Chittagong University of Engineering & Technology

About: Chittagong University of Engineering & Technology is a education organization based out in Chittagong, Bangladesh. It is known for research contribution in the topics: Computer science & Renewable energy. The organization has 1200 authors who have published 1444 publications receiving 10418 citations. The organization is also known as: Engineering College, Chittagong & Bangladesh Institute of Technology, Chittagong.

Automated detection of COVID-19 from X-ray images using CNN and Android mobile

Abstract: The prevalence of the coronavirus disease 2019 (COVID-19) pandemic has made a huge impact on global health and the world economy. Easy detection of COVID-19 through any technological tool like a mobile phone can help a lot. In this research, we focus on detecting COVID-19 from X-ray images on Android mobile with the help of Artificial Intelligence (AI). A convolutional neural network (CNN) model is developed in MATLAB and then converted to the CNN model to TensorFlow Lite (TFLite) model to deploy on Android mobile. An Android application is developed which uses the TFLite model to detect COVID-19 using X-ray images. By employing a 5-fold cross-validation, an average accuracy of 98.65%, sensitivity of 98.49%, specificity of 98.82%, precision of 98.81%, and F1-score of 98.65% are achieved in COVID-19 detection. With our developed Android application, users can detect COVID-19 from X-ray images on Android mobile, and it will be helpful for the diagnosis of COVID-19.

A semi-fragile watermarking method using slant transform and LU decomposition for image authentication

Abstract: Semi-fragile watermarking has been widely used for content authentication. In this paper, we propose a semi-fragile watermarking method using slant transform (ST) and LU decomposition (LUD) for image authentication. Initially, the watermark image is scrambled using an algorithm to enhance the confidentiality of the image. The host image is separated into red, green, and blue channels. The red channel is divided into 8×8 non-overlapping blocks. ST is applied to each block to get the ST coefficients. LU decomposition is then applied to these coefficients to obtain the lower and upper triangular matrix. Watermark data is embedded into the upper triangular matrix of ST coefficients using an embedding equation. Simulation results indicate that proposed method produces high quality watermarked image, provides secure embedding, extraction and authentication. Moreover, it effectively detects malicious tempering on image while being resistant to various content preserving manipulations. Furthermore, it shows superior performance than the state-of-the-art methods in terms of imperceptibility.

Seismic Responses of a Bridge Pier Isolated by High Damping Rubber Bearing: Effect of Rheology Modeling

Abstract: This study is aimed at evaluating seismic responses of a bridge pier isolated by high damping rubber bearing (HDRBs), subjected to intra-plate and inter-plate earthquake ground motion records. In this regard, a conventional bilinear model and two elasto-visco-plasticity-based rheology models (the original rheology model [36] and an improved rheology model proposed in the current study) of HDRBs have been utilized in this study. In the first part of the paper, the adequacy of the two elasto-visco-plasticity-based rheology models has been checked in predicting the mechanical behaviour of the HDRBs, subjected to sinusoidal loadings. The numerical results of the HDRBs have shown that the improved rheology model can predict the mechanical behaviour of the bearings in a quite better way in comparison to the original rheology model, particularly at higher shear strain levels of the bearings. In the second part, seismic response analysis of a 3-DOF bridge superstructure–pier–foundation (s–p–f) system has been evaluated. In the end, nonlinear dynamic analysis using a standard direct time integration approach has been carried out. The seismic responses of the s–p–f system considered in the current study are the pier and deck displacements, the shear force of the bridge pier, the shear strain of the bearing and the total hysteretic energy of the bearings. The analytical results have shown that the rheology modeling of HDRBs has a significant effect on seismic responses of bridge pier.

Investigation of mechanical properties of al2o3-20 wt % zro2 composites as a function of sintering temperature

Abstract: High purity nanocrystalline α-alumina powder was mixed with 20 wt% ZrO2 by slurry method sintered at temperature (Ts) 1450°C, 1500°C, 1550°C and 1600°C for 2 hour. The density, porosity, structural properties and mechanical properties of Al2O3-ZrO2 composites with respect to sintering temperature have been explored in the present work. The XRD spectra indicate that α-Al2O3, t and m-ZrO2 are the crystalline phases present in 20 wt% ZTA composites for all sintering temperature. It is observed that with higher sintering temperature the intensity of m-ZrO2 phases increases and the t-ZrO2 phases decreases. However, t-ZrO2 retention becomes much easier to trigger the transformation to monoclinic. Higher density of 20 wt% ZTA has been achieved at 1600oC, whereas the highest porosity was obtained for sintering temperature 1450°C.The microstructures of the samples was studied by using SEM which represents highly homogeneous and finer structure at 1600oC. The effect of sintering temperature on hardness, elastic modulus and flexural strength were investigated and has been found to increase with the increase of sintering temperature. Maximum