Multi-objective optimization of electric-discharge machining process using controlled elitist NSGA-II

Parametric optimization of electric discharge machining (EDM) process is a multi-objective optimization task. In general, no single combination of input parameters can provide the best cutting speed and the best surface finish simultaneously. Genetic algorithm has been proven as one of the most popular multi-objective optimization techniques for the parametric optimization of EDM process. In this work, controlled elitist non-dominated sorting genetic algorithm has been used to optimize the process. Experiments have been carried out on die-sinking EDM by taking Inconel 718 as work piece and copper as tool electrode. Artificial neural network (ANN) with back propagation algorithm has been used to model EDM process. ANN has been trained with the experimental data set. Controlled elitist non-dominated sorting genetic algorithm has been employed in the trained network and a set of pareto-optimal solutions is obtained.

     

Quality changes of sea bass slices wrapped with gelatin film incorporated with lemongrass essential oil

Microbiological, chemical and physical changes of sea bass slices wrapped with gelatin film incorporated with 25% (w/w) lemongrass essential oil (LEO) during storage of 12 days at 4 °C were investigated. Sea bass slices wrapped with LEO film had the retarded growth of lactic acid bacteria (LAB), psychrophilic bacteria and spoilage microorganisms including H?S-producing bacteria and Enterobacteriaceae throughout storage of 12 days in comparison with the control and those wrapped with gelatin film without LEO (G film) (P<0.05). Lowered changes of colour, K value, total volatile base nitrogen (TVB) and TBARS value were also found in LEO film wrapped samples, compared with those wrapped with G film and control, respectively. Therefore, the incorporation of LEO into gelatin film could enhance the antimicrobial and antioxidative properties of the film, thereby maintaining the qualities and extending the shelf-life of the sea bass slices stored at refrigerated temperature.     

Food insecurity in urban poor households in Mumbai, India

India ranks 66th of 88 countries in the Global Hunger Index and has a quarter of the world??s hungry. Food security status of 377 million inhabitants of India??s urban areas, of which one-fourth live in extreme poverty, is poorly documented. The purpose of this study was to determine (a) the extent of food insecurity among households in urban slums, (b) to quantitatively assess their subjective experiences related to food insecurity and (c) to identify sub-groups among the urban poor that are vulnerable to food insecurity. A cross-sectional, interviewer-administered survey of adult female respondents from 283 households, selected using two-stage cluster sampling, was conducted in slums across three municipal wards in the city of Mumbai. Food insecurity, as measured by the Household Food Insecurity Access Scale (HFIAS), was found in a large number of households in the urban slums of Mumbai; 59.7?% (n?=?169) households were categorized as severely food-insecure, 16.6?% (n?=?47) as mildly to moderately food-insecure, and 23.7?% (n?=?67) as food-secure. Further analysis revealed that severe food insecurity was significantly associated with lower monthly household income and other socioeconomic status measures such as lower household monthly per capita income, lower rank in the standard of living index (SLI) and less monthly per capita expense on food items. Households where the woman was the primary income-earner and contributed the largest share to the monthly household income, and was older, less educated, with less media use or access were more likely to experience severe food insecurity. Although corrective steps at the household level such as livelihood security schemes and income generation programs are necessary, they will not be sufficient to eliminate this problem; state intervention is required in order to assure food security for the urban poor. The Government of India has drafted a Food Security Bill; but the criteria for determining which households are vulnerable and deserving are still being debated. The findings of this study highlight the urgency of corrective action and also provide pointers for the identification of vulnerable or priority sub-groups. Food security policies and programs have to be implemented immediately and effectively in order to ensure that subsidies and food items are allocated to the households of the vulnerable urban poor.     

Effect of Green Tea Extract in Combination with Ascorbic Acid on the Retardation of Melanosis and Quality Changes of Pacific White Shrimp During Iced Storage

Melanosis and quality changes of Pacific white shrimp (Litopenaeus vannamei) treated with 0.1% green tea extract (GTE) in combination with ascorbic acid (AA) at different levels (0%, 0.005%, and 0.01%) were monitored during iced storage of 12?days. Based on in vitro study, 0.1% GTE inhibited polyphenoloxidase (PPO) from cephalothorax of Pacific white shrimp by 60.2%. Nevertheless, 0.1% GTE in combination with 0.01% AA exhibited the greater PPO inhibitory activity (93.0%) (P?<?0.05). When shrimp treated with 0.1% GTE in combination with AA (0.005 or 0.01%; GTE + AA), the increase in psychrophilic bacteria and spoilage microorganisms including H₂S- producing bacteria and enterobacteriaceae were retarded to a higher extent, in comparison with the control and those treated with 1.25% sodium metabisulfite (SMS; P?<?0.05). The coincidental lowered rates of increase in pH, total volatile base content and thiobarbituric acid reactive substances were obtained in the shrimp treated with GTE + AA (P?<?0.05). Additionally, shrimp treated with GTE + AA had the lower melanosis score but higher score for color, odor, taste, flavor, and overall likeness, compared with the control and those treated with SMS (P?<?0.05). Generally, AA at levels of 0.005% and 0.01% showed a similar synergist effect with GTE on both melanosis inhibition as well as retardation of quality loss of shrimp.     

