Design of Tri-Band MIMO Antenna with Improved Isolation using DGS and Vias

Wireless Personal Communications - An antenna which is used for multipurpose like WiMAX, RADAR altimeter and X-band applications proposed. A tri-band multiple-input–multiple-output antenna...     

A HGGSA Approach to Beam Forming for DOA Estimation in Smart Antenna Arrays

Beam forming is one of the most important processes in smart antenna systems for DOA estimation. The most important function in beam forming is changing beam pattern of antenna for a particular angle. If the antenna does not change the position for the specified angle, the signal losses will be high. For avoiding this, a hybrid method, called HGGSA (hybrid genetic and gravity search algorithm) is proposed that is developed by combining genetic algorithm and GSA to beam forming for DOA estimation in smart antenna arrays. In the proposed method, if an angle is given as input, it will give the maximum signal gain in the beam pattern of the antenna with corresponding position and phase angle after searching through the space based on the HGGSA algorithm.

     

Energy transfer processes between primary and secondary dopants in polystyrene solutions dissolved in 1,4‐dioxane

High molecular weight polystyrene prepared by emulsion polymerization was characterized by gel permeation chromatography, differential scanning calorimetry, and solution viscosity. Prepared polystyrene was used to study the energy transfer processes using Exalite 416 and Coumarin 515 dyes as the primary and the secondary dopants. Absorption and emission spectra of the dyes in polystyrene (PS) solution of concentration 2.5 g/dL in 1,4‐dioxane have been measured. Absorption spectrum of the acceptor dye, Coumarin 515 (wavelength shifter), at 403 nm matches with the emission spectrum of the donor dye, Exalite 416. Continuous wave emission spectra of these wavelength shifters have been studied by changing the concentration of Coumarin 515 dye (accepter) while keeping the Exalite 416 (donor) concentration (10^?4 M) fixed in the PS solution. Energy transfer process has been discussed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 336–341, 2005     

Lead adsorption study on combustion derived <Emphasis Type="Italic">γ</Emphasis>-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> surface

New combustion synthetic route for the synthesis of nanosized γ-Fe₂O₃ by microwave-assisted route is reported. X-ray density, tap density and powder density of prepared γ-Fe₂O₃ are calculated. Adsorption study of Pb²⁺ on combustion derived nanosized γ-Fe₂O₃ is studied by dynamic method. The γ-Fe₂O₃ structure and lead adsorbed γ-Fe₂O₃ (Pb-γ-Fe₂O₃) are studied by X-ray diffraction (XRD). Additional lead peaks in Pb-γ-Fe₂O₃ sample pattern confirm the lead adsorption. Morphology of as prepared γ-Fe₂O₃ and Pb-γ-Fe₂O₃ is studied by scanning electron micrograph (SEM) technique. Varied morphology for Pb-γ-Fe₂O₃ compared to its γ-Fe₂O₃ is observed. Variation of bonding in Pb-γ-Fe₂O₃ sample due to lead adsorption is viewed by infrared spectroscopic (IR) technique. Energy dispersive X-ray microanalysis (EDX) is scanned for the lead adsorbed γ-Fe₂O₃ to know the presence of lead on γ-Fe₂O₃ surface. The eluent lead solution is characterized by atomic absorption spectroscopy (AAS) and solution conductivity (SC). Reduction in the concentration and increase in conductance of eluent lead solution is observed. The potential use of solid adsorbents for the adsorption of heavy metal pollutants is envisaged in the present work.     

