551 research outputs found

    Exogenous Forces in the Development of Our Banking System

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    A new method to optimize with orthonormal constraints is described, where a particular composition of plane (Givens) rotations is used to parameterize decision variables in terms of angles. It is showed that this parameterization is complete and that any orthonormal k-by-nmatrix can be derived to a set of no more than kn-k(k+1) angles. The technique is applied to the emph {feature extraction problem} where a linear subspace is optimized with respect to non-linear objective functions. The Optimal Discriminative Projection (ODP) algorithm is described. ODP is a data compression or feature extraction algorithm that combines powerful model optimization with regularization to avoid over training. The ODP is used primarily for classification problems

    A challenge to the Delta G~0 interpretation of hydrogen evolution

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    Platinum is a nearly perfect catalyst for the hydrogen evolution reaction, and its high activity has conventionally been explained by its close-to-thermoneutral hydrogen binding energy (G~0). However, many candidate non-precious metal catalysts bind hydrogen with similar strengths, but exhibit orders-of-magnitude lower activity for this reaction. In this study, we employ electronic structure methods that allow fully potential-dependent reaction barriers to be calculated, in order to develop a complete working picture of hydrogen evolution on platinum. Through the resulting ab initio microkinetic models, we assess the mechanistic origins of Pt's high activity. Surprisingly, we find that the G~0 hydrogen atoms are kinetically inert, and that the kinetically active hydrogen atoms have G's much weaker, similar to that of gold. These on-top hydrogens have particularly low barriers, which we compare to those of gold, explaining the high reaction rates, and the exponential variations in coverages can uniquely explain Pt's strong kinetic response to the applied potential. This explains the unique reactivity of Pt that is missed by conventional Sabatier analyses, and suggests true design criteria for non-precious alternatives

    Refined SRP Stack Memory Analysis by Exploiting Critical Sections for Shared Resources

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    International audienceIn this paper we refine previous results on stack memory analysis for SRP based systems. For a task J we associate the section of code in between a resource request and release of R to a sub-task J R . If J R is implemented as a function, the stack usage of J R can be accounted for locally (and not part of the initial allocation for J as done in previously published work.

    Arbetsmaskiners bidrag till luftföroreningar i tätorter

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    The Swedish government has decided an action plan against particulate matter (PM10) within the county of Stockholm. Among other thing, the action plan stipulate that measures shall be taken in order to increase the knowledge about emissions of PM10 from non-road mobile machinery and their contribution to the air quality within densely populated areas. Non-road mobile machinery are characterised as mobile machinery not intended for the use of passenger- or goods-transport on the road, and equipped with an internal combustion engine as specified in directive 97/68/EC and directive 2000/25/EC, i.e. agricultural and forestry tractors and construction equipment such as wheel loaders, excavators, articulated haulers and mobile cranes. The purpose of this project, which was financed by the Swedish national road administration, was to update and summarise the current knowledge concerning fuel consumption and emissions from non-road mobile machinery and their contribution to the air quality in densely populated areas. A more specific aim of the project was to estimate the occurrence and age distribution and annual work hours of non-road mobile machinery within densely populated areas. Furthermore, annual fuel consumption and emissions amounts were also derived. Usually a single emission factor for each pollutant has been used when estimating emissions from the entire non-road mobile machinery sector, which has resulted in fairly uncertain results. Previous research has shown that it is not possible to develop one single set of emission factors that gives representative results for all types of non-road mobile machinery and operations (Hansson et al., 2001; Starr et al., 1999; Ullman et al., 1999). The latest research within the EMMA-projects in Sweden about the presence, use and emissions from non-road mobile machinery has resulted in better knowledge and data concerning emissions from non-road mobile machinery. Within the present project, emissions from non-road mobile machinery in two densely populated areas or population centres with different sizes have been studied. One large population centre represented by the city of Stockholm and one small represented by the town of Ljungby. The calculation of fuel consumption and emissions from non-road mobile machinery within the city of Stockholm has been conducted in accordance with the advanced approach presented by the emission inventory guidebook from the European Environement Agency (EEA, 2005). However, the methodology has been modified in order to thoroughly represent the actual assembly of non-road mobile machinery including the work performed by those machines annually. The same model that was used to derive fuel consumption has been employed for emissions as well. Compared with using average information, more reliable data were obtained through describing the number of machines, annual hour, engine power, load factor, specific fuel consumption and emissions amounts for each type of non-road mobile machinery and model year. All data were stored and used in different matrices, one for each variable. In total 31 different types of machines were defined for which data were collected for all model years from 1982 to 2006. Extensive inventories of non-road mobile machinery were carried out for both the city of Stockholm and Ljungby. For Stockholm the inventory contained both number of units and annual work hour as function of the age of the machinery. Reliable data could be obtained through the Swedish Machinery Testing Institute’s accredited inspection database in combination with statistics over both annual sale returns and registered machinery from the national vehicle database. The results from the inventory showed that about 2 800 non-road mobile machinery with both varying age and annual work hours operated within the city of Stockholm. In the city of Ljungby, less than 100 non-road mobile machinery were estimated to operate, thus called for an alternative method for the inventory. Based on data from local contractors that operated in the city of Ljungby, annual work hour for different types of non-road mobile machinery were collected. The result showed that about 48 000 hours of work with non-road mobile machinery were carried out within the city of Ljungby annually. Moreover, the majority of the work were performed with wheel loaders and different types of excavators. In table S1 annual emission- and fuel consumption amounts from the non-road mobile machinery sector in the cities of Stockholm and Ljungby year 2006 are shown

