88 research outputs found

    A Nonparametric Multivariate Control Chart Based on Data Depth

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    For the design of most multivariate control charts, it is assumed that the observations follow a multivariate normal distribution. In practice, this assumption is rarely satisfied. In this work, a distribution-free EWMA control chart for multivariate processes is proposed. This chart is based on equential rank of data depth measures. --

    Application and Use of Multivariate Control Charts In a BTA Deep Hole Drilling Process

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    Deep hole drilling methods are used for producing holes with a high length-to-diameter ratio, good surface finish and straightness. The process is subject to dynamic disturbances usually classified as either chatter vibration or spiralling. In this paper, we will focus on the application and use of multivariate control charts to monitor the process in order to detect chatter vibrations. The results showed that chatter is detected and some alarm signals occurs at time points which can be connected to physical changes of the process. --

    Monitoring of the BTA Deep Hole Drilling Process Using Residual Control Charts

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    Deep hole drilling methods are used for producing holes with a high lengthto- diameter ratio, good surface finish and straightness. The process is subject to dynamic disturbances usually classified as either chatter vibration or spiralling. In this work, we propose to monitor the BTA drilling process using control charts to detect chatter as early as possible and to secure production with high quality. These control charts use the residuals obtained from a model which describes the variation in the amplitude of the relevant frequencies of the process. The results showed that chatter is detected and some alarm signals are related to changing physical conditions of the process. --

    Revisiting global trends in freshwater insect biodiversity

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    A recent global meta-analysis reported a decrease in terrestrial but increase in freshwater insect abundance and biomass (van Klink et al., Science 368, p. 417). The authors suggested that water quality has been improving, thereby challenging recent reports documenting drastic global declines in freshwater biodiversity. We raise two major concerns with the meta-analysis and suggest that these account for the discrepancy with the declines reported elsewhere. First, total abundance and biomass alone are poor indicators of the status of freshwater insect assemblages, and the observed differences may well have been driven by the replacement of sensitive species with tolerant ones. Second, many of the datasets poorly represent global trends and reflect responses to local conditions or nonrandom site selection. We conclude that the results of the meta-analysis should not be considered indicative of an overall improvement in the condition of freshwater ecosystems.FH and GK are supported through the project“Species protection through environmental friendly lighting”funded bythe Federal Agency for Nature Conservation (BfN) within the framework of the Federal Programme for BiologicalDiversity with funds from the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU).AM acknowledges funding through US NSF Macrosystems Biology Program (grant no. 1442595), and SD by the LeibnizCompetition (J45/2018). The authors are grateful to the reviewers and the editor for their comments, which helpedimprove the text. Open access funding enabled and organized by Projekt DEA

    Sicherung von DĂ€mmen, Deichen und Stauanlagen : Handbuch fĂŒr Theorie und Praxis ; Vol. V - 2015

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    Die UniversitĂ€t Siegen beschĂ€ftigt sich seit ĂŒber 15 Jahren wissenschaftlich und im Bereich der anwendungsorientierten Forschung mit diesem Thema und hat dazu mittlerweile fĂŒnf Symposien durchgefĂŒhrt. Mit der Veröffentlichung soll die langjĂ€hrige Tradition als etablierte wissenschaftliche Plattform mit einem Wissensaustausch auf europĂ€ischer Ebene fortgesetzt werden. Die Bearbeitung dieser Thematik erfolgt auf der Basis der bewĂ€hrten Kooperation zwischen Geotechnik und Wasserbau an der UniversitĂ€t Siegen. Aktuelle Ereignisse, wie z.B. die aus England oder Australien im Februar des Jahres 2014, machen uns aber auch deutlich, dass ein absoluter Schutz gegen Extremereignisse nicht möglich ist. Sie zeigen aber auch, dass dort wo technischer Hochwasserschutz konsequent umgesetzt wurde SchĂ€den vermieden werden konnten. Wir sind nach den Ereignissen in den vergangenen Jahren aufgefordert wissenschaftlich noch leistungsfĂ€higere und duktilere Systeme zu entwickeln. Weiter ist die Wissenschaft in der Pflicht, die Zivile Sicherheit im Hochwasser-schutz permanent zu bewerten, zu bearbeiten und ganzheitliche-interdisziplinĂ€re und lĂ€nderĂŒbergreifende Lösungen fĂŒr die Zivilgesellschaft einzufordern

    A global agenda for advancing freshwater biodiversity research

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    Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation

    A global agenda for advancing freshwater biodiversity research

    Get PDF
    Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation.Peer reviewe

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