Fabrication and testing of natural fibre composites: Vakka, sisal, bamboo and banana

A study has been carried out to investigate the tensile, flexural and dielectric properties of composites made by reinforcing vakka as a new natural fibre into a polyester resin matrix. The fibres extracted by retting and manual processes have been used to fabricate the composites. These composites are tested for tensile, flexural and dielectric properties and compared with those of established composites like sisal, bamboo and banana made under the same laboratory conditions. The composites are fabricated up to a maximum volume fraction of fibre of 0.37 in the case of tensile testing, and 0.39 for flexural and dielectric testing. It has been observed that the tensile properties increase with respect to volume fraction of fibre for vakka fibre composite and are also more than those of sisal and banana composites and comparable to those of bamboo composites. The flexural strength of vakka fibre composite is more than that of banana composite and is closer to sisal fibre composite with respect to the volume fraction of fibre, where as the flexural modulus is much higher than those of banana and sisal fibre composites and also very much closer to bamboo fibre composites. The dielectric strength of vakka fibre composite increases with increase in volume fraction of fibre in the composite unlike the case of sisal, bamboo and banana composites. The dielectric strength being a unique feature of vakka fibre composite, can be suggested for electrical insulation applications.     

Photoelectrochemical properties of brush plated Cd x Zn1−x Se films

Cd _x Zn_1−x Se films(0 ≤ x ≤ 1) were deposited for the first time by the brushplating technique at room temperature from an aqueous bath containing zincsulphate, cadmium sulphate and selenium oxide. The deposition current densitywas varied in the range of 50–250 mA cm⁻². The as deposited films exhibitedcubic structure. Composition of the films was estimated by EDAX studies. XPSstudies indicated the binding energies corresponding to Zn(2p_3/2), Cd(3d_5/2 and 3d_3/2) and Se(3d_5/2 and 3d_3/2). Optical band gap of the films varied from 1.72 to 2.70 eV as the composition varied from CdSe to ZnSe side. Atomic forcestudies indicated grain size in the range of 20–150 nm. Photoelectrochemical cells were made with polysulphide as the redox electrolyte. The output was maximum for the photoelectrodes of composition Cd_0.9Zn_0.1Se.     

Induced crystallization and physical properties of Li2O–CaF2–P2O5:TiO2 glass system: Part I. Characterization, spectroscopic and elastic properties

Li₂O–CaF₂–P₂O₅ glasses mixed with different concentrations of TiO₂ (ranging from 0 to 0.8 mol%) were crystallized at 500 °C. The samples are characterized by X-ray diffraction, scanning electron microscopy and differential thermal analysis techniques. Spectroscopic properties (IR and Raman) and elastic properties (viz., Young's modulus E, shear modulus G and micro-hardness H) at room temperature are studied. The X-ray diffraction and the scanning electron microscopic studies revealed the presence of lithium phosphate, lithium titanium phosphate and titanium phosphate crystal phases. The differential thermal analysis traces of these samples exhibit three crystalline temperatures. The IR and Raman spectra of these samples have exhibited bands due to TiO₄ and TiO₆ structural units in addition to the conventional bands due to various phosphate structural groups. The analysis of these results indicated that the sample crystallized with 0.6 mol% of TiO₂ possesses the highest density, high mechanical strength and more compact network.     

Designing fault-tolerant real-time computer systems with diversified bus architecture for nuclear power plants

Fault-tolerant real-time computer (FT-RTC) systems are widely used to perform safe operation of nuclear power plants (NPP) and safe shutdown in the event of any untoward situation. Design requirements for such systems need high reliability, availability, computational ability for measurement via sensors, control action via actuators, data communication and human interface via keyboard or display. All these attributes of FT-RTC systems are required to be implemented using best known methods such as redundant system design using diversified bus architecture to avoid common cause failure, fail-safe design to avoid unsafe failure and diagnostic features to validate system operation. In this context, the system designer must select efficient as well as highly reliable diversified bus architecture in order to realize fault-tolerant system design. This paper presents a comparative study between CompactPCI bus and Versa Module Eurocard (VME) bus architecture for designing FT-RTC systems with switch over logic system (SOLS) for NPP.     

