Temporal variations in coda attenuation associated with the 2008 Wenchuan(M_(W)7.9)Earthquake in SW,China

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.

Identifying human body states by using a flexible integrated sensor

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.