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.

Utilization of Multi-Resonant Defected Ground Structure Resonators in the Oscillator Feedback for Phase Noise Reduction of K-Band VCOs in 0.18- $\mu$ m CMOS Technology

Abstract: This work proposes a new theory to reduce the phase noise of K-band Voltage-Controlled Oscillators (VCOs) in Complementary Metal Oxide Semiconductor (CMOS) process by introducing one or more transmission poles around the parallel resonance of an LC-tank circuit. Introduction of transmission poles beside the parallel resonance of the LC-tank circuit sharpens the skirt characteristics of the Scattering ( $\vert \text{S}\vert$ ) parameters of the resonators. In return, sharp $\vert \text{S}\vert $ -parameters slope enhances the resonator loaded quality (Q) factor without compromising the unloaded Q-factor. In addition, the transmission pole can be realized near the second harmonic of the oscillation. This allocation of the transmission pole leads to the cancellation of this second harmonic and a further reduction of the phase noise. The proposed theory is verified by three different designs based on defected ground structure (DGS) resonators. These designs realized a low-band transmission pole before the parallel resonance, a high-band transmission pole after the parallel resonance, and dual-band transmission poles around the parallel resonance. First, each design is verified and compared to the others using circuit and electromagnetic simulations to establish the Q-factor improvement. Then, each of the resonators is utilized in a differential VCO topology and the phase noise reduction in post-layout simulations is confirmed. Finally, two chips are fabricated in 0.18- $\mu $ m CMOS technology and measured. The measurement results are in good agreement with the simulations, which confirm our claim about the proposed theory.

A Computational Approach to Pertinent Feature Extraction for Diagnosis of Melanoma Skin Lesion

Abstract: Melanoma, starts growing in melanocytes, is less common but more serious and aggressive than any other types of skin cancers found in human. Melanoma skin cancer can be completely curable if it is diagnosed and treated in an early stage. Biopsy is a confirmation test of melanoma skin cancer which is invasive, time consuming, costly and painful. To prevent this problem, research regarding computerized analysis of skin cancer from dermoscopy images has become increasingly popular for last few years. In this research, we extract the pertinent features from dermoscopy images related to shape, size and color properties based on ABCD rule. Although ABCD features were used before, these features were mostly calculated to reflect asymmetry, compactness index as border irregularity, color variegation and average diameter. This paper proposes one asymmetry feature, three border irregularity features, one color feature and two diameter features as distinctive and pertinent. Implementation of our approach indicates that each of these proposed features is able to detect melanoma lesions with over 72% accuracy individually and the overall diagnostic system achieves 98% classification accuracy with 97.5% sensitivity and 98.75% specificity. Therefore, this method could assist dermatologist for making decision clinically.

Occlusion handling and human detection based on Histogram of Oriented Gradients for automatic video surveillance

Abstract: Human detection in a video surveillance system has vast application areas including suspicious event detection and human activity recognition. In the current environment of our society suspicious event detection is a burning issue. For that reason, this paper proposes a framework for detecting humans in different appearances and poses by generating a human feature vector. Initially, every pixel of a frame is represented as an incorporation of several Gaussians and use a probabilistic method to refurbish the representation. These Gaussian representations are then estimated to classify the background pixels from foreground pixels. Shadow regions are eliminated from foreground by utilizing a Hue-Intensity disparity value between background and current frame. Then morphological operation is used to remove discontinuities in the foreground extracted from the shadow elimination process. Partial occlusion handling is utilized by color correlogram to label objects within a group. After that, the framework generates ROIs by determining which of the foregrounds represent human by considering conditions related to human body. Finally, Histogram of Oriented Gradients (HOG) feature is extracted from ROI for classification. Various videos containing moving humans are utilized to evaluate the proposed framework and presented outcomes demonstrate the adequacy.

Harvesting electrical power from waste heat using stirling engine

Abstract: Different processes that use energy and machines that do work do not have perfect efficiency. So energy is wasted from these processes in the form of heat. Power generating stations, industrial processes, rice mills, brick fields and other human activities are major sources of waste heat. Mud stoves used in rural areas for cooking purpose produce above 85% of waste heat. This wasted heat can be used to generate electrical power using Stirling engine (SE). Stirling engine is a heat engine that is operated at different temperature levels by cyclic operation of compression and expansion of working gas. A DC generator is coupled with the SE to generate electrical energy. In this research amount of waste heat from significant sources has been presented and theoretical analysis has been made to harvest electrical power using a displacer type SE. Utilizing helium as working fluid and a DC generator having 90% efficiency a SE with displacer swept volume of 7.37 ×10-4 m3 can generate 80 watt of electrical power at 115 rpm engine frequency. In this mathematical approach the phase angle is 90o and the temperature difference is about 150 0K. The setup discussed is working as a personal power plant for each rural household.