Browsing by Author "Nurul Islam, Md."

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A Feasibility Study of Solar-Wind Hybrid System in Urban Area of Bangladesh
(Military Institute of Science and Technology, 2014-12) Shueb Al Hasan, Capt; Nurul Islam, Md.; Akter, Faisal
Utilization of renewable energy resources have been the most important and prospective field to seek new energy sources to meet up the increasing demand in power all over the world specially in a developing country like Bangladesh. Among the renewable resources, wind and solar being the most popular ones due to abundant ease of accessibility and convertibility to the electricity. The paper presents the next generation of power energy systems where generation will not be dependent on fossil fuel, using solar and wind energy systems. The thesis is emphasized on the feasibility study of hybrid energy system (comprising solar and wind) from literature followed by evaluation of performance through simulation. The primary focus of this study is to develop a dynamic model for a small standalone hybrid power generation system for the urban as well as coastal areas and compare their performance. For designing and studying the feasibility of the system, software named ‘HOMER’ was used. HOMER software has been used for analyzing the performance of the system. Different performance analysis includes feasibility, sensitivity, cost and sustainability were measured using the software. Our designed solar wind hybrid power system capacity is 650 Watts. It is proposed as the model with LED lights and limited fans which are considered as domestic load. It is found that the proposed system reduces CO2 emission.
Role of aluminum, cobalt co-doping on the band gap tuning of TiO2 thin film deposited by spray pyrolysis
(Department of Physics, BUET, 2019-11-24) Nurul Islam, Md.; Podder, Dr. Jiban
Titanium dioxide (TiO2) thin films were prepared by a spray pyrolysis technique onto a glass substrate. The film properties are characterized by Field-emission scanning electron microscopy, Energy-dispersive X-ray spectroscopy (EDX), Atomic force microscopy (AFM), X-ray diffraction (XRD) technique, and four-probe point method. The Scanning electron microscope and Atomic force microscope images of pristine samples have shown particle shape. The pore diameters are found to be in between 6 nm to 9 nm for Al doped, spherical and slender shaped particles are ranging from 42 nm to 50 nm for co-doped sample observed by field emission scanning electron microscope. The EDX spectra show that all studied samples are stoichiometric. AFM images show that the surface roughness are varying from 34.72 nm to 89.83 nm. The XRD pattern shows that the brookite phase is present in pure, doped and co-doped samples. The cell parameters have been analyzed by FULLPROF package. The lattice parameters are found in good agreements with the experimental and theoretical results. For different compositions of as-deposited studied films, the optical band gap energy varies from 3.52 eV to 3.70 eV for doped and 3.52 eV to 3.57 eV for co-doped samples. The optical properties show that the films are highly transparent in the visible region. The (Al, Co) samples transparency decrease with increasing co-doping as compared to pristine one and reverse phenomena occurred in absorption spectra. The resistivity gradually decreases with an increase of temperature, which confirms that the samples exhibit semiconducting behavior. Experimental studied structural parameters were used in theoretical calculation via Material studio 8.0. The mechanical properties indicated that the optimized sample is ductile and possesses a low bulk modulus. Pristine and Al-doped and (Al, Co) co-doped samples are found to have an indirect electrical band gap, mechanical stability. The electrical band gap of the samples varies from 3.11 eV to 4.39 eV for doped and 2.38 eV to 3.11 eV for co-doped samples. The absorbance edge is shifted to the lower energy region after (Al, Co) co-doped (red shift). The charge density map indicated that the covalent bond is present in all samples. A combined analysis of the structural, morphological, electronic, and optical properties of the compound suggests that the studied sample is a potential candidate for gas sensing and optoelectronic applications.
Soil improvement by using vertical drains and preloading
(Department of Civil Engineering, 1989-08) Nurul Islam, Md.; Zoynul Abedin, Dr. Md.
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