Time domain analysis is an essential implement to study the buffeting behavior of long-span bridges for it can consider the non-linear effect which is significant in long-span bridges. The prerequisite of time domain ...Time domain analysis is an essential implement to study the buffeting behavior of long-span bridges for it can consider the non-linear effect which is significant in long-span bridges. The prerequisite of time domain analysis is the accurate description of 3D turbulence winds. In this paper, some hypotheses for simplifying the 3D turbulence simulation of long-span cable-stayed bridges are conducted, considering the structural characteristics. The turbulence wind which is a 3D multivariate stochastic vector process is converted into four independent 1D univariate stochastic processes. Based on recorded wind data from structural health monitoring system (SHMS) of the Sutong Bridge, China, the measured spectra expressions are then presented using the nonlinear least-squares fitting method. Turbulence winds at the Sutong Bridge site are simulated based on the spectral representation method and the Fast Fourier transform (FFT) technique, and the relevant results derived from target spectra including measured spectra and recommended spectra are compared. The reliability and accuracy of the presented turbulence simulation method are validated through comparisons between simulated and target spectra (measured and recommended spectra). The obtained turbulence si-mulations can not only serve further analysis of the buffeting behavior of the Sutong Bridge, but references for structural anti-wind design in adjacent regions.展开更多
An adaptable and compact fast pulse sampling module was developed for the neutron–gamma discrimination. The developed module is well suited for low-cost and low-power consumption applications. It is based on the Domi...An adaptable and compact fast pulse sampling module was developed for the neutron–gamma discrimination. The developed module is well suited for low-cost and low-power consumption applications. It is based on the Domino Ring Sampler 4(DRS4) chip, which offers fast sampling speeds up to 5.12 giga samples per second(GSPS) to digitize pulses from front-end detectors. The high-resolution GSPS data is useful for obtaining precise real-time neutron–gamma discrimination results directly in this module. In this study, we have implemented real-time data analysis in a field programmable gate array. Real-time data analysis involves two aspects: digital waveform integral and digital pulse shape discrimination(PSD). It can significantly reduce the system dead time and data rate processed offline. Plastic scintillators(EJ-299-33), which have proven capable of PSD, were adopted as neutron detectors in the experiments. A photomultiplier tube(PMT)(model #XP2020) was coupled to one end of a detector to collect the output light from it. The pulse output from the anode of the PMT was directly passed onto the fast sampling module. The fast pulse sampling module was operated at 1 GSPS and 2 GSPS in these experiments, and the AmBe-241 source was used to examine the neutron–gamma discrimination quality. The PSD results with different sampling rates and energy thresholds were evaluated. The figure of merit(FOM) was used to describe the neutron–gamma discrimination quality. The best FOM value of 0.91 was obtained at 2 GSPS and 1 GSPS sampling rates with an energy threshold of 1.5 MeV_(ee)(electron equivalent).展开更多
Based on the BL09 terminal of China Spallation Neutron Source(CSNS),single event upset(SEU)cross sections of14 nm fin field-effect transistor(FinFET)and 65 nm quad data rate(QDR)static random-access memories(SRAMs)are...Based on the BL09 terminal of China Spallation Neutron Source(CSNS),single event upset(SEU)cross sections of14 nm fin field-effect transistor(FinFET)and 65 nm quad data rate(QDR)static random-access memories(SRAMs)are obtained under different incident directions of neutrons:front,back and side.It is found that,for both technology nodes,the“worst direction”corresponds to the case that neutrons traverse package and metallization before reaching the sensitive volume.The SEU cross section under the worst direction is 1.7-4.7 times higher than those under other incident directions.While for multiple-cell upset(MCU)sensitivity,side incidence is the worst direction,with the highest MCU ratio.The largest MCU for the 14 nm FinFET SRAM involves 8 bits.Monte-Carlo simulations are further performed to reveal the characteristics of neutron induced secondary ions and understand the inner mechanisms.展开更多
Background Fast neutron detection is meaningful in many research fields such as space environment monitoring.A scintillating fiber array model for fast neutron detection was proposed and developed in 1980s.Aerospace a...Background Fast neutron detection is meaningful in many research fields such as space environment monitoring.A scintillating fiber array model for fast neutron detection was proposed and developed in 1980s.Aerospace applications of the model require electronics in small size.Purpose To design a dedicated electronic system to readout and process the 384-channel signals from scintillating fiber array,and to use the designed system to fabricate a neutron detector for aerospace applications.Methods With the method of nuclear recoil,fast neutron is detected by tracking recoil proton of n–p scatter in scintillating plastic fibers.Using the peak-holding circuits and multiplexers,the system size and power consumption were reduced.Results The detector fabricated with the designed system,had 34 cm×34 cm×27 cm mechanical size,20.4 kg weight,and 30.05W power consumption.Comparing to traditional waveform sampling electronics,the designed electronics was highly integrated and had a small size.The readout electronics also gave a better energy resolution of 39%in neutron detection,while the energy resolution was 43%in previous version.Conclusion In this study,a highly integrated readout electronic system was designed and verified.The detector using the system gave good performance.The designed electronics had potential development in fast neutron detection and other high energy physics detection system.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 50725828, 50908046, and 50978056)the Teaching & Scientific Research Fund for Excellent Young Teachers of Southeast University+2 种基金the Open Fund of Jiangsu Key Laboratory of Environmental Impact and Structural Safety in Engineeringthe Basic Scientific & Research Fund of Southeast University (No. Seucx-201106)the Priority Academic Program Development Foundation of Jiangsu Higher Education Institutions, China
文摘Time domain analysis is an essential implement to study the buffeting behavior of long-span bridges for it can consider the non-linear effect which is significant in long-span bridges. The prerequisite of time domain analysis is the accurate description of 3D turbulence winds. In this paper, some hypotheses for simplifying the 3D turbulence simulation of long-span cable-stayed bridges are conducted, considering the structural characteristics. The turbulence wind which is a 3D multivariate stochastic vector process is converted into four independent 1D univariate stochastic processes. Based on recorded wind data from structural health monitoring system (SHMS) of the Sutong Bridge, China, the measured spectra expressions are then presented using the nonlinear least-squares fitting method. Turbulence winds at the Sutong Bridge site are simulated based on the spectral representation method and the Fast Fourier transform (FFT) technique, and the relevant results derived from target spectra including measured spectra and recommended spectra are compared. The reliability and accuracy of the presented turbulence simulation method are validated through comparisons between simulated and target spectra (measured and recommended spectra). The obtained turbulence si-mulations can not only serve further analysis of the buffeting behavior of the Sutong Bridge, but references for structural anti-wind design in adjacent regions.
