Wall Cracks Detection in Aerial Images Using Improved Mask R-CNN

The present paper proposes a detection method for building exterior wall cracks since manual detection methods have high risk and low efficiency.The proposed method is based on Unmanned Aerial Vehicle(UAV)and computer vision technology.First,a crack dataset of 1920 images was established using UAV to collect the images of a residential building exterior wall under different lighting conditions.Second,the average crack detection precisions of different methods including the Single Shot MultiBox Detector,You Only Look Once v3,You Only Look Once v4,Faster Regional Convolutional Neural Network(R-CNN)and Mask R-CNN methods were compared.Then,the Mask R-CNN method with the best performance and average precision of 0.34 was selected.Finally,based on the characteristics of cracks,the utilization ratio of Mask R-CNN to the underlying features was improved so that the average precision of 0.9 was achieved.It was found that the positioning accuracy and mask coverage rate of the proposed Mask R-CNN method are greatly improved.Also,it will be shown that using UAV is safer than manual detection because manual parameter setting is not required.In addition,the proposed detection method is expected to greatly reduce the cost and risk of manual detection of building exterior wall cracks and realize the efficient identification and accurate labeling of building exterior wall cracks.

Activity enhancement of acetate precursor prepared on MnO_(x)-CeO_(2) catalyst for low-temperature NH_(3)-SCR: Effect of gaseous acetone addition

MnO_(x)-CeO_(2) catalysts are developed by hydrolysis driving redox method using acetate precursor(3 Mn1 Ce-Ac) and nitrate precursor(3 Mn1 Ce-N) for the selective catalytic reduction(SCR) of NO_(x) by NH_(3).A counterpart sample(Cop-3 Mn1 Ce) was prepared by the NH_(3)·H_(2) O co-precipitation method for comparison purpose.Combining the results of physicochemical properties characterization and performance test,we find that the 3 Mn1 Ce-Ac catalyst with some nanorod structures is highly active for the deNOx process.The SCR activity of the 3 Mn1 Ce-Ac catalyst is more admirable than the 3 Mn1 Ce-N and the Cop-3 Mn1 Ce catalysts due to plentiful Lewis acid sites,excellent low-temperature reducibility,and superior surface area resulted from O_(2) generation during the pre paration procedure.The 3 Mn1 Ce-Ac still exhibits the greatest performance for the deNO_(x )process when gaseous acetone is in the SCR feed gas.The NOx conversion and N2 selectivity over the 3 Mn1 Ce-Ac are both improved by gaseous acetone above150℃ due to the inhibition of SCR undesired side reactions(NSCR & C-O reactions) and "slow-SCR" process.