221 research outputs found

    A new space-vector-modulation algorithm for a three-level four-leg NPC inverter

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    For power conversion systems interfaced to 4-wire supplies, four-leg converters have become a standard solution. A four-leg converter allows good compensation of zero-sequence harmonics and full utilization of the dc-link voltage. These are very important features when unbalanced and/or non-linear loads are connected to the system. This paper proposes a 3D-SVM algorithm and provides a comprehensive analysis of the algorithm implemented on a three-level, four-leg NPC converter. The algorithm allows a simple definition of the different switching patterns and enables balancing of the dc-link capacitor voltages using the redundancies of the converter states. A resonant controller is selected as the control strategy to validate the proposed SVM algorithm in a 6kW experimental rig

    Exceptional Record of Mid-Pleistocene Vertebrates Helps Differentiate Climatic from Anthropogenic Ecosystem Perturbations

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    Mid-Pleistocene vertebrates in North America are scarce but important for recognizing the ecological effects of climatic change in the absence of humans. We report on a uniquely rich mid-Pleistocene vertebrate sequence from Porcupine Cave, Colorado, which records at least 127 species and the earliest appearances of 30 mammals and birds. By analyzing \u3e20,000 mammal fossils in relation to modern species and independent climatic proxies, we determined how mammal communities reacted to presumed glacial-interglacial transitions between 1,000,000 and 600,000 years ago. We conclude that climatic warming primarily affected mammals of lower trophic and size categories, in contrast to documented human impacts on higher trophic and size categories historically. Despite changes in species composition and minor changes in small-mammal species richness evident at times of climatic change, overall structural stability of mammal communities persisted \u3e600,000 years before human impacts

    A mobile-based solution for supporting end-users in the composition of services

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s11042-016-3910-4Currently, technologies and applications evolve to create eco-systems made up of a myriad of heterogeneous and distributed services that are accessible anytime and anywhere. Even though these services can be used individually, it is their coordinated and combined usage what provide an added value to end-users. In addition, user¿s wide adoption of mobile devices for daily activities have fostered a shift in the role played by end-users towards Internet data and services. However, existing solutions to service composition are not targeted to ordinary end-users. More easy-to-use tools have to be offered to end-users to make sure that they are successfully accepted and used by them. To this end, the work presented in this paper supports end-users in the creation of service compositions by using mobile devices. We present a Domain Specific Visual Language (DSVL) for end-users that allows them to create service compositions. A tool specifically designed for mobile devices supports this DSVL.This work has been developed with the support of MINECO under the project SMART ADAPT TIN2013-42981-P and co-financed with ERDF.Valderas Aranda, PJ.; Torres Bosch, MV.; Mansanet Benavent, I.; Pelechano Ferragud, V. (2016). A mobile-based solution for supporting end-users in the composition of services. Multimedia Tools and Applications. 1-31. https://doi.org/10.1007/s11042-016-3910-4S131Athreya B, Bahmani F, Diede A, Scaffidi C (2012) End-user programmers on the loose: a study of programming on the phone for the phone. In IEEE Symposium on Visual Languages and Human-Centric Computing (VL/HCC), Innsbruck, Austria, pp. 75–82Atoma (2015) Atoomam, a touch of magic. Accesible at: https://www.atooma.com/ . 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Wiley, New YorkGil M, Serral E, Valderas P, Pelechano V (2013) Designing for user attention: a method for supporting unobtrusive routine tasks. Sci Comput Program 78(10):1987–2008Gubbi J, Buyya R, Marusic S, Palaniswami M (2013) Internet of things (IoT): a vision, architectural elements, and future directions. Futur Gener Comput Syst 29(7):1645–1660Haines W, Gervasio M, Spaulding A, Peintner B (2010) Recommendations for end-user development. In ACM Workshop on User-Centric Evaluation of Recommender Systems and their Interfaces, Barcelona, Spain, pp. 42-49Häkkilä J, Korpipää P, Ronkainen S, Tuomela U (2005) Interaction and end-user programming with a context-aware mobile application. In: Human-computer interaction-INTERACT 2005. Springer, Berlin, pp. 927–937ICIS (2015) Internet Computing in the Internet of Services. Summer School. Department of Informatics Engineering of the University of Coimbra. Available at: http://icis.uc.pt/ . 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X Jornadas de Ciencia e Ingeniería de Servicios (JCIS 2014), 25–35Mansanet I, Torres V, Valderas P, Pelechano V (2015) IoT Compositions by and for the Crowd. XI Jornadas de Ciencia e Ingeniería de Servicios (JCIS 2015)Neil T (2014) Mobile design pattern gallery: UI patterns for smartphone apps. “O’Reilly Media, Inc.”, SebastopolNielsen J (2005) Ten usability heuristics. https://www.nngroup.com/articles/ten-usability-heuristics . Last time accessed: February 2016Renger M, Kolfschoten GL, de Vreede GJ (2008) Challenges in collaborative modeling: A literature review. In Advances in enterprise engineering I, held at CAiSE 2008, Montpellier, 10. 61–77Repenning A, Ioannidou A (2006) What makes end-user development tick? 13 design guidelines. End user development, Human-Computer Interaction Series, vol 9, pp. 51–85Runeson P, Höst M (2009) Guidelines for conducting and reporting case study research in software engineering. 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Pattern Languages of Programs Conference (pp. 13–16)Weber B, Reichert M, Rinderle S (2008) Change patterns and change support features - enhancing flexibility in process-aware information systems. Data Knowl Eng 66:438–466Yu J, Sheng QZ, Han J, Wu Y, Liu C (2012) A semantically enhanced service repository for user-centric service discovery and management. Data Knowl Eng 72:202–21

