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Analysis of Thermomagnetic Convection in a Vertical Layer of Ferromagnetic Fluid under Inclined Magnetic Field
No full textThis thesis is submitted to the Department of Mathematics, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Mathematics, April 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 50-52).The main purpose of this study is to deal with the magneto-gravitational convection in a layer of ferromagnetic fluids between two vertical non-magnetic plates. One of the plates is kept at constant temperature. A uniform inclined external magnetic field under nonzero gravity conditions has been considered. In this research both the gravitational and magnetic effects are taken into account. Two distinct mechanisms, namely, thermogravitational(buoyancy-driven) and thermomagnetic, lead to the apprearance of various instability modes. The characteristics of all instability modes are investigated. The three types of instability patterns relating to thermogravitational, magnetic and magnetogravitational convection are found to exist in a normal magnetic field. The inclined external magnetic field conducts the preferential change of instability structures toward the hot wall, it induces an asymmetry with the problem, and then it brings qualitative change in the stability characteristics. It is found because of the angle of inclination of the magnetic field, where a preferred magnetic field is kept in an orientation angle that introduces maximum magneto-gravitational instability. The destabilizing effects due to thermal disturbances and the variation of fluid magnetization has been found in the flow domain. However, the related variation of a magnetic field can draw the energy from the perturbed flow field, which is depending on the orientation of the applied field thus playing a stabilizing role. The role of the buoyancy effects shifts from destabilizing in the
gravity-dominated flow to stabilizing in flows with strong magnetic effects is also found.Mst. Lovly KhatunMaster of Science in Mathematic
A Scalable Storage System For Structured Data
No full textThis thesis is submitted to the Department of Computer Science and Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Computer Science and Engineering, December 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 67-70).Array based storage system is a key choice of many featured applications such as
Scientific, engineering, and financial computing applications; for their easy maintenance.
However, the lack of scalability of the conventional approaches degrades with the
Dynamic size of data sets as they entail reallocation in order to preserve expanded data
Velocity. To maintain the velocity of data, the storage system must be scalable enough by
Allowing subjective expansion on the boundary of array dimension. Again, for an array
based storage system, if the number of dimension and length of each dimension of the
Array is very high then the required address space overflows and hence it is impossible to
Allocate such a big array. We demonstrate a dynamic scalable array storage scheme
Namely Scalable Array Indexing (SAl) that can be an efficient choice of large volume
Dynamic data management by removing the problems of the existing ones. The SAl
converts an n dimensional array to 2 dimensions. Traditionally, the dynamic array models
need indices for each dimensions. Since, SAl is a 2 dimensional dynamic model it reduces
the index overhead significantly and compromises relatively faster data accessing. We also
propose another scalable structure based on the SAl scheme to increase storage utilization.
We named the structure as Segment based Scalable Array Indexing (SSAI). Using our
SSAI structure, we also offer an efficient encoding with good comparison ratio and range
of usability. All the operations are presented with sufficient theoretical analysis and
experimental resultsMehnuma Tabassum OmarMaster of Science in Computer Science and Engineerin
Synthesis and Antimicrobial Activities of Chromene Derivatives
