A Comparison of Exact and Heuristic Routines for Lot-Size Determination in Multi-Stage Assembly Systems

This paper discusses heuristics for the determination of lot-sizes in multi-stage systems, some based on current industrial practice, and gives computational times and solution values for the heuristic routines. These values are compared with optimal solutions derived from a dynamic programming formulation of the problem.     

Prediction of Gas‐Phase Adsorption Isotherms Using Neural Nets

This study investigated a number of models (the modified Sips', Dubinin‐Astakhov's, VSM theory, the generalized Khan et al.'s model and a simple artificial neural network (ANN)) to predict the effect of temperature on equilibrium adsorption of hydrocarbon gases and vapors on activated carbon. Published data on the adsorption of methane, ethane and propane on activated carbon at 311 K to 505 K were used to estimate the parameters of the conventional models and train the network. Then, the conventional models and the ANN were used to predict the isotherm at a single temperature for each adsorbate, and these results were compared with experimental data. It was found that the ANN model had a lower mean relative error than the conventional models.     

Biological conversion of hydrogen sulphide to elemental sulphur in a fixed-film continuous flow photo-reactor

The green sulphur bacterium Chlorobium thiosulfutophilum was used to remove hydrogen sulphide from synthetic industrial wastewater and convert it to elemental sulphur in a fixed-film continuous-flow photosynthetic bioreactor. Twenty 150 mm x 3 mm ID Tygon tubes formed the active part of the reactor resulting in a total volume of 21.2 mL. Seven steady states were achieved under different experimental conditions using this tubular photo-reactor. Sulphide loading rates ranged from 111 to 328 mg/hL under influent flowrates of 9.0-42.4 mL/h and hydraulic retention times of 0.50-2.35 h. The irradiance at the reactor surface averaged 25.4 W/m2. The sulphide removal rates were found to be 82-100% and elemental sulphur recovery rates were found to be 75-95%. The maximum sustainable sulphide loading rate was found to be 286 mg/h L, which is 2.5 times higher than the previous reported highest value. Sulphide loading rate was found to be the function of radiant flux per unit reactor volume and the bacteriochlorophyll concentration as expressed by the van Niel curve.     

Functional properties of protein concentrates and isolates produced from cashew (Anacardium occidentale L.) nut

Protein isolates and concentrates were obtained from defatted cashew nut powder by two methods: alkaline extraction-isoelectric precipitation (IP) and alkaline extraction-methanol precipitation (MP). The functional properties of cashew nut protein isolates, concentrates and powder were significantly different (p < 0.05). Cashew nut protein isolate (CNPI) had higher water and oil absorption capacities (2.20 ml/g and 4.42 ml/g, respectively), emulsifying stability index (447%), foam capacity and stability (45% and 55%, respectively), and least gelation capacity (13.5%) than cashew nut protein concentrate (CNPC), which was also higher than that of defatted cashew nut powder (DCNP). However, emulsifying activity index (12.45%) and bulk density (0.31) of CNPI were lower than that of CNPC, which were also lower than that of DCNP. The water solubility of CNPI (95%) and CNPC (95%) was not significantly different (p > 0.05) among the samples, but was significantly different (p < 0.05) from that of DCNP (75%). The CNPI, CNPC and DCNP showed decreasing solubility with decreasing pH, with the minimum solubility being observed at a pH range of 4.0–4.5, confirming the isoelectric point of cashew proteins. However, higher water solubility, emulsifying activity, and foaming property were observed at an alkaline pH than at an acidic pH in all samples.