Application of analytical network process for analysis of product design characteristics of lean remanufacturing system: a case study

The modern manufacturing systems are adopting with lean practices to ensure value addition and waste elimination. Also, product recovery options are found to be vital. Appropriate product design characteristics are identified, and their prioritization is framed as decision-making problem with multiple criteria. Analytical network process is used as solution methodology. The objective of the study is to formulate multi-criteria decision making problem for assessment of lean remanufacturing product design characteristics. The priority order of lean remanufacturing operations is obtained. The study is exemplified with a case conducted with reference to remanufacture of an automotive component. The priority order of criteria is Disassembly > Cleaning > Inspection > Remanufacturing > Reassembly. The inferences desired from the study would facilitate cleaner manufacturing practices. Sensitivity analysis is conducted and practical validity of the method has been tested with an industrial case study.     

Effect of C/Ti ratio on densification,microstructure and mechanical properties of TiCx prepared by reactive spark plasma sintering

Titanium carbide (TiC) has been widely used as reinforcement in metal matrix composites and is known to exist over a wide range of stoichiometry. In this study, the effect of C/Ti ratio on the densification kinetics, grain size, lattice parameter, hardness and elastic modulus of TiC_x prepared by reactive spark plasma sintering (RSPS) is presented. Commercial purity titanium was ball milled with 5, 7.5, 10, 12.5, 15 and 17.5 wt% carbon black powder for 5 h and subjected to RSPS to prepare TiC_x samples with different C/Ti ratio. Dense TiC_x samples with ‘x′ ranging from 0.34 to 0.78 could be prepared by RSPS at 1400 °C. Increasing C/Ti ratio was found to increase the activation energy thereby reducing the rate of sintering and also resulted in finer grain size. The lattice parameter and the ratio of intensities of (200) to (111) peaks were correlated with the C/Ti ratio. The hardness and elastic modulus were shown to increase significantly with increase in C/Ti ratio.     

Renewal approximations of the doubly stochastic Poisson processes

In this paper, we analyze two approaches to approximate a doubly stochastic Poisson (DSP) process by a renewal process. A DSP process consists of Poisson processes whose rates alternate between two levels. Each rate remains for renewal times forming an alternating renewal process. Such processes can be used to model situations in reliability, inventory, queueing and production systems. We develop two expressions for the Laplace-Stieltjes transforms of the interrenewal time distributions of the renewal processes that approximate a DSP process. We then use these approximations to develop expressions for the stationary loss probability in a G/M/1/0 system. We evaluate the quality of these approximations by comparing them against exact results. Our approximations should be of significant use in several practical applications.     

Environmental regulations and innovation activities — a view point

The impact of environmental regulations on innovative activity is explored in this paper using state‐level and company level data on patents, new product introductions, emissions, and penalties. A significant effect of environmental regulations on corporate innovative activity is found. In addition, excellence in environmental performance appears to have an indirect effect on innovation performance of companies.     

Does it pay to be green?

This paper examines the relationships between the environmental performances and financial performances of large U.S. companies. The environmental performance is measured in pollution in pounds per sales revenue and financial performance in profit margins and stock market values. An analysis of more than 230 companies shows that lower pollution per sales revenue has a positive impact on the profit margins and stock market values. Pollution is also found to have a direct impact on environmental compliance, spills and various other legal infractions.     

Kinetic and equilibrium studies on the biosorption of textile dyes onto Plantago ovata seeds

The powdered seeds of Plantago ovata (PSPO) were utilized for the removal of Malachite Green (MG) and Rose Bengal (RB) dyes from aqueous media by batch adsorption. The Fourier transform infra red spectroscopy (FTIR) results showed that both the dyes were adsorbed between the cellulose matrices, and this has been verified from the intensifying and narrowing aromatic C-H bending vibration. The morphology of the dye laden adsorbent was studied by scanning electron microscopy (SEM), which showed that the dyes were adsorbed between the cellulose matrices of the adsorbent. The PSPO was found to be very effective for the removal of MG and RB at pH 7, and equilibrium was attained within 200 min. The kinetic study indicated that the rate limiting step for MG and RB adsorption may be chemisorption and intraparticle diffusion. Adsorption equilibrium data were fitted to Langmuir, Freundlich, Redlich-Peterson and Temkin adsorption isotherms. It is inferred from the equilibrium studies that the adsorption of MG follows the Freundlich isotherm and the adsorption of RB follows the Langmuir isotherm. The maximum monolayer adsorption capacity of the PSPO was found to be 86.23 mg/g for MG and 81.23 mg/g for RB, respectively.     

Two step biodiesel production from Calophyllum inophyllum oil: Studies on thermodynamic and kinetic modelling of modified β‐zeolite catalysed pre‐treatment

Biodiesel is one of the alternative fuels that can help in reducing oil dependence. β‐Zeolite was modified with phosphoric acid and the modified β‐zeolite was used as catalyst for the esterification of free fatty acids (FFA) present in pinnai oil and its effect on esterification reaction was studied. Influence of catalyst amount, methanol to oil ratio and temperature on specific reaction rate was modelled using Langmuir–Hinshelwood (LH) kinetics, pseudo first order kinetics and Arrhenius equation, respectively. The kinetic constant values obtained in LH kinetics show that the adsorption capacity of FFA on catalyst surface was approximately 23 times higher than that of methanol. From pseudo first order kinetic modelling it is found that methanol to oil molar ratio of 9 gives the optimum k value. Thermodynamic studies were also performed to prove the endothermic nature of Pβ catalysed esterification reaction. © 2011 Canadian Society for Chemical Engineering     

Removal of cadmium(II) from aqueous solution by agricultural waste cashew nut shell

Cashew nut shell (CNS) is a low cost adsorbent that has been used for the removal of cadmium(II) from an aqueous solution. The effects of various parameters such as solution pH, CNS concentration, contact time, initial cadmium(II) concentration and temperature were examined. The CNS was effective for the quantitative removal of cadmium(II) ions in acidic conditions and equilibrium was achieved in 30 min. The experimental data were analyzed by two-parameter (Langmuir, Freundlich, Temkin and Dubinin-Radushkevich) and three-parameter models (Redlich- Peterson, Koble-Corrigan, Toth and Sips) by nonlinear regression analysis. The characteristic parameters for each isotherms and related correlation coefficients have been determined by using MATLAB 7.1. Thermodynamic parameters such as ??G ^o , ??H ^o and ??S ^o have also been evaluated, and it was found that the sorption process was feasible, spontaneous and exothermic. Pseudo-first-order, pseudo-second-order, Elovich kinetic and intraparticle diffusion models were selected to follow the adsorption process. The results of the kinetic study show that the adsorption of cadmium(II) could be described by the pseudo-second order equation, suggesting that the adsorption process is presumably chemisorption. A single-stage batch adsorber was designed for different adsorbent dose-to-effluent volume ratios using the Freundlich equation. The results indicate that the cashew nut shell could be used to effectively adsorb cadmium(II) from an aqueous solution.     

Switched poisson process/g/1 queue with service interruptions

In this paper, we develop an expression for the expected waiting time in a single server queueing system subject to interruptions with alternately varying Poisson arrival and renewal service rates. This queueing system is useful to model situations in production, computer and telecommunication systems in which customer arrivals and service requirements differ depending on whether the server is working or not. We develop an expression for the expected waiting time by approximating the virtual delay process by a Brownian motion. Our approximation for the expected waiting time involves only the means and variances and does not depend on any assumptions regarding the interarrival, service or switching time distributions. We present simulation results to illustrate the quality of our approximations.