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 high performance and ultra-thin CdTe solar cells with SnTe BSF from numerical analysis

Abstract: Polycrystalline Cadmium Telluride (CdTe) is one of the leading solar cell materials for its efficiency, cost-effective and thermal stability. In this research work, numerical analysis is done by AMPS (Analysis of Microelectronic and Photonic Structures) simulator to investigate the cell performances (Jsc, FF, Voc, efficiency and temperature stability) of ultra-thin CdTe solar cell. Reduction of absorber layer was done and observed that 1 μm absorber layer is enough for acceptable range of cell conversion efficiency in the proposed cell. The possibility of this ultra-thin CdTe absorber layer was investigated, together with 100 nm SnTe back surface field (BSF) layer to reduce the barrier height in the valence band and to minimize the recombination losses at the back contact of the CdTe PV cell. From the investigation, it was found that the proposed ultra-thin cell have conversion efficiency of 18.68% (Jsc = 21.47 mA/cm2, FF = 0.85, Voc = 1.02 V) without BSF and with 100 nm SnTe BSF conversion efficiency increased to 22.61% (Jsc = 24.27 mA/cm2, FF = 0.876, Voc = 1.06 V) with only 0.7 μm of CdTe absorber layer. Moreover, without BSF and with SnTe BSF, the normalized efficiency of the proposed cell was linearly decreased with the increasing operating temperature at the gradient of −0.18%/°C and −0.16%/°C found in this analysis respectively, which indicated better stability of the proposed CdTe solar cell.

Study of hydrodynamic size distribution and hyperthermia temperature of chitosan encapsulated zinc-substituted manganese nano ferrites suspension

Abstract: Hyperthermia opens a safe alternative for cancer treatment. Researchers synthesize new materials that can be successfully used for the biomedical application. We have synthesized Mn1-xZnxFe2O4 (0.2 ≤ x ≤ 1.0, in the steps of 0.2) and coated the samples with chitosan. The structural properties of the nanoparticles were determined by XRD and TEM analysis. Face-centered cubic structure of the nano ferrites has been revealed by XRD analysis. It has been found that both the theoretical and experimental lattice constant decreases with the addition of zinc. The range of theoretical and experimental lattice constants is 8.336 A to 8.275 A and 8.460 A to 8.399 A, respectively. EDS studies revealed the elemental distribution of both bare and coated ferrite nanoparticles. VSM has characterized the field dependent magnetization. Mossbauer spectroscopy revealed that all samples exhibit superparamagnetic behavior except Mn0.8Zn0.2Fe2O4. The shift of iron ion in the octahedral site from the tetrahedral site was observed with the addition of zinc. The maximum hydrodynamic diameter of the coated samples was found around 220 nm which is suitable for the biomedical application. The maximum hyperthermia temperature of the coated samples has been estimated.

Face to Face Collisions of Ion Acoustic Multi-Solitons and Phase Shifts in a Dense Plasma

Abstract: This work investigates the interactions among ion acoustic (IA) single- and multi-soliton and their corresponding phase shifts in an unmagnetized plasma composed of degenerate electrons, positrons, and positive ions. Two-sided Korteweg-de Vries (KdV) equations are derived by employing the extended Poincare-Lighthill-Kuo (PLK) method for the stretched coordinates. The single- and multi-soliton solutions of the KdV equations are constructed by using the Hirota’s method. The phase shifts are determined for two-, four-, six-, and eight-IA scattering solitons. The effect of positron concentration on electrostatic IA resonances due to the interactions among solitons and their corresponding phase shifts are investigated.

Dust ion acoustic multi-shock wave excitations in the weakly relativistic plasmas with nonthermal nonextensive electrons and positrons

Abstract: This article investigates the dust ion acoustic multi-shock wave excitations in weakly relativistic multi-component plasma by assuming nonthermal, nonextensive electrons and positrons, relativistic ion fluid having kinetic viscosity and immobile dust Burgers equation is derived to investigate such excitations by applying the reductive perturbation method The exponential functions are directly implemented to determine the novel multi-shock wave solution of Burgers equation The dust ion acoustic (DIA) multi-shock wave excitations are investigated systematically to reveal the effects of parameters, namely, viscosity coefficient of ions, positron to electron density ratio, immobile dust to electron density ratio, ion to electron temperature ratio, electron to positron temperature ratio, and relativistic streaming factor of ions in the presence of nonthermal, nonextensive, and concurrently acting nonthermal and nonextensive electrons as well as positrons It is found that the amplitudes and widths of not only single, but also multi-shock wave compressive and rarefactive electrostatic potential structures are changed with the influence of all plasma parameters The obtained results may be useful to analyze the nature of DIA multi-shock wave phenomena in various astrophysical as well as space environments (particularly, in pulsar relativistic winds with supernova ejecta) and future studies in plasma laboratory