No full textThis thesis is submitted to the Department of Chemistry, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Chemistry, May 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 85-96).The design and synthesis of chalcone and chromene derivatives and their antibacterial activities were studied in this research. Conveniently, all products were synthesized from commercially available acetophenone, 4-hydroxybenzaldehyde and dimedone. Different synthetic strategies were used to obtain an easily accessible chromene scaffold with appropriate handles. At first, this research work was involved in an efficient procedure for the attachment of 4-hydroxybenzaldehyde and acetophenone in the presence of 10% NaOH to produce 3-(4-Hydroxy-phenyl)-1-phenyl-propenone. 4-{3-[(2,4-Dinitro-phenyl)-hydrazono]-3-phenyl-propenyl}-phenol phenylamine has been synthesized by the reaction of 2,4 dinitro phenyl hydrazine with chalcone. Reaction of dimedone with chalcone under refluxing condensation using dry benzene and zinc chloride as a catalyst to give the corresponding chromene derivative 4-(4-Hydroxy-phenyl)-7,7-dimethyl-2-phenyl-4,6,7,8-tetrahydro-chromen-5-one. This reaction also carried out by Microwave Irradiation and use ethanol as a solvent, without any catalyst. It was found that the preparation time for the compounds was reduced from 72 hours to 5-10 minutes during microwave irradiation. The structures of the all synthesized compounds were characterized by their IR, 1H NMR spectral data. The antibacterial and antifungal activity of the compounds was also investigated. The antimicrobial activity of the compounds at concentration 300 μg/disc was performed against three gram-positive bacteria (Bacillus cereus, Staphylococcus aureus and Listeria monocytogenes) and three gram-negative bacteria (Escherichia coli, Salmonella typhimurium, and citobacteria frundi) by Kirby-Bauer disc diffusion method using Ciprofloxacin as standard. Antifungal screening was carried out against one fungi (Tricodarma harzianum) using Michonazole as standard. Compound, I, 3-(4-Hydroxy-phenyl)-1-phenyl-propenone exhibits no activity against the tested bacterial strains Bacillus cereus, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, Citrobacter freundii, but showed moderate activity against the tested bacteria Staphylococcus aureus having inhibition zone 8 mm and also show antifungal activity aganist Trichoderma harzianum inhibition zone 10mm. Compound, II, 4-{3-[(2,4-Dinitro-phenyl)-hydrazono]-3-phenyl-propenyl}-phenol exhibits no activity against gram negative, gram positive strains but showed antifungal activity against Trichoderma harzianum inhibition zone 6 mm. Compound, III, 4-(4-Hydroxy-phenyl)-7,7-dimethyl-2-phenyl-4,6,7,8-tetrahydro-chromen-5-one showed activity against Gram positive, Gram negative except Listeria monocytogenes, Escherichia coli, Salmonella typhimurium. This compound, III also showed antifungal activity against Trichoderma harzianum inhibition zone 8 mm.Md. Tarikul IslamMaster of Science in Chemistr
Extraction of Biodiesel from Castor Oil and Study of Its Properties
No full textThis thesis is submitted to the Department of Energy Science and Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Energy Science and Engineering, February, 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 74-78).Energy demand is increasing worldwide with expected fossil fuel shortages, alternative
energy resources need to be explored. Moreover, the high fossil energy utilization with its
unfavorable impact on environment and climate changes entitle for bio-fuels. In
Bangladesh energy consumption is increasing at a rapid rate due to rapid industrialization,
transportation and mechanization. Increasing pressure of population and increasing use of
energy in agriculture, industrial, domestic and public sectors is an area of concern. At the
same time, the need to meet energy demand has created huge capital requirements needed
for setting up power plants, pipe-lines, ports, terminals, railway tracks to move fuel etc.
Biodiesel fuel can be defined as medium length (C16 to C18) chains of fatty acids, and is
comprised mainly of mono-alkyl fatty acid esters. It is made through a chemical process
called transesterification where by the glycerin is separated from the fat or vegetable oil.
The process leaves behind two products: methyl esters (biodiesel) and glycerin.
In the present work the production of biodiesel from castor oil by transesterification of the
raw oil with methanol in the presence of H2SO4 and NaOH as catalyst. Castor oil (Ricinus
Communis L.) enclosed high value of fatty acid which makes transesterification process be
converted into methyl esters (biodiesel) due to high solubility in methanol. Biodiesel
produced from castor oil has been one of the most significant studies for current
researcher. Also methyl esters are transformed from castor oil by etherification process.
Various fuel properties of biodiesel produced from castor oil like density, viscosity, flash
point, fire point, pour point, calorific value were characterized and compared with the
properties of standard petro-diesel. It could be concluded that these oil from castor oil can
be used as a viable alternative to the diesel fuel.Mohammad Siddiqur RahmanMaster of Science in Energy Science and Engineerin
