Browsing by Author "Ahsan Habib, Md."

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Analytical modeling of cutting force and cutting temperature in turning steel under cryogenic cooling condition
(Department of Industrial and Production Engineering (IPE), 2013-12) Ahsan Habib, Md.; Dhar, Dr. Nikhil Ranjan
In the machining operation the energy dissipated is converted into heat which raises the temperature in the cutting zone. The increase of cutting temperature results tool wear, surface roughness, dimensional inaccuracy significantly. Not only is the cutting temperature, cutting force also increases with tool wear which results the increase of power and specific energy consumption. The cutting temperature restrains productivity, quality and hence machining economy, can be controlled by the application of cutting fluid. But conventional cutting fluids are ineffective to control the temperature in maximum cutting zones. So cryogenic cooling is environmental friendly new approach to control the temperature desirably. Cryogenics is the study of the production of very low temperature (-196°C) and the behavior of materials at that temperature. The physical behavior during metal cutting has been changed because of cutting condition, cutting environment and work/tool material. The aim of the present work is to investigate the role of cryogenic cooling on the formation of chip, cutting temperature and force and then develop analytical model for cutting temperature and force in turning 42CrMo4 steel under cryogenic cooling condition. The m.files of matlab has been used to determine the modeled value of cutting force and cutting temperature under cryogenic cooling condition. From an economic viewpoint, it is evident that having knowledge about the machining responses such as, cutting forces, cutting temperature and work piece surface integrity at different cutting conditions would be highly desirable as a means of realizing cost savings, increased productivity, efficiency and for preventing any hazard occurring to the machine, cutting tool or the deterioration of the quality.
Common-mode outage modelling for composite system reliability assessment using sequential monte carlo simulation technique
(Department of Electrical and Electronic Engineering, 1998-09) Ahsan Habib, Md.; Mashiur Rahman Bhuiyan, Dr.
The reliability assessment of composite generation and transmission systems now-a-days has drawn prime interest in the area of power system plamung. designing and evaluation of reliability. As the demand of the modem society is to have electrical energy as economically as possible with a specified degree of reliability, therefore, there is a significant need to assess the reliability of the composite systems. To evaluate the specified reliability of the composite systems it is necessary to include all the operational factors. Power system reliability assessment can be divided into two basic aspects: adequacy and security. Most of the probabilistic techniques presently available for reliability evaluation are in the domain of adequacy assessment. There are two basic techniques available in the literature for reliability evaluation of composite systems: the analytical approach and simulation approach. Analytical approach represents the system by analytical models and evaluate the indices from these models using mathematical solutions. Monte Carlo simulation methods, however, estimate the indices by a simulating the actual process and random behaviour of tile system. When complex operating conditions are involved and! or the number of severe events is relatively large, Monte Carlo methods are often preferable. Power system reliability evaluation by simulation can be applied in two ways: non-sequential or randomly and sequential or chronological order. The available technique for composite generation and transmission system nonnally consider only simultaneous independent outages because usually the conunon.mode failure rate is small i.e. typical values only of the order of 10% of independent failure rates. But such failures might have severe consequence on the system performance. Many utilities are, tllereforc now using common-mode representations for composite system adequacy analysis. AltllOugh the state space transition diagram for conunon-mode outages are well established. But they can only be utilized in random or non-sequential simulation not in sequential simulation. In case of conunon.mode outage. several departure transition may occur from each state, then it is difficult to predict the next transition. To overcome this difficulty a new approach has been developed in this research. This new algorithm is accommodated in the sequential simulation procedmes to evaluate power system with common-mode failures. Several conunon-mode outage groups are considered and thdr effect on reliability indices are shown in tlJis thesis. So the inadequacies associated with common-mode outages in a composite power system are higWighted more accurately in this thesis. Therefore. the results of such a study arc of great importance to the system planner and operator during the design and operation phases of a power system for more exhaustive analysis. In this research IEEE-IUS is evaluated using sequential Monte Carlo simulation technique for numerical evaluation.
Studies on degradation of dyes present in the industrial effluents
(Department of Chemistry , BUET, 2001-09) Ahsan Habib, Md.; Ullah, Dr. Md. Rafique
Brilliant Golden yellow, BGY, a textile dye, has been chosen for studying its degradation characteristics. Two methods of degradation have been tried. These methods are Fenton and mediated photodegradation. Two semiconducting oxides have been chosen as mediators. These are TiO, (rutile) and ZnO. BGY solution shows absorption peak at A",415:t 2 nm with E"'7.81x 103 Lmor'cm" at 29°C. The concentrations ofBGY was about 5.10xl0"M to 3.00 x 10,4M, the solution initial pH varied beltween 2.50 to 6.20. The concentration of H,O, was between 8.00 x 1O.4Mto 5.00 x IO'3M, the concentration of Fe (III) 2.00 x 10"M to 1.00 x I0.4M. The amount ofTiO, per 50 ml solution was 1.00 x 10.3 to 4.50 X 10'3g and the amount of ZnO per 50 m!. was 2.50 x 10'3 to 10.00 X 10,3g. The Fenton degradation of the BGY was complete within 10 minutes and so long '---- H,O, was in sufficiently large amount. The other parameters did not affect the % degradation of the dye, which was about 93% even in the presence 410 nm light. In the oxide mediated photodegradation 100% degradation of the BGY could be achieved by using 320 nm light. ZnO mediated degradation appeared to be faster. TiO, mediated degradation appeared to be dependent on the amount ofTiO" other parameters hardly affected the photodegradation process. Langmuir-Hinshelwood kinetic model has been applied to the mediated degradation. It gives some idea why ZnO is a better mediator for photodegradation ofBGY.