Natural circulation studies in a lead bismuth eutectic loop

Lead Bismuth Eutectic (LBE) is increasingly getting more attraction as the coolant for advanced reactor systems. It is also the primary coolant of the Compact High Temperature Reactor (CHTR), being designed at BARC. A loop has been set up for thermal hydraulics, instrument development and material related studies relevant to CHTR. Steady state natural circulation experimental studies were carried out for different power levels. Transient studies for start-up of natural circulation in the loop, loss of heat sink and step power change have also been carried out. An 1D code named LeBENC has been developed at BARC to simulate the natural circulation characteristics in closed loops. The salient features of the code include ability to handle non-uniform diameter components, axial thermal conduction in fluid and heat losses from the piping to the environment. This paper deals with the experimental studies carried out in the loop. Detailed validation of the LeBENC code with the experimental data is also discussed in the paper.     

Undesirable Enzymatic Browning in Crustaceans: Causative Effects and Its Inhibition by Phenolic Compounds

Undesirable enzymatic browning mediated by polyphenol oxidase (E.C. 1.14.18.1) on the surface of seafood from crustaceans have been a great concern to food processors, causing quality losses of seafood products. Seafoods especially from crustaceans are worldwide consumed due to their delicacy and nutritional value. However, black spot formation (melanosis) is the major problem occurring in crustaceans during postmortem handling and refrigerated storage induce deleterious changes in organoleptic properties and, therefore, decreases commercial value. Polyphenoloxidase (PPO), the copper-containing metalloprotein involved in oxidation of phenol to quinone is the major biochemical reaction of melanosis formation. This enzymatic mechanism causes unappealing blackening in postharvest crustaceans. To alleviate the melanosis formation in crustaceans, use of phenolic compounds from plant extract can serve as antimelanotics and appears to be a good alternative to the conventional sulfites which are associated with health-related disorders. In this review, we focuses on the unique features about the structure, distribution, and properties of PPO as well as mechanism of melanosis formation and provide a comprehensive deeper insight on the factors affecting melanosis formation and its inhibition by various antimelanotics including newly discovered plant phenolic compounds.     

Simple first-order translinear-C current-mode all-pass sections

A first-order translinear-C current-mode (CM) all-pass section (APS) using two current-controlled conveyors (CCCII) and a single capacitor is given. A canonical CM-APS using only one dual-output CCCII and one capacitor is also derived from the proposed configuration. The circuits are analysed for the non-idealities of CCCII and possess attractive sensitivity performance. The proposed circuits are electronically tunable over a wide frequency range. RSPICE simulation results for ac analysis, transient analysis and harmonic distortions are incorporated to verify the theory.     

Spatial correlation in grain misorientation distribution

Grain misorientation was studied in relation to the nearest neighbor’s mutual distance using electron back-scattered diffraction measurements. The misorientation correlation function was defined as the probability density for the occurrence of a certain misorientation between pairs of grains separated by a certain distance. Scale-invariant spatial correlation between neighbor grains was manifested by a power law dependence of the preferred misorientation vs. inter-granular distance in various materials after diverse strain paths. The obtained negative scaling exponents were in the range of ?2 ± 0.3 for high-angle grain boundaries. The exponent decreased in the presence of low-angle grain boundaries or dynamic recrystallization, indicating faster decay of correlations. The correlations vanished in annealed materials. The results were interpreted in terms of lattice incompatibility and continuity conditions at the interface between neighboring grains. Grain-size effects on texture development, as well as the implications of such spatial correlations on texture modeling, were discussed.     

Issues and strategies in composite fabrication via friction stir processing: A review

Friction stir processing (FSP) is an expeditiously emerging novel technique involving exterior layer modification, which enables one to successfully fabricate surface composites (SCs) as well as bulk composites of the metal matrix. SCs constitute an exclusive class of composites which exhibit improved surface properties while retaining the bulk properties unaltered. During initiative years, FSP was employed in development of SCs of light metal alloys like aluminum. But, nowadays, it has gained a shining role in the field of SC fabrication of various nonferrous alloys like aluminum, magnesium, copper, and even ferrous metals like steel etc. This article reviews the current trends, various issues, and strategies used to enhance the efficiency of the fabrication process of SCs. Factors involved in the process of SC fabrication are discussed and classified with a new approach. Also, variation of microstructural and mechanical characteristics with these factors is reviewed. In addition to a brief presentation on the interaction between various inputs and their effects on properties, a summary of literature on SC fabrication for different metals is tabulated with prominent results. Subsequently, shortfalls and future perspectives of FSP on SC fabrication domain are discussed.