and high humidity concentration, more convective rainfall and local heavy rainfall, and have better performance in precipitation forecast. Appropriate parameterization schemes can reasonably describe the physical process related to heavy rainfall in South China in the AFRS, such as low-level convergence, latent heat release, vertical transport of heat and water vapor, thereby depicting the multi-scale interactions of low-level jet and meso-scale convective systems in heavy rainfall suitably, and improving the prediction of heavy rainfall in South China in the AFRS as a result.展开更多
To represent model uncertainties more comprehensively,a stochastically perturbed parameterization(SPP)scheme consisting of temporally and spatially varying perturbations of 18 parameters in the microphysics,convection...To represent model uncertainties more comprehensively,a stochastically perturbed parameterization(SPP)scheme consisting of temporally and spatially varying perturbations of 18 parameters in the microphysics,convection,boundary layer,and surface layer parameterization schemes,as well as the stochastically perturbed parameterization tendencies(SPPT)scheme,and the stochastic kinetic energy backscatter(SKEB)scheme,is applied in the Global and Regional Assimilation and Prediction Enhanced System-Regional Ensemble Prediction System(GRAPES-REPS)to evaluate and compare the general performance of various combinations of multiple stochastic physics schemes.Six experiments are performed for a summer month(1-30 June 2015)over China and multiple verification metrics are used.The results show that:(1)All stochastic experiments outperform the control(CTL)experiment,and all combinations of stochastic parameterization schemes perform better than the single SPP scheme,indicating that stochastic methods can effectively improve the forecast skill,and combinations of multiple stochastic parameterization schemes can better represent model uncertainties;(2)The combination of all three stochastic physics schemes(SPP,SPPT,and SKEB)outperforms any other combination of two schemes in precipitation forecasting and surface and upper-air verification to better represent the model uncertainties and improve the forecast skill;(3)Combining SKEB with SPP and/or SPPT results in a notable increase in the spread and reduction in outliers for the upper-air wind speed.SKEB directly perturbs the wind field and therefore its addition will greatly impact the upper-air wind-speed fields,and it contributes most to the improvement in spread and outliers for wind;(4)The introduction of SPP has a positive added value,and does not lead to large changes in the evolution of the kinetic energy(KE)spectrum at any wavelength;(5)The introduction of SPPT and SKEB would cause a 5%-10%and 30%-80%change in the KE of mesoscale systems,and all three stochastic schemes(SPP,SPPT,and SKEB)mainly affect the KE of mesoscale systems.This study indicates the potential of combining multiple stochastic physics schemes and lays a foundation for the future development and design of regional and global ensembles.展开更多
Photodetectors equipped with multi-parameter control hold the potential to deliver exceptional performance in a wide range of scenarios,paving the way for developing novel spin-opto-electronic devices.Nevertheless,the...Photodetectors equipped with multi-parameter control hold the potential to deliver exceptional performance in a wide range of scenarios,paving the way for developing novel spin-opto-electronic devices.Nevertheless,the integration of such capabilities within a single device is challenging due to the necessity of harmonizing multiple materials with varying degrees of freedom.In this study,we introduce the van der Waals magnet CrSBr,featuring inherent anisotropy and distinctive spin-electronic coupling,to this realm.The linear dichroic ratio of the photocurrent in CrSBr tunneling device can reach~60 at 1.65 K,and the photoresponse experiences a significant boost with increasing magnetic field.Additionally,the unique spin-charge coupling engenders a photon energy-dependent photocurrent that is modulated by an external field and is validated by first-principle calculations.Our findings elucidate the effective multi-parameter control of photodetection based on vdWs magnet CrsBr,highlighting its potential applications in cutting-edge optoelectronic devices and as a highly sensitive probe medium.展开更多