    Scaled and Dynamic Optimizations of Nudged Elastic Bands

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    We present a modified nudged elastic band routine that can reduce the number of force calls by more than 50% for bands with non-uniform convergence. The method, which we call "dyNEB", dynamically and selectively optimizes states based on the perpendicular forces and parallel spring forces acting on that region of the band. The convergence criteria are scaled to focus on the region of interest, i.e., the saddle point, while maintaining continuity of the band and avoiding truncation. We show that this method works well for solid state reaction barriers---non-electrochemical in general and electrochemical in particular---and that the number of force calls can be significantly reduced without loss of resolution at the saddle point

    Intelligent systems in the context of surrounding environment

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    We investigate the behavioral patterns of a population of agents, each controlled by a simple biologically motivated neural network model, when they are set in competition against each other in the Minority Model of Challet and Zhang. We explore the effects of changing agent characteristics, demonstrating that crowding behavior takes place among agents of similar memory, and show how this allows unique `rogue' agents with higher memory values to take advantage of a majority population. We also show that agents' analytic capability is largely determined by the size of the intermediary layer of neurons. In the context of these results, we discuss the general nature of natural and artificial intelligence systems, and suggest intelligence only exists in the context of the surrounding environment (embodiment). Source code for the programs used can be found at http://neuro.webdrake.net/

    Low Prevalence of Rotavirus and High Prevalence of Norovirus in Hospital and Community Wastewater after Introduction of Rotavirus Vaccine in Nicaragua

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    Rotavirus (RV) and norovirus (NoV) are major causes of pediatric diarrhea and are altogether associated with approximately 800,000 deaths in young children every year. In Nicaragua, national RV vaccination program using the pentavalent RV5 vaccine from Merck was implemented in October 2006. To determine whether RV vaccination decreased the overall number of RV infections, we investigated the occurrence of RV and NoV in wastewater in the city of León from July 2007 to July 2008 and compared these data with pre-vaccination data. The major finding was the low prevalence of RV compared to NoV in all sampling points (11% vs 44%, p<0.05), and that RV concentration was lower as compared to NoV. RV was observed mainly during the rainy season (July–September), and the majority of all RV detected (6/9) belonged to subgroup (SG) I. The partial VP7-gene obtained from one RV positive sample was similar (99% nt identity) to a G6 VP7-gene of bovine origin and similar to the corresponding gene of the vaccine strain (98%). Furthermore RV G-types 2 and 4 were found in the incoming wastewater. NoV strains were detected throughout the year, of which a majority (20/21) were of genotype GII.4. We conclude that the introduction of RV vaccination reduced the transmission of RV in the community in Nicaragua. However, the burden of diarrhea in the country remains high, and the high prevalence of NoVs in hospital and municipal wastewater is noteworthy. This study highlights the need for further assessment of NoV following RV vaccine introduction
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