The capability of embedded piezoelectric wafer active sensors(PWAS)to perform in-situ nondestructive evaluation(NDE)for structural health monitoring(SHM)of reinforced concrete(RC)structures strengthened with fiber rei...The capability of embedded piezoelectric wafer active sensors(PWAS)to perform in-situ nondestructive evaluation(NDE)for structural health monitoring(SHM)of reinforced concrete(RC)structures strengthened with fiber reinforced polymer(FRP)composite overlays is explored.First,the disbond detection method were developed on coupon specimens consisting of concrete blocks covered with an FRP composite layer.It was found that the presence of a disbond crack drastically changes the electromecfianical(E/M)impedance spectrum lneasurcd at the PWAS terlninals.The spectral changes depend on the distance between the PWAS and the crack tip.Second,large scale experiments were conducted on a RC beam strengthened with carbon fiber reinforced polymer(CFRP)composite overlay.The beam was subject to an accelerated fatigue load regime in a three-point bending configuration up to a total of 807,415 cycles.During these fatigue tests,the CFRP overlay experienced disbonding beginning at about 500,000 cycles.The PWAS were able to detect the disbonding before it could be reliably seen by visual inspection.Good correlation between the PWAS readings and the position and extent of disbond damage was observed.These preliminary results demonstrate the potential of PWAS technology for SHM of RC structures strengthened with FRP composite overlays.展开更多
【目的】探讨检测急性肺栓塞患者的血浆脑钠肽（BNP）、肌钙蛋白I（cTnI）及D‐二聚体（D‐dimer）水平变化的临床意义。【方法】选择本院2009年1月至2013年12月收治的急性肺栓塞患者64例，根据患者病情分为大面积肺栓塞组（ n ＝27）...【目的】探讨检测急性肺栓塞患者的血浆脑钠肽（BNP）、肌钙蛋白I（cTnI）及D‐二聚体（D‐dimer）水平变化的临床意义。【方法】选择本院2009年1月至2013年12月收治的急性肺栓塞患者64例，根据患者病情分为大面积肺栓塞组（ n ＝27）和非大面积肺栓塞组（ n ＝37），对两组患者血浆cTnI、BNP及D‐dimer水平进行测定，观察比较两组患者各指标水平的变化及右心功能和病死率。【结果】大面积肺栓塞组BN P、血浆cTnI水平明显高于非大面积肺栓塞组，两组比较差异有显著性（ P ＜0．05）；两组D‐dimer浓度比较差异无统计学意义（ P ＞0．05）；大面积肺栓塞组的右心功能不全者和病死率均高于非大面积肺栓塞组，两组比较差异有统计学意义（ P ＜0．05）。【结论】检测BNP、cTnI及D‐dimer水平对APE患者临床诊断、临床决策及预后判断具有重要的临床意义。展开更多
基金the National Seienee Foundation through grants NSF#CMS-9908293 and NSF INT-9904493the Federal Highway Administration and the South Carolina Department of TransPortation(projeet Number 614)
文摘The capability of embedded piezoelectric wafer active sensors(PWAS)to perform in-situ nondestructive evaluation(NDE)for structural health monitoring(SHM)of reinforced concrete(RC)structures strengthened with fiber reinforced polymer(FRP)composite overlays is explored.First,the disbond detection method were developed on coupon specimens consisting of concrete blocks covered with an FRP composite layer.It was found that the presence of a disbond crack drastically changes the electromecfianical(E/M)impedance spectrum lneasurcd at the PWAS terlninals.The spectral changes depend on the distance between the PWAS and the crack tip.Second,large scale experiments were conducted on a RC beam strengthened with carbon fiber reinforced polymer(CFRP)composite overlay.The beam was subject to an accelerated fatigue load regime in a three-point bending configuration up to a total of 807,415 cycles.During these fatigue tests,the CFRP overlay experienced disbonding beginning at about 500,000 cycles.The PWAS were able to detect the disbonding before it could be reliably seen by visual inspection.Good correlation between the PWAS readings and the position and extent of disbond damage was observed.These preliminary results demonstrate the potential of PWAS technology for SHM of RC structures strengthened with FRP composite overlays.
文摘【目的】探讨检测急性肺栓塞患者的血浆脑钠肽（BNP）、肌钙蛋白I（cTnI）及D‐二聚体（D‐dimer）水平变化的临床意义。【方法】选择本院2009年1月至2013年12月收治的急性肺栓塞患者64例，根据患者病情分为大面积肺栓塞组（ n ＝27）和非大面积肺栓塞组（ n ＝37），对两组患者血浆cTnI、BNP及D‐dimer水平进行测定，观察比较两组患者各指标水平的变化及右心功能和病死率。【结果】大面积肺栓塞组BN P、血浆cTnI水平明显高于非大面积肺栓塞组，两组比较差异有显著性（ P ＜0．05）；两组D‐dimer浓度比较差异无统计学意义（ P ＞0．05）；大面积肺栓塞组的右心功能不全者和病死率均高于非大面积肺栓塞组，两组比较差异有统计学意义（ P ＜0．05）。【结论】检测BNP、cTnI及D‐dimer水平对APE患者临床诊断、临床决策及预后判断具有重要的临床意义。
