Effect of cobalt on the electrical conductive property of epoxy resins

Cobalt acrylate (CoA₂) has been treated with bisphenol‐A and epichlorohydrin to modify epoxy resins. It was cured with p‐acetylbenzilidene triphenyl arsonium ylide. The properties such as epoxide equivalent weight (equiv/100 g), molecular weight, hydrolyzable chlorine content increases whereas hydroxyl content, refractive index decreases in the presence of CoA₂. The cured epoxy resins shows improve electrical conductivity due to the incorporation of CoA₂ with epoxy resins. The influence of complex formation of CoA₂ with either linkage of epoxy resins were investigated by spectroscopy. The decrease in T_g from differential scanning calorimetry support the improve in flexibility. The dispersion of cobalt in epoxy resins matrix was confirmed by scanning electron microscope. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Model reduction and controller design for a nonlinear heat conduction problem using finite element method

The mathematical models for dynamic distributed parameter systems are given by systems of partial differential equations. With nonlinear material properties, the corresponding finite element (FE) models are large systems of nonlinear ordinary differential equations. However, in most cases, the actual dynamics of interest involve only a few of the variables, for which model reduction strategies based on system theoretical concepts can be immensely useful. This paper considers the problem of controlling a three dimensional profile on nontrivial geometries. Dynamic model is obtained by discretizing the domain using FE method. A nonlinear control law is proposed which transfers any arbitrary initial temperature profile to another arbitrary desired one. The large dynamic model is reduced using proper orthogonal decomposition (POD). Finally, the stability of the control law is proved through Lyapunov analysis. Results of numerical implementation are presented and possible further extensions are identified.     

Separation of toluene–methanol mixtures by pervaporation using crosslink IPN membranes

Polyvinyl alcohol (PVOH) has been chemically modified by crosslink copolymerization of acrylic acid (AA) and hydroxyethylmethacrylate (HEMA) in aqueous solution of PVOH and finally crosslinking PVOH to produce a full interpenetrating network (IPN) membrane termed as PVAH. Accordingly, three such full crosslink IPNs membranes, i.e. PVAHI, PVAHII and PVAHIII containing varied weight ratio of PVOH and copolymer have been synthesized and used for pervaporative separation of methanol from its mixtures with toluene. For comparison, a conventional PVOH membrane crosslinked with glutaraldehyde has also been used for the same pervaporation study. The flux and selectivity of these IPN membranes were found to be much higher than the conventional glutaraldehyde crosslinked PVOH membrane. Among the three membranes, PVAHII with 50 wt% polyAH incorporation showed optimum performance in terms of flux and methanol selectivity.     

Optimal control of a nonlinear induction heating system using a proper orthogonal decomposition based reduced order model

This paper considers the problem of obtaining control inputs for induction heating processes involving nonlinearities and nontrivial geometries. The considered system falls within the much broader class of multiphysics or coupled, distributed parameter systems that are well known for the challenges they pose towards modeling, simulation and control. The approach is based on the versatile finite element method (FEM) widely popular in industry for modeling of such systems. The large dynamic model obtained through FEM is reduced using proper orthogonal decomposition (POD) technique, applicable to nonlinear systems, while preserving the input–output characteristics almost exactly. In the present work, using the reduced model, an optimal control input current for the induction heating system is obtained, for transferring the temperature profile over an axi-symmetric work piece from any initial temperature profile to any other desired temperature profile. The reduced model enables application and numerical implementation of established optimal control techniques based on Hamilton–Jacobi–Bellman theory for the system. Further, although the controller is developed using the reduced model, it is shown to perform perfectly well when used with the original unreduced model as well. Results of the numerical implementation are presented to evaluate the overall proposed approach.     