基金supported by the Instrument Developing Project of the Chinese Academy of Sciences(No.29201707)
文摘An adaptable and compact fast pulse sampling module was developed for the neutron–gamma discrimination. The developed module is well suited for low-cost and low-power consumption applications. It is based on the Domino Ring Sampler 4(DRS4) chip, which offers fast sampling speeds up to 5.12 giga samples per second(GSPS) to digitize pulses from front-end detectors. The high-resolution GSPS data is useful for obtaining precise real-time neutron–gamma discrimination results directly in this module. In this study, we have implemented real-time data analysis in a field programmable gate array. Real-time data analysis involves two aspects: digital waveform integral and digital pulse shape discrimination(PSD). It can significantly reduce the system dead time and data rate processed offline. Plastic scintillators(EJ-299-33), which have proven capable of PSD, were adopted as neutron detectors in the experiments. A photomultiplier tube(PMT)(model #XP2020) was coupled to one end of a detector to collect the output light from it. The pulse output from the anode of the PMT was directly passed onto the fast sampling module. The fast pulse sampling module was operated at 1 GSPS and 2 GSPS in these experiments, and the AmBe-241 source was used to examine the neutron–gamma discrimination quality. The PSD results with different sampling rates and energy thresholds were evaluated. The figure of merit(FOM) was used to describe the neutron–gamma discrimination quality. The best FOM value of 0.91 was obtained at 2 GSPS and 1 GSPS sampling rates with an energy threshold of 1.5 MeV_(ee)(electron equivalent).
基金Project supported by the Key-Area Research and Development Program of Guangdong Province,China(Grant No.2019B010145001)the National Natural Science Foundation of China(Grant Nos.12075065 and 12175045)the Applied Fundamental Research Project of Guangzhou City,China(Grant No.202002030299)
文摘Based on the BL09 terminal of China Spallation Neutron Source(CSNS),single event upset(SEU)cross sections of14 nm fin field-effect transistor(FinFET)and 65 nm quad data rate(QDR)static random-access memories(SRAMs)are obtained under different incident directions of neutrons:front,back and side.It is found that,for both technology nodes,the“worst direction”corresponds to the case that neutrons traverse package and metallization before reaching the sensitive volume.The SEU cross section under the worst direction is 1.7-4.7 times higher than those under other incident directions.While for multiple-cell upset(MCU)sensitivity,side incidence is the worst direction,with the highest MCU ratio.The largest MCU for the 14 nm FinFET SRAM involves 8 bits.Monte-Carlo simulations are further performed to reveal the characteristics of neutron induced secondary ions and understand the inner mechanisms.
基金This work was supported by the Ministry of Science and Technology of China(2013YQ03062902)CAS pilot strategic science and technology projects(XDA14020502)the National Natural Science Foundation of China(U1332202).
文摘Background Fast neutron detection is meaningful in many research fields such as space environment monitoring.A scintillating fiber array model for fast neutron detection was proposed and developed in 1980s.Aerospace applications of the model require electronics in small size.Purpose To design a dedicated electronic system to readout and process the 384-channel signals from scintillating fiber array,and to use the designed system to fabricate a neutron detector for aerospace applications.Methods With the method of nuclear recoil,fast neutron is detected by tracking recoil proton of n–p scatter in scintillating plastic fibers.Using the peak-holding circuits and multiplexers,the system size and power consumption were reduced.Results The detector fabricated with the designed system,had 34 cm×34 cm×27 cm mechanical size,20.4 kg weight,and 30.05W power consumption.Comparing to traditional waveform sampling electronics,the designed electronics was highly integrated and had a small size.The readout electronics also gave a better energy resolution of 39%in neutron detection,while the energy resolution was 43%in previous version.Conclusion In this study,a highly integrated readout electronic system was designed and verified.The detector using the system gave good performance.The designed electronics had potential development in fast neutron detection and other high energy physics detection system.