目的探讨生境成像(habitat imaging,HI)无创定量可视化前列腺癌(prostate cancer,PCa)分区异质性并预测其危险度的可行性。材料与方法回顾性收集2018年1月至2024年8月在西京医院行多参数磁共振成像(multi-parameteric magnetic resonanc...目的探讨生境成像(habitat imaging,HI)无创定量可视化前列腺癌(prostate cancer,PCa)分区异质性并预测其危险度的可行性。材料与方法回顾性收集2018年1月至2024年8月在西京医院行多参数磁共振成像(multi-parameteric magnetic resonance imaging,mpMRI)扫描,包括扩散加权成像、体素内非相干运动加权成像和扩散峰度成像,并经根治性前列腺切除术(radical prostatectomy,RP)后病理证实为PCa的147例患者的临床及影像资料,以7∶3分为训练集和测试集。根据RP结果分为移行区(transition zone,TZ)和外周区(peripheral zone,PZ)PCa。整合每体素表观扩散系数(apparent diffusion coefficient,ADC)、灌注分数(perfusion fraction,f)和平均峰度(mean kurtosis,MK)值,划分生境亚区,生成生境地图,从临床、病理、影像多维度比较PZ和TZ PCa间差异。根据2019版国际泌尿病理协会(International Society of Urological Pathology,ISUP)指南,匹配生境地图与RP标本以评估各亚区ISUP分级,将患者分为低危组(ISUP≤2)和高危组(ISUP≥3)。logistic回归分析高危PCa相关特征并构建基于分区的HI(zone-based HI,zHI)-临床影像模型评估危险度,并评估模型效能。结果根据肘部法所示最佳聚类簇数划分3个生境亚区,生境1较生境2、3的ADC、f值更低,MK值更高。相较于TZ,PZ PCa患者临床、病理特征更恶,生境1占比更高。logistic回归分析示解剖分区(OR=3.50,95%CI:1.01~12.09)和生境1占比(OR=3.63,95%CI:1.37~9.62)是高危PCa的独立危险因素(P<0.05)。zHI-临床影像模型评估危险度在训练集和测试集的曲线下面积(area under the curve,AUC)分别为0.889(95%CI:0.822~0.955)和0.883(95%CI:0.740~0.925)。结论本研究多维度验证了PCa分区异质性,并基于解剖分区和HI特征构建模型,对PCa危险度的无创定量可视化预测具有增益效能。展开更多
Oil and gas pipelines are of great importance in China,and pipeline security problems pose a serious threat to society and the environment.Pipeline safety has therefore become an integral part of the entire national e...Oil and gas pipelines are of great importance in China,and pipeline security problems pose a serious threat to society and the environment.Pipeline safety has therefore become an integral part of the entire national economy.Landslides are the most harmful type of pipeline accident,and have directed increasing public attention to safety issues.Although some useful results have been obtained in the investigation and prevention of pipeline-landslide hazards,there remains a need for effective monitoring and early warning methods,especially when the complexity of pipeline-landslides is considered.Because oil and gas pipeline-landslides typically occur in the superficial soil layers,monitoring instruments must be easy to install and must cause minimal disturbance to the surrounding soil and pipeline.To address the particular characteristics of pipelinelandslides,we developed a multi-parameter integrated monitoring system called disaster reduction stick equipment.In this paper,we detail this monitoring and early warning system for pipeline-landslide hazards based on an on-site monitoring network and early warning algorithms.The functionality of our system was verified by its successful application to the Chongqing Loujiazhuang pipeline-landslide in China.The results presented here provide guidelines for the monitoring,early warning,and prevention of pipeline geological hazards.展开更多
文摘Multi-radar signal separation is a critical process in modern reconnaissance systems. However, the complicated battlefield is typically confronted with increasing electronic equipment and complex radar waveforms. The intercepted signal is difficult to separate with conventional parameters because of severe overlapping in both time and frequency domains. On the contrary, time-frequency analysis maps the 1D signal into a 2D time-frequency plane, which provides a better insight into the signal than traditional methods. Particularly, the parameterized time-frequency analysis (PTFA) shows great potential in processing such non stationary signals. Five procedures for the PTFA are proposed to separate the overlapped multi-radar signal, including initiation, instantaneous frequency estimation with PTFA, signal demodulation, signal separation with adaptive filter and signal recovery. The proposed method is verified with both simulated and real signals, which shows good performance in the application on multi-radar signal separation.
