This paper aims at reviewing and analysing the method of reflections, which is an iterative procedure designed for solving linear boundary value problems set in multiply connected domains. Being based on a decomposition of the domain boundary, this method is particularly well-suited to numerical solvers relying on boundary integral representation. For both the sequential and parallel forms of the method appearing in the literature, we interpret the procedure in terms of projection operators. Using a Hilbert space setting and orthogonality, we prove the unconditional convergence of the sequential form and propose a modification of the parallel one that makes it unconditionally converging. Several examples of boundary value problems that enter such a framework are given, an alternative proof of convergence is provided in a case which does not. A few numerical tests conclude the study.
A fuel microemulsion based on blend of diesel fuel:sunflower oil (4:1), water, 1-butanol (co-surfactant), and a blend of Tween 80, Span 80 and 1-buthyl-3-methylimidazolium nitrate ionic liquid as surfactant is formulated and optimized regarding the amounts of co-surfactant, water and oily phase. The fuel microemulsions were for upto one year stable on the bench and their density and viscosity were comparable to neat diesel fuel. The size of water droplets in fuel microemulsions are measured by dynamic light scattering (about 10 nm) with a very narrow size distribution. The optimum results are obtained by using a blend of Span 80:Tween 80:1-buthyl-3-methylimidazolium nitrate, 70:26.25:3.75, respectively, as surfactant. The engine combustion tests at various engine speeds and full load indicated that the brake-specific fuel consumption, torque, brake power and exhaust gas temperature are decreased in fuel microemulsion compared to neat diesel fuel. Carbon dioxide and nitrogen oxide emissions were reduced by 4–5%, and unburned hydrocarbons and carbon monoxide emissions were increased by 18.4% and 1.18%, respectively, for optimum fuel microemulsion compared to neat diesel fuel. The results are promising to introduce a way to improve the diesel fuel performance in terms of its environmental impacts.
The Djebel El Hamra Pb-Zn-Ba-Sr (Hg) deposits in northern Tunisia are hosted in a post-nappe anticline with a core of a Triassic evaporite diapir affected by the NE–SW-trending Ghardimaou-Cap Serrat lineament. Three stages of mineralization occurred in the Triassic dolostone: stages I and II caused alternating deposition of sulfate (Ba, Sr) and sulfide (sphalerite, galena) minerals; stage III formed late-stage calcite-marcasite-cinnabar. Zebra textures record the syntectonic transition from compression to extension in the Late Tortonian-Messinian interval. Two fluid end-members were involved in sulfate deposition: one low-salinity (L1, ~3 wt% eq. NaCl) fluid, probably from a meteoric origin, and a Na-Ca-Cl brine (L2, ~22 wt% eq. NaCl) solution which originated from the Triassic diapiric source. A third end-member fluid (L3) with long residence time in the basement was also involved in the Pb-Zn deposition. The δ 34 S values from a cluster of sulfates around +16‰, show a Triassic evaporate source. The sulfur in sphalerite resulted from bacterial sulfate reduction (BSR); however, crystallization in a closed system resulted in a range of δ 34 S between +1.6 and +26.5‰. The δ 34 S values in galena (−28.4 to +8.2‰) are consistent with a BSR and thermochemical sulfate reduction (TSR) origin of the sulfur. Secondary ion mass spectrometry (SIMS) lead isotope data in galena ( 207 Pb/ 204 Pb: 15.595 to 16.193, 206 Pb/ 204 Pb: 18.673 to 18.939, 208 Pb/ 204 Pb: 38.330 to 40.572) point to local contributions (sedimentary and Cenozoic magmatic rocks) to the main source from the Precambrian basement. Ore deposition occurred at a depth of about 2 km at temperatures between 80 and 250 °C. A shallow magmatic heat source was the cause of these thermal fluctuations.
In this report, a standardized protocol is proposed for the evaluation of short-term wind power prediction systems. It describes a number of reference prediction models, and it is argued that the use of persistence as a reference prediction models leads to slightly misleading and over-optimistic conclusions about the performance. The use of the protocol is demonstrated using results from both on-shore and off-shore wind farms. The work is a part of the ANEMOS project (EU R&D project), where the protocol is used to evaluate more than 10 prediction systems. A PROTOCOL FOR STANDARDIZING THE PERFORMANCE EVALUATION OF SHORT-TERM WIND POWER PREDICTION MODELS H. Madsen1∗, G. Kariniotakis, H.Aa. Nielsen, T.S. Nielsen, P. Pinson 1 Technical University of Denmark, Informatics and Mathemat ical Modeling, DK-2800 Lyngby 2 Ecole des Mines de Paris, Center for Energy Studies, F-06904 Sophia-Antipolis Cedex
A process in three steps involving a gas-liquid contactor with an organic phase, a TPPB and a liquid/liquid separator to recover the organic phase for its recycling was proposed to treat hydrophobic Volatile Organic Compounds. Among the processes tested for liquid/liquid separation (settling, hydrocyclone and centrifugation), the latter appeared to be the most efficient. The centrifugal acceleration needed for the separation of oil and water was found to be dependent on the viscosity of the oil used and the presence of microorganisms. The force required for phases' separation was found to be reduced in the presence of selected commercial demulsifiers.
