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Synthesis of (1-x)bife0.9La0.1O3+x(Ni0.6Zn0.4Fe0.94V0.06O4) Nanostructured Multiferroic Composites and Study of its Structural, Magnetic and Electrical Properties
No full textThis thesis is submitted to the Department of Physics, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Physics, February 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 104-116).The multiferroic composites (1-x) BiFe0.9La0.1O3+ x (Ni0.6Zn0.4Fe0.94V0.06O4) are made with
the combination of perovskite and ferrite materials. The nanoparticles are synthesized by using solid state reaction method and some mechanical dispersion techniques like magnetic stirring, ultrasonification and centrifugation. X-ray diffraction method with Rietveld refinement was established to see multiphase formation that consists with perovskite and ferrite compositions. From Rietveld analysis, rhombohedral to orthorhombic phase transition was found up to x = 0.7 and the pure cubic ferrite structure was found for x = 1 content. At x = 0, the sample is in rhombohedral and orthorhombic mixed phases but with the increasing in x (as ferrite content) the cubic phase was visible. At fully ferrite contents where x = 1, there has no rhombohedral and orthorhombic phase has been visible but only cubic phase is formed. The goodness of fitting confirmed that the composites are made with well distribution of perovskite and ferrite materials. The results from Rietveld analysis
show that the increasing Ni0.6Zn0.4Fe0.94V0.06O4 (NZVFO) contents the ferrite phase fraction was increased whereas the perovskite phase fraction decreased. The Field emission scanning electron microscopy (FESEM) has been used to understand the surface morphology of composites. The proportion and contribution of particles inside the composites have been found by EDX analysis. Initially, all prepared samples were heated at 150oC and the nanostructure was confirmed by FEESEM photograph where the size of particles were about 20 ~ 30 nm and after increasing annealing temperature, increase in grain size is clearly observed. At 300oC, 450oC, 600oC and 850oC annealing temperatures the grain sizes are in between 30~40 nm, 50~80 nm, 160 ~ 260 nm and 800 ~ 1700 nm respectively. The magnetization, saturation magnetization and coercivity has calculated by using Vibration sample magnetometer (VSM), where magnetization is lowest for pure BiFe0.9La0.1O3 (BLFO) perovskite phase and increased with increasing NZVFO ferrite contents. The magnetization is maximum for x = 1 which may be contributed by total of ferrimagnetic contents. The temperature dependent magnetization was taken at 5Oe constant field for both of heating and cooling mechanism where the Curie temperatures have Curie temperatures are 364oC and 350oC for pure perovskite mixed phases (x = 0) and cubic ferrite phase (x = 1) respectively. The frequency dependent dielectric constant is maximum for Bismuth perovskite content but it was lower as ferrite contents increased. On the other hand resistivity increased with increasing ferrite content. Frequency dependent permeability was maximum for pure NZVFO content but in BLFO content, permeability became low.Md. Rabiul HassanDepartment of Physic
Optimization of Sand Casting Parameters for Reducing Casting Defects Using Taguchi Method and Casting Simulation Technique
No full textThis thesis is submitted to the Department of Industrial Engineering and Management, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Engineering in Industrial Engineering and Management, March 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 31-33).The aim of the present work is to reduce the rejection rate of cast products in a foundry shop due to casting defects in sand casting process using a statistical tool namely Taguchi method and a computer aided simulation technique. Conventional techniques require a larger number of trials for checking outputs when the variety of input conditions increase and this problem can be reduced using this two techniques. In this investigation, the various casting process parameters such as moisture content (%), green compression strength (g/cm2) and permeability number are considered and organized according to Taguchi L18 orthogonal array. Taguchi approach is utilized to find out the most significant control factors which will reduce casting defects. Besides, the percentage contribution of process parameter has been determined using statistical Analysis of variance (ANOVA). Finally, the general regression equation is formulated and better cast product is obtained with less defects and it is validated by means of confirmation test. It is observed from experimental trials in foundry shop that average value of minimum casting defect is 3.1% for aluminum flywheel. Not only that in this thesis an attempt has been taken to redesign gating and feeding system for producing a casting free from defects. Defects such as shrinkage porosity, improper solidification, air entrapment, mold erosion are directly related with gating and feeding system design. Number of iterations using casting simulation software are performed for mold filling and solidification analysis to reduce the rejection level in cast component. With new gating and feeding system design improvement in casting yield (about 15%) is observed.Mst. Nazma SultanaMaster of Science in Engineering in Industrial Engineering and Managemen
Development of a Laboratory Scale Drainage Wastewater Treatment Plant for Khulna Municipality
