A bio inspired and trust based approach for clustering in WSN

Wireless sensor network (WSN) is a special kind of ad-hoc network consists of battery powered low cost sensor nodes with limited computation and communication capabilities deployed densely in a target area. Clustering in WSN plays an important role because of its inherent energy saving capability and suitability for highly scalable network. This paper is an extended version of our previous work (Sahoo et al. 2013a). Although the clustering strategy presented in this paper is same as our previous work but here a light weight dynamic TRUST model along with honey bee mating algorithm is presented, which will only prevent malicious node to be a cluster head. The choice of light weight TRUST model makes our clustering method more secure and energy efficient, which are most pivotal issues for resource constrained sensor network. We have also introduced a priority scheme among the trust metrics which is more realistic. Furthermore, the use of honey bee mating algorithm finds most appropriate node as cluster head. Simulation results are also presented here to compare the performance of our algorithm with low energy adaptive clustering hierarchy and advertisement time-out driven bee mating approach to maintain fair energy level in sensor networks.     

Measurement of thermal diffusivity of solids using infrared thermography

We report measurement of thermal diffusivity of solid samples by using a continuous heat source and infrared thermal imaging. In this technique, a continuous heat source is used for heating the front surface of solid specimen and a thermal camera for detecting the time dependent temperature variations at the rear surface. The advantage of this technique is that it does not require an expensive thermal camera with high acquisition rate or transient heat sources like laser or flash lamp. The time dependent heat equation is solved analytically for the given experimental boundary conditions. The incorporation of heat loss correction in the solution of heat equation provides the values of thermal diffusivity for aluminum, copper and brass, in good agreement with the literature values.     

Effects of high hydrostatic pressure on the mechanical behavior of a crystalline polymer–polyoxymethylene

The true stress-true strain behavior of polyoxymethylene, n(-CH₂O), as an example of a bulk semi-crystalline polymer, has been investigated for constant hydrostatic environmental pressures from 1 atmosphere to 8 kilobars with the principal objectives of elucidating the factors controlling flow and fracture. Experiments were conducted in uniaxial tension at room temperature and constant strain rate. The tensile observations were supplemented by measurements of bulk compressibility and stress relaxation behavior at pressure. In contrast with metals and inorganic compounds, the modulus, yield stress and fracture stress of POM increase strongly with pressure by a factor of approximately three at 8 kilobars. The modulus increase is shown from the stress relaxation measurements to be associated with a pressure-induced increase in the β-transition temperature which points to the potential usefulness of the concept of pressure-temperature super-position of mechanical behavior. The characteristics of the pressure dependence of the yield stress demonstrate that yield criteria based on continum mechanics considerations, including the Mohr or Coulomb-Navier criterion, are not valid for general deformation (non-plane strain) conditions in this polymer. The concept of a critical volume change determining the initiation of yielding is suggested to be applicable to semi-crystalline polymers. Comparison with analogous changes in yield stress with temperature points to an increasing contribution to the control of yielding by the initially disordered regions with increasing pressure or decreasing temperature. The fracture behavior observed at pressure eliminates the concepts of a critical stress as a fracture criterion for POM and of a simple reduction in normal stress at points of stress concentration as the principal effect of the applied pressure on fracture.     

Fabrication and absorption intensity analyses of Er2O3 nanoparticles suspended in polymethyl methacrylate

Nanoparticles suspended in polymeric host materials are found to have tremendous potential for various photonic and biological applications due to their unique material properties. Polymethyl methacrylate (PMMA) is known to be one of the best vinyl polymers owing to its excellent dimensional quality, weather resistance, easiness of synthesis, resistance to laser damage, and high mechanical strength. In this article, we describe a methodology to fabricate thin discs of nanocrystalline erbium oxide (Er₂O₃) suspended in PMMA (Er₂O₃/PMMA). The optical transparency of PMMA was confirmed in the ultraviolet, visible, and the near‐infrared regions of the electromagnetic spectrum, making it possible to observe only the Er₂O₃ spectra over the wavelength investigated. The room‐temperature absorption spectrum of Er₂O₃/PMMA has been taken in the 400 to 820 nm wavelength region. Analysis of the spectrum reveals a consistent agreement between our experimental data and those reported earlier for Er³⁺ in nanocrystalline Er³⁺ : Y₂O₃. A solid solution exists between Er₂O₃ and Er³⁺ : Y₂O₃ in terms of their physical properties. Therefore, our experimental results conclude that the presence of PMMA does not significantly alter the crystal symmetry as well as the co‐ordination environment of the Er³⁺ ions in Er₂O₃. Our results also emphasize that the Er₂O₃/PMMA may have future possibilities for numerous technological applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Stability of active components of cardamom oleoresin in co-crystallized sugar cube during storage

Cardamom oleoresin was co-crystallized to formulate flavoured sugar cubes for table top use in tea. The flavoured sugar cubes were packed in two-layer composite and three-layer metalized laminate packaging materials and evaluated for 5 months at relative humidities of 33%, 63% and 93% and temperatures of 5 °C, 25 °C and 45 °C, respectively. The major active components of cardamom oleoresin viz. 1,8-cineole and α-terpinyl acetate in the co-crystallized sugar cubes was quantified by gas chromatography throughout the storage period. The major active components of cardamom in the oleoresin, freshly prepared flavoured sugar cubes, and in sugar cubes stored under extreme condition of storage at 45 °C under all the relative humidities were identified by GCMS. The rate of degradation of 1,8-cineole was higher than α-terpinyl acetate as seen from the kinetic study and activation energy in both the packaging materials under all conditions of storage.     

Radiation amplification with help of the intrinsic Josephson effect

The use of the intrinsic Josephson effect in layered high-T_c superconductors for amplification of a signal in the presence of a strong pump radiation is investigated. Calculations are done both for thin films and massive material with a surface parallel to the c-direction, assuming normal incidence of the radiation with electric field parallel to the c-direction for parameter values relevant for high-T_c materials. In both cases high signal gain is obtained in a limited range of frequencies and pump power.     

Network Architecture and Wireless Ad Hoc Routing for Airborne Internet Services

Wireless Personal Communications - The passengers traveling in aircraft require access to the internet to effectively utilizing their precious in-flight time. Providing internet services to such...