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  • 1
    Publication Date: 2016-08-05
    Description: The force-directed paradigm is one of the few generic approaches to drawing graphs. Since force-directed algorithms can be extended easily, they are used frequently. Most of these algorithms are, however, quite slow on large graphs, as they compute a quadratic number of forces in each iteration. We give a new algorithm that takes only O ( m + n log n ) time per iteration when laying out a graph with n vertices and m edges. Our algorithm approximates the true forces using the so-called well-separated pair decomposition. We perform experiments on a large number of graphs and show that we can strongly reduce the runtime, even on graphs with less than a hundred vertices, without a significant influence on the quality of the drawings (in terms of the number of crossings and deviation in edge lengths).
    Electronic ISSN: 1999-4893
    Topics: Computer Science
    Published by MDPI Publishing
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  • 2
    Publication Date: 2018
    Description: Summary Proponents of material recycling typically point to two environmental benefits: disposal (landfill/incinerator) reduction and primary production displacement. However, in this paper we mathematically demonstrate that, without displacement, recycling can delay but not prevent any existing end‐of‐life material from reaching final disposal. The only way to reduce the amount of material ultimately landfilled or incinerated is to produce less in the first place; material that is not made needs not be disposed. Recycling has the potential to reduce the amount of material reaching end of life solely by reducing primary production. Therefore, the “dual benefits” of recycling are in fact one, and the environmental benefit of material recycling rests in its potential to displace primary production. However, displacement of primary production from increased recycling is driven by market forces and is not guaranteed. Improperly assuming all recycled material avoids disposal underestimates the environmental impacts of the product system. We show that the potential magnitude of this error is substantial, though for inert recyclables it is lower than the error introduced by improperly assuming all recycled material displaces primary material production. We argue that life cycle assessment end‐of‐life models need to be updated so as not to overstate the benefits of recycling. Furthermore, scholars and policy makers should focus on finding and implementing ways to increase the displacement potential of recyclable materials rather than focusing on disposal diversion targets.
    Print ISSN: 1088-1980
    Electronic ISSN: 1530-9290
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Wiley
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  • 3
    Publication Date: 2016-04-21
    Description: Regional data needed for effective stream restoration include hydraulic geometry relationships (i.e., regional curves) and reference channel morphology parameters. Increasingly ecological conditions are being considered when designing, implementing, and assessing restoration efforts. We provide morphology relationships and associated ecological endpoint curves for reference streams in the Alabama piedmont. Twenty-one reference stream reaches were identified in the Tallapoosa drainage of Alabama, ranging from 0.2 to 242 km2 drainage area. Geomorphic surveys were conducted in each stream to measure riffle cross-sections and longitudinal profiles and related to drainage area to develop regional curves. Fish, crayfish, and benthic macroinvertebrates were collected from each surveyed reach and related to drainage area and geomorphic data to provide associated biological community endpoints. Bankfull channel cross-section area, width, mean depth, and estimated discharge were strongly correlated to watershed drainage area, similar to efforts in other areas of the Piedmont ecoregion. Multiple measures of fish assemblages and crayfish size were strongly predicted by drainage area and geomorphic dimensions. Macroinvertebrates showed no taxonomic and limited functional relationships with drainage area and geomorphic dimension. These tools, which integrate geomorphological and ecological conditions, can result in improved stream evaluations and designs increasing the effectiveness of stream restoration projects.
    Electronic ISSN: 2073-4441
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI Publishing
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  • 4
    Publication Date: 2016-10-28
    Description: ABSTRACT Branched glycerol dialkyl glycerol tetraethers (brGDGTs) were abundant in surface sediments of freshwater lakes and in catchment soils at altitudes from 10 to 2020 m in New Zealand. Significant differences in brGDGT compositions between lake sediments and soils indicate sources from separate microbial habitats. An expanded modern calibration dataset comprising 33 lakes has enabled a revised calibration function for determining past m ean a nnual air t emperature (MAT) from brGDGTs in New Zealand lake sediments: MAT (°C) = −31.664 × MBT m  + 16.252 ( n  = 30). The function uses a modified methylation index of branched tetraethers (MBT m ) that incorporates brGDGT III in the numerator to overcome the lower correlation found between our larger dataset and the unmodified MBT which had been used for previous calibrations. Calibrations combining the cyclization index of branched tetraethers (CBT) and the MBT m or using only certain brGDGTs are possible but have limitations. The revised function shows slightly higher correlation with MAT ( R 2  = 0.75) than previous calibrations, which were based on nine sites. The refined calibration function is applied to a ∼16 000-year lake sediment sequence from northern South Island, New Zealand, and yields temperature reconstructions that are consistent with independently derived climate trends from the same sequence.
    Print ISSN: 0267-8179
    Electronic ISSN: 1099-1417
    Topics: Geography , Geosciences
    Published by Wiley
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  • 5
    Publication Date: 2017-10-14
    Print ISSN: 1088-1980
    Electronic ISSN: 1530-9290
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Wiley
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  • 6
    Publication Date: 2018-05-16
    Description: Remote Sensing, Vol. 10, Pages 754: Radiometric Performance of the TerraSAR-X Mission over More Than Ten Years of Operation Remote Sensing doi: 10.3390/rs10050754 Authors: Marco Schwerdt Kersten Schmidt Patrick Klenk Núria Tous Ramon Daniel Rudolf Sebastian Raab Klaus Weidenhaupt Jens Reimann Manfred Zink The TerraSAR-X mission, based on two satellites, has produced SAR data products of high quality for a number of scientific and commercial applications for more than ten years. To guarantee the stability and the reliability of these highly accurate SAR data products, both systems were first accurately calibrated during their respective commissioning phases and have been permanently monitored since then. Based on a short description of the methods applied, this paper focuses on the radiometric performance including the gain and phase properties of the transmit/receiver modules, the antenna pattern checked by evaluating scenes acquired over uniformly distributed targets and the radiometric stability derived from permanently deployed point targets. The outcome demonstrates the remarkable performance of both systems since their respective launch.
