4,187 research outputs found
A Proposal for Measuring Science, Technology and Innovation Activities
Get PDFAlso available from http://www.sfu.ca/cprost/?p=31
The Main Central thrust and the South Tibetan detachment in the Dadeldhura klippe (West Nepal): New insights for the evolution of the Himalayan metamorphic core
Get PDFAbstract HKT-ISTP 2013
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Camping Violations Analyzed
Get PDFResearchers pinpointed young men in a study of illegal camping, fire-building, and behavior from 1973 to 1975. First published in Appalachia in 1977
Distributed Formal Concept Analysis Algorithms Based on an Iterative MapReduce Framework
Get PDFWhile many existing formal concept analysis algorithms are efficient, they
are typically unsuitable for distributed implementation. Taking the MapReduce
(MR) framework as our inspiration we introduce a distributed approach for
performing formal concept mining. Our method has its novelty in that we use a
light-weight MapReduce runtime called Twister which is better suited to
iterative algorithms than recent distributed approaches. First, we describe the
theoretical foundations underpinning our distributed formal concept analysis
approach. Second, we provide a representative exemplar of how a classic
centralized algorithm can be implemented in a distributed fashion using our
methodology: we modify Ganter's classic algorithm by introducing a family of
MR* algorithms, namely MRGanter and MRGanter+ where the prefix denotes the
algorithm's lineage. To evaluate the factors that impact distributed algorithm
performance, we compare our MR* algorithms with the state-of-the-art.
Experiments conducted on real datasets demonstrate that MRGanter+ is efficient,
scalable and an appealing algorithm for distributed problems.Comment: 17 pages, ICFCA 201, Formal Concept Analysis 201
Bioconversion of potatoes residues or surplus potatoes to ethanol under non axenic conditions [abstract]
Get PDFBiofuels can offer an alternative to fossil fuels in the context of climate change and fossil reserves depletion. With 3 million tons of potatoes produced in 2007 and a high yield per hectare of 47 tons, Belgium is the 19th largest producer in the world. The residual and surplus potatoes could be used to produce bioethanol by fermentation. We examined the feasibility of a simple ethanol fermentation process under non axenic conditions. The substrate was pretreated with commercial amylases or by adding as low as 10% FM (Fresh Matter) barley malt. It was then fermented with Saccharomyces cerevisiae. Ethanol and volatile fatty acids were analyzed by GC-FID and soluble sugars were analyzed with the Anthrone method. Starch from potatoes was hydrolyzed to soluble sugars. Hydrolysis seems to continue with 10% FM of barley malt after 48 h while the hydrolysis stopped or decelerated with commercial enzymes. With 10% FM of malt, 3 h of hydrolysis and 7 days of fermentation, an ethanol concentration of 42 g.l-1 was obtained and the conversion yield was 139 gethanol.kg-1 DM. The fermentation conversion yield of soluble sugars to ethanol was > 82% and the endogenous competition was limited. However, starch hydrolyzing seems to be a limiting step under the conditions tested. Commercial enzymes did not provide better results under the same conditions
Influence of topography on tide propagation and amplification in semi-enclosed basins
Get PDFAn idealized model for tide propagation and amplification in semi-enclosed rectangular basins is presented, accounting for depth differences by a combination of longitudinal and lateral topographic steps. The basin geometry is formed by several adjacent compartments of identical width, each having either a uniform depth or two depths separated by a transverse topographic step. The problem is forced by an incoming Kelvin wave at the open end, while allowing waves to radiate outward. The solution in each compartment is written as the superposition of (semi)-analytical wave solutions in an infinite channel, individually satisfying the depth-averaged linear shallow water equations on the f plane, including bottom friction. A collocation technique is employed to satisfy continuity of elevation and flux across the longitudinal topographic steps between the compartments. The model results show that the tidal wave in shallow parts displays slower propagation, enhanced dissipation and amplified amplitudes. This reveals a resonance mechanism, occurring when\ud
the length of the shallow end is roughly an odd multiple of the quarter Kelvin wavelength. Alternatively, for sufficiently wide basins, also Poincaré waves may become resonant. A transverse step implies different wavelengths of the incoming and reflected Kelvin wave, leading to increased amplitudes in shallow regions and a shift of amphidromic points in the direction of the deeper part. Including the shallow parts near the basin’s closed end (thus capturing the Kelvin resonance mechanism) is essential to reproduce semi-diurnal and diurnal\ud
