Optimal Temperature Control of Large Scale District Heating Networks

International audienceThe present paper synthetizes four years of research conducted by our team in collaboration with CCIAG, the operating company of the Grenoble large scale district heating network. This research focused on the design of a model predictive controller that optimizes the distribution of heat by an appropriate scheduling of supply temperatures and differential pressure at the production level. The controller relies on a heat load prediction covering a 24 h anticipation horizon combined with a constrained optimization problem. More specifically, our research was divided in four topics. First, we proposed and assessed various day-ahead load prediction models. An original feature of our work is to explicitly account for the network storage effect resulting from supply temperature variations. Second, we formulated a linear problem consisting of an objective function reflecting the production costs and a set of constraints representing, inter alia, the heat transport dynamics. In our solution, some of the parameters (e.g. producer-consumer temperature transportation delay) of the optimization program are periodically updated using dynamic simulation. Third, a fast fluid-dynamic simulation code based on a reduced-order model was designed and assessed. Finally, the developed models were all implemented and assembled in a decision support software tool called PEGASE. We proved the feasibility of running our controller in real-time for a large-scale DHN and the proposed solution is currently being evaluated by CCIAG

Compendium gezondheidszorg en -statistiek: de cijfers en het verhaal erachter

Dit compendium bundelt in vijf hoofdstukken het cijfermateriaal dat relevant is voor elke gezondheidsactiviteit. Nieuw in deze editie zijn gegevens uit de Gezondheidsenquête 2003 betreffende de epidemiologie, tabellen over de diagnoses in ziekenhuizen (MKG 2000), de meest frequente heelkundige prestaties, de repartitie van de uitgaven per regio, de gemiddelde prijs per hospitalisatie en per regio...Vijf eminente specialisten - Dirk Corens, Walter Sermeus, Paul Gemmel, Henri Vanden Bavière en Rudy Van Tielen - plaatsen alle cijfers in een bredere context

Robust Bidirectional Continuous Electrowetting Based on Metal–Semiconductor (M–S) Diodes

We demonstrate bidirectional continuous electrowetting by embedding metal–semiconductor diodes in the electrowetting substrate. Unlike conventional electrowetting on dielectric, bidirectional continuous electrowetting uses a single electrode pair to actuate a droplet through long distances. As long as the voltage potential is maintained between two end electrodes, the droplet moves toward the electrode with the higher potential. However, previously reported material systems had limited success in repeated actuation. In this work, diodes based on Schottky barriers were fabricated by forming metal–semiconductor junctions between titanium and high-resistivity n-type silicon. The performance enhancements were evaluated using current–voltage measurements of interface pairs. When the titanium is coated with gold to limit electrochemical reactions, the Schottky diodes achieved superior performance compared to electrochemical diodes previously studied. Droplet speed range from 8 to 240 mm/s is reported. Under repeated actuation, the speed of the droplet showed no degradation for up to 2000 cycles (experiment duration)