High‐strength biodegradable poly(vinyl alcohol)/fly ash composite films

We prepared biodegradable composite films of poly(vinyl alcohol) (PVA) and fly ash (FA) spanning 5, 10, 15, 20, and 25 wt % concentrations by casting aqueous solutions. The tensile strengths of the composite films were increased proportionally via the addition of FA. The strength of the film was enhanced by 193% with 20% FA compared to the neat PVA control. Further addition of FA deviated from the linear trend. The moduli of the composites also increased proportionally with FA addition to 212% at 20 wt % FA addition compared to the control. The percentage strain at break exponentially decreased with the addition of FA. In the dynamic mechanical behavior, the storage and loss moduli both increased with FA content. The tan δ peaks corresponding to the glass‐transition temperature shifted 5–10°C higher above the control sample (73°C). This shift was attributed to a reduction in the mobility of PVA segments because they were anchored by the FA surface. The reductions in mobility manifested in strong interfacial interactions were indicative of hydrogen bonding. Broadening and reduction in the intensities of the stretching and bending peaks of ? OH, ? CH and ? C?O of PVA in the Fourier transform infrared spectra were observed. This suggested that hydrogen bonding was active between the functional groups in the FA and PVA chains. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Characterization of a differential fiber Bragg grating sensor for oil-water boundary detection

We investigate the operating characteristics of an oil-water boundary detector utilizing differential interrogation of fiber Bragg grating sensors. The system resolution is shown to be stable with respect to the choice of strain actuator and long-term temperature changes and changes in the initial strain on the fiber string. Fluid flow, particularly turbulent flow, is found to reduce system resolution significantly for the current system design. Improvements in the system design are required to minimize the effects of fluid flow and to accurately detect the presence of oil-water emulsions.     

Modeling of plasma spray coating process using statistical regression analysis

This study aimed to correlate outputs of a plasma spray coating process with its input parameters. Central composite design of experiments had been followed to conduct the experiments on plasma spray coating process, in order to collect its input–output data. The effects of four input parameters, namely primary gas flow rate, stand-off distance, powder flow rate, and arc current on three outputs (responses), such as thickness, porosity, and microhardness of the coatings, had been studied using non-linear statistical regression analysis. Such an analysis yielded the response equations, and viability of these equations had been tested on a set of experimentally obtained cases. The above four process parameters were found to have varying influences on different responses. However, all the above three responses were found to be significantly dependent on primary gas flow rate.     

Performance of diesel engine using biodiesel obtained from mixed feedstocks

Availability of identified tree species bearing non-edible oil has a region specific production characteristics and availability of sufficient amount at a given place is always uncertain. Moreover, the any prospective biodiesel production and utilization programe would need to consider more and one feedstock to meet the target. There could be another reason to investigate feasibility of mixed feedstocks considering strength and weakness of biodiesel fuel properties specific to feedstocks. Considering the above the present investigation is carried out to study the fuel characteristics of biodiesel obtain from mixed feedstocks of three species of oil feedstocks namely polonga, koroch and jatropha. An attempt has been made in this paper to give an overview of the application of mixed biodiesel in CI Engine. Properties of biodiesel obtained from mixed feedstocks (BOMF) satisfy different biodiesel standards. Performance of BOMF fueled engine gives better result than the individual biodiesels.     

Microstructural characterization of dissimilar friction stir welds between AA2219 and AA5083

Fusion welding of dissimilar aluminum alloys is very challenging. In the present work, Al-Cu alloy AA2219-T87 was friction stir welded to Al-Mg alloy AA5083-H321. Weld microstructures, hardness, and tensile properties were evaluated in as-welded condition. Microstructural studies revealed that the nugget region was primarily composed of alloy 2219, which was placed on the advancing side. No significant mixing of the two base materials in the nugget region was observed. Hardness studies revealed that the lowest hardness in the weldment occurred in the heat-affected zone on alloy 5083 side, where tensile failure were observed to take place. Tensile tests indicated a joint efficiency of around 90%, which is substantially higher than what can be achieved with conventional fusion welding. Overall, the results show that satisfactory butt welds can be produced between AA2219-T87 and Al-Mg alloy AA5083-H321 sheets using friction stir welding.     