tide observations in the Gulf of California, the Adriatic Sea and the Persian Gulf
Systemic analysis of production scenarios for bioethanol produced from ligno-cellulosic biomass [abstract]
Get PDFDefining alternatives for non-renewable energy sources constitutes a priority to the development of our societies. One of these alternatives is biofuels production starting from energy crops, agricultural wastes, forest products or wastes. In this context, a "second generation" biofuels production, aiming at utilizing the whole plant, including ligno-cellulosic (hemicelluloses, cellulose, lignin) fractions (Ogier et al., 1999) that are not used for human food, would allow the reduction of the drawbacks of bioethanol production (Schoeling, 2007). However, numerous technical, economical, ethical and environmental questions are still pending. One of the aims of the BioEtha2 project, directed by the Walloon Agricultural Research Centre, is to define the position of bioethanol produced from ligno-cellulosic biomass among the different renewable energy alternatives that could be developed in Wallonia towards 2020. With this aim, and in order to answer the numerous questions in this field, the project aims at using tools and methods coming from the concept of "forecasting scenarios" (Sebillotte, 2002; Slegten et al., 2007; For-learn, 2008). This concept, based on a contemporary reality, aims to explore different possible scenarios for the future development of alternative sources of energy production. The principle is to evaluate, explore, possible futures of the studied problematic, through the establishment of possible evolution trajectories. We contribute to this prospective through a systemic approach (Vanloqueren, 2007) that allows lightening the existing interactions within the system "ligno-cellulosic biomass chain" without isolating it from its environment. We explain and sketch the two contexts needed to identify primary stakes. The global context includes inter-dependant and auto-regulating fields such as society, politics, technology and economy. These four fields influence each part of the "chain" with specific tools. However, the interest and possible action fields lay within the intermediary context representing the "resources" such as agriculture, forestry, "driving" elements such as mobility, mediation elements such as territories and environment and concurrent elements such as non-cellulosic biomass, the energy mix and the non-energy valorization
Efficient and robust reconstruction of botanical branching structure from laser scanned points
Get PDFThis paper presents a reconstruction pipeline for recovering branching structure of trees from laser scanned data points. The process is made up of two main blocks: segmentation and reconstruction. Based on a variational k-means clustering algorithm, cylindrical components and ramified regions of data points are identified and located. An adjacency graph is then built from neighborhood information of components. Simple heuristics allow us to extract a skeleton structure and identify branches from the graph. Finally, a B-spline model is computed to give a compact and accurate reconstruction of the branching system. © 2009 IEEE.published_or_final_versionThe 11th IEEE International Conference on Computer-Aided Design and Computer Graphics (CAD/Graphics '09), Huangshan, China, 19-21 August 2009. In Proceedings of 11th CAD/Graphics, 2009, p. 572-57
Effect of heuristics on serendipity in path-based storytelling with linked data
Get PDFPath-based storytelling with Linked Data on the Web provides users the ability to discover concepts in an entertaining and educational way. Given a query context, many state-of-the-art pathfinding approaches aim at telling a story that coincides with the user's expectations by investigating paths over Linked Data on the Web. By taking into account serendipity in storytelling, we aim at improving and tailoring existing approaches towards better fitting user expectations so that users are able to discover interesting knowledge without feeling unsure or even lost in the story facts. To this end, we propose to optimize the link estimation between - and the selection of facts in a story by increasing the consistency and relevancy of links between facts through additional domain delineation and refinement steps. In order to address multiple aspects of serendipity, we propose and investigate combinations of weights and heuristics in paths forming the essential building blocks for each story. Our experimental findings with stories based on DBpedia indicate the improvements when applying the optimized algorithm
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