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.

Design of an orthogonal feed circularly polarized microstrip array antenna suitable for large scale extensible arrays

Abstract: This paper presents a circularly polarized 1×2 array antenna for X-band applications. Both-sided MIC technology is effectively used to design this array antenna as the array antenna consists of both microstrip lines and slot lines to realize the feed network. Patch elements and microstrip lines are placed on the top surface of the substrate and slot lines on the reverse surface (ground plan) of the substrate. Each of the patches is excited by two orthogonal feed lines. One of the feed lines is ahead by an odd multiple of quarter wavelength than the other feed line. This strategy makes the each patch circularly polarized. The impedance bandwidth is about 630 MHz and the 3-dB axial ratio bandwidth is more than 1%. This array antenna is very suitable to make large scale extensible array antennas by using it as a unit array.

Developing a System for Automatic Detection of Books

Abstract: Managing a large number of books is a challenging task for humans. Our proposed system would assist librarians in efficiently sorting books and keeping an up-to-date inventory of huge books. Many methods for detecting only the book spine in a picture have been created. However, not every strategy is perfect. So, this paper presents an automated book detection system that can quickly identify books by reading their titles. Firstly, images are captured from random position. Secondly books in the image are segmented by using Canny Edge Detection and line segmentation. After book spine segmentation stage, an OCR engine is applied to the segmented images to extract book titles and ready for recognition of next stage. Then maximum string matching score is calculated with extracted text for all data of a column of database where all book’s Title are enlisted. For which index of database system will get the maximum score, book category information will be extracted of that index.

Cooperative secondary user selection as a relay for the primary system in underlay cognitive radio networks

Abstract: We consider an underlay cognitive radio network consisting of a single pair of primary transmitter-receiver PTx-PRx and a group of M secondary transmitter-receiver pairs STx-SRx within the transmission range of the primary system. Secondary transmitters are partitioned into two groups K, KeM active secondary transmitters ST i , i e {1, 2,…, K} which may transmit data with the co-existence of PTx below a certain interference threshold to the primary receiver and (M-K) inactive secondary transmitters ST j , je {1, 2,…, (M-K)} which are in idle state, ready to assist the primary system when the data rate between PTx and PRx over a direct link falls below the target rate R target . In this paper, we propose a cooperative relay selection scheme where one of the inactive ST j which achieves the primary target R target will be selected as a best relay to forward the primary information. Simulation results show the effectiveness of our proposed system.

Change of structural and magnetic property due to zinc substitution and sintering temperature of nano-crystalline Cobalt ferrite

Abstract: Co1–xZnxFe2O4 (x = 0.2, 0.4, 0.6 and 0.8) were synthesized using typical wet chemical co-precipitation technique. The ferrite specimen have been sintered at 700°C and 900°C for three hours in air. ...

Experimental and COSMO-RS Simulation Studies on the Effects of Polyatomic Anions on Clay Swelling.

Abstract: Ionic liquids (ILs) can play a vital role in clay swelling inhibition during hydraulic fracturing. Previous studies highlighted the effect of side-chain length attached to the cationic core and different anions possessing almost the same chemical properties on inhibition performance. However, polyatomic anions have the potential to superiorly inhibit swelling compared to monoatomic anions. In this study, three ILs, namely, 1-butyl-3-methylimidazolium chloride (BMIMCl), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6), were utilized to assess the effects of polyatomic anions on clay swelling inhibition. These performances were compared with the performances of a conventional inhibitor, potassium chloride (KCl). X-ray diffraction (XRD) testing was applied to check the mineral components present in the bentonite clay sample studied in this research. Clay swelling inhibition performance and rheological properties of these ILs were evaluated by the bentonite plate soaking test, linear swelling test, and rheological test. The swelling inhibition mechanisms were investigated through ζ-potential measurement, Fourier transform infrared (FT-IR) spectroscopy, and contact angle measurement. Moreover, COSMO-RS computer simulation was conducted to explain the inhibition mechanisms theoretically. The results demonstrated that BMIMPF6 showed superior inhibition performance and reduced the swelling by 21.55%, while only 9.26% reduction was attained by potassium chloride (KCl). The adsorption ability on the bentonite surface through electrostatic attraction, higher activity coefficient, and less electronegativity of PF6- anion played a vital role in attaining such superior inhibition performance by BMIMPF6.