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The tool allocation problem in a flexible manufacturing system generally aims at (1) maximizing throughput (2) minimizing machining cost (3) minimizing system imbalance. This paper presents a heuristic approach of loading a set of tools to the different machining centres in the case of variable machining time. Concepts of fuzzy set theory to determine threshold machining time and a potency index (PI) to prioritize parts tire used to solve the problem. [ABSTRACT FROM AUTHOR]

Being a powerful tool in modelling industrial and service operations, Petri net (PN) has been extremely used in different domains, but its application in safety study is limited. In this study, we model the gantry crane operations used for industrial activities using generalized stochastic PNs. The complete cycle of operations of the gantry crane is split into three parts namely inspection and loading, movement of load, and unloading of load. PN models are developed for all three parts and the whole system as well. The developed PN models have captured the safety issues through reachability tree. The hazardous states are identified and how they ultimately lead to some unwanted accidents is demonstrated. The possibility of falling of load and failure of hook, sling, attachment and hoist rope are identified. Possible suggestions based on the study are presented for redesign of the system. For example, mechanical stoppage of operations in case of loosely connected load, and warning system for use of wrong buttons is tested using modified models. [ABSTRACT FROM PUBLISHER]

The concentrations of the trace metals Mn, Zn, Cr, V, Co, Ni, Ba, Pb, Cu, Cd, As and Hg, their spatial distribution, and their correlation as a function of physico-chemical parameters were investigated for grab sediment samples collected from different locations across the Thane Creek, Mumbai, India. Hydride generation atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, and differential pulse anodic stripping voltammetry were adopted for chemical analyses. Various geochemical indices were evaluated. The studied metal/metalloids were compared with sediment quality guideline values. Besides, the role of different physico-chemical parameters of the sediments such as pH, CaCO3, cation exchange capacity, total carbon, and of the relative composition in respect to very coarse, coarse and medium sand, fine sand and very fine sand, silt and clay fraction were also critically investigated. Positive one-to-one correlations between fine sand and very fine sand, silt and clay, and total carbon with sediment metal concentrations have been noticed. Multiple regression analysis reveals strong positive correlations between sediment metal concentrations and total carbon content only. [ABSTRACT FROM AUTHOR]

In this article, an order-level inventory system for deteriorating items has been developed with demand rate as a function of selling price. The demand and the deterioration rate are price dependent and time proportional, respectively. We have considered a perishable item that follows a three-parameter Weibull distribution deterioration. Shortages are not permitted in our model. The optimal solution is illustrated with a numerical example and the sensitivity analysis of parameters is carried out. [ABSTRACT FROM PUBLISHER]

Retention time measurements on reverse phase HPLC columns at isocratic conditions are used to estimate the octanol-water partition coefficient for 16 polycyclic aromatic hydrocarbons (PAHs). The log Kow values for PAHs ranged from 3.32 (napthalene) to 6.30 (Indeno(1,2,3-cd)pyrene). The estimated values obtained from the present study were in good agreement with the literature values. This is a simple and rapid method for simultaneous determination of octanol-water partition coefficients for different PAHs. [ABSTRACT FROM AUTHOR]

Isocratic reversed phase high performance liquid chromatography (HPLC) with ultra violet (UV) detection was optimized for separation and quantification of polycyclic aromatic hydrocarbons (PAHs). Acetonitrile-water mixture (70 : 30 v/v) was used as mobile phase at a flow rate of 1.5 mL per minute. The volume of the sample loop was 0.1 mL. The UV detection was carried out at 254 nm. A method for the simultaneous determination of PAHs in aerosols is described. The recoveries of the compounds are in the range of 89–99% for the extraction. The detection limits typically are at the low to sub-ng/m3. Concentrations of PAHs in aerosol samples collected at five different locations in Mumbai, India were measured. In addition to PAHs in ambient aerosols, concentrations of PAHs in indoor aerosol samples, where kerosene is used as cooking fuel, were also measured. [ABSTRACT FROM AUTHOR]