针对钢筋混凝土结构锈蚀检测难的问题,采用金属磁记忆(Metal Magnetic Memory)无损检测技术,开展了钢筋混凝土锈蚀检测试验,探索其内部钢筋锈蚀与漏磁信号之间的特征关系。首先对10片试验梁采用电化学加速锈蚀,然后对锈蚀后的试验梁进...针对钢筋混凝土结构锈蚀检测难的问题,采用金属磁记忆(Metal Magnetic Memory)无损检测技术,开展了钢筋混凝土锈蚀检测试验,探索其内部钢筋锈蚀与漏磁信号之间的特征关系。首先对10片试验梁采用电化学加速锈蚀,然后对锈蚀后的试验梁进行漏磁信号采集,最后开展破坏性试验来验证钢筋锈蚀情况。结果表明:钢筋锈蚀区域用漏磁信号切向分量Bx曲线交点或其梯度dBx/dx曲线判断;当漏磁探头提离高度Z=2 cm时,漏磁信号切向分量极值增量ΔBx_i与钢筋锈蚀深度h呈明显线性相关性;钢筋断裂可以通过漏磁信号切向分量Bx极值或其梯度dBx/dx极值相对上一个阶段不再增加来进行判别。并通过COMSOL建模验证了试验梁锈蚀检测试验结果的可靠性。展开更多
Background：Magnetic resonance （MR） imaging provides a unique,noninvasive diagnostic platform to quantify the physiological and biochemical variables of skeletal muscle at rest.This study was to investigate the diff...Background：Magnetic resonance （MR） imaging provides a unique,noninvasive diagnostic platform to quantify the physiological and biochemical variables of skeletal muscle at rest.This study was to investigate the difference in thigh skeletal muscles between snowboarding halfpipe athletes and healthy volunteers via multiparametric MR imaging.Methods：A comparative study was conducted between 12 healthy volunteers and 14 snowboarding halfpipe athletes.MR scanning targeted the left leg at the level of the proximal thigh on a 3.0T MR system.The measured parameters compared between the two groups included T1,T2,T2＊ relaxation times,fat fraction （FF）,and cross-sectional area （CSA） of the quadriceps femoris and the hamstring muscles.Statistical analysis was carried out using independent sample t-test.Interrater reliability was also assessed with intraclass correlation coefficients （ICCs）.Results：It was statistically equivalent between two groups in age,body mass index,thigh circumference,calf circumference,systolic blood pressure,and resting heart rate （all P ＞ 0.05）.However,the T1 and T2 values of the hamstring muscles in the athlete group were found to be significantly shorter than those in control group （T1：1063.3 ± 24.1 ms vs.1112.0 ± 38.2 ms in biceps femoris,1050.4 ± 31.2 ms vs.1095.0 ± 39.5 ms in semitendinosus,1053.1 ± 31.7 ms vs.1118.4 ± 40.0 ms in semimembranosus,respectively;T2：33.4 ± 0.7 ms vs.36.1 ± 1.9 ms in biceps femoris,34.6 ± 2.0 ms vs.37.0 ± 1.9 ms in semitendinosus,36.9 ± 1.5 ms vs.38.9 ± 2.4 ms in semimembranosus,respectively;all P ＜ 0.05） although T2＊ relaxation time was detected with no significant difference.The FF of the hamstring muscles was obviously less than the control group （5.5 ± 1.9％ vs.10.7 ± 4.7％,P ＜ 0.001）.In addition,the quadriceps＇ CSA in the athlete group was substantially larger than the control group （8039.0 ± 1072.3 vs.6258.2 ± 852.0 mm2,P ＜ 0.001）.Interrater reliability was excellent （ICC：0.758-0.994）.Conclusion：Multiple MR imaging parameters indicated significant differences between snowboarding halfpipe athletes and healthy volunteers in the thigh skeletal muscles.展开更多
文摘针对钢筋混凝土结构锈蚀检测难的问题,采用金属磁记忆(Metal Magnetic Memory)无损检测技术,开展了钢筋混凝土锈蚀检测试验,探索其内部钢筋锈蚀与漏磁信号之间的特征关系。首先对10片试验梁采用电化学加速锈蚀,然后对锈蚀后的试验梁进行漏磁信号采集,最后开展破坏性试验来验证钢筋锈蚀情况。结果表明:钢筋锈蚀区域用漏磁信号切向分量Bx曲线交点或其梯度dBx/dx曲线判断;当漏磁探头提离高度Z=2 cm时,漏磁信号切向分量极值增量ΔBx_i与钢筋锈蚀深度h呈明显线性相关性;钢筋断裂可以通过漏磁信号切向分量Bx极值或其梯度dBx/dx极值相对上一个阶段不再增加来进行判别。并通过COMSOL建模验证了试验梁锈蚀检测试验结果的可靠性。
基金This work was supported by grants from the National Key Research and Development Program of China （No. 2016YFC0107102） and the National Natural Science Foundation of China （No. 30871211 and No. 81271538）.
文摘Background：Magnetic resonance （MR） imaging provides a unique,noninvasive diagnostic platform to quantify the physiological and biochemical variables of skeletal muscle at rest.This study was to investigate the difference in thigh skeletal muscles between snowboarding halfpipe athletes and healthy volunteers via multiparametric MR imaging.Methods：A comparative study was conducted between 12 healthy volunteers and 14 snowboarding halfpipe athletes.MR scanning targeted the left leg at the level of the proximal thigh on a 3.0T MR system.The measured parameters compared between the two groups included T1,T2,T2＊ relaxation times,fat fraction （FF）,and cross-sectional area （CSA） of the quadriceps femoris and the hamstring muscles.Statistical analysis was carried out using independent sample t-test.Interrater reliability was also assessed with intraclass correlation coefficients （ICCs）.Results：It was statistically equivalent between two groups in age,body mass index,thigh circumference,calf circumference,systolic blood pressure,and resting heart rate （all P ＞ 0.05）.However,the T1 and T2 values of the hamstring muscles in the athlete group were found to be significantly shorter than those in control group （T1：1063.3 ± 24.1 ms vs.1112.0 ± 38.2 ms in biceps femoris,1050.4 ± 31.2 ms vs.1095.0 ± 39.5 ms in semitendinosus,1053.1 ± 31.7 ms vs.1118.4 ± 40.0 ms in semimembranosus,respectively;T2：33.4 ± 0.7 ms vs.36.1 ± 1.9 ms in biceps femoris,34.6 ± 2.0 ms vs.37.0 ± 1.9 ms in semitendinosus,36.9 ± 1.5 ms vs.38.9 ± 2.4 ms in semimembranosus,respectively;all P ＜ 0.05） although T2＊ relaxation time was detected with no significant difference.The FF of the hamstring muscles was obviously less than the control group （5.5 ± 1.9％ vs.10.7 ± 4.7％,P ＜ 0.001）.In addition,the quadriceps＇ CSA in the athlete group was substantially larger than the control group （8039.0 ± 1072.3 vs.6258.2 ± 852.0 mm2,P ＜ 0.001）.Interrater reliability was excellent （ICC：0.758-0.994）.Conclusion：Multiple MR imaging parameters indicated significant differences between snowboarding halfpipe athletes and healthy volunteers in the thigh skeletal muscles.
