305,211 research outputs found
Numerical simulation of hydrodynamics and bank erosion in a river bend
No full textWe present an integrated analysis of bank erosion in a high-curvature bend of the gravel bed Cecina River (central Italy). Our analysis combines a model of fluvial bank erosion with groundwater flow and bank stability analyses to account for the influence of hydraulic erosion on mass failure processes, the key novel aspect being that the fluvial erosion model is parameterized using outputs from detailed hydrodynamic simulations. The results identify two mechanisms that explain how most bank retreat usually occurs after, rather than during, flood peaks. First, in the high curvature bend investigated here the maximum flow velocity core migrates away from the outer bank as flow discharge increases, reducing sidewall boundary shear stress and fluvial erosion at peak flow stages. Second, bank failure episodes are triggered by combinations of pore water and hydrostatic confining pressures induced in the period between the drawdown and rising phases of multipeaked flow events
Closing secondary channels in large sand-bed braided rivers
No full textLarge braided rivers have many beneficial roles, from provision of water for agriculture and means of transport to various ecosystem services. However, they are geomorphologically active, which results in problems with bank erosion and navigability. Some of the largest rivers may have bank line shifts of hundreds of meters per year (Baki and Gan, 2012). This leads to loss of homes and good agricultural land, destruction of infrastructure and flood protection works. River training measures are used to combat these problems and reclaim lost land. Conventional structures, mostly developed in smaller watercourses, are problematic in very large and unpredictable braided rivers, due to their required size, cost, inflexibility and environmental disturbance (Nakagawa et al., 2013). More adaptable, cheaper (local materials) and less disturbing measures are required. One promising possibility is the use of recurrent measures (such as bandals) to close aggressive secondary channels (Mosselman, 2006). Coupled with a prediction model for planform changes and erosion (such as Klaassen et al., 1993), this can be a very flexible and efficient way to protect nearby land against bank erosion, start land reclamation or improve navigability. A.J.F. Hoitink, T.V. de Ruijsscher, T.J. Geertsema, B. Makaske, J. Wallinga, J.H.J. Candel, J. Poelman (Eds.) NCR days 2017, Febr. 1-3, 2017. Book of abstracts, NCR publication 41-2017.Rivers, Ports, Waterways and Dredging Engineerin
A review of techniques available for delimiting the erodible river corridor: a sustainable approach to managing bank erosion
No full textTraditional policies for managing river bank erosion are currently being reconsidered as a result of increased awareness regarding the unsustainable nature of some forms of bank protection, and the role played by bank erosion in providing ecosystem services and supporting geomorphological functions. River managers are therefore increasingly seeking to preserve bank erosion within a defined erodible corridor. This paper provides an overview of the erodible corridor concept, focusing on the provision of guidelines for applying the concept in practice. We argue that a nested approach is required to address management objectives across a range of scales (network scale, reach scale, local scale) and review the different geomorphic tools that are available to help managers define the extent and inner sensitivity of the erodible corridor. These tools include simple rules of thumb such as evaluation of the equilibrium meander amplitude, historical approaches based on overlays of historical channel position, and simulation modelling. The advantages and limitations of each of these tools are discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Sistemas de informações sua estrutura e gerenciamento
No full textTCC (Graduação) - Universidade Federal de Santa Catarina. Centro Socioeconômico. Curso de Ciências Contábeis0 surgimento de novas tecnologias tem levado as empresas para um constante aperfeiçoamento, procurando melhorar a qualidade dos serviços e produtos, para serem competitivos e continuarem concorrendo no mercado. Neste contexto, torna-se imprescindível estabelecer metas e buscar ferramentas disponíveis para se adequarem as exigências do mercado. Partindo desta necessidade, as organizações buscam formas de se organizarem para obterem os recursos necessários para o bom andamento das atividades. 0 planejamento adequado da administração é um ponto que deve ser feito com atenção, pois é a partir deste que se inicia o controle das atividades. Para tanto tem-se que buscar instrumentos que auxiliem o processo gerencial da empresa. A qualidade da decisão tomada depende da informação que é obtida. Os sistemas de informações foram criados para dar apoio as organizações a atingirem suas metas. Auxiliando na avaliação de todas as areas da empresa, como, operacional; mercadológica; financeira; administrativa, enfim, auxiliar na obtenção de lucros e redução de custos
Morphological effects of spatially varying grain size and bed roughness in rivers
No full textMany morphological models that are in use today, make use of spatially constant grain sizes and bed roughness. Application of this spatially constant grain size and bed roughness is not a correct representation of reality. When making use of actually measured grain sizes, the prediction of the morphological changes does not necessarily improve. Linear analyses of the application of spatially varying grain sizes show that the spatial variation of grain sizes can have much impact on the bed topography in rivers. Two different linear analyses have been conducted by Mosselman & Sloff (1998) and Sieben (2000). One shows a difference in the length and dampening of the bed perturbations due to free excitation. The other shows the existence of a response in the bed topography like a superimposed waveform, due to forced excitation. Implementation of the spatially varying grain size resulted for Olesen's experiment (1985) in effects according to free and forced excitation. For the models of the Waal bend at Nijmegen and Pannerdense Kop, the effects were according to forced excitation. Both linear analyses show morphological effects due to the spatially varying grain size as well as due to spatially varying bed roughness. The spatial variation of the bed roughness should, according to the analyses, have a counteracting morphological effect in regard to the morphological effects of the spatially