ASKME: adaptive sampling with knowledge-driven vectorization of mechanical engineering drawings

We propose here an efficient algorithm for high-level vectorization of scanned images of mechanical engineering drawings. The algorithm is marked by several novel features, which merit its superiority over the existing techniques. After preprocessing and necessary refinement of junction points in the image skeleton, it first extracts the graphic primitives, such as lines, circles, and arcs, based on certain digital geometric properties of straightness and circularity in the discrete domain. The primitives are classified into different types with all associated details based on fast and efficient geometric analysis. The vector set is succinctly reduced by such classification in tandem with further consolidation to make out meaningful objects like rectangles and annuli, together with hatching information. Exhaustive testing shows the efficiency of the algorithm and also its robustness and stability toward any affine transformation and injected noise. Easy reconstruction to scalable vector graphics demonstrates its readiness and usability as a state-of-the-art solution.     

Removal of Rancid-Acid Odor of Expeller-Pressed Virgin Coconut Oil by Gamma Irradiation: Evaluation by Sensory and Electronic Nose Technology

Expeller-pressed virgin coconut oil, known to have disagreeable rancid-acid odor due to the presence of octanoic acid, was subjected to gamma (γ) irradiation for removal of the same. Sensory evaluation in tandem with electronic nose (Heracles and ENOVISION) analyses established that the oil irradiated at 4.2 kGy had no rancid-acid odor (absence of octanoic acid) at the end of 28 days of storage at 23 ± 2 °C. Therefore, 4.2 kGy was established as the “appropriate irradiation dose” for removal of rancid-acid odor of virgin coconut oil. A “deodorization index” with respect to rancid-acid odor was also developed using electronic nose for confirmation of this “appropriate dose” and thereby provided possible means of preventing detrimental effects of high dose of γ-irradiation in oils. GC–MS analysis of hydrocarbons extracted from oil irradiated at 4.2 kGy by supercritical carbon dioxide extraction revealed radiolysis of octanoic acid resulting in elimination of rancid-acid odor. Further, γ-irradiation at 4.2 kGy did not affect the antioxidant potency of coconut oil rendering it a safe and healthy alternative to conventional deodorization techniques for oils. Development of methodology for assessment of rancid-acid odor of coconut oil using electronic nose has been reported for the first time in this work.     

Supercritical carbon dioxide extraction of lutein from yellow maize (<Emphasis Type="Italic">Zea mays</Emphasis>) kernels: process optimization based on lutein content,antioxidant activity,and ω-6/ω-3 fatty acid ratio

Yellow maize kernels were subjected to supercritical carbon dioxide (SC-CO₂) extraction to obtain a lutein-rich extract with potential nutraceutical properties. SC-CO₂ extraction parameters (pressure and temperature) were optimized by employing a full-factorial (3²) design of experiments and response surface methodology, based on yield of lutein, antioxidant activity, and ω-6/ω-3 fatty acid ratio of the extracts. A Chrastil equation was also developed for predicting the solubility of lutein in SC-CO₂ under different extraction conditions. The optimized extraction condition was obtained at 500 bar, 70 °C for 90 min, at which the extract was found to possess a unique combination of the highest lutein yield (275.00 ± 3.50 μg/g of dry weight), along with a well-balanced ω-6/ω-3 fatty acid ratio (3:1). Moreover, the total phenol content and antioxidant activity were also found to be the highest at this condition. This lutein-rich extract is a promising nutraceutical or dietary supplement in the food industry.     

Comparative aroma profiles using supercritical carbon dioxide and Likens–Nickerson extraction from a commercial brand of Basmati rice

A comparative evaluation of the extraction of the aroma constituents of a popular commercial brand of Basmati rice using Likens–Nickerson extraction and supercritical fluid extraction (SFE) with carbon dioxide was carried out. SFE at 50 °C and 120 bar for 2 h provided appreciable extraction of the volatile constituents of the rice as compared with Likens–Nickerson extraction. The advantages of smaller sample size, shorter time of extraction and negligible possibility of artefacts with the SFE technique merit its use for recovery of aroma volatiles from Basmati rice. Copyright © 2003 Society of Chemical Industry