http://dspace.daffodilvarsity.edu.bd:8080/handle/123456789/1546 2026-04-04T11:23:58Z http://dspace.daffodilvarsity.edu.bd:8080/handle/20.500.11948/525 THREE-DIMENSIONAL CHARACTERISTICS OF THE COHERENT FINE SCALE EDDY IN TURBULENCE Uddin, M. Ashraf; Tanahashi, Mamoru; Miyauchi, Toshio This paper presents the three-dimensional characteristics of coherent fine scale eddies related to their axis in homogeneous isotropic turbulence in order to understand the detailed features of the fine scale eddy in turbulence. The coherent fine scale eddy and their axis are identified by an auto tracking algorithm from the Direct Numerical Simulation (DNS) database, where DNS is performed based on a spectral method. It is shown that the axis of each fine scale eddy contains several nodes, in which these nodes are identified by the minima of second invariant (Q) of the velocity gradient tensor on the axis. It is also shown that the number of nodes increases for strong and relatively long eddy but it decreases for weak and short eddy. At each node the axis bends with a large angle. The maximum azimuthal velocity and axial velocity of coherent fine scale eddy show relatively large fluctuations along their axis, while the diameter is nearly constant along the entire axis of the fine scale eddy. The coherent fine scale eddies have large advection velocity but the dissipation rate along the axis of the eddy is not so large. 2010-07-01T00:00:00Z http://dspace.daffodilvarsity.edu.bd:8080/handle/20.500.11948/524 INVESTIGATION ON MECHANICAL PROPERTIES OF A356 NANOCOMPOSITES FABRICATED BY ULTRASONIC ASSISTED CAVITATION Donthamsetty, Suneel; D, Nageswara Rao. This paper presents mechanical properties of A356 matrix nanocomposites fabricated by reinforcing nano silicon carbide (SiC) particles at 0.1 to 0.5 weight percent with the aid of ultrasonic cavitation. SiC nanoparticles synthesized by bottom-up and top-down approach are used in this work as reinforcements and change in mechanical properties are observed. For comparision, A356 matrix composite reinforced with microparticles at 0.5 wt% by stir casting also prepared. Till now, SiC nanoparticles produced by bottom up approach were used as reinforcements in A356 alloy by so many researchers to improve mechanical properties. But in this work, nanoparticles produced by high energy ball milling (Top-down approach) are also used as reinforcements. It is observed that there is reduction in tensile properties compared to the composites prepared by reinforcing nanoparticles via bottom up approach but significant increase compared to the composites prepared by reinforcing same amount of microparticles by stir casting. The reasons may be due to the non-uniformity in size of particles and contamination while milling nanoparticles. However, the change in properties is less and use of nanoparticles via top down approach is admissible when compared to the cost of nanoparticles synthesized from bottom up approach or chemical routes. 2010-07-01T00:00:00Z http://dspace.daffodilvarsity.edu.bd:8080/handle/20.500.11948/523 INTEGRATION OF TECHNOLOGIES TO IMPROVE THE PHARMACEUTICALS WASTE MANAGEMENT IN BANGLADESH Hossain, K. M. Z.; Rahman, M. A; Sharif, N.; Haque, S.M.E. An investigation was carried out to minimize the pollution load of pharmaceuticals industries by using integrated waste management technologies. Effluents were physically, chemically and biologically treated using three-stages advanced effluent treatment system. The dust particles were discharged to the atmosphere after filtration and the solid wastes were burnt in a pyrolytic incinerator at about 1100oC temperature. The physico-chemical characteristics of treated effluent were measured using Ultra Violet-Visible spectrophotometer and the emitted dust particles were analyzed using High Performance Liquid Chromatography (HPLC) to determine the discharge amount. The biological oxygen demand, chemical oxygen demand, total dissolved solid, chloride and sulphide contents of the treated effluent were found within allowable limit. The dust particles were also emitted to the environment below 0.5 mg/L. The solid wastes were reduced to 25% by volume after combustion. It was found that integrated waste management system of pharmaceutical industries can minimize the pollution load to ensure a safe ecological environment. 2010-07-01T00:00:00Z http://dspace.daffodilvarsity.edu.bd:8080/handle/20.500.11948/522 HMM BASED HAND GESTURE RECOGNITION: A REVIEW ON TECHNIQUES AND APPROACHES MONI, M. A. Many ways of communications are used between human and computer, while using gesture is considered to be one of the most natural ways in a virtual reality system. Hand gesture is one of the typical methods of non-verbal communication for human beings and we naturally use various gestures to express our own intentions in everyday life. Gesture recognizers are supposed to capture and analyze the information transmitted by the hands of a person who communicates in sign language. This is a prerequisite for automatic sign-to-spoken-language translation, which has the potential to support the integration of deaf people into society. This paper present part of literature review on ongoing research and findings on different technique and approaches in gesture recognition using Hidden Markov Models (HMMs) for vision-based approach. 2010-07-01T00:00:00Z