ELECTRIC RESISTANCE MEASUREMENT OF CARBON FIBRE SMART CONCRETE

After having measured the electric resistance of carbon firbre reinforced concrete (CFRC) by applying a D. C. current, it was found that the current passing through the specimen under a constant voltage decreased with the time, and if changing the value of voltage, the electric resistance was obviously affected. When current flew through the specimen, polarisation emerged under a high votage (>5 upsilon), but that could be neglected under a low voltage (<5 upsilon).(1)

Detecting Impact Damage in Carbon Fabric/epoxy-matrix Composites by Ultrasonic F-scan and Electrical Resistance Measurement

The status and the variation of electrical resistance of impacted carbon fiber/epoxy-matrix composites were studied by ultrasonic F-scan and electrical resistance measurement The experimental results shows that impact damage energy threshold value of carbon fabric/epoxy-matrix composites can determine by using ultrasonic F-scan. When the impact energy exceeds the threshold value, damage is generated in composites. Electrical resistance of impacted composites is changed owing to the contact of each carbon fiber unit in composites, which cause a change of the series-parallel in conductors. The veracity of detecting impact damage in composites can be improved in this case.

Evaluation of Impact Damage Tolerance in Carbon Fabric/epoxy-matrix Composites by Electrical Resistance Measurement

Impact damage tolerance is provided in intensity design on composites. The compression intensity of impacted composites requires more than 60% of its original intensity. The influence of impact on compressive intensity and electrical resistance of carbon fabric/epoxy-matrix composites was studied in this paper. The experimental results shows that impact can cause damage in composites, degenerate compressive intensity, and increase resistance. The electrical resistance change rate was used as an evaluation indicator of impact damage tolerance of composites. Impact damage, which results from the applying process of composites, can be identified in time by electrical resistance measurement. So, the safety performance of composites can also be improved.

Tectonic activity and earthquake risk in the Chengnanhe fault zone in Weihai city,Shandong province,China,obtained by using an integrated prospecting technique in geophysics and geology

For city planning and reducing potential earthquake risk,it’s necessary to detect the information of the buried faults in an urban area especially,including the location and activities.An integrated technique with geophysical and geological methods,including the shallow seismic reflection profile,electrical resistivity measurement,geologic borehole section,and exploration trench,was used to detect the Chengnanhe fault,which is one of the two main faults passing through the Weihai urban area in Shandong province,China.The results show that it is a normal fault striking with E-W direction,and it is relatively inactive and stable.By using the thermoluminescence(TL)dating,we found that the Chengnanhe fault initiated in mid-Pleistocene and there was no offset after late Pleistocene.Such an integrated technique with multiple geological and geophysical methods provides a significant assessment of earthquake risk for city planning in urban areas.

Evaluation method of rock damage under uniaxial compression based on unit series-parallel electrical conductive model

The evaluation of rock damage behaviour is an important requirement for ensuring stability control and safety prediction in rock engineering.However,they have not been able to obtain sufficiently accurate and dynamic results due to the insufficient evaluation method.In this study,by means of fractals and unit series division,a unit series-parallel conductive model of damaged rock is derived,and a new evaluation method of rock damage under uniaxial compression was proposed.Rock was damaged by uniaxial compression,while electrical measurements and X-ray microscopy tests were performed to obtain the damaged rock resistivity,porosity,and fractal dimension variation.By establishing the relationship between defined meso-damage factor and resistivity,rock damage evolution law under axial compression was obtained.The results indicate that the growth trend was agree with the classical statistical damage model,which verified the accuracy of the results obtained by the proposed method.Moreover,as the strain increased,the damage factor determined by resistivity gradually decreased to0.06 firstly and then increased rapidly to 0.79.Different from previous damage evolution law,brittle failure was observed and the cracks development in each stage was considered,including the closure(negative damage)and expansion(positive damage)of cracks.

Thermal analysis in high power GaAs-based laser diodes

The thermal characteristics of 808 nm Al Ga As/Ga As laser diodes（LDs） are analyzed via electrical transient measurements and infrared thermography. The temperature rise and thermal resistance are measured at various input currents and powers. From the electrical transient measurements, it is found that there is a significant reduction in thermal resistance with increasing power because of the device power conversion efficiency. The component thermal resistance that was obtained from the structure function showed that the total thermal resistance is mainly composed of the thermal resistance of the sub-mount rather than that of the LD chip, and the thermal resistance of the sub-mount decreases with increasing current. The temperature rise values are also measured by infrared thermography and are calibrated based on a reference image, with results that are lower than those determined by electrical transient measurements. The difference in the results is caused by the limited spatial resolution of the measurements and by the signal being captured from the facet rather than from the junction of the laser diode.

Phase diagram and transport properties of Sb-doped Ca0.88La0.12Fe2As2 single crystals

The effects of isovalent Sb substitution on the superconducting properties of the Ca0.88La0.12Fe2（As1-ySby）2 system have been studied through electrical resistivity measure- ments. It is seen that the antiferromagnetic or structural transition is suppressed with Sb content, and a high-To superconducting phase, accompanied by a low-Tc phase, emerges at 0.02 ≤y ≤ 0.06. In this intermediate-doping regime, normal-state transport shows non-Fermi-liquid-like behaviors with nearly T-linear resistivity above the high-Tc phase. With further Sb doping, this high-Tc phase abruptly vanishes for y 〉 0.06 and the conventional Fermi liquid is restored, while the low-T,, phase remains robust against Sb inlpurities. The coincidence of the high-Tc phase and non-Fermi liquid transport behaviors in the intermediate Sb-doping regime suggests that AFM fluctuations play an important role in the observed non-Fermi liquid behaviors, which may be intimately related to the unusual nonbulk high-Tc phase in this system.