An optimization-based control strategy for energy efficiency of discrete manufacturing systems.

In order to reduce the global energy consumption and avoid highest power peaks during operation of manufacturing systems, an optimization-based controller for selective switching on/off of peripheral devices in a test bench that emulates the energy consumption of a periodic system is proposed. First, energy consumption models for the test-bench devices are obtained based on data and subspace identification methods. Next, a control strategy is designed based on both optimization and receding horizon approach, considering the energy consumption models, operating constraints, and the real processes performed by peripheral devices. Thus, a control policy based on dynamical models of peripheral devices is proposed to reduce the energy consumption of the manufacturing systems without sacrificing the productivity. Afterward, the proposed strategy is validated in the test bench and comparing to a typical rule-based control scheme commonly used for these manufacturing systems. Based on the obtained results, reductions near 7% could be achieved allowing improvements in energy efficiency via minimization of the energy costs related to nominal power purchased.

Magnesium sulfate induces translocation of protein kinase C isoenzymes alpha and delta in myometrial cells from pregnant women.

OBJECTIVES: The purpose of this study was to determine the effect of magnesium sulfate on protein kinase C (PKC) translocation in myometrial cells from pregnant women. STUDY DESIGN: Myometrium was obtained at the time of cesarean delivery from women at term before labor. Cultured myometrial cells were treated with magnesium sulfate (3, 5, and 10 mmol/L), oxytocin (0.1 micromol/L), or 12-O-tetradecanoylphorbol-13-acetate (TPA, 0.1 micromol/L). The translocation of PKC isozymes alpha (calcium dependent) and delta (calcium independent) from cytosol to membrane fractions was assessed with use of Western blot analysis. RESULTS: In unexposed control cells, the majority of PKC alpha and delta was located in the cytosol fraction. Exposure to magnesium sulfate for 60 minutes induced translocation of both PKC alpha and delta at concentrations as low as 5 and 3 mmol/L, respectively. The magnitude of magnesium sulfate induced translocation for PKC delta is similar to that seen after oxytocin or TPA exposure but less for PKC alpha. Exposure to oxytocin for 30 minutes and 60 minutes induced translocation of PKC alpha and delta, respectively. Exposure to TPA for 5 and 30 minutes induced translocation of PKC alpha and PKC delta, respectively. In calcium-free media, only TPA induced translocation of these two isoenzymes. CONCLUSION: Magnesium sulfate stimulates PKC translocation in cultured myometrial cells from pregnant women. Magnesium sulfate and oxytocin require extracellular calcium to induce translocation of both PKC alpha and delta.