Closure of part-through fatigue cracks at the notch root

This paper describes a study of fatigue closure of part-through cracks in notched, 5 mm thick, Al---Cu alloy sheet specimens. The study used a specially designed electron fractography technique which enables accurate assessment of closure and its development wit crack extension, as well as its variation across the crack front. The effect of prior overloads on notch root crack closure was also investigated.     

Genotypic variation and relationships between quality traits and trace elements in traditional and improved rice (Oryza sativa L.) genotypes

In this study, we assessed the extent of genotypic differences among rice genotypes for grain size, milling quality, cooking properties, protein, and the mineral contents of Fe, Zn, Mn, and Cu in unpolished rice varieties. Further, relationship among grain quality traits and mineral contents was determined. The results showed that the visible difference could be found in the mineral contents among rice genotypes studied. The contents of Fe and Zn in traditional genotypes were significantly higher than those of improved cultivars. There was a negative correlation between grain yield and mineral contents. However, Fe, Zn, Mn, and Cu contents appeared to be positively correlated. The relationships between mineral element contents and cooking quality traits viz., kernel length after cooking and kernel linear elongation ratio were positively correlated, indicated the role of micronutrients in cooking quality traits. Both Fe and Cu contents were correlated positively and significantly with head rice recovery. The eigen values of 1st 6 principal components (PC) were > 1.0. The present study suggests that breeding for high minerals will be probably realistic.     

Lung computed axial tomography image segmentation using possibilistic fuzzy C-means approach for computer aided diagnosis system

Soft computing is an associate rising field that plays a crucial half in the area of engineering and science. One of the most significant applications of soft computing is image segmentation. It focuses on an exploiting tolerance of imprecision and uncertainty. Segmentation supported soft computing remains a difficult task within the medical field. Medical images are habitually used in the segmentation process to extract the meaningful portions and to know and clarify the condition of the particular patient. In this article, we implement an efficient possibilistic fuzzy C-means (PFCM) approach to segment the lung portion in the computed tomography (CT) image and the result shows that it improves the segmentation accuracy upto 98.5012% and results are compared with existing segmenting approaches like fuzzy possibilistic C-means method, fuzzy bitplane method and so forth. Also, the PFCM approach increases the diagnostic accuracy of the computer aided diagnosis system using CT images. The radiologist may utilize this computer aided diagnosis system results as a second opinion of their diagnosed results.     

Varactor controlled frequency and polarization reconfigurable microstrip antenna

A single feed compact microstrip antenna achieving frequency and polarization diversity using a varactor is presented. A simple patch antenna with an X‐slot constitutes the fundamental structure. The frequency and polarization agility is realized by varying the reactance of an embedded varactor at the center of the X‐slot with respect to the biasing from 0 to 25 V. The prototype fabricated on a substrate of dielectric constant (ε_r) 4.4 and height (h) 1.6 mm is fed by a proximity feed fabricated using the same substrate. By controlling the bias voltage of the varactor, the polarization of the antenna can be switched between linear and circular polarization. Furthermore, the proposed antenna offers stable broadside radiation characteristics without any extra impedance matching circuit. The frequency and polarization diversities of this design could potentially improve the reliability of wireless communication systems. The details of the antenna are presented and discussed. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2011.     

Electromagnetic Biostimulation of Living Cultures for Biotechnology, Biofuel and Bioenergy Applications

The surge of interest in bioenergy has been marked with increasing efforts in research and development to identify new sources of biomass and to incorporate cutting-edge biotechnology to improve efficiency and increase yields. It is evident that various microorganisms will play an integral role in the development of this newly emerging industry, such as yeast for ethanol and Escherichia coli for fine chemical fermentation. However, it appears that microalgae have become the most promising prospect for biomass production due to their ability to grow fast, produce large quantities of lipids, carbohydrates and proteins, thrive in poor quality waters, sequester and recycle carbon dioxide from industrial flue gases and remove pollutants from industrial, agricultural and municipal wastewaters. In an attempt to better understand and manipulate microorganisms for optimum production capacity, many researchers have investigated alternative methods for stimulating their growth and metabolic behavior. One such novel approach is the use of electromagnetic fields for the stimulation of growth and metabolic cascades and controlling biochemical pathways. An effort has been made in this review to consolidate the information on the current status of biostimulation research to enhance microbial growth and metabolism using electromagnetic fields. It summarizes information on the biostimulatory effects on growth and other biological processes to obtain insight regarding factors and dosages that lead to the stimulation and also what kind of processes have been reportedly affected. Diverse mechanistic theories and explanations for biological effects of electromagnetic fields on intra and extracellular environment have been discussed. The foundations of biophysical interactions such as bioelectromagnetic and biophotonic communication and organization within living systems are expounded with special consideration for spatiotemporal aspects of electromagnetic topology, leading to the potential of multipolar electromagnetic systems. The future direction for the use of biostimulation using bioelectromagnetic, biophotonic and electrochemical methods have been proposed for biotechnology industries in general with emphasis on an holistic biofuel system encompassing production of algal biomass, its processing and conversion to biofuel.     

