Articles written in Sadhana

    • A novel image compression model by adaptive vector quantization: modified rider optimization algorithm


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      In recent days over the internet, the uploading of enormous new images is being made every day, and they necessitate large storage to accumulate the image data. For the earlier few decades, more analysts have evolved skillful image compression schemes to enhance the compression rates and the image quality. In this work, Vector Quantization is used, which uses the Linde–Buzo–Gray algorithm. As a novel intention, the codebooks are optimized by an improved optimization algorithm. In this approach, the database image is firstlyseparated into a set of blocks, i.e., pixels, and these sets of blocks are referred to as vectors. Then a suitable codeword is selected for each vector such that is the closest representation of that input vector. The encoder generates a codebook by mapping the vectors on the basis of these code words, and the compression of the vectors takes place. The encoder then sends a compressed stream of these vectors by pointing out their indices from the codebook to the decoder through a channel. The decoder then decodes the index to find out thecompressed vector and places it on the image. For attaining a better image compression effect, the codebook is optimized using the Best Fitness Updated Rider Optimization Algorithm. The optimization of codebooks is doneso that the summation of the compression ratio and the error difference between the original and decompressed images has to be minimized. Moreover, the proposed model is scruntized with other existing algorithms, and the experimental outcomes are validated.

    • Study of microstructure and mechanical properties of NiTi wire cladding on super austenitic stainless steel 904L by TIG cladding process


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      NiTi wire coating was preplaced on super austenitic stainless steel (904L) for enhancing the surface mechanical property. Melting of NiTi wire of 1 mm diameter formed a clad track on the 904L stainless steel substrate using the TIG cladding process. The influence of TIG current on microstructure, phase formation,micro-hardness and abrasive wear resistance characteristics of the clad surface have been investigated. The maximum average micro-hardness of the NiTi clad layer was 952HV at current of 40 A which is 5.95 times greater than the substrate material 904L. The EDS and XRD study of the NiTi coating layer confirmed theformation of NiTi, NiTi2, and B2 (NiTiFeCr) structure as major constituent phases and some intermetallic (CrFe-Ni) which improved the mechanical properties of the clad layer. The pin on disc type sliding abrasive wear of the NiTi clad layer showed the improvement of wear resistance up to 8.83 times compared to the substrate 904L.

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