Author
Naseer Ahmed
Other affiliations: Taibah University, Quaid-i-Azam University, Loughborough University ...read more
Bio: Naseer Ahmed is an academic researcher from University of Balochistan. The author has contributed to research in topics: Medicine & Dentistry. The author has an hindex of 17, co-authored 66 publications receiving 952 citations. Previous affiliations of Naseer Ahmed include Taibah University & Quaid-i-Azam University.
Topics: Medicine, Dentistry, Machining, Cutting tool, Biology
Papers published on a yearly basis
Papers
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TL;DR: In this article, an experimental study and computational (finite element) model of both CT and UAT forces acting on the cutting tool in UAT are studied, and their dependence on vibration amplitude, frequency and vibration direction as well as on cutting parameters, such as feed rate and cutting speed, are investigated.
102 citations
25 May 2006-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the analysis of the surface layer formed on a workpiece treated with ultrasonically assisted turning (UAT) in comparison to conventional turning (CT) was performed.
Abstract: The paper is focused on the analysis of the surface layer formed on a workpiece treated with ultrasonically assisted turning (UAT) in comparison to conventional turning (CT). Various experimental methods are used to study the difference between the two machining techniques: nanoindentation, light microscopy and scanning electron microscopy (SEM). The experimental part of the paper studies the material response to CT and UAT in terms of material's hardness, residual stresses, and changes in the microstructure. The difference in the distribution of residual stresses in the machined surface layer is further studied by means of numerical (finite element) simulations. A three-dimensional thermomechanically coupled finite element (FE) model of both UAT and CT is used to study temperature distributions in the process zone and thermally induced stresses. Numerical results are compared with the obtained experimental data.
101 citations
TL;DR: In this paper, the authors further developed the finite element (FE) model of ultrasonically assisted turning discussed in Mitrofanov et al. This model is used to study the effect of cutting parameters (such as the cutting speed, depth of cut and feed rate) and influence of lubrication on various features of two turning techniques, including cutting forces and chip shapes.
82 citations
TL;DR: The findings are helpful in characterization of functional abnormalities and may facilitate the understanding of molecular mechanisms and biological function of S-nitrosylation in AD pathology.
82 citations
TL;DR: Mitrofanov et al. as mentioned in this paper presented a recently developed 3D model of UAT as an extension to their initial 2D model, which allows studying various 3D effects in turning, such as oblique chip formation, as well as to analyse the influence of tool geometry on process parameters, e.g. cutting forces and stresses generated in the workpiece material.
75 citations
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TL;DR: In this article, a review of recent developments in non-equilibrium statistical physics is presented, focusing on phase transitions from fluctuating phases into absorbing states, the universality class of directed percolation is investigated in detail.
Abstract: This review addresses recent developments in non-equilibrium statistical physics. Focusing on phase transitions from fluctuating phases into absorbing states, the universality class of directed percolation is investigated in detail. The survey gives a general introduction to various lattice models of directed percolation and studies their scaling properties, field-theoretic aspects, numerical techniques, as well as possible experimental realizations. In addition, several examples of absorbing-state transitions which do not belong to the directed percolation universality class will be discussed. As a closely related technique, we investigate the concept of damage spreading. It is shown that this technique is ambiguous to some extent, making it impossible to define chaotic and regular phases in stochastic non-equilibrium systems. Finally, we discuss various classes of depinning transitions in models for interface growth which are related to phase transitions into absorbing states.
1,475 citations
TL;DR: In this paper, the authors review the catalytic reactions for the removal of NO and discuss the reduction of NO in the presence of NH3, CO, H-2 or hydrocarbons as well as the decomposition of NO.
1,110 citations
TL;DR: In this article, a review of recent developments in nonequilibrium statistical physics is presented, focusing on phase transitions from fluctuating phases into absorbing states, and several examples of absorbing-state transitions which do not belong to the directed percolation universality class are discussed.
Abstract: This review addresses recent developments in nonequilibrium statistical physics. Focusing on phase transitions from fluctuating phases into absorbing states, the universality class of directed percolation is investigated in detail. The survey gives a general introduction to various lattice models of directed percolation and studies their scaling properties, field-theoretic aspects, numerical techniques, as well as possible experimental realizations. In addition, several examples of absorbing-state transitions which do not belong to the directed percolation universality class will be discussed. As a closely related technique, we investigate the concept of damage spreading. It is shown that this technique is ambiguous to some extent, making it impossible to define chaotic and regular phases in stochastic nonequilibrium systems. Finally, we discuss various classes of depinning transitions in models for interface growth which are related to phase transitions into absorbing states.
1,081 citations
01 Jan 1988
694 citations
01 Jul 2008-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: In this paper, the basic kinematic relationships for 1D and 2D VAM (circular/elliptical tool path) are described and the periodic separation between the tool rake face and uncut material, characteristic of VAM, is related to observed reductions in machining forces and chip thickness.
Abstract: Vibration-assisted machining (VAM) combines precision machining with small-amplitude tool vibration to improve the fabrication process. It has been applied to a number of processes from turning to drilling to grinding [9] , [36] . The emphasis on this literature review is the turning process where VAM has been applied to difficult applications such as diamond turning of ferrous and brittle materials, creating microstructures with complex geometries for products like molds and optical elements, or economically producing precision macro-scale components in hard alloys such as Inconel or titanium. This review paper presents the basic kinematic relationships for 1D (linear vibratory tool path) and 2D VAM (circular/elliptical tool path). Typical hardware systems used to achieve these vibratory motions are described. The periodic separation between the tool rake face and uncut material, characteristic of VAM, is related to observed reductions in machining forces and chip thickness, with distinct explanations offered for 1D and 2D modes. The reduced tool forces in turn are related to improvements in surface finish and extended tool life. Additional consideration is given to the intermittent cutting mechanism and how it reduces the effect of thermo-chemical mechanisms believed responsible for rapid wear of diamond tools when machining ferrous materials. The ability of VAM to machine brittle materials in the ductile regime at increased depth of cut is also described.
657 citations