In this paper we consider the problem of a firm the that builds inventory of identical items that it acquires by participating in auctions in order to satisfy its own market demand. The objective of the firm is to have a procurement strategy that maximizes the expected present value of the profit, both for finite and infinite planning horizons. We present an MDP formulation of the problem. Unde...

Operations researchers have always assumed that when a product’s unit cost is constant and its demand curve is known and stationary, a retailer of the product would find it optimal to replenish the inventory with a fixed quantity and to sell the product always at a fixed price. We present, with proof, a model that shows that, in such a case, an e-tailer is better off using a continuously increa...

People’s ideas about communications have changed completely, nowadays when this subject is mentioned almost everyone thinks of wireless communications. The demand for broadband wireless communications offering greater and greater data rates is endless, and the radio-technology community is trying harder and harder to satisfy this demand. Recently, there was the worldwide launch of 4th generatio...

Nowadays, Companies have to deal with an uncertain demand which is more difficult to handle when it has a non-stationary pattern. Simultaneous decrease of customer service and increase of stock costs are the most significant effects of such demand uncertainty. To deal with this issue, inventory optimization models must be adapted to cover a multi-echelon network structure and to consider altern...

Traffic dynamics at a merging junction can be numerically solved with discrete conservation equationsand so-called supply-demand methods. In this paper, we first introduce a continuous multi-commoditykinematic wave model of merging traffic and then develop a new framework for constructing the solutionsto its Riemann problem with jump initial conditions. In the supply-demand spac...

OBJECTIVE to evaluate the association between psychological demands, control over the work and the reduction of work ability of nursing professionals. METHOD this cross-sectional study involved 498 nursing professionals of a university hospital in the State of Rio Grande do Sul, Brazil. Data collection was carried out in 2009 using the Brazilian versions of the Work Ability Index and Job Stre...

Effluent discharge from septic tanks is affecting the environment in developing countries. The most challenging issue facing these countries is the cost of inadequate sanitation, which includes significant economic, social, and environmental burdens. Although most sanitation facilities are evaluated based on their immediate costs and benefits, their long-term performance should also be investig...

The hemipteran (Insecta) diversity in the upper part of the Kerian River Basin was low with only 8 families and 16 genera recorded at 4 study sites from 3 rivers. Water bug composition varied among sampling sites (Kruskal-Wallis χ (2) = 0.00, p<0.05) but was not affected by wet-dry seasons (Z = 0.00, p>0.05). All recorded water parameters were weakly associated with generic abundance but the bi...

In this study, the ecological parameters of the effluent obtained from dyeing of scoured and mercerised organic cotton single jersey fabrics with textile reactive dyes adopting exhaust dyeing method was investigated. The dyes used include regular (Navacron H and FN) reactive dyes and low impact (Remazol and Levafix) reactive dyes along with inorganic salt (sodium sulphate) and biosalt (trisodiu...

Biogas yield of mixtures of cattle slurry and cheese whey, rates of production of methane, removal efficiencies of chemical oxygen demand (COD) and biological oxygen demand (BOD) from the mixtures were investigated at 35°C. Four feed regimens (by volume) were studied. Stable biogas production of 621 l/kg Volatile Solids at an Hydraulic Retention Time of 42 days in a mixture containing 50% slurr...