Detailed variational analysis of single mode trapezoidal index fiber involving two simple approximations of fundamental mode with comparison relating accurate prediction of propagation characteristics

A detailed variational analysis of single-mode trapezoidal index fibre to investigate its propagation characteristics involving two simple approximations of fundamental mode is presented. It is shown in respect of computation of normalized field that the single parameter variational function having Gaussian and modified Bessel variations in the core and cladding, respectively, is more accurate in comparison with the Gaussian function over a wide range of values of normalized frequency and aspect ratio. Also, it predicts the propagation characteristics, more accurately, than the Gaussian function from variational and recently reported Marcuse-type formulations. Further, in terms of such range of values, a complete formulation of variational parameter for the Gaussian-modified Bessel function is prescribed for ready reference to the system users to predict the modal field and propagation characteristics.     

Energy Efficient Routing Protocol for Ambient Assisted Living Environment

Wireless Personal Communications - Ambient assisted living (AAL) is focused on providing assistance to patients primarily in their natural environment to improve their quality of life. AAL domain...     

Insights into the microstructural parameters and mechanical property correlation of Al3Ti phase reinforced Al based nanocomposites

Variations in the microstructural properties of Al/Al₃Ti nanocomposites, prepared through stir casting technique were examined by x‐ray diffraction analysis using modified Warren Averbach and modified Williamson method. The study revealed that screw dislocations are predominantly generated in the nanocomposites, which contain higher volume percent of Al₃Ti. However, at lower Al₃Ti content, the finer intermetallic particulates during rolling, are displaced from their initial position, which lead to decrease in percent screw dislocation and subsequent increase in percent edge dislocation. Evolution of the different microstructural features in the nanocomposites were related to the variations in the composition. Textural studies were carried out to understand the effect of compositional variation on the microstructure and properties of the nanocomposites. It has been found that due to the presence of high strain, Brass type structure and the γ fiber are predominant texture component in the nanocomposites. The contribution of microstructure and microstructural parameters, e. g. dislocation density, dislocation type and textural characteristics along with the fractographical analysis were shown to have links with the mechanical properties of the nanocomposites     

Long-term outcome of adult-onset minimal-change nephropathy

BACKGROUND: Adult-onset minimal-change nephropathy has been associated with a slower response to corticosteroids and a less benign prognosis when compared to children. However, there are few long-term outcome data reported. METHODS: We have reviewed retrospectively 51 idiopathic adult-onset minimal-change nephropathy patients investigated and treated at a single centre. RESULTS: Male to female ratio was 1:1.4, mean age at diagnosis was 37 years, and average length of follow-up was 14.1 years. Significant comorbidity was identified in 33%. A raised serum creatinine was found in 55% but returned to normal almost invariably upon remission. At presentation, hypertension was found in 47% of patients, microscopic haematuria in 33%, hypercholesterolaemia and hypertriglyceridaemia in 96%, and hyperuricaemia in 42%. Remission (complete or partial) was achieved by 46, 70 and 92% within 4, 8 and 21 weeks respectively, in patients treated with steroids; steroid resistance was encountered in 8%. The time to remission was positively correlated with age (P = 0.002) and initial albumin level (P = 0.005), and negatively correlated to the number of subsequent relapses (P = 0.029); 33% of patients had a spontaneous remission at some time during the disease course. Patients with multiple relapses were treated with cyclophosphamide and 63% of them had remained in remission after 5 years. Hypertension was present in 25% of patients after an average interval of 11 years. At the time of the final follow-up, only three patients had a raised creatinine and all but three patients were in complete remission. CONCLUSIONS: Adult-onset minimal-change nephropathy shares the same good long-term outcome as the childhood counterpart, with sustained remission and preserved renal function.     

Low-temperature decomposition of hydrated transition metal chlorides on hydrous gel substrates

The thermal decomposition of hydrated transition metal chlorides of nickel, cobalt and iron was studied on a highly dispersed alumina gel substrate. The salts were found to decompose at significantly lower temperatures than the unsupported materials. This was found to be as a result of strongly bound surface water, characteristic of this type of hydrous alumina. The resulting decomposed products were highly homogeneous and reactive, forming ceramic precursor compounds at much lower temperatures than conventional methods.     

Inorganic sol gel synthesis of zirconium titanate fibres

This note describes the preparation of zirconium titanate gel fibres from an aqueous mixed zirconia titania sol. The fibres are well formed and free of shot. Heat treatment to 750 °C produces a crystalline porous zirconium titanate fibre which shows a good (1%) strain to break. Further firing to 1100 °C causes a deterioration in properties, with retention of some porosity and a reduced strain to break. Recommendations for improving the material are suggested.     

Catalytic activity of a soft composite material: Nanoparticle location–activity relationship

A nanostructure, fiber-shaped morphology of a conjugated polymer (poly-5 amono-ortho-cresol, PAOC) has been synthesized using palladium acetate as the oxidizing agent. A one pot, in situ chemical synthesis approach has been utilized in which palladium acetate was reduced during the polymerization process of 5-amono-o-cresol (AOC) and formed well dispersed palladium nanoparticles in the polymer fibers. The resultant composite material was characterized by means of optical, thermo and micro-analytical techniques. The elemental identity of the nanoparticles was determined by means of electron energy loss spectroscopy (EELS) mapping using analytical transmission electron microscopy (TEM). Subsequently, the sample was used as a catalyst for a model gas-phase hydrogenation reaction. The activation and deactivation behaviour of the catalyst as a function of temperature is discussed in the light of different phase transition points of the polymer as well as the orientation of the palladium nanoparticles. The fact that palladium nanoparticles (2 nm) were uniformly distributed throughout the polymer matrix makes the composite material an excellent hybrid structure.     

Static and fatigue behavior of adhesive joints in SMC-SMC composites

This paper discusses the static and fatigue behavior of adhesively bonded single lap joints in SMC-SMC composites. Effects of lap length and adhesive thickness on the static and fatigue strength of SMC-SMC adhesive joints are studied. Effects of SMC surface preparation and test speed on the joint performance are evaluated. Finally, the effect of water exposure on the joint durability is also investigated. Results show that the static behavior of adhesive joints in SMC-SMC composites is significantly influenced by the lap length and adhesive thickness. With an increase in lap length from 12.7 mm to 38.1 mm, the joint failure load increases by 37%. The joint failure load also increases with the adhesive thickness, but it reaches a maximum at an adhesive thickness of 0.33 mm and then decreases. However, lap length and adhesive thickness have negligible effect on the ratio of fatigue strength to static strength. The fatigue strength at 10⁶ cycles is approximately 50% to 54% of the static strength for various adhesive thicknesses and lap lengths investigated in this study. Adhesive failure, fiber tear or combination of these two failure modes are observed during both static and fatigue tests.