The paper presents an image watermarking algorithm based on Contourlet Transform (CT) and QR factorization method. Contourlet Transform is used to transform both the cover and watermark image into subbands. The watermarking is applied to the Contourlet Transform as the human visual system is comparatively less sensitive to edges of the image. The low frequency coefficients of an image contain the highest energy. Thus the lowest frequency coefficients of the contourlet transformed original and watermark image are selected for watermarking. The selected coefficients are then decomposed using QR factorization method. The QR factorized coefficients of watermark image is embedded into the QR factorized original image values. Inverse QR and inverse CT is then applied on the watermark embedded coefficients of image to obtain the watermarked image. Experimental results show that the proposed algorithm is a better technique as compared to other watermarking schemes based on Contourlet Transform. The proposed watermarking scheme is imperceptible and robust against image processing attacks such as Gaussian noise, scaling, compression, salt and pepper noise.
The ISM (Industrial Scientific and Medical) bands in the radio frequency space in India offer two alternative spectra to implement wireless network for advanced metering infrastructure (AMI). These bands lie in the range of 2.4GHz and sub-GHz frequencies 865 to 867 MHz This paper aims to examine the suitability of both options by designing and executing experiments in laboratory as well as carrying out field trials on electricity meters to validate the selected option. A parameter, communication effectiveness index (CEI2) is defined to measure the effectiveness of 2 way data communication (packet exchange) between two points under different scenarios of buildings and free space. Both 2.4 GHz and Sub-GHz designs were implemented to compare the results. The experiments were conducted across 3 floors of a building. Validation of the selected option was carried out by conducting a field trial by integrating the selected radio frequency (RF) modem into the single phase electricity meters and installing these meters across three floors of the building. The methodology, implementation details, observations and resulting analytical conclusion are described in the paper.
The miniaturization of the devices into nanoscale has enabled ultra high density chips, but at the cost of increased defect density. In this manuscript, Markov Random Field (MRF) approach is used to evaluate the device reliability in the
presence of high defect density. Both hard and soft errors have been considered. We have presented a NANOLAB based fault model of 8-bit full adder, basic building block being 2:1 multiplexer. At each level, a Triple Modular Redundancy (TMR) is employed to enhance reliability. The results are compared with another 8-bit full adder, designed using logic gates. Assuming defect rate up to 10%, the circuits are evaluated for stuck at faults. Further, we have augmented the NANOLAB tool to include a design library of various types of flip flops. A 4-bit SISO right shift register is used as vehicle for exemplifying our approach. The fault tolerant approach N-Modular Redundancy (NMR) is compared at different levels of granularity and for varying levels of N. It is observed that NMR fails to provide the device fault tolerance when defect rate is higher than a threshold value.
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