Showing papers by "Ghulam Ishaq Khan Institute of Engineering Sciences and Technology published in 2003"
TL;DR: In this paper, the microstructure and interfacial reactions in an aluminum-fullerene (Al/C60) composite produced by pressurized liquid metal infiltration (squeeze casting) of a tap-packed C60 powder preform were studied.
68 citations
08 Dec 2003
TL;DR: The paper discusses the design of a fuzzy logic controller for a twin rotor MIMO system that is superior to the system performance with a conventional PID or LQR controller, over the whole range of operating conditions.
Abstract: The paper discusses the design of a fuzzy logic controller for a twin rotor MIMO system. The system has three degrees of freedom, but we have designed the controller for two degrees of freedom (DOF) only, i.e., travel and elevation. The controller is designed such that a change in one degree should have minimum effect on the other and overall the system should remain stable. We have designed two fuzzy logic controllers: one for travel control and one for elevation: both are designed in MATLAB and have Sugeno inference. For the twin rotor MIMO system, commonly known as the helicopter problem, many conventional controllers exist. Our controller's performance had to be better than, or at least equal to, their's. To test the controller on a practical system was not possible, therefore we used simulations to benchmark the performance of the fuzzy logic controller. The simulation results show that the system performance with a fuzzy logic controller is superior to the system performance with a conventional PID or LQR controller, over the whole range of operating conditions.
33 citations
01 Feb 2003
TL;DR: In this article, a design based on a combustion chamber of variable geometry was proposed to reduce nitrogen oxides emission of diesel engines, but the desired effects could be achieved only when intensive interaction of combustion products with the catalyst-coated surface was provided.
Abstract: In-cylinder catalysis as a method for reducing the nitrogen oxides emission of diesel engines has been investigated experimentally. Desirable effects could be achieved only when intensive interaction of combustion products with the catalyst-coated surface was provided. It was found that a design based on a combustion chamber of variable geometry could give useful results, particularly for non-turbocharged engines.
6 citations
25 Mar 2003
TL;DR: An adaptive wavelet transform based on an image coder that employs a stack-run representation for quantized transform coefficients and benefits from the intra-subband redundancies is presented.
Abstract: Summary form only given. An adaptive wavelet transform based on an image coder that employs a stack-run representation for quantized transform coefficients and benefits from the intra-subband redundancies is presented. The compression algorithm can be divided into four parts. First, an adaptive wavelet packet basis is selected for representing the given image using certain entropy-based cost functions. Second, the wavelet packet coefficients are quantized using an optimal scalar quantizer for Laplacian distribution. Third, the quantized coefficient is represented with stack-run coding generating a redundant symbol stream. Finally, this symbol stream is entropy coded using a higher order arithmetic coder.
1 citations
01 Jan 2003
TL;DR: The development of an adaptive wavelet image coder based on stack-run representation of the quantized coefficients that exploits the redundancies present within individual subbands and its addressing complexity is much lower than that of the wavelet zerotree coding algorithms.
Abstract: We report on the development of an adaptive wavelet image coder based on stack-run representation of the quantized coefficients. The coder works by selecting an optimal wavelet packet basis for the given image and encoding the quantization indices for significant coefficients and zero runs between coefficients using a 4-ary arithmetic coder. Due to the fact that our coder exploits the redundancies present within individual subbands, its addressing complexity is much lower than that of the wavelet zerotree coding algorithms. Experimental results show coding gains of up to 1:4dB over the benchmark wavelet coding algorithm.
1 citations