Supplier asset allocation in a pool-based electricity market

A power supplier in a pool-based market needs to allocate his generation capacities to participate in contract and spot markets. In this paper, the optimal portfolio selection theory is introduced for this purpose. A model applying this theory is proposed to solve the supplier asset allocation problem. Real market data are used in a numerical study to test the proposed model. The results show that different asset allocation solutions can yield very different risk-return tradeoffs for a supplier, and the proposed method can be potentially useful in suppliers' decision making. © 2007 IEEE.published_or_final_versio

Sedimentation of the Lower Cretaceous Xiagou formation and Its Response to Regional Tectonics in the Qingxi Sag, Jiuquan Basin, NW China

Under the constraint of an isochronous sequence stratigraphic framework, sediment infill of the Xiagou Formation reflects the overall control of dynamic tectonic movements and episodic sedimentations in the Qingxi Sag. Structure reactivity during post-depositional processes could cause stratigraphic variations in longitudinal time and lateral space. This study documents sediment infill features and their response to the tectonic evolutions of the Qingxi Sag. The data sets include comparison of cores, well drilling, 3D seismic, inter-well correlation, wave impedance inversion profiles, original strata recovery data, sedimentary fades spatial evolution and their superimposition with paleogeomorphology. The Jiuquan Basin is a Mesozoic-Cenozoic superposition basin comprising an early rifting graben phase and a later compression phase. Since the Early Cretaceous, the basin has undergone four major tectonic episodes: 1) extension during the Early Cretaceous, 2) tectonic inversion caused by northwest-southeast contraction from the Late Cretaceous to the Paleocene, 3) weak extension from the Eocene to the Miocene and 4) contraction from the Miocene to the present. Therefore, the Jiuquan Basin is the product of taphrogenic, collisional and shearing movements. Seismic interpretations of sequence and maximum flooding surface divide the Xiagou Formation into three third order sequences: SQK1g(0), SQK1g(1) and SQK1g(2+3). Five sedimentary facies associations are identified: the shoreland plain, fan delta dominated sedimentary systems, turbidite deposits, shallow lakes and half-deep lake systems. From K1g(0) to K1g(2+3), decreased sandstone percentages in three fan delta areas indicate a continuously transgressive process, which shows the transition from proximal to distal sites in most statistic wells and an obvious decrease of fan delta scales. The northeast-southwest faults control the lakeward distributions of delta fronts and turbidite fans. The correspondence of sedimentary infill and its response to tectonic movements have been demonstrated in the Qingxi Sag. The more active eastern part of the northeastern boundary fault has an important influence on the northeastward migration of depocenters in the Xiagou Formation. The topography developed continuously from K1g(0) to K1g(2+3), but the diminished subsidence indicates the dominant geological process varying from intense fault rifting in an early period to relatively gentle and overall subsidence in a later period during the Early Cretaceous. (C) 2013 Elsevier Ltd. All rights reserved.Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education TPR-2011-09Project of "Double strong effect, driving mechanism and hydrocarbon significance of tectonic activity during depositional period of Dongying Formation in Qikou and Nanpu Sag, Eastern China" 41272122Geological Science

Experimental verification of the "rainbow" trapping effect in plasmonic graded gratings

We report the first experimental observation of trapped rainbow1 in graded metallic gratings2-4, designed to validate theoretical predictions for this new class of plasmonic structures. One-dimensional tapered gratings were fabricated and their surface dispersion properties tailored by varying the grating period and depth, whose dimensions were confirmed by atomic force microscopy. Reduced group velocities and the plasmonic bandgap were observed. Direct measurements on graded grating structures show that light of different wavelengths in the 500-700nm region is "trapped" at different positions along the grating, consistent with computer simulations, thus verifying the "rainbow" trapping effect. The trapped rainbow effect offers exciting pathways for optical information storage and optical delays in photonic circuits at ambient temperature

How hungry are different Brassica oilseed crops for sulphur fertilizer to optimize seed yield, quality, and S uptake in northeastern Saskatchewan?

Non-Peer Reviewe

Géomatériaux imprimables en 3D

International audienceOne of the many attributes of 3D printing is the ability to produce particles with independent control of morphology and material properties, parameters that are inexorably entwined in naturally occurring geomaterials. In this paper we describe the 3D printing of surrogate granular materials, show examples of the particles produced and present results showing their ability to capture real soil behaviour. Three approaches are demonstrated for the three dimensional generation of model grains. The first method involves the superimposition of a fractal surface with higher level stochastic features on the face of a closed volume such as a geodesic spheroid. The second method involves the use of Fourier descriptors or fractal geometry generated from 2D cross sections and their interpolation to produce simulated geomaterial particles in three dimensions. The third method involves the generation of complex particles by the aggregation of polyhedral elements such as cubes or octahedra which is suitable for the simulation and fabrication of porous or branching particles. Finally, we discuss applications of the fabrication of surrogate materials by 3D printing for use as standardised, printable geomaterials in future up-scaled geotechnical experiments and other geomechanical research.https://doi.org/10.1680/jgeot.15.P.034L'un des nombreux attributs de l'impression 3D est la capacité de produire des particules avec un contrôle indépendant de la morphologie et des propriétés du matériau, paramètres inextricablement liés dans les géomatériaux naturels. Dans cet article, nous décrivons l'impression 3D de matériaux granulaires de substitution, montrons des exemples de particules produites et présentons les résultats montrant leur capacité à capturer le comportement réel du sol. Trois approches sont démontrées pour la génération tridimensionnelle de grains modèles. La première méthode implique la superposition d'une surface fractale avec des caractéristiques stochastiques de niveau supérieur sur la face d'un volume fermé tel qu'un sphéroïde géodésique. La deuxième méthode implique l'utilisation de descripteurs de Fourier ou de géométrie fractale générés à partir de sections transversales 2D et leur interpolation pour produire des particules de géomatériau simulées en trois dimensions. La troisième méthode implique la génération de particules complexes par l'agrégation d'éléments polyédriques, tels que des cubes ou des octaèdres, qui conviennent à la simulation et à la fabrication de particules poreuses ou ramifiées. Enfin, nous discutons des applications de la fabrication de matériaux de substitution par impression 3D pour une utilisation en tant que géomatériaux imprimables et normalisés dans de futures expériences géotechniques à grande échelle et autres recherches géomécaniques.https://doi.org/10.1680/jgeot.15.P.03

Optimasi Proses Injeksi Dengan Metode Taguchi

At this time about 3% of products produced by "X" plastic factory does not reach the standard. This factory has a problem to minimize the amount of defects. Taguchi method is used to lower the level of product defects. From the field survey, all the suspected factors can be obatained and it is shown ini the fishbone diagram. From the suspected factors, the factory chose factors that are to be used ini the experiments. Experiments were conducted using those four factors : pellet material percentage (60%, 70%, 80%), temperature (217°C, 225°C, 233°C), injection pressure (92 Bar, 93 Bar, 94 Bar), screw speed (81%, 83%, 85%). Taguchi method provide the combination and number of experiments. From each level of defects condition, analysis was done to obtain the affecting variables. The results of analysis shows that the combination of pellet material (80%), temperature (225°C), injection pressure (93 Bar), screw speed (83%) can minimize the amount of defects to 0.3%