Diethyl ether as an ignition improver for biogas homogeneous charge compression ignition (HCCI) operation - An experimental investigation

This paper deals with experimental investigations of a homogeneous charge compression ignition (HCCI) engine using biogas as a primary fuel and diethyl ether (DEE) as an ignition improver. The biogas is inducted and DEE is injected into a single-cylinder engine. For each load condition, best brake thermal efficiency DEE flow rate is determined. The results obtained in this study are also compared with those of the available biogas-diesel dual-fuel and biogas spark ignition (SI) modes. From the results, it is found that biogas-DEE HCCI mode shows wider operating load range and higher brake thermal efficiency (BTE) at all loads as compared to those of biogas-diesel dual-fuel and biogas SI modes. In HCCI mode, at 4.52 bar BMEP, as compared to dual-fuel and SI modes, BTE shows an improvement of about 3.48 and 9.21% respectively. Also, nitric oxide (NO) and smoke emissions are extremely low, and carbon monoxide (CO) emission is below 0.4% by volume at best brake thermal efficiency points. Also, in general, in HCCI mode, hydrocarbon (HC) emissions are lower than that of biogas SI mode. Therefore, it is beneficial to use biogas-DEE HCCI mode while using biogas in internal combustion engines.     

The Reliability and Predictive Ability of a Biomarker of Oxidative DNA Damage on Functional Outcomes after Stroke Rehabilitation

We evaluated the reliability of 8-hydroxy-2′-deoxyguanosine (8-OHdG), and determined its ability to predict functional outcomes in stroke survivors. The rehabilitation effect on 8-OHdG and functional outcomes were also assessed. Sixty-one stroke patients received a 4-week rehabilitation. Urinary 8-OHdG levels were determined by liquid chromatography–tandem mass spectrometry. The test-retest reliability of 8-OHdG was good (interclass correlation coefficient = 0.76). Upper-limb motor function and muscle power determined by the Fugl-Meyer Assessment (FMA) and Medical Research Council (MRC) scales before rehabilitation showed significant negative correlation with 8-OHdG (r = −0.38, r = −0.30; p < 0.05). After rehabilitation, we found a fair and significant correlation between 8-OHdG and FMA (r = −0.34) and 8-OHdG and pain (r = 0.26, p < 0.05). Baseline 8-OHdG was significantly correlated with post-treatment FMA, MRC, and pain scores (r = −0.34, −0.31, and 0.25; p < 0.05), indicating its ability to predict functional outcomes. 8-OHdG levels were significantly decreased, and functional outcomes were improved after rehabilitation. The exploratory study findings conclude that 8-OHdG is a reliable and promising biomarker of oxidative stress and could be a valid predictor of functional outcomes in patients. Monitoring of behavioral indicators along with biomarkers may have crucial benefits in translational stroke research.     

Computer-aided analysis of reinforced concrete columns subjected to axial compression and bending. Part II: T-shaped sections

This paper presents the writer's experience in investigating numerically the strength behaviour of short T-shaped reinforced concrete (RC) columns in order to provide design aids for structural engineers. Computer programs were developed for the analytical study of T-shaped RC column sections subjected to uniaxial/biaxial bending with axial compression. The interaction curves for L-shaped members, in Part I [Mallikarjuna and P. Mahadevappa, Comput. Struct. 44, 1121–1138 (1992)], and for T-shaped sections, in the present paper, were derived to provide advice for design information. This paper deals with the definitions and materials that are used in the limit state design of reinforced concrete structures. The programs presented here are written to operate in a conversational mode so that the analyst can respond to messages from the computer.     

Thickness dependent properties of nickel oxide thin films deposited by dc reactive magnetron sputtering

Nickel oxide thin films of various thicknesses were grown on glass substrates by dc reactive magnetron sputtering technique in a pure oxygen atmosphere with sputtering power of 150 W and substrate temperature of 523 K. Crystalline properties of NiO films as a function of film thickness were investigated using X-ray diffraction. XRD analysis revealed that (200) is the preferred orientation and the orientation of the films changed from (200) to (220) at film thickness of 350 nm. The maximum optical transmittance of 60% and band gap of 3.82 eV was observed at the film thickness of 350 nm. The lowest electrical resistivity of 5.1 Ω cm was observed at a film thickness of 350 nm, thereafter resistivity increases with film thickness.