Reduced VDAC1, Maintained Mitochondrial Dynamics and Enhanced Mitochondrial Biogenesis in a Transgenic Tau Mouse Model of Alzheimer’s Disease

Alzheimer’s disease (AD) is one of the most common forms of neurodegeneration, defined by reduced cognitive function, which is caused by the gradual death of neurons in the brain. Recent studies have shown an age-dependent rise in the levels of voltage-dependent anion channel 1 (VDAC1) in AD. In addition, we discovered an aberrant interaction between VDAC1 and P-TAU in the brains of AD patients, which led to abnormalities in the structural and functional integrity of the mitochondria. The purpose of our study is to understand the protective effects of reduced VDAC1 against impaired mitochondrial dynamics and defective mitochondrial biogenesis in transgenic TAU mice. Recently, we crossed heterozygote VDAC1 knockout (VDAC1^+/−) mice with transgenic TAU mice to obtain double-mutant VDAC1^+/−/TAU mice. Our goal was to evaluate whether a partial decrease in VDAC1 lessens the amount of mitochondrial toxicity in transgenic Tau (P301L) mice. We found that mitochondrial fission proteins were significantly reduced, and mitochondrial fusion and biogenesis proteins were increased in double-mutant mice compared to TAU mice. On the basis of these discoveries, the current work may have significance for the development of reduced-VDAC1-based treatments for individuals suffering from AD as well as other tauopathies.     

Size Control of In Situ Synthesized TiB2 Particles in Molten Aluminum

Metallurgical and Materials Transactions A - Aluminum-matrix nanocomposites offer advantageous properties over conventional aluminum alloys. However, controlling the size and size distribution of...     

Efficiency enhancement of a commercial natural gas liquid recovery plant: A MINLP optimization analysis

ABSTRACT

This paper aims at modeling and optimizing a Middle East-based commercial natural gas liquid (NGL) recovery and fractionation plant, using a predictive process simulator. NGL units are known to be highly energy-intensive as steam-based heating and refrigeration-based cryogenic cooling are critical requirements for their operation. Indeed, these units govern the degree of profitability of gas plants especially during low natural gas price scenarios. As a result, this study explores the ways of improving the performance of NGL units through a deterministic optimization analysis. A steady state model of the plant is built using gPROMS process builder followed by validation using plant data to ensure the model accuracy. A mixed integer nonlinear programming optimization problem is formulated with the objective of maximizing the net revenue of the plants by means of manipulating various decision variables such as feed gas temperature, column operating pressure, feed stage location, reflux and boil up ratios subject to specific process constraints. Optimization problem is solved using outer approximation equality relaxation augmented penalty algorithm. It is determined that the process optimization yields an additional revenue of 4.1 MM USD annually due to ~22% increase in Liquefied Petroleum Gas (LPG) production, ~6% increase in Naphtha production, and ~16% reduction in steam consumption in the reboiler of the columns.     

Short-channel modeling of bulk accumulation MOSFETs

Physically based short-channel effect (SCE) models are derived for bulk accumulation MOSFETs. Using the proposed models, threshold voltage rolloff, subthreshold swing, and subthreshold current can be accurately calculated; this enables physical insights into device scaling behavior, and prediction of scaling limits. The models enable optimization of accumulation MOSFETs, resulting in small SCE, and low process sensitivity. The models are equally applicable to inversion MOSFETs, and allow easy comparison between accumulation and inversion MOSFETs. Novel application areas of accumulation MOSFETs are identified where they perform better than inversion MOSFETs (better on-current and lower SCE for a given off-current). With mid-band metal gate, accumulation MOSFETs perform better than inversion MOSFETs in ultra low power applications. For poly gate CMOS, accumulation MOSFETs perform better than inversion MOSFETs in low standby power applications.     

A comparative study on CdSe synthesized at low temperature

CdSe is a well-known semiconductor which finds applications as photoconductors, photovoltaic cells and other optoelectronic devices. In this paper structural studies and carrier concentration measurements of vacuum evaporated CdSe films obtained by using CdSe synthesized by simple precipitation technique are presented.     

The effect of preaging on the delayed aging of Al−7Si−0.3Mg

Al−7Si−0.3Mg is a commonly used commercial casting alloy because of its excellent castability combined with good mechanical properties. The post-casting heat treatment isone factor that affects the mechanical properties; during heat treatment, a delay between solutionizing and artificial aging (delayed aging) leads to a reduction in hardness, ultimate tensile strength, and yield strength in the alloy. The investigation reported here was aimed at understanding the extent to which the harmful effect of delayed aging on hardness/strenght can be nullified. The results obtained were explained using Pashley’s kinetic model. S. Murali earned his Ph.D. in physical and mechanical metallurgy from the Indian Institute of Science (Metallurgy Department) in 1994. He is currently a postdoctoral fellow at the Indian Institute of Science. Y. Arunkumar earned his M.E. in mechanical engineering from the Indian Institute of Science in 1993. He is currently a lecturer at Malnad Engineering College, India. P.V.J. Chetty earned his M.E. in metallurgical engineering from the Indian Institute of Science in 1993. He is currently manager of Mineral Pulverising Mills in India. K.S. Raman earned his Ph.D. in mechanical metallurgy from the Indian Institute of Science in 1970. He is currently a professor in the Department of Metallurgy at the Indian Institute of Science. K.S.S. Murthy earned his Ph.D. in foundry metallurgy from the Indian Institute of Science in 1969. He is currently a professor in the mechanical engineering department at the Indian Institute of Science.