基金National Natural Science Foundation of China(41405104)Specialized Project for Public Welfare Industries(Meteorological Sector)(GYHY201306004)+2 种基金Guangdong Science and Technology Planning Project(2012A061400012)Project of Guangdong Provincial Meteorological Bureau for Science and Technology(2013A04)Science and Technology Plan for the 12th Five-Year of Social and Economic Development(2012BAC22B00)
文摘An ensemble prediction system based on the GRAPES model, using multi-physics, is used to discuss the influence of different physical processes in numerical models on forecast of heavy rainfall in South China in the annually first raining season(AFRS). Pattern, magnitude and area of precipitation, evolution of synoptic situation, as well as apparent heat source and apparent moisture sink between different ensemble members are comparatively analyzed. The choice of parameterization scheme for land-surface processes gives rise to the largest influence on the precipitation prediction. The influences of cumulus-convection and cloud-microphysics processes are mainly focused on heavy rainfall;the use of cumulus-convection parameterization tends to produce large-area and light rainfall. Change in parameterization schemes for land-surface and cumulus-convection processes both will cause prominent change in forecast of both dynamic and thermodynamic variables, while change in cloud-microphysics processes show primary impact on dynamic variables. Comparing simplified Arakawa-Schubert and Kain-Fritsch with Betts-Miller-Janjic schemes, SLAB with NOAH schemes, as well as both WRF single moment 6-class and NCEP 3-class with simplified explicit schemes of phase-mixed cloud and precipitation shows that the former predicts stronger low-level jets and high humidity concentration, more convective rainfall and local heavy rainfall, and have better performance in precipitation forecast. Appropriate parameterization schemes can reasonably describe the physical process related to heavy rainfall in South China in the AFRS, such as low-level convergence, latent heat release, vertical transport of heat and water vapor, thereby depicting the multi-scale interactions of low-level jet and meso-scale convective systems in heavy rainfall suitably, and improving the prediction of heavy rainfall in South China in the AFRS as a result.
基金National Key Research and Development(R&D)Program of China,(Grant No.2018YFC1507405).
文摘To represent model uncertainties more comprehensively,a stochastically perturbed parameterization(SPP)scheme consisting of temporally and spatially varying perturbations of 18 parameters in the microphysics,convection,boundary layer,and surface layer parameterization schemes,as well as the stochastically perturbed parameterization tendencies(SPPT)scheme,and the stochastic kinetic energy backscatter(SKEB)scheme,is applied in the Global and Regional Assimilation and Prediction Enhanced System-Regional Ensemble Prediction System(GRAPES-REPS)to evaluate and compare the general performance of various combinations of multiple stochastic physics schemes.Six experiments are performed for a summer month(1-30 June 2015)over China and multiple verification metrics are used.The results show that:(1)All stochastic experiments outperform the control(CTL)experiment,and all combinations of stochastic parameterization schemes perform better than the single SPP scheme,indicating that stochastic methods can effectively improve the forecast skill,and combinations of multiple stochastic parameterization schemes can better represent model uncertainties;(2)The combination of all three stochastic physics schemes(SPP,SPPT,and SKEB)outperforms any other combination of two schemes in precipitation forecasting and surface and upper-air verification to better represent the model uncertainties and improve the forecast skill;(3)Combining SKEB with SPP and/or SPPT results in a notable increase in the spread and reduction in outliers for the upper-air wind speed.SKEB directly perturbs the wind field and therefore its addition will greatly impact the upper-air wind-speed fields,and it contributes most to the improvement in spread and outliers for wind;(4)The introduction of SPP has a positive added value,and does not lead to large changes in the evolution of the kinetic energy(KE)spectrum at any wavelength;(5)The introduction of SPPT and SKEB would cause a 5%-10%and 30%-80%change in the KE of mesoscale systems,and all three stochastic schemes(SPP,SPPT,and SKEB)mainly affect the KE of mesoscale systems.This study indicates the potential of combining multiple stochastic physics schemes and lays a foundation for the future development and design of regional and global ensembles.
基金supported by the National Key R&D Program of China(no.2022YFA1203902)the National Natural Science Foundation of China(no.12425402 and no.12250007)+1 种基金Bejing Natural Science Foundation(no.JQ21018)the China Postdoctoral Science Foundation(2023TQ0003 and 2023M740122).
