Showing papers by "Ghulam Ishaq Khan Institute of Engineering Sciences and Technology published in 2005"
TL;DR: In this article, a weak and strong convergence of an iterative scheme in a uniformly convex Banach space under a condition weaker than compactness was studied. But the convergence of the scheme was not considered.
Abstract: In this paper, we are concerned with the study of an iterative scheme with errors involving two nonexpansive mappings. We approximate the common fixed points of these two mappings by weak and strong convergence of the scheme in a uniformly convex Banach space under a condition weaker than compactness.
137 citations
TL;DR: The influence of substrate surface temperature and oxidation state on the flattening of alumina and stainless steel particles and the morphology of resulting splats were studied in this article, where splat morphology of both materials transformed from splashed one to disk-shaped one.
Abstract: The influence of the substrate surface temperature and oxidation state on the flattening of alumina and stainless steel particles and the morphology of resulting splats were studied in the current work. Particles were sprayed by a d.c. plasma gun on polished plain carbon steel and low alloy steel substrates preheated by plasma jet at different temperatures in air or in an oxidation limiting nitrogen shroud system added around substrates. Extensively fragmented splats of alumina and stainless steel were collected on substrates kept at room temperature. On substrates preheated to 573 (±20) K, the splat morphology of both materials transformed from splashed one to disk-shaped one. Optimal flattening degrees for stainless steel and alumina splats were measured for this substrate temperature, and the former particles exhibited flattening degree of the order of 1.2 times those of alumina. On plain carbon steel substrates, preheated in air at temperatures well above 573 K, the particle flattening degree decreased drastically and collected splats were extensively fragmented with bubbles like holes in them. The splashing and bubble formation in splats on preheated substrate were more dominating for low viscosity and higher Reynolds number stainless steel particles. The splat flattening–splashing and bubble formation were effectively limited by preheating substrates in the nitrogen shroud system. After a detailed characterization of substrate surface oxide layers, formed under different preheating conditions, it was concluded that splat morphology and flattening were only partially affected by the oxide chemical composition and thickness and were principally controlled by the surface roughness (more exactly its topography), induced by the oxidation.
57 citations
TL;DR: In this article, the formation of nanosized TiC particles in both Cu-rich phase and Cu-sn-Ti-Zr intermetallic regions of the alloy was investigated.
Abstract: Melting experiments of Cu-Sn-Ti-Zr filler metal powder containing cellulose nitrate and graphite, respectively, resulted in the formation of nanosized TiC particles in both Cu-rich phase and CuSn 3 Ti 5 intermetallic regions of the alloy (see figure). The variation of the binder type and content allows to tailor the properties of the filler metals in terms of erosion resistance, decisive for a new generation of superabrasive tools.
32 citations
TL;DR: In this article, the effect of welding parameters and geometrical size on residual stress distribution in welded pipe-flange joints is analyzed. But the authors focus on a single-pass metal inert gas welding with single “V” Butt-weld geometry.
Abstract: This paper presents results of detailed three-dimensional finite element simulation of residual stress distribution in welded Pipe-Flange Joints with emphasis on the effect of welding parameters and geometrical size of the model. Single-pass Metal Inert Gas welding with single “V” Butt-weld geometry is used in the study. The effect of two basic welding parameters including welding current and speed and two geometrical parameters i.e. pipe diameter and wall-thickness are examined. For both welding current and welding speed, three sets of parameters comprising of low, medium and high values are used. To analyze the effect of each parameter explicitly only one parameter is changed at one time. In most of the cases 100 mm nominal pipe diameter is used. A FE Model for 200 mm nominal pipe diameter is also analyzed to determine the effect of pipe diameter.
27 citations
TL;DR: In this paper, the effect of mechanical constraints on welding distortions and residual stresses in a pipe-flange joint is investigated and the results show that axial displacement and tilt of the flange face are strongly dependant on the constraint conditions.