    Pliocene and Pleistocene geologic and climatic evolution in the San Luis Valley of south-central Colorado

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    Sediments of the Alamosa Formation spanning the upper part of the Gauss and most of the Matuyama Chrons were recovered by coring in the high (2300 m) San Luis Valley of south-central Colorado. The study site is located at the northern end of the Rio Grande rift. Lithologic changes in the core sediments provide evidence of events leading to integration of the San Luis drainage basin into the Rio Grande. The section, which includes the Huckleberry Ridge Ash (2.02 Ma) and spans the entire Matuyama Chron, contains pollen, and invertebrate and vertebrate fossils. Stable isotope analyses of inorganic and biogenic carbonate taken over most of the core indicate substantially warmer temperatures than occur today in the San Luis Valley. At the end of the Olduvai Subchron, summer precipitation decreased, summer pan evaporation increased, and temperatures increased slightly compared to the earlier climate represented in the core. By the end of the Jaramillo Subchron, however, cold/wet and warm/dry cycles become evident and continue into the cold/wet regime associated with the deep-sea oxygen-isotope Stage 22 glaciation previously determined from outcrops at the same locality. Correspondence between the Hansen Bluff climatic record and the deep-sea oxygen-isotope record (oxygen-isotope stages from about 110-18) is apparent, indicating that climate at Hansen Bluff was responding to global climatic changes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29956/1/0000316.pd

    Depauperate Avifauna in Plantations Compared to Forests and Exurban Areas

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    Native forests are shrinking worldwide, causing a loss of biological diversity. Our ability to prioritize forest conservation actions is hampered by a lack of information about the relative impacts of different types of forest loss on biodiversity. In particular, we lack rigorous comparisons of the effects of clearing forests for tree plantations and for human settlements, two leading causes of deforestation worldwide. We compared avian diversity in forests, plantations and exurban areas on the Cumberland Plateau, USA, an area of global importance for biodiversity. By combining field surveys with digital habitat databases, and then analyzing diversity at multiple scales, we found that plantations had lower diversity and fewer conservation priority species than did other habitats. Exurban areas had higher diversity than did native forests, but native forests outscored exurban areas for some measures of conservation priority. Overall therefore, pine plantations had impoverished avian communities relative to both native forests and to exurban areas. Thus, reports on the status of forests give misleading signals about biological diversity when they include plantations in their estimates of forest cover but exclude forested areas in which humans live. Likewise, forest conservation programs should downgrade incentives for plantations and should include settled areas within their purview

    Updating the evolutionary history of Carnivora (Mammalia): a new species-level supertree complete with divergence time estimates

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    Multigene phylogeny of the Mustelidae: Resolving relationships, tempo and biogeographic history of a mammalian adaptive radiation

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    <p>Abstract</p> <p>Background</p> <p>Adaptive radiation, the evolution of ecological and phenotypic diversity from a common ancestor, is a central concept in evolutionary biology and characterizes the evolutionary histories of many groups of organisms. One such group is the Mustelidae, the most species-rich family within the mammalian order Carnivora, encompassing 59 species classified into 22 genera. Extant mustelids display extensive ecomorphological diversity, with different lineages having evolved into an array of adaptive zones, from fossorial badgers to semi-aquatic otters. Mustelids are also widely distributed, with multiple genera found on different continents. As with other groups that have undergone adaptive radiation, resolving the phylogenetic history of mustelids presents a number of challenges because ecomorphological convergence may potentially confound morphologically based phylogenetic inferences, and because adaptive radiations often include one or more periods of rapid cladogenesis that require a large amount of data to resolve.</p> <p>Results</p> <p>We constructed a nearly complete generic-level phylogeny of the Mustelidae using a data matrix comprising 22 gene segments (~12,000 base pairs) analyzed with maximum parsimony, maximum likelihood and Bayesian inference methods. We show that mustelids are consistently resolved with high nodal support into four major clades and three monotypic lineages. Using Bayesian dating techniques, we provide evidence that mustelids underwent two bursts of diversification that coincide with major paleoenvironmental and biotic changes that occurred during the Neogene and correspond with similar bursts of cladogenesis in other vertebrate groups. Biogeographical analyses indicate that most of the extant diversity of mustelids originated in Eurasia and mustelids have colonized Africa, North America and South America on multiple occasions.</p> <p>Conclusion</p> <p>Combined with information from the fossil record, our phylogenetic and dating analyses suggest that mustelid diversification may have been spurred by a combination of faunal turnover events and diversification at lower trophic levels, ultimately caused by climatically driven environmental changes. Our biogeographic analyses show Eurasia as the center of origin of mustelid diversity and that mustelids in Africa, North America and South America have been assembled over time largely via dispersal, which has important implications for understanding the ecology of mustelid communities.</p
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