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.

Design and parametric analysis of a planar array antenna for circular polarization

Abstract: A new circularly polarized planar array antenna using linearly polarized microstrip patches is designed and optimized for X-band wireless communication applications. Four square patch elements with feed network are used to design the circularly polarized array antenna. The feed network consists of microstrip lines on the obverse side of the dielectric substrate and slot line on the reverse side of the substrate. Both-sided MIC technology is successfully employed to apply its inherent advantages in the design process of the array structure. The unequal feed line is used to create 90° phase difference between the linearly polarized patches. Therefore, the circular polarization is realized by the combination of linearly polarized patches and unequal feed line. Characteristics of the proposed array are investigated by using two electromagnetic (EM) simulators: advanced design system and EMPro. The −10 dB impedance bandwidth of the antenna is around 5%. The 3 dB axial ratio bandwidth of 1.48% is obtained. The design of the proposed antenna along with parametric study is presented and discussed.

Removal of Chromium (VI) from Effluent by a Magnetic Bioadsorbent Based on Jute Stick Powder and its Adsorption Isotherm, Kinetics and Regeneration Study

Abstract: A novel magnetic bioadsorbent based on jute stick powder (MB-JSP) was synthesized with Fe2+ and Fe3+ solutions by in situ co-precipitation technique and applied for the elimination of Cr (VI) from aqueous solution. The adsorption capability of fresh jute stick powder (JSP) was also studied to compare with the magnetic bioadsorbent (MB-JSP). The characteristics of these bio-adsorbents were measured individually. The magnetic saturation of MB-JSP touched 14.25 emu/g which was sufficient for the separation of MB-JSP from aqueous solution. This magnetic bioadsorbent worked perfectly within a substantial pH range of 1–2. The Cr (VI) removal by MB-JSP was seamlessly supported by the Langmuir isotherm model (R2 = 0.997–0.999) and pseudo-second-order kinetic model (R2 = 0.994–0.995). The maximum capacity of Cr(VI) adsorption by MB-JSP and JSP were 47.125 and 30.422 mg/g, respectively at 303.15 K by Langmuir isotherm model. The regeneration experiment specified its merit of regeneration and firmness with the recovery efficiency of 90.17% and 80.23% for MB-JSP and JSP, respectively. It was observed by considering the results that the removal Cr(VI) ions was accomplished via the attraction between the opposite charges of different functional groups present on the adsorbents surface and ion exchange. Moreover, the process of removal was very effective and a rapid separation from aqueous solution was achieved.

Physical properties of new MAX phase borides M2SB (M = Zr, Hf and Nb) in comparison with conventional MAX phase carbides M2SC (M = Zr, Hf and Nb): Comprehensive insights

Abstract: In this article, a detailed study of the recently synthesized MAX phase borides M2SB (M = Zr, Hf and Nb) has been performed via first principles technique. Investigation of mechanical hardness, elastic anisotropy, optical properties, dynamical stability and thermal properties are considered for the first time. The estimated values of stiffness constants and elastic moduli are found in good agreement with available results. The micro and macro hardness (Hmicro and Hmacro) parameters are calculated. The Vickers hardness is also calculated using Mulliken population analysis. The electronic density of states and charge density mapping are used to explain the variation of stiffness constants, elastic moduli and hardness parameters among the studied ternary borides. The Nb2SB compound is found to show best combination of mechanical properties. Mixture of covalent and ionic bonding within these borides is explained using Mulliken population analysis. The direction dependent values of Youngs modulus, compressibility, shear modulus and Poissons ratio are visualized by 2D and 3D representations and different anisotropic factors are calculated. The important optical constants are calculated and analyzed. The metallic nature of the studied borides is confirmed from the DOS and optical properties. The reflectivity spectra reveal the potential use of Zr2SB as coating materials to diminish solar heating. The studied borides are dynamically stable as confirmed from the phonon dispersion curves. The characteristic thermodynamic properties have also been calculated and analyzed. The physical properties of corresponding 211 MAX phase carbides are also calculated for comparison with those of the titled ternary borides.