The steel-shell concrete immersed tube(SSIT)with the self-compacting concrete(SCC)has been applied in the Shenzhen–Zhongshan Link,and the SSIT is prone to the void defect during the concrete pouring process.This work...The steel-shell concrete immersed tube(SSIT)with the self-compacting concrete(SCC)has been applied in the Shenzhen–Zhongshan Link,and the SSIT is prone to the void defect during the concrete pouring process.This work aims to study the flow behavior of the SCC and investigate the generation and distribution of the void defect in the SSIT,and the computational fluid dynamics(CFD)models are adopted to solve the above problems.To verify the CFD models,the slump test,L-box test,and field test based on Ok.the impact image method are carried out.The effects of the connecting hole spacing,the exhaust hole number,the exhaust hole position and the pouring speed on the flow behavior and the void defects distribution are quantitatively compared.According to the comparison results,the standard compartment with 300 mm connecting hole spacing and 10 exhaust holes is the optimal compartment structure design,and the concrete pouring speed of 15 m^(3)/h is the optimal construction method.This work demonstrates that the CFD model offers a useful way to evaluate the generation and distribution features of the void defects for the steel–concrete–steel structure.展开更多
In this study,waveform data obtained from Western Sichuan Seismic Array(WSSA)in China was utilized to reveal the temporal variations in coda attenuation around the eastern Tibet Plateau and Western Sichuan.Based on th...In this study,waveform data obtained from Western Sichuan Seismic Array(WSSA)in China was utilized to reveal the temporal variations in coda attenuation around the eastern Tibet Plateau and Western Sichuan.Based on the single-scattering model,coda attenuation factor QC^(-1)is calculated in narrower overlapping frequency bands at 1.0-24 Hz by measuring the coda decay rates for local earthquakes before and after the Wenchuan mainshock.The temporal variations in coda attenuation are investigated within three periods.The periodⅠlasted from January 2007 to the end of 2007.The periodⅡlasted from January 2008 till Wenchuan earthquake.The periodⅢlasted from the mainshock to the end of 2008.The resulted temporal variations demonstrate an increase in average QC^(-1)by approximately 35%-45%in the vicinity of Longmenshan and 30%-35%in Sichuan Basin after the Wenchuan earthquake in lower frequency bands within 1.25-8 Hz.On the contrary,the average QC^(-1)is shown to decrease by approximately10%-18%in southern segment of Longmenshan,15%-38%in the Chuan-Dian block,and 10-12%in the South China block.These results are confirmed by a statistical t-test at 99.9%confidence level No statistically significant change in QC^(-1)(<10%)is found in the Songpan-Ganzi block after the mainshock.Temporal variations of coda attenuation differ significantly in individual blocks after the mainshock.The coda attenuation is proposed to be a beacon to tectonic static stress changes associated with the Wenchuan earthquake.展开更多
Flexible sensors are required to be lightweight,compatible with the skin,sufficiently sensitive,and easily integrated to extract various kinds of body vital signs during continuous healthcare monitoring in daily life....Flexible sensors are required to be lightweight,compatible with the skin,sufficiently sensitive,and easily integrated to extract various kinds of body vital signs during continuous healthcare monitoring in daily life.For this,a simple and low-cost flexible temperature and force sensor that uses only two carbon fiber beams as the sensing layer is reported in this work.This simple,flexible sensor can not only monitor skin temperature changes in real time but can also extract most pulse waves,including venous waves,from most parts of the human body.A pulse diagnostic glove containing three such flexible sensors was designed to simulate pulse diagnostic methods used in traditional Chinese medicine.Wearable equipment was also designed in which four flexible sensors were fixed onto different body parts(neck,chest,armpit,and fingertip)to simultaneously monitor body temperature,carotid pulse,fingertip artery pulse,and respiratory rate.Four important physiological indicators—body temperature(BT),blood pressure(BP),heart rate(HR),and respiratory rate(RR)—were extracted by the wearable equipment and analyzed to identify exercise,excited,tired,angry,and frightened body states.展开更多
基金supported by the R&D Projects in Key Areas of Guangdong Province(No.20191105).