variation of the grain size. Application of spatially varying bed roughness resulted for Olesen's experiment in effects according to free and forced excitation. For the other two models the implementation of spatially varying bed roughness resulted in effects according to forced excitation. Implementation of a grain size distribution which has reached an equilibrium state leads to a bed level response according to free excitation. While the implementation of a grain size distribution which has not reached an equilibrium, like in rivers with variable discharge, leads to a bed level response according to forced excitation. Implementation of an alluvial bed roughness predictor led to no satisfactory results for Olesen's experiment and the Waal bend at Nijmegen. However, for the model of Pannerdense Kop the results of the computation matched the prototype better than the computation with uniform grain sizes and bed roughness. This was caused by two main effects. The first was a forced excitation due to the spatially varying bed roughness. The second was a change in the sediment distribution at the bifurcation.Civil Engineering and Geoscience
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Reconstruction and Analysis of the Po River Inundation of 1951
No full textFlood inundation models have become essential tools in flood risk management, being used also in the analysis of historical flood events, which is often needed for a reliable assessment of the potential flood hazard. This study aims at reconstructing the 1951 inundation of the Polesine Region, Italy. The 1951 flooding was a mayor natural catastrophe that caused a large inundated area (1080 km2) and produced devastating social consequences. The reconstruction of the 1951 hydraulic conditions is based on partial knowledge of discharges and water stages at the Pontelagoscuro gauging station (downstream of the 1951 levee breach) using extrapolation of the rating curves beyond the measurement range. This is, even today, something open to uncertainty. We applied a decoupled hybrid approach to the hydraulic modeling: a 1D model is used to simulate the flow into the river and to compute the flow through the levee breach; this result is then adopted as the inflow condition for a 2D model application on the inundated area. A good agreement between the patterns of the observed and reconstructed inundation areas was found, and the timing of the inundation was also found to be close to the information derived from the historical chronicles. The results of the flood inundation modelling exercise provide two practical insight: (i) obstacles in the floodplains increased the flooded area by 40% and prolonged the time to reach the sea from 5 to 15 days, (ii) the peak discharge of the event was overestimated by up to 20
Proposta de gerenciamento dos recursos financeiros e não financeiros do setor administrativo da empresa 4s informática indústria e comércio ltda, por meio do balanced scorecard
No full textTCC (Graduação) - Universidade Federal de Santa Catarina. Centro Socioeconômico. Curso de Ciências ContábeisEste estudo parte da premissa de que os métodos de gestão baseados exclusivamente em informações financeiras que utilizam os dados passados não respondem às necessidades das empresas de produzir os diferenciais exigidos pela sociedade e de atender as mudanças constantes do mercado. Nesse cenário se enquadram as práticas gerenciais da 4S Informática Indústria e Comércio Ltda, a qual utiliza um sistema de gestão baseado somente em dados financeiros; entretanto, seus gestores estão conscientes de que esse sistema de gestão não mais atende as suas necessidades. Este estudo, de caráter exploratório e empírico, subdivide-se em dois momentos. Inicialmente, apresenta-se uma revisão bibliográfica sobre gerenciamento e a ferramenta de gestão Balanced Scorecard (BSC). Em seguida, apresenta-se uma aplicação do Balanced Scorecard (BSC), ferramenta esta capaz de promover a gestão estratégica por meio da consideração simultânea de informações financeiras e não financeiras, em um estudo de caso específico: a empresa 4S Informática. Assim, o objetivo do presente trabalho é construir o BSC da empresa 4S Informática, com vistas a possibilitar ao setor administrativo (i) gerenciar seus recursos financeiros e não financeiros; (ii) definir e comunicar os objetivos e (iii) alinhar seus processos internos. A justificativa para tal esforço reside no fato de esses objetivos configurarem-se como funções do setor administrativo e de que, até o presente momento, não existe um procedimento formalizado e sistematizado nem para realizá-las, nem para gerenciá-las. Com a pesquisa foi possível desenvolver o mapa estratégico e o BSC da empresa como um todo, bem como gerar seu perfil de desempenho, o que veio por possibilitar claramente seu desempenho atual e sua situação frente às metas dos objetivos estratégicos. Como resultado, foi possível estender este trabalho ao departamento administrativo, onde se pôde observar a necessidade da atividade de gerenciamento na empresa 4S Informática, bem como oferecer subsídio para tal atividade
Erosie van rivieroevers
No full textOevers staan sinds kart in het middelpunt van de belangstellingbij beheerders van oppervlaktewateren in Nederland. Niet langerbeschouwt men oevers slechts als randverschijnsel, maar alsobjecten met een duidelijk eigen plaats en functie.Het streven om te komen tot een integraal waterbeleid leidtautomatisch oak tot een meer integrale visie op oeverbeheer. Ditbetekent dat er niet alleen aandacht wordt besteed aan detechnische functies van oevers (verdediging, gladheid,afdichting, scheepvaart), maar oak aan andere functies, met namedie aangaande natuur en recreatie.Binnen Rijkswaterstaat heeft dit geleid tot de instelling van hetProject Milieuvriendelijke Oevers (PMO). Tevens is in mei 1987vanuit de Stichting CUR de preadviescommissie PC 59 gestart, dieonderzoek betreffende constructieve aspecten vanmilieuvriendelijke oevers voorbereidt.Binnen PMO of PC 59 is nog geen sluitende definitie van hetbegrip ~milieuvriendelijke oever~ overeengekomen. Milieuvriendelijkmateriaalgebruik en gelijkenis met natuurlijke oeverslijken vanuit civiel-technisch gezichtspunt de twee essentielecomponenten: Milieuvriendelijk materiaalgebruik en Gelijkenis met naturlijke oevers. De twee componenten kunnen strijdig ZlJn, bijvoorbeeld detoepassing van puin afkomstig van een sloop: milieuvriendelijk inde zin van hergebruik van materialen, niet milieuvriendelijk in de zin van een zo natuurlijk mogelijke oever.Hydraulic EngineeringCivil Engineering and Geoscience
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