    Electronic ISSN: 2072-4292
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by MDPI Publishing
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  • 7
    Publication Date: 2017-05-24
    Description: Sentinel-1B is the second of two C-Band Synthetic Aperture Radar (SAR) satellites of the Sentinel-1 mission, launched in April 2016—two years after the launch of the first satellite, Sentinel-1A. In addition to the commissioning of Sentinel-1B executed by the European Space Agency (ESA), an independent system calibration was performed by the German Aerospace Center (DLR) on behalf of ESA. Based on an efficient calibration strategy and the different calibration procedures already developed and applied for Sentinel-1A, extensive measurement campaigns were executed by initializing and aligning DLR’s reference targets deployed on the ground. This paper describes the different activities performed by DLR during the Sentinel-1B commissioning phase and presents the results derived from the analysis and the evaluation of a multitude of data takes and measurements.
    Electronic ISSN: 2072-4292
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by MDPI Publishing
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  • 8
    Publication Date: 2017-04-29
    Description: Global human population growth is associated with many problems, such as food and water provision, political conflicts, spread of diseases and environmental destruction. The mitigation of these problems is mirrored in several global conventions and programs, some of which however are conflicting. Here we discuss the conflicts between biodiversity conservation and disease eradication. Numerous health programs aim at eradicating pathogens, and many focus on the eradication of vectors, such as mosquitos or other parasites. As a case study, we focus on the ‘Pan African Tsetse and Trypanosomiasis Eradication Campaign’ (PATTEC), which aims at eradicating a pathogen ( Trypanosoma ) as well as its vector, the entire group of tsetse flies (Glossinidae). As the distribution of tsetse flies largely overlaps with the African hotspots of freshwater biodiversity, we argue for a strong consideration of environmental issues when applying vector control measures, especially the aerial applications of insecticides. Furthermore, we want to stimulate discussions on the value of species and whether full eradication of a pathogen or vector is justified at all. Finally, we call for a stronger harmonization of international conventions. Proper environmental impact assessments need to be conducted before control or eradication programmes are carried out to minimize negative effects on biodiversity. This article is protected by copyright. All rights reserved
    Print ISSN: 1755-263X
    Electronic ISSN: 1755-263X
    Topics: Biology
    Published by Wiley on behalf of The Society for Conservation Biology.
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  • 9
    Publication Date: 2017-02-06
    Description: The so-called circular economy—the concept of closing material loops to preserve products, parts, and materials in the industrial system and extract their maximum utility—has recently started gaining momentum. The idea of substituting lower-impact secondary production for environmentally intensive primary production gives the circular economy a strong intuitive environmental appeal. However, proponents of the circular economy have tended to look at the world purely as an engineering system and have overlooked the economic part of the circular economy . Recent research has started to question the core of the circular economy—namely, whether closing material and product loops does, in fact, prevent primary production. In this article, we argue that circular economy activities can increase overall production, which can partially or fully offset their benefits. Because there is a strong parallel in this respect to energy efficiency rebound, we have termed this effect “circular economy rebound.” Circular economy rebound occurs when circular economy activities, which have lower per-unit-production impacts, also cause increased levels of production, reducing their benefit. We describe the mechanisms that cause circular economy rebound, which include the limited ability of secondary products to substitute for primary products, and price effects. We then offer some potential strategies for avoiding circular economy rebound. However, these strategies are unlikely to be attractive to for-profit firms, so we caution that simply encouraging private firms to find profitable opportunities in the circular economy is likely to cause rebound and lower or eliminate the potential environmental benefits.
    Print ISSN: 1088-1980
    Electronic ISSN: 1530-9290
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Wiley
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  • 10
    Publication Date: 2018-09-18
    Description: Materials, Vol. 11, Pages 1745: Layer by Layer Mesoporous Silica-Hyaluronic Acid-Cyclodextrin Bifunctional “Lamination”: Study of the Application of Fluorescent Probe and Host–Guest Interactions in the Drug Delivery Field Materials doi: 10.3390/ma11091745 Authors: Kun Nie Qi An Jeffrey I. Zink Xiang Yu Yihe Zhang The layer-by-layer technique was exploited to adjust the magnitude of the host–guest interactions between adamantane and cyclodextrin. The effect depends on numerous complex and changeable growth profiles of the films and the number of bilayers. These composite films of mesoporous silica nanoparticles and hyaluronic acid–cyclodextrin(HA-CD) were constructed to load the fluorescent dyes and peptides. The release rates of these molecules would decrease with an increase in the number of layers. A laser scanning confocal microscope was utilized to obtain the diffusion coefficient of fluorescein isothiocyanate. Hybrid films could be applied to increase the loading of different kinds of molecules and could also be integrated into the lamination to delay the rate of release.
    Electronic ISSN: 1996-1944
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by MDPI Publishing
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