Abstract: This paper presents a detailed three-dimensional finite element (FE) study to investigate the effect of mechanical constraints on welding distortions and residual stresses in a pipe–flange joint. The FE model of a pipe–flange joint is subjected to sequentially couple nonlinear transient thermo-mechanical analysis to simulate complex welding phenomena. Single-pass gas metal arc welding for single 'V' butt-weld joint geometry of a 100 mm diameter pipe with compatible weld-neck ANSI flange class #300 of low carbon steel is simulated. Two tack-welds at 90° and 270° from the weld start position are modelled. Four different constraint conditions representing the welding of unassembled joints, welding of assembled joints, welding of assembled joints with reflective symmetry and welding of perfectly constrained joints are analysed. To model the constraints and boundary conditions more realistically contact pairs are used between the matching surfaces of different structural components. Basic FE models are validated with experimental data for temperature distribution and deformations. Predicted welding distortions and residual stresses are compared and discussed in detail. From the results, axial displacement and tilt of the flange face are found to be strongly dependant on the constraint conditions. Minimum axial distortion on the flange face is found for rigidly clamped flanges. However, residual stresses have a weak dependence on the constraints set.
24 citations
TL;DR: In this paper, the Lindeberg type condition of asymptotical normality and Berry-Esseen type bound for disjoint uniform k-spacings were derived.
17 citations
27 Aug 2005
TL;DR: In this article, the authors describe an approach for an on-road vehicle detection system with the view of driving assistance using the Haar wavelet packet transform (HAWPT).
Abstract: The paper describes a novel, approach for an on road vehicle detection system with the view of driving assistance. The presented technique generates the initial hypothesis by detecting the shadows projected by vehicles on the road surface. The results of detection are then verified using the Haar wavelet packet transform. The verification step compares the standard deviations of the best basis vector of the hypothesized vehicle with pre-computed feature vector of similar values for different vehicular structures. Experimental results confirm the validity of the presented approach in different lightening conditions and scenarios. The presented technique is capable of detecting vehicles at twelve frames per sec which makes it ideal for real time pre-crash sensing.
15 citations
15 Dec 2005
TL;DR: GP is used to develop an optimal composite classifier (OCC) having better performance than individual SVM classifiers, and the experimental results demonstrate that OCC is more effective, generalized and robust.
Abstract: In this paper, we are proposing a combination scheme of kernels information of support vector machines (SVMs) for improved classification task using genetic programming. In the scheme, first, the predicted information is extracted by SVM through the learning of different kernel functions. GP is then used to develop an optimal composite classifier (OCC) having better performance than individual SVM classifiers. The experimental results demonstrate that OCC is more effective, generalized and robust. Specifically, it attains high margin of improvement at small features. Another side advantage of our GP based intelligent combination scheme is that it automatically incorporates the issues of optimal kernel and model selection to achieve a higher performance prediction model.
10 citations
TL;DR: In this article, a study of proper affine vector fields in plane symmetric static space-times by using the rank of the Rieman matrix and holonomy was performed, and it was shown that the special class of the above space times admit proper vector fields.
Abstract: A study of proper affine vector fields in plane symmetric static space-times by using the rank of the Rieman matrix and holonomy. Studying proper affine vector fields in each case, It is shown that the special class of the above space-times admit proper affine vector fields.
2 citations
01 Jan 2005
TL;DR: In this paper, an approach is developed to find approximate solutions to the restricted circular three body problem using the Lambert's wave function, which is useful in approximately describing the position vectors of three spherically symmetric masses, one having a much smaller mass than the other two.
Abstract: An approach is developed to find approximate solutions to the restricted circular three body problem. The solution is useful in approximately describing the position vectors of three spherically symmetric masses, one of which has a much smaller mass than the other two. These masses perform free motion under each others’ gravitational influence. The set of solutions is found using the Lambert’s wave function.
1 citations
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TL;DR: The problem of describing the free motions of three gravitating bodies under each others gravitational influence is one of the oldest of unsolved problems of classical mechanics as discussed by the authors, and it is on these lines that we will explore the problem.
Abstract: The problem of describing the free motions of three gravitating bodies under each others gravitational influence is one of the oldest of unsolved problems of classical mechanics. Henry Poincare proved in his dictum that due to the nature of the instabilities involved in the problem, it could not be solved. Yet closed form approximations for the problem can be found and it is on these lines that we will explore the problem. It will be shown that closed form approximations for the associated trajectories can be found.
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TL;DR: In this paper, a study of conformally flat but non flat Bianchi type I and cylindrically symmetric static space-times according to proper projective symmetry is given by using some algebraic and direct integration techniques.
Abstract: A study of conformally flat but non flat Bianchi type I and cylindrically symmetric static space-times according to proper projective symmetry is given by using some algebraic and direct integration techniques. It is shown that the special class of the above space-times admit proper projective vector fields.