文摘The steel-shell concrete immersed tube(SSIT)with the self-compacting concrete(SCC)has been applied in the Shenzhen–Zhongshan Link,and the SSIT is prone to the void defect during the concrete pouring process.This work aims to study the flow behavior of the SCC and investigate the generation and distribution of the void defect in the SSIT,and the computational fluid dynamics(CFD)models are adopted to solve the above problems.To verify the CFD models,the slump test,L-box test,and field test based on Ok.the impact image method are carried out.The effects of the connecting hole spacing,the exhaust hole number,the exhaust hole position and the pouring speed on the flow behavior and the void defects distribution are quantitatively compared.According to the comparison results,the standard compartment with 300 mm connecting hole spacing and 10 exhaust holes is the optimal compartment structure design,and the concrete pouring speed of 15 m^(3)/h is the optimal construction method.This work demonstrates that the CFD model offers a useful way to evaluate the generation and distribution features of the void defects for the steel–concrete–steel structure.
基金supported by the National Natural Science Foundation of China(No.41874161 and No.41720104006)the Youth Innovation Promotion Association Foundation of the Chinese Academy of Sciences(No.2019069)Guangdong Provincial Key R&D Program(No.2019B111105002)。
文摘In this study,waveform data obtained from Western Sichuan Seismic Array(WSSA)in China was utilized to reveal the temporal variations in coda attenuation around the eastern Tibet Plateau and Western Sichuan.Based on the single-scattering model,coda attenuation factor QC^(-1)is calculated in narrower overlapping frequency bands at 1.0-24 Hz by measuring the coda decay rates for local earthquakes before and after the Wenchuan mainshock.The temporal variations in coda attenuation are investigated within three periods.The periodⅠlasted from January 2007 to the end of 2007.The periodⅡlasted from January 2008 till Wenchuan earthquake.The periodⅢlasted from the mainshock to the end of 2008.The resulted temporal variations demonstrate an increase in average QC^(-1)by approximately 35%-45%in the vicinity of Longmenshan and 30%-35%in Sichuan Basin after the Wenchuan earthquake in lower frequency bands within 1.25-8 Hz.On the contrary,the average QC^(-1)is shown to decrease by approximately10%-18%in southern segment of Longmenshan,15%-38%in the Chuan-Dian block,and 10-12%in the South China block.These results are confirmed by a statistical t-test at 99.9%confidence level No statistically significant change in QC^(-1)(<10%)is found in the Songpan-Ganzi block after the mainshock.Temporal variations of coda attenuation differ significantly in individual blocks after the mainshock.The coda attenuation is proposed to be a beacon to tectonic static stress changes associated with the Wenchuan earthquake.
基金It is mainly supported by Guangdong Natural Science foundation for Distinguished Young Scholar(2015A030306031)National Natural Science Foundation of China(51802229)+5 种基金Natural Science Foundation of Guangdong Province(2018A030313561)Innovation and strong school engineering fund of Guangdong Province(2016KQNCX169 and 2017KTSCX186)This work is also supported in part by the Science and Technology Projects of Jiangmen((2017)307,(2017)149,and(2018)352)Cooperative education platform of Guangdong Province((2016)31)Key Laboratory of Optoelectronic materials and Applications in Guangdong Higher Education(2017KSYS011)Science Foundation for Young Teachers of Wuyi University(2018td04).
文摘Flexible sensors are required to be lightweight,compatible with the skin,sufficiently sensitive,and easily integrated to extract various kinds of body vital signs during continuous healthcare monitoring in daily life.For this,a simple and low-cost flexible temperature and force sensor that uses only two carbon fiber beams as the sensing layer is reported in this work.This simple,flexible sensor can not only monitor skin temperature changes in real time but can also extract most pulse waves,including venous waves,from most parts of the human body.A pulse diagnostic glove containing three such flexible sensors was designed to simulate pulse diagnostic methods used in traditional Chinese medicine.Wearable equipment was also designed in which four flexible sensors were fixed onto different body parts(neck,chest,armpit,and fingertip)to simultaneously monitor body temperature,carotid pulse,fingertip artery pulse,and respiratory rate.Four important physiological indicators—body temperature(BT),blood pressure(BP),heart rate(HR),and respiratory rate(RR)—were extracted by the wearable equipment and analyzed to identify exercise,excited,tired,angry,and frightened body states.
