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: Renewable energy & Dielectric. 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.

Evaluation of physicochemical and trace metal qualities of rainwater in the south-eastern region of Bangladesh

Abstract: The chemical characteristics of rainwater in the south-eastern region of Bangladesh were investigated in this study in addition to identifying the potential sources of different precipitation constituents, which have often been unexplored or not well covered in the literature. Rainwater pH, major ions and trace metals were measured in samples collected from five different locations with different land-use patterns of the Chattogram Metropolitan area (CMA) during two rainy seasons. The results of this study showed variability in rainwater quality across the sites signifying site-specific influences. The mean concentration of all measured physicochemical parameters, ions and trace metals in rainwater samples was also found to be significantly lower compared with the drinking water quality standard of Bangladesh and WHO guidelines. The correlation matrix and principal component analysis (PCA) indicated that and originated from anthropogenic sources, while the average concentration of trace metals found in rainwater was exhibited in the following order: Zn>Cu>Fe>Cr>Mn>Pb>Cd. The findings of this study could be used as a reference to further investigate the influences of industrial, urban and agricultural emissions that regulate the chemical characteristics of the atmosphere in particular areas of study.

A Transparent Conductive Material Based Circularly Polarized Nano-antenna for THz Applications

Abstract: In this paper, an optically transparent circularly polarized E-shaped antenna is presented for THz applications. THz antennas are important for inter-satellite communication systems to enable the adequate spatial resolution, wide bandwidth, superior data rates and highly directional beam with secured data transmission. Due to the non-ionizing nature and penetration capability of THz radiation, the application of THz antenna is gaining momentum in space communications and security systems. Transparent conductive material namely indium tin oxide is deployed as patch. Due to low conductivity, the performance of ITO based antenna is slightly reduced which is overcome by loading another transparent highly conductive material namely carbon nanotube as cover over the patch. Circular polarization is acquired by introducing orthogonality between two resonating degenerate current modes with the aid of the two unequal parallel slits of E-shaped patch along with inserted E-shaped and I-shaped slots into the patch. 10-dB impedance bandwidth of 22.2% and 3-dB axial ratio bandwidth of 9.14% are achieved with good radiation performance which makes this simple nano-antenna suitable for THz applications.

Introducing antiparallel back to back connected thyristor for speed control of three phase induction motor

Abstract: Thyristors are mostly used power electronics device and implemented in various motor control appliances because of its lower cost, smaller size, lower losses of power, market availability and greater switching characteristics. In this research work, the speed of three phase induction motor is precisely controlled by using anti-parallel back to back connected thyristors in the stator side and stator voltage of induction motor is varied by varying firing angle of the pulses those are fed to the gate of thyristors. A zero crossing detection circuit is designed for detecting the starting of the input voltage. PIC 16f877A is programmed to generate gate pulses in a particular sequence. For smoother control and to prevent abrupt rise of (dv/dt) an RC snubber circuit is also connected across each thyristor pair. Moreover, the relationship between the voltage, speed and firing angle are evaluated and graphically represernted.

Seismic response analysis of base isolated building: effect of lead rubber bearing characteristics

Abstract: Seismic response of a base isolated building is studied for varying properties of Lead rubber bearing. An eight storied educational building is taken into consideration as a structure of interest. Properties of the lead rubber bearing are altered to find the most optimum value of important parameters to obtain a minimum earthquake response of the building. The most important parameters are taken into consideration: initial stiffness (K1), yield strength (Fy/W) and post-to-pre yield stiffness (K2/K1). Three different ground motions are considered in the present analysis and applied in the longitudinal direction of the structure. Base shear, roof acceleration and bearing displacement are utilized to evaluate the performance of the isolated building. It is found that these parameters influence the response of the building significantly and seismic response of the structure reaches to a minimum value for a specific value of the bearing parameter. Finally, some recommendations are made based on the present seismic analysis with different ground motions.

Optical recognition of vehicle license plates

Abstract: This paper describes a new approach to analyze road images which often contain vehicles and extract license plate (LP) from natural properties by finding vertical and horizontal edges. In this paper, initially, segmentation technique named as sliding concentric windows (SCW) on the basis of a novel adaptive image segmentation technique for detecting candidate region. Color verification for candidate region by using HSI color model on the basis of using hue and intensity in HSI color model verifying green and yellow LP and white LP, respectively. Tilt correction in horizontal direction by the least square fitting with perpendicular offsets (LSFPO) is proposed and implemented for estimating rotation angle of the LP region. Then the whole image is rotated for tilt correction in horizontal direction by this angle. Tilt correction in vertical direction by reorientation of the titled LP candidate through inverse affine transformation is proposed and implemented for removing shear from the LP candidates. Finally, statistical based template matching technique is used for recognition of Korean plate characters. Various LP images are used with a variety of conditions to test the proposed method and results are presented to prove its effectiveness.