Browsing by Publisher "Old City Publishing"

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    A distributed image compression algorithm for wireless multimedia sensor networks
    (Old City Publishing, 2015) Alaybeyoglu A.
    Recent advances in multimedia sensor networks made the image sensors applicable in many different types of sensor network applications such as environmental monitoring, surveillance and target tracking. Especially for image based applications, image data is needed to be compressed due to the requirement of large amount of data for representing the visual data. Although image compression is made for gaining from the energy consumption, this process requires very high computational power when an only single node takes this process on. Because of the constraints in energy, memory and the computational power, nodes should share the image processing tasks to balance the computational load on the sensor networks. In order to achieve this, we propose a distributed image compression algorithm which is based on Discrete Wavelet Transform for wireless multimedia sensor networks. We compared the proposed algorithm both with the centralized and the distributed approaches. Simulation results show that the proposed algorithm performs better than the compared algorithms for energy consumption, system lifetime and the image quality parameters. © 2015 Old City Publishing, Inc.
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    Laser shock processing of 6061-T6 aluminium alloy: Thermal modelling and analysis
    (Old City Publishing, 2016) Zafar H.; Saklakoglu N.; Irizalp S.G.; Khan S.; Shuja S.Z.; Boran K.; Yilbas B.S.
    Laser shock processing of 6061-T6 aluminium alloy is carried out. Temperature and stress fields are simulated in line with the experimental conditions. Metallurgical changes due to the laser shock and microhardness in the laser treated region are examined using analytical tools that include scanning and transmission electron microscopes and microhardness tester. The depth of shock affected region, plastic strain, and dislocation density are determined numerically and experimentally in the laser treated region. It is found that the temperature attains high values at the centre of the irradiated spot resulting in high rate of evaporation at the surface. The recoil pressure formed, due to high evaporation rate, at the laser treated surface results in plastic deformation of about 500 mm below the surface. A dislocation density of the order 2 × 1013 to 4 × 1013 cm-2 occurs in the surface region. Although high temperature gradients result in high stress levels in the region below the surface vicinity, high recoil pressure results in crack free surface with compressive stress. © 2016 Old City Publishing, Inc.