文摘Photodetectors equipped with multi-parameter control hold the potential to deliver exceptional performance in a wide range of scenarios,paving the way for developing novel spin-opto-electronic devices.Nevertheless,the integration of such capabilities within a single device is challenging due to the necessity of harmonizing multiple materials with varying degrees of freedom.In this study,we introduce the van der Waals magnet CrSBr,featuring inherent anisotropy and distinctive spin-electronic coupling,to this realm.The linear dichroic ratio of the photocurrent in CrSBr tunneling device can reach~60 at 1.65 K,and the photoresponse experiences a significant boost with increasing magnetic field.Additionally,the unique spin-charge coupling engenders a photon energy-dependent photocurrent that is modulated by an external field and is validated by first-principle calculations.Our findings elucidate the effective multi-parameter control of photodetection based on vdWs magnet CrsBr,highlighting its potential applications in cutting-edge optoelectronic devices and as a highly sensitive probe medium.
文摘目的探讨生境成像(habitat imaging,HI)无创定量可视化前列腺癌(prostate cancer,PCa)分区异质性并预测其危险度的可行性。材料与方法回顾性收集2018年1月至2024年8月在西京医院行多参数磁共振成像(multi-parameteric magnetic resonance imaging,mpMRI)扫描,包括扩散加权成像、体素内非相干运动加权成像和扩散峰度成像,并经根治性前列腺切除术(radical prostatectomy,RP)后病理证实为PCa的147例患者的临床及影像资料,以7∶3分为训练集和测试集。根据RP结果分为移行区(transition zone,TZ)和外周区(peripheral zone,PZ)PCa。整合每体素表观扩散系数(apparent diffusion coefficient,ADC)、灌注分数(perfusion fraction,f)和平均峰度(mean kurtosis,MK)值,划分生境亚区,生成生境地图,从临床、病理、影像多维度比较PZ和TZ PCa间差异。根据2019版国际泌尿病理协会(International Society of Urological Pathology,ISUP)指南,匹配生境地图与RP标本以评估各亚区ISUP分级,将患者分为低危组(ISUP≤2)和高危组(ISUP≥3)。logistic回归分析高危PCa相关特征并构建基于分区的HI(zone-based HI,zHI)-临床影像模型评估危险度,并评估模型效能。结果根据肘部法所示最佳聚类簇数划分3个生境亚区,生境1较生境2、3的ADC、f值更低,MK值更高。相较于TZ,PZ PCa患者临床、病理特征更恶,生境1占比更高。logistic回归分析示解剖分区(OR=3.50,95%CI:1.01~12.09)和生境1占比(OR=3.63,95%CI:1.37~9.62)是高危PCa的独立危险因素(P<0.05)。zHI-临床影像模型评估危险度在训练集和测试集的曲线下面积(area under the curve,AUC)分别为0.889(95%CI:0.822~0.955)和0.883(95%CI:0.740~0.925)。结论本研究多维度验证了PCa分区异质性,并基于解剖分区和HI特征构建模型,对PCa危险度的无创定量可视化预测具有增益效能。
基金financially supported by National Key R&D Program of China (No. 2018YFC1505201)National Natural Science Foundation of China (No. 41901008)+2 种基金Open Fund Project of Key Laboratory of Mountain Hazards and Surface Processes of the Chinese Academy of Sciencesthe Fundamental Research Funds for the Central Universities (Grant NO. 2682018CX05)financially supported by China Scholarship Council
文摘Oil and gas pipelines are of great importance in China,and pipeline security problems pose a serious threat to society and the environment.Pipeline safety has therefore become an integral part of the entire national economy.Landslides are the most harmful type of pipeline accident,and have directed increasing public attention to safety issues.Although some useful results have been obtained in the investigation and prevention of pipeline-landslide hazards,there remains a need for effective monitoring and early warning methods,especially when the complexity of pipeline-landslides is considered.Because oil and gas pipeline-landslides typically occur in the superficial soil layers,monitoring instruments must be easy to install and must cause minimal disturbance to the surrounding soil and pipeline.To address the particular characteristics of pipelinelandslides,we developed a multi-parameter integrated monitoring system called disaster reduction stick equipment.In this paper,we detail this monitoring and early warning system for pipeline-landslide hazards based on an on-site monitoring network and early warning algorithms.The functionality of our system was verified by its successful application to the Chongqing Loujiazhuang pipeline-landslide in China.The results presented here provide guidelines for the monitoring,early warning,and prevention of pipeline geological hazards.
