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Query: "author" (Michael P. O'Connell) .

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Resolvability and convexity properties in the Sierpiński product of graphs
Michael A. Henning, Sandi Klavžar, Ismael G. Yero, 2024, original scientific article

Abstract: Let $G$ and $H$ be graphs and let $f \colon V(G)\rightarrow V(H)$ be a function. The Sierpiński product of $G$ and $H$ with respect to $f$, denoted by $G \otimes _f H$, is defined as the graph on the vertex set $V(G)\times V(H)$, consisting of $|V(G)|$ copies of $H$; for every edge $gg'$ of $G$ there is an edge between copies $gH$ and $g'H$ of $H$ associated with the vertices $g$ and $g'$ of $G$, respectively, of the form $(g,f(g'))(g',f(g))$. The Sierpiński metric dimension and the upper Sierpiński metric dimension of two graphs are determined. Closed formulas are determined for Sierpiński products of trees, and for Sierpiński products of two cycles where the second factor is a triangle. We also prove that the layers with respect to the second factor in a Sierpiński product graph are convex.
Keywords: Sierpiński product of graphs, metric dimension, trees, convex subgraph
Published in DiRROS: 16.02.2024; Views: 95; Downloads: 41
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Partial domination in supercubic graphs
Csilla Bujtás, Michael A. Henning, Sandi Klavžar, 2024, original scientific article

Abstract: For some $\alpha$ with $0 < \alpha \le 1$, a subset $X$ of vertices in a graph $G$ of order $n$ is an $\alpha$-partial dominating set of $G$ if the set $X$ dominates at least $\alpha \times n$ vertices in $G$. The $\alpha$-partial domination number ${\rm pd}_{\alpha}(G)$ of $G$ is the minimum cardinality of an $\alpha$-partial dominating set of $G$. In this paper partial domination of graphs with minimum degree at least $3$ is studied. It is proved that if $G$ is a graph of order $n$ and with $\delta(G)\ge 3$, then ${\rm pd}_{\frac{7}{8}}(G) \le \frac{1}{3}n$. If in addition $n\ge 60$, then ${\rm pd}_{\frac{9}{10}}(G) \le \frac{1}{3}n$, and if $G$ is a connected cubic graph of order $n\ge 28$, then ${\rm pd}_{\frac{13}{14}}(G) \le \frac{1}{3}n$. Along the way it is shown that there are exactly four connected cubic graphs of order $14$ with domination number $5$.
Keywords: domination, partial domination, cubic graphs, supercubic graphs
Published in DiRROS: 15.02.2024; Views: 94; Downloads: 43
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Citizen science is a vital partnership for invasive alien species management and research
Michael J.O. Pocock, Tim Adriaens, Sandro Bertolino, René Eschen, Franz Essl, Philip E. Hulme, Jonathan M. Jeschke, Helen E. Roy, Heliana Teixeira, Maarten De Groot, 2023, original scientific article

Abstract: Invasive alien species (IAS) adversely impact biodiversity, ecosystem functions and socio-economics. Citizen science can be an effective tool for IAS surveillance, management and research, providing large datasets over wide spatial extents and long time periods, with public participants generating knowledge that supports action. We demonstrate how citizen science has contributed knowledge across the biological invasion process, especially for early detection and distribution mapping. However, we recommend that citizen science could be used more for assessing impacts and evaluating the success of IAS management. Citizen science does have limitations and we explore solutions to two key challenges: ensuring data accuracy and dealing with uneven spatial coverage of potential recorders (which limits the dataset’s ‘fit for purpose’). Greater co-development of citizen science with public stakeholders will help us better realise its potential across the biological invasion process and across ecosystems globally while meeting the needs of participants, local communities, scientists and decision-makers.
Keywords: biosecurity, community science, invasion continuum, invasive alien species, monitoring, volunteers
Published in DiRROS: 25.01.2024; Views: 179; Downloads: 104
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Extending BIM for air quality monitoring
Michael Nicolas Mrissa, Jan Vcelak, László Hajdu, Balázs Dávid, Miklós Ferenz Krész, Jakub Michal Sandak, Anna Malgorzata Sandak, Rok Kanduti, Monika Varkonji, Anja Jutraž, Katja Malovrh Rebec, 2020, published scientific conference contribution

Abstract: As we spend more than 90% of our time inside buildings, indoor environmental quality is a major concern for healthy living. Recent studies show that almost 80% of people in European countries and the United States suffer from SBS (Sick Building Syndrome), which affects physical health, productivity and psychological well-being. In this context, environmental quality monitoring provides stakeholders with crucial information about indoor living conditions, thus facilitating building management along its lifecycle, from design, construction and commissioning to usage, maintenance and end-of-life. However, currently available modelling tools for building management remain limited to static models and lack integration capacities to efficiently exploit environmental quality monitoring data. In order to overcome these limitations, we designed and implemented a generic software architecture that relies on accessible Building Information Model (BIM) attributes to add a dynamic layer that integrates environmental quality data coming from deployed sensors. Merging sensor data with BIM allows creation of a digital twin for the monitored building where live information about environmental quality enables evaluation through numerical simulation. Our solution allows accessing and displaying live sensor data, thus providing advanced functionality to the end-user and other systems in the building. In order to preserve genericity and separation of concerns, our solution stores sensor data in a separate database available through an application programming interface (API), which decouples BIM models from sensor data. Our proof-of-concept experiments were conducted with a cultural heritage building located in Bled, Slovenia. We demonstrated that it is possible to display live information regarding environmental quality (temperature, relative humidity, CO2, particle matter, light) using Revit as an example, thus enabling end-users to follow the conditions of their living environment and take appropriate measures to improve its quality
Keywords: Building Information Model, internet of things, environmental quality monitoring, healthy living
Published in DiRROS: 19.01.2024; Views: 154; Downloads: 70
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Fire safety assessment of sprinkler systems for car parks using the J-value methodology
Malika Alimzhanova, Michael Spearpoint, Grunde Jomaas, 2022, original scientific article

Abstract: A J-value assessment was carried out to quantify the costs and benefits of sprinkler system installation in car parks, both with respect to life safety and property protection. Nine scenarios were established based on collected input data. All car park types were considered for the USA, England, Scotland, Wales and the UK nations collectively, while separate considerations were made for multi-storey car parks (MSCPs) in the UK and for MSCPs, underground and other parking types in England. Even when assuming 100% sprinkler effectiveness, the J-values for the nine scenarios were all larger than unity (ranging from 5 to 555), thus indicating that the installation of sprinklers is not a cost-effective investment for car parks from a societal point of view. The analysis showed that different car park types must be treated separately, due to specifics of structure and fire statistics. The lowest J-values were obtained for MSCPs and underground car parks. Sprinkler installation mainly provides property protection benefits, because of property loss savings substantially outweigh those associated with life safety. Even though sprinklers were not cost-effective for car parks in the current analysis, the scarcity of data and new emerging technologies suggests that further investigation is needed.
Keywords: cost-benefit analysis, J-value, life quality index, Car parks, Sprinkler systems
Published in DiRROS: 09.01.2024; Views: 143; Downloads: 40
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