28,198 research outputs found

    Smart green infrastructure in a smart city – the case study of ecosystem services evaluation in Krakow based on i-Tree Evo software

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    It is a common perception that urban greenery does not bring any rational benefits, while profits from real estates are obvious. Therefore, the cities green infrastructure (urban forests, parks, trees, lawns, meadows, etc.) are constantly threatened with housing and development. However, urban greenery plays a substantial role in improving the quality of urbanites’ life, which is particularly significant in terms of predicted 70% urbanization rate by 2050. Healthy and well managed city green infrastructure can improve air quality, remove particulate matters (PM) and CO2 sequestrate carbon, cool down temperature or protect against winds. These functions of vegetation are known as ecosystem services (ES). Recognizing the value of ES provided by green infrastructure is crucial for urban planning and management in terms of assuring sustainable urban development. In our study we used the i-Tree Eco (USDA Forest Service) software, which quantifies vegetation structure, environmental effects and values of ES. The i-Tree Eco model is based on air pollution and local meteorological data along with the field data from inventory of city vegetation. Requiring easy to collect (e.g. based on LiDAR 3D point clouds) input data and having user-friendly interface, the i-Tree Eco has a potential of becoming a very useful tool for planners and managers in their everyday work. In this paper we present a case study of ES evaluation for the “Krakowski Park” in Krakow (582 trees on 4.77 hectares, with domination of Fraxinus excelsior, Ulmus laevis and Betula pendula). For the analysed 2015 year, the Krakowski Park trees stored in total 441.59 t of carbon, removed 184 kg of air pollutants and contributed to 220 m3 of avoided runoff. Total value of ecosystem services provided by the Krakowski Park in year 2015 was EUR 5.096 (EUR 8.76 tree/year). In our further work we intend to expand the ES evaluation on other green areas in Krakow and on a wider range of ES

    The Different Structures of the Two Classes of Starless Cores

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    We describe a model for the thermal and dynamical equilibrium of starless cores that includes the radiative transfer of the gas and dust and simple CO chemistry. The model shows that the structure and behavior of the cores is significantly different depending on whether the central density is either above or below about 10^5 cm-3. This density is significant as the critical density for gas cooling by gas-dust collisions and also as the critical density for dynamical stability, given the typical properties of the starless cores. The starless cores thus divide into two classes that we refer to as thermally super-critical and thermally sub-critical.This two-class distinction allows an improved interpretation of the different observational data of starless cores within a single model.Comment: ApJ in pres

    Evaluation of Docker Containers for Scientific Workloads in the Cloud

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    The HPC community is actively researching and evaluating tools to support execution of scientific applications in cloud-based environments. Among the various technologies, containers have recently gained importance as they have significantly better performance compared to full-scale virtualization, support for microservices and DevOps, and work seamlessly with workflow and orchestration tools. Docker is currently the leader in containerization technology because it offers low overhead, flexibility, portability of applications, and reproducibility. Singularity is another container solution that is of interest as it is designed specifically for scientific applications. It is important to conduct performance and feature analysis of the container technologies to understand their applicability for each application and target execution environment. This paper presents a (1) performance evaluation of Docker and Singularity on bare metal nodes in the Chameleon cloud (2) mechanism by which Docker containers can be mapped with InfiniBand hardware with RDMA communication and (3) analysis of mapping elements of parallel workloads to the containers for optimal resource management with container-ready orchestration tools. Our experiments are targeted toward application developers so that they can make informed decisions on choosing the container technologies and approaches that are suitable for their HPC workloads on cloud infrastructure. Our performance analysis shows that scientific workloads for both Docker and Singularity based containers can achieve near-native performance. Singularity is designed specifically for HPC workloads. However, Docker still has advantages over Singularity for use in clouds as it provides overlay networking and an intuitive way to run MPI applications with one container per rank for fine-grained resources allocation

    The promise of recent and future observatories and instruments

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    The identification of the carrier(s) of diffuse interstellar bands (DIBs) is one of the oldest mysteries in stellar spectroscopy. With the advent of 8-10m-class telescopes substantial progress has been made in measuring the properties of DIBs in the optical and near-infrared wavelength domain, not only in the Galaxy, but also in different environments encountered in Local Group galaxies and beyond. Still, the DIB carriers have remained unidentified. The coming decade will witness the development of extremely large telescopes (GMT, TMT and E-ELT) and their instrumentation. In this overview I will highlight the current instrumentation plan of these future observatories, emphasizing their potential role in solving the enigma of the DIBs.Comment: Talk presented at IAU Symposium 297 "The Diffuse Interstellar Bands", CUP proceedings editors: Jan Cami and Nick Co

    Reading in the 21st century; reading at scale

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    Essay from a festshrift that was originally published in: Reading for faith and learning : essays on scripture, community, and libraries in honor of M. Patrick Graham / edited by John B. Weaver and Douglas L. Gragg. Abilene : Abilene Christian University Press, 2017

    Status of the TMT site evaluation process

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    The Thirty Meter Telescope (TMT) is currently acquiring site characterization data at ve candidate sites. The site testing equipment includes instruments for measuring the seeing and seeing proles, meteorological conditions, cloudiness, precipitable water vapor, etc. All site testing equipment and data have gone through extensive calibrations and verications in order to assure that a reliable and quantitative comparison between the candidate sites will be possible. Here, we present an update on the status of the site selection work, the equipment characterizations and the resulting accuracies of our site selection data

    Private Governance Responses to Climate Change: The Case of Global Civil Aviation

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    This Article explores how private governance can reduce the climate effects of global civil aviation. The civil aviation sector is a major contributor to climate change, accounting for emissions comparable to a top ten emitting country. National and international governmental bodies have taken important steps to address civil aviation, but the measures adopted to date are widely acknowledged to be inadequate. Civil aviation poses particularly difficult challenges for government climate mitigation efforts. Many civil aviation firms operate globally, emissions often occur outside of national boundaries, nations differ on their respective responsibilities, and demand is growing rapidly. Although promising new technologies are emerging, they will take time to develop and adopt. This Article argues that private initiatives can overcome many of these barriers. Private initiatives can motivate civil aviation firms to act absent government pressure at the national level and can create pressure for mitigation that transcends national boundaries. The Article argues that it is time to develop a private climate governance agenda for civil aviation and identifies examples of the types of existing and new initiatives that could be included in the effort. If public and private policymakers can overcome the tendency to focus almost exclusively on public governance, private initiatives can yield large and prompt emissions reductions from global civil aviation, buy time for more comprehensive government measures, and complement the government measures when they occur

    COVID-19 and the climate-energy nexus

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    Analysing the COVID-19 pandemic’s impact on the climate-energy nexus, raises three important questions. First, what does this global health and economic crisis mean for the future of fossil fuels, particularly oil? Because of the drop in economic activity, greenhouse gas emissions have plummeted, but how can we ensure a structural decline that is aligned with the Paris Agreement? Third, how can we embed the ideas of a “just transition” within the broader post-pandemic “green recovery”? This policy brief offers a glimpse of the direction away from fossil fuels that our global energy system must take to govern the post-pandemic worl
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