Production,remanufacturing and waste disposal models for the cases of pure and partial backordering

Production, remanufacture and waste disposal models in the literature assume that produced and recovered (repaired or remanufactured) items are of the same quality. However, a recent study considered a more realistic situation where produced and remanufactured items are incompatible. That is, they are not perceived by customers to have the same quality characteristics. This results in a lost sales situation for produced (remanufactured) items when they are requested by customers during the remanufacturing (production) period. In today’s competitive market, where firms thrive to sustain or increase the market share for their products, a stock-out situation where demand is completely lost seems to go contrary to the objectives of these firms. In reality, a firm may choose to either backorder fully or partially their unsatisfied demand. This paper extends along this line of research by modelling these stock-out situations. Several stock-out cases are considered for which mathematical models are developed and numerical examples are provided with their results discussed.     

Characterization of gelatin/cellulose acetate nanofibrous scaffolds: Prediction and optimization by response surface methodology and artificial neural networks

Gelatin/cellulose acetate electrospun nanofibers are a good candidates for simulation of extracellular matrix (ECM). Electrospinning of the blend is controlled by many parameters such as applied voltage, gap distance, solvent composition, polymer composition and solution concentration. The individual and interactive effects of these parameters on pH, electrical conductivity (EC) and viscosity of solutions, and diameter and quality of fibers were investigated. Response surface methodology (RSM) and artificial neural networks (ANNs) were considered to model and optimize the responses. EC, pH and viscosity of solutions were dependent on the solution parameters. The solvent composition and solution concentration had an influence on the fiber diameter and quality. The optimum conditions for fabricating qualified nanofibers with minimum diameter were 16.9 kV, 15.3 cm, 77.5 wt % of gelatin, 88.9 vol % of acetic acid and solution concentration of 20 wt %/vol %. Uniform beadless nanofibers with a diameter of 284 nm were attained at this optimum condition.