Solution of PDEs-electrically coupled systems with electrical analogy

This paper presents an approach to solve coupled systems where electrical/mechanical devices, whose behaviour is governed by a PDE or a system of PDEs, are connected together through an electrical circuit. In an earlier paper [1], it had been shown that PDEs can be modeled by an electrical equivalent circuit generated from the complete set of equations arising from the Finite Element Method (FEM). In this paper, the approach is extended to solve a system of PDEs. The approach allows the simulation of coupled systems with circuit simulation tools alone since the resultant system becomes an electrical circuit after an application of electrical analogy. The coupled system is solved by directly replacing PDE devices with the equivalent circuits. Further, a special circuit simulation technique, viz. multiport decomposition is used in order to solve a large coupled system. A sequential as well as a parallel simulator is built for coupled problems based on the proposed approach. A circuit with 100 linear PDE devices (the equivalent circuit contains 8 million nodes) has been simulated using the parallel simulator in less than 1 h. We have achieved a speedup of 5 over the sequential simulator using 8 processors on distributed memory architecture. The characteristic of p–n junction diode (drift–diffusion equation) is analyzed by our circuit simulator to show that the proposed approach can be used to build a circuit-cum-device simulator.     

Field emission studies of Te nanorods grown on Si (111) substrate

Tellurium nanorods were grown on silicon (111) substrates by thermal evaporation. The synthesized Te nanorods were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), prior to the field emission investigations. The TEM image revealed that the nanorods are needle-like having diameter less than 20 nm and length in the range of 200-400 nm. The selected area electron diffraction (SAED) pattern and high resolution TEM micrographs clearly reveal the crystalline nature of the Te nanorods. The field emission studies were carried out in a planar diode (close proximity) configuration at background pressure of ∼1 × 10⁻⁹ mbar. An emission current density of ∼8.5 μA/cm² has been drawn at an applied field of ∼3.2 V/μm. The Folwer-Nodhiem plot, showed a non-linear behaviour. The high value of field enhancement factor (β ∼ 1 × 10⁴), estimated from the slope of the F-N plot, suggests that the emission is indeed from the nanometric tips of the Te nanorods. The emission current stability studied at the preset value ∼3.5 μA over duration of more than 3 h is found to be very good, suggesting the use of Te nanorods as promising electron source for field emission based micro/nano-electronic devices.     

FINITE ELEMENT ANALYSIS OF A VERTICAL RECTANGULAR PLATE COUPLED WITH AN UNBOUNDED FLUID DOMAIN ON ONE SIDE USING A TRUNCATED FAR BOUNDARY

The dynamic pressure distribution on a rectangular plate attached to a rigid wall and supporting an infinitely large extent of fluid subjected to a harmonic ground excitation is evaluated in the time domain. Governing equations for the fluid domain are set considering the compressibility of the fluid with negligibly small change in density and a linearized free surface. A far boundary condition for the three-dimensional fluid domain is developed so that the far boundary is truncated at a closer proximity to the structure. The coupled problem is solved independently for the structure and the fluid domain by transferring the acceleration of the plate to the fluid and pressure of the fluid to the plate in sequence. Helmholtz equation for the three-dimensional fluid domain and Mindlin's theory for the two-dimensional plate are used for the solution of the interacting domains. Finite element technique is adopted for the solution of this problem with pressure as nodal variable for the fluid domain and displacement for the plate. The time dependent equations are solved in each of the interacting domain using Newmark-b method. The effectiveness of the technique is demonstrated and the influences of surface wave, exciting frequency and flexibility of the plate on dynamic pressure are investigated.     

Heat-induced Maillard reaction of the tripeptide IPP and ribose: Structural characterization and implication on bioactivity

Maillard reaction products (MRPs) were prepared from aqueous model mixtures containing 60 g L^? 1 ribose and 30 g L^? 1 of the bioactive tripeptide IPP (Ile-Pro-Pro), heated at 98 °C. MRP and associated reactions with changes in IPP were observed within one hour of heat-treatment. The pH of MRPs decreased significantly during the heat treatment of IPP–ribose mixtures from 9.0 to 7.6 after one hour. The amino group content, IPP and ribose concentration decreased significantly during heat treatment. The fluorescence intensity of the IPP–ribose MRPs reached the maximum within 2 h. Modification of the UV/vis spectra for IPP–ribose MRPs was mainly due to a condensation reaction of IPP with ribose. Compounds with molecular weight between 300 and 650 Da were dominant while compounds smaller than 250 Da were also produced during the reactions, as characterized by size exclusion chromatography. Mass spectrometry revealed that IPP was conjugated to ribose at the N-terminal (m/z of 458.3) upon heat-treatment. The presence of ribose also promoted peptide degradation to dehydrated IP (m/z of 211.1). IPP–ribose MRPs lost the known angiotensin-I-converting enzyme (ACE) inhibitory activity of IPP; however, strong antioxidant properties were detected.