No full textThis thesis is submitted to the Department of Civil Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Civil Engineering, August 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 101-106)Cities in developing countries are experiencing unparalleled growth and rapidly increasing water supply and sanitation coverage that will continue to release growing volumes of wastewater. Wastewater is increasingly being used for irrigation in urban and peri-urban agriculture, and even in distant rural areas downstream of the very large cities. The present study was conducted to analyse municipal wastewater quality parameters of the existing drainage outlets over Mayur River around Khulna city and to develop a laboratory scale treatment plant for safe disposal and prevent environmental pollutions. To fulfil the purpose of the research, wastewater samples from three municipal drain outlets were collected and analysed for selecting treatment system and the evaluation of effluent’s suitability for irrigation use as well as safe disposal into surface water bodies. From the analysis of physico-chemical characteristics of wastewater, it can be seen that pH, EC, BOD, COD, alkalinity, hardness, chloride, nitrate and sulfate values were not fully satisfy the irrigation standard limit as the wastewater was highly polluted. The BOD and COD concentration of wastewater sample were varied from 57-226 mg/l and 320-435 mg/l respectively and the total coliform ranged from 70000-98050 N/100ml. Chloride and hardness values were of high range as the collected samples were heavily polluted by organic matter and microorganisms. Therefore, a laboratory scale treatment technology has been developed for the treatment of this wastewater. Treatment technologies adopted are primary sedimentation followed by aeration, chemical precipitation and filtration. In treated wastewater BOD5, COD and TDS were found to be in the range of 40-115 mg/l, 160-256 mg/l and 1356-1500 mg/l respectively. These test results suggest that the performance of the developed treatment plant was not adequate to fulfil the acceptable limit (ECR'97) for safe disposal into surface water bodies. Based on preliminary treatment results, some modifications of developed laboratory scale treatment plant were done by activated sludge process followed by granular media filtration. As a result, the final BOD, COD and TDS concentration of effluents were found 1.38-1.78 mg/l, 32-128 mg/l and 590-1667 mg/l respectively which satisfy ECR'97 standard limits for safe disposal into inland water bodies. Comparing with national (ECR'97) and international (FAO'85) wastewater quality standards, the effluents of modified treatment plant may be reused for irrigation purposes that would be able to meet the increasing water demand for the farmers and can be safely disposed into the surrounding water bodies of Khulna city.Md. Rasel SheikhMaster of Science in Civil Engineerin
Relationship between Monsoon Rainfall and Winter Minimum Temperature over Bangladesh
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, January 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (page 32).In this thesis it has been tried to find the correlation between the rainfall of the monsoon
months and the minimum temperature of the winter months and rainfall of the monsoon
season and minimum temperature of the winter season all over Bangladesh. The thermal
capacity of the soil changes with the available moisture present in the soil. So it is
assumed/expected that winter minimum temperature has some relationship/dependency on
the monsoon rainfall. Hence regression equation is developed to estimate winter minimum
temperature on the basis of the monsoon rainfall. In this research work the data of 34 stations
all over Bangladesh has been used. These raw data have been collected from Bangladesh
Meteorological Department (BMD). The collected raw data have been processed by
developing and using Fortran code to obtain the monthly and seasonal average. The data have
been broken decade wise because of the data volume and data distribution is not suitable
enough for a single calculation by taking the whole period. For the analysis purpose a
package software has been used to get the regression equation and the coefficient of
determination (r2) from which the coefficient of correlation(r) is determined. The primary
investigation showed that the relationship is not systematic and guided not to accommodate
all the results. So only 9 stations has been chosen region wise: two stations from southern,
two from eastern, two from northern, two from western and one from central region. The
following cases has been investigated
i) Monsoon rainfall vs Winter minimum temperature
ii) July rainfall vs January minimum temperature
iii) August rainfall vs January minimum temperature
It has been found that some correlation coefficients are positive and some are negative. On
the basis of magnitude out of 108 possible cases only 39 have been found with values greater
than or equal to 0.4. It is also observed that except the stations of the northern region all other
stations experienced negative correlation between August rainfall and January minimum
temperature during the decade 1994-2003. It is also found that the negative correlation
coefficients less than or equal to 0.4 is not found in the southern and central regions.Md. Mahmudul HasanMaster of Science in Mathematic
Modification of Small Covered Van to Increase Fuel Efficiency Using Simulation
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, February 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 20-21).In gross, burning a certain amount of fuel in the similar environmental scenario if a vehicle can move more with respect to other vehicle is said to be more fuel efficient. This fuel efficiency certainly has dependency on the drag experienced by the vehicle. So if the drag on the vehicle can be reduced, automatically the fuel efficiency of the vehicle will be increased. There are two way to control the drag, passive and active control. To test the effectiveness of the drag control can be done either through simulation or by direct testing. In this research a passive control is used, inserting some additional shape on the small covered van and is tested through simulation. Three different shapes have been added in the simulation to get idea to reduce drag. For the simulation purpose a CFD software has been used and the result supplied by the software is presented as the result. It has been found that using this passive strategy the drag is reduced. Thus by introducing of some modification the fuel efficiency can be increased.Mahmuda Khatun MuktaMaster of Science in Mathematic
