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Montevideo, Uruguay

Cowles J.M.,University of Minnesota | Wragg P.D.,University of Minnesota | Wright A.J.,FIT | Powers J.S.,University of Minnesota | And 2 more authors.
Global Change Biology | Year: 2016

Ecosystems worldwide are increasingly impacted by multiple drivers of environmental change, including climate warming and loss of biodiversity. We show, using a long-term factorial experiment, that plant diversity loss alters the effects of warming on productivity. Aboveground primary productivity was increased by both high plant diversity and warming, and, in concert, warming (≈1.5 °C average above and belowground warming over the growing season) and diversity caused a greater than additive increase in aboveground productivity. The aboveground warming effects increased over time, particularly at higher levels of diversity, perhaps because of warming-induced increases in legume and C4 bunch grass abundances, and facilitative feedbacks of these species on productivity. Moreover, higher plant diversity was associated with the amelioration of warming-induced environmental conditions. This led to cooler temperatures, decreased vapor pressure deficit, and increased surface soil moisture in higher diversity communities. Root biomass (0-30 cm) was likewise consistently greater at higher plant diversity and was greater with warming in monocultures and at intermediate diversity, but at high diversity warming had no detectable effect. This may be because warming increased the abundance of legumes, which have lower root : shoot ratios than the other types of plants. In addition, legumes increase soil nitrogen (N) supply, which could make N less limiting to other species and potentially decrease their investment in roots. The negative warming × diversity interaction on root mass led to an overall negative interactive effect of these two global change factors on the sum of above and belowground biomass, and thus likely on total plant carbon stores. In total, plant diversity increased the effect of warming on aboveground net productivity and moderated the effect on root mass. These divergent effects suggest that warming and changes in plant diversity are likely to have both interactive and divergent impacts on various aspects of ecosystem functioning. © 2016 John Wiley & Sons Ltd. Source

Hiyama M.,Fukuoka Institute of Technology | Ikeda M.,Seikei University | Barolli L.,FIT | Takizawa M.,Seikei University
Journal of Ambient Intelligence and Humanized Computing | Year: 2010

In this paper, we present the performance analysis of two link state routing protocols: OLSR and B.A.T.M.A.N.. We investigate the effect of mobility and topology changing in the throughput of a MANET testbed. We study the impact of best-effort traffic for two link state routing protocols. We also investigate the impact of multiflow traffic in the network. Experimental time is 10 s. In this work, we consider three experimental models and we assess the performance of our testbed in terms of throughput, round trip time and packet loss. From our experiments, we found that B.A.T.M.A.N. protocol has better goodput than OLSR protocol. However, for mobile nodes, OLSR protocol has better goodput than B.A.T.M.A.N. protocol. © Springer-Verlag 2010. Source

Lee D.-K.,KAIST | Lee J.-S.,KAIST | Han J.-H.,KAIST | Yoshiyuki K.,FIT
2010 World Automation Congress, WAC 2010 | Year: 2010

To construct the system matrix of a small flight vehicle model for pure plunging motion, the aerodynamic forces acting on the small flight vehicle model were measured using a Magnetic Suspension and Balance System (MSBS) for various angles of attack and elevator deflection angles. The MSBS, a kind of non-contact type balance installed onto the KAIST low speed wind tunnel, replaced the conventional mechanical balance system, so that the support interference effects in wind tunnel tests were eliminated. Furthermore, it enables us to easily control and change the position and the attitude of an object. The stability coefficients and the stability derivatives of a small flight vehicle model were obtained from the results of wind tunnel tests and the equation of motion of the small flight vehicle model was constructed in the state-space form, which is called the system matrix of the small flight vehicle model. © 2010 TSI Press. Source

Oda T.,Fukuoka Institute of Technology | Barolli A.,Seikei University | Xhafa F.,University of Barcelona | Barolli L.,FIT | And 2 more authors.
Journal of Ambient Intelligence and Humanized Computing | Year: 2013

Wireless Mesh Networks (WMNs) have become an important networking infrastructure for providing cost-efficient broadband wireless connectivity. WMNs are showing their applicability in deployment of medical, transport and surveillance applications in urban areas, metropolitan, neighboring communities and municipal area networks. In this paper, we deal with connectivity and coverage problem of WMN. Because these problems are known to be NP-Hard, we propose and implement a system based on Genetic Algorithms (GAs). We evaluate the performance of the proposed system by different scenarios using different metrics such as client distribution, crossover rate, mutation rate, coverage area and giant component. The simulation results show that for 32 × 32 and 64 × 64 grid area, Linear Ranking is good selection operator and offers the best network connectivity and user coverage. © 2012 Springer-Verlag. Source

Martinez G.,FIT | Val L.,FIT
Proceedings of the 2014 Latin American Computing Conference, CLEI 2014 | Year: 2014

This paper presents the development of a distributed computing framework based on standard web technologies. The workload is specified as Javascript code, split into pieces served via HTTP and executed by web workers inside the clients' web browser. Initially developed to run genetic algorithms in a parallel fashion, our implementation has been generalized into a system powerful enough to run any kind of computationally intensive work. It allows running a distributed algorithm in a huge number of different devices. There are no special software requirements since every modern platform with a powerful CPU and a network connection has at least one web browser available. The tests show tasks can be run in web browsers in a secure and efficient manner. We show the great portability and performance achieved using a simple test bed problem. © 2014 IEEE. Source

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