Dynamic Threshold Based Throughput Enhancement in Cognitive Radio Network Using Hidden Markov Model with State Prediction

Wireless Personal Communications - The enhancement of throughput is one of the key issues in the cognitive radio network. In this paper, a channel status prediction scheme based on hidden Markov...     

Laboratory measurements of the light scattering properties of bentonite clay particles embedded in a cylindrical polymer matrix

The volume scattering function and degree of linear polarization of randomly oriented bentonite clay particles were investigated as a function of scattering angle at 543.5?nm, 594.5?nm and 632.8?nm incident laser wavelengths by using a detector array-incorporated laboratory light scattering setup. Readings were taken in steps of 1° from an angle of 10° to 170° and each detector was separated from the next one by an angle of 10°. A transparent cylindrical polymer matrix made of cycloaliphatic amine-cured thermosetting epoxy resin was used to hold the scattering samples in front of the laser beam. For background correction the measurements were taken in differential mode.     

Influence of Sediment Layers on Dynamic Behavior of Aged Concrete Dams

The assessment of response of an aged concrete dam is important for the prediction of its behavior during earthquakes, so that remedial measures can be taken at the right time to withstand future earthquakes. The assessment is necessary, since the analyses procedures may become obsolete and the state of the art may change as the time of construction and the structural material may deteriorate due to harsh environmental conditions. At the same time, the sediment will be accumulated at the reservoir bottom on the upstream side of the dam. The process of siltation depends on the reservoir topography and climatic variability, i.e., increased flood frequency and river inflow. The decision of retrofitting or strengthening the aged dam necessitates accurate analysis of the same in the presence of accumulated sediment. In this paper, an approach to include the time-dependent degradation of concrete owing to environmental factors and mechanical loading in terms of isotropic degradation index is presented. The absorption of pressure waves at the bottom of the reservoir due to the presence of sediments has been incorporated in the hydrodynamic pressure equation. The response of an aged concrete dam in the presence of sediment layers under seismic excitation is studied. The outcomes show the efficiency of the proposed algorithm.     

Analysis of Performance of BPSK in an Additive Combination of Impulsive and Gaussian Noise

We analyze the bit error rate (BER) performance ofa correlation receiver subject to impulsive plusGaussian noisewith coherent binary phase-shift keying (BPSK). The impulsive component of the noise is assumed to be due torandom occurrences of impulses following a Poisson arrival process.Using the moments of theimpulsive component, aseries expression for the BERis derived by a Taylor's series approach. From this expression, approximate formulae for extreme valuesof signal-to-noise ratio (SNR) and impulse arrival rate (IAR)are obtained. Numerical results show thatwhen the square root raisedcosine pulse is used, (1) the BER performance improves with increaseof the rolloff factor, but the improvement becomes more significantwith decrease of the Gaussian-to-total noise ratioor increase of the IAR,(2) as the rolloff factor increases, a decrease of the IARdegrades the BER performance for low SNRs, but improves it for high SNRs.     

Mechanical properties of protein‐stabilized starch‐based supercritical fluid extrudates

Mechanical properties of starch‐based supercritical fluid extrusion (SCFX) extrudates were correlated to their structure. Thermosetting ingredients were added to the feed and the extrudate was dried to set the expanded structure. Compared to whey protein concentrate with 34% protein (WPC‐34), addition of egg white (EW) gave a softer skin and a fragile but well formed cellular structure. For drying between 70 and 100 °C, the overall structure was more homogenous for EW added. A higher modulus was associated with a larger number average of sides in a cell face and higher percentage of closed cells. Ashby's model (1983) for non‐food cellular solids gave a good fit to our data for relating relative compressive modulus to relative bulk density. A linear regression model indicated that bulk density alone was a good predictor of mechanical strength.     

An improved analytical model for static pull-in voltage of a flexured MEMS switch

Microsystem Technologies - This paper presents the design of low-k meander based MEMS shunt capacitive switch with beam perforations. A closed form model to accurately calculate the pull-in voltage...     

Structural variations in layered alkaline earth metal cyclohexyl phosphonates

Two series of alkaline earth metal cyclohexyl phosphonates, M(C₆H₁₁PO₃H)₂(H₂O) (M = Ca, Sr and Ba) (1–3) and M(C₆H₁₁PO₃)(H₂O) (M = Mg, Ca, Sr, and Ba) (4–7) have been synthesized under mild reaction conditions. All new compounds have been characterized using elemental analysis, IR, TGA and powder X-ray diffraction techniques. The molecular structure of compound 2 determined using single crystal X-ray diffraction technique reveals a layered polymeric structure.     

Jatropha curcas oil based alkyd/epoxy resin/expanded graphite (EG) reinforced bio-composite: Evaluation of the thermal,mechanical and flame retardancy properties

Bio-composites were prepared from blends of Jatropha curcas oil based alkyd and epoxy resin with different weight percentage of expanded graphite (EG). The effect of EG loading on the thermal, mechanical, flame retardancy and water absorption properties of the bio-composites were studied. Significant improvement in thermal and mechanical properties was observed with 5 wt% EG loading. The prepared bio-composites were characterized by fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, X-ray diffractometry and tensile strength measurement. Morphological study showed the homogeneous dispersion of the EG sheets in the resin matrix. Limiting oxygen index (LOI) of the bio-composites showed a noticeable improvement in flame retardancy in comparison to neat blend of alkyd and epoxy resin. In vitro degradation of the bio-composites showed low degradation in phosphate buffer solution (pH 7.4).     

Synthesis of expanded graphite filled polyaniline composites and evaluation of their electrical and electrochemical properties

A series of conducting polyaniline/expanded graphite (PA/EG) composite was synthesized by in situ polymerization of aniline in acid medium followed by the addition of expanded graphite in various proportions (1, 2 and 3 wt%). The synthesized samples were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, ultraviolet–visible absorption, X-ray diffraction and by electrical conductivity measurements. The dc electrical conductivities of the composites were dramatically increased compared with pure polyaniline and found to be 0.50 × 10² S/cm to 6.11 × 10² S/cm. The PA/EG composites showed a reversible electrochemical response up to 150th repeated cycles as revealed by the cyclic voltametry study.     

Effects of Nickel Oxide (NiO) nanoparticles on the performance characteristics of the jatropha oil based alkyd and epoxy blends

Plant oil based alkyd resin was prepared from jatropha oil and blended with epoxy resin. Subsequently, alkyd/epoxy/NiO nanocomposites with different wt % of NiO nanoparticles have been prepared by mechanical mixing of the designed components. The structure, morphology, and performance characteristics of the nanocomposites were studied by UV‐visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and universal testing machine (UTM). The alkyd/epoxy/NiO nanocomposites showed the gradual increase in thermal stability with increasing NiO content. With 3 wt % NiO content the tensile strength of the nanocomposite increased by 19 MPa (more than twofold) when compared with the pristine polymer. Limiting oxygen index (LOI) value of the nanocomposites indicate that the incorporation of NiO nanoparticles even in 1 wt % can greatly improves the flame retardant property of the nanocomposites. This study confirms the strong influence of NiO nanoparticles on the thermal, mechanical, and flame retardant properties of the alkyd/epoxy/NiO nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41490.