Corrosion and Wear Behaviors of Cr-Doped Diamond-Like Carbon Coatings

A combination of plasma-enhanced chemical vapor deposition and magnetron sputtering techniques has been employed to deposit chromium-doped diamond-like carbon (DLC) coatings on stainless steel, silicon and glass substrates. The concentrations of Cr in the coatings are varied by changing the parameters of the bipolar pulsed power supply and the argon/acetylene gas composition. The coatings have been studied for composition, morphology, surface nature, nanohardness, corrosion resistance and wear resistance properties. The changes in I _D /I _G ratio with Cr concentrations have been obtained from Raman spectroscopy studies. Ratio decreases with an increase in Cr concentration, and it has been found to increase at higher Cr concentration, indicating the disorder in the coating. Carbide is formed in Cr-doped DLC coatings as observed from XPS studies. There is a decrease in sp ³/sp ² ratios with an increase in Cr concentration, and it increases again at higher Cr concentration. Nanohardness studies show no clear dependence of hardness on Cr concentration. DLC coatings with lower Cr contents have demonstrated better corrosion resistance with better passive behavior in 3.5% NaCl solution, and corrosion potential is observed to move toward nobler (more positive) values. A low coefficient of friction (0.15) at different loads is observed from reciprocating wear studies. Lower wear volume is found at all loads on the Cr-doped DLC coatings. Wear mechanism changes from abrasive wear on the substrate to adhesive wear on the coating.     

Visible light active photocatalytic degradation of bisphenol-A using nitrogen doped TiO2

Nitrogen doped titania was prepared by low temperature sol-gel method using titanium precursor and nitrogen containing bases like triethylamine and tetramethyl ammonium hydroxide compounds. The materials were characterized by XRD, BET, SEM, XPS, DRS-UV, and FT-IR techniques. DRS-UV study substantially indicates shift of the absorption edge of TiO2 to lower energy region. The phase composition, crystallinity, specific surface area, and visible light activity of nitrogen doped titania depend upon the preparation conditions. Photocatalytic degradation of bisphenol-A in aqueous medium was investigated by TiO2 and nitrogen doped TiO2 under visible light irradiation in a batch photocatalytic reactor. The results indicate higher visible light activity for nitrogen doped TiO2 than commercial TiO2 (Degussa P25) for bisphenol-A degradation. The influence of various parameters such as initial concentration of bisphenol-A, catalyst loading and pH was examined for maximum degradation efficiency.     

Photocatalytic degradation of phenol over TiO2 powder: The influence of peroxomonosulphate and peroxodisulphate on the reaction rate

Advanced oxidation processes (AOPs) have been developed as an emerging technology for treating hazardous organics in wastewater and groundwater. In the present study, the effect of oxidants [peroxomonosulphate (PMS) and peroxodisulphate (PDS)] on the photocatalytic oxidation of phenol on illuminated TiO₂ surfaces has been investigated. The efficiencies of these oxidants on photocatalytic degradation of phenol are compared with that of H₂O₂. The experimental results indicate that these oxidants exhibited enhanced rates of mineralization of phenol. A reaction mechanism, involving the generation of both hydroxyl radicals and sulphate radicals, was proposed.     

Spectral analysis of atmospheric radar signal using higher orderspectral estimation technique

Higher order spectral estimation techniques have been applied to the backscattered signals received from the troposphere and lower stratosphere by the Gadanki mesosphere-stratosphere-troposphere (MST) radar. These techniques allow identification of signals that have non-Gaussian probability distribution. To understand these processes and their effect on estimation of the atmospheric parameters, power spectrum, and bispectrum analyses have been performed on the signals received in both vertical and off-vertical directions. The results show that the backscattered echoes received in the vertical direction are significantly non-Gaussian, while those received in the off-vertical direction are inferred to have predominant Gaussian component. It is demonstrated that the bispectral analysis technique has capability for estimating the vertical wind component with greater accuracy than that derived from the commonly employed fast Fourier transform based power spectral technique