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  • 1
    Electronic Resource
    Electronic Resource
    Minimization of load reduction in pipe networks subject to interrupted supply (1975)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 9 (1975), S. 477-483 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper considers the question of reduction of loads on a pipe network, which may be necessary as a result of failure in supply or interruption of a pipe. The non-linear relationship between pressure loss and flow along a pipe makes the problem of minimizing the reduction of loads also non-linear. An iterative linear approximation technique is therefore adopted. When the question is formulated as a problem in linear programming, the constraints include nodal pressures as well as loads. It is shown how the number of these constraints may be reduced.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620090214
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  • 2
    Electronic Resource
    Electronic Resource
    Security assessment of gas networks (1977)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 11 (1977), S. 963-973 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A measure of the severity of a pipeline failure is the minimum reduction in load in the network necessary to ensure that no node falls below its minimum pressure. The expected loss of sales is calculated as the product of the minimum reduction in load and the expected duration of the period during which the pipeline will be in the inoperable state, and thus reflects both the severity and the frequency of the failure. Consequently, this index, whose evaluation involves network theory, optimization and probability theory, serves as a measure of the insecurity of the gas network.The security index can be evaluated for all points within a system, providing a basis of comparison between the relative vulnerability of different parts. The relative level of security of different design proposals can also be assessed using this index.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620110605
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of ions in aqueous media on hydroxyapatite induction by silica gel and its relevance to bioactivity of bioactive glasses and glass-ceramics (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 4 (1993), S. 221-229 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Hydroxyapatite induction by a synthesized pure silica hydrogel was examined in various simulated body fluids (SBFs) having different magnesium, calcium, and phosphate ion concentrations as well as pH values. The silica hydrogel generated biologically active apatite on its surface by taking up calcium and phosphorous ionic groups from a surrounding SBF that was prepared to emulate the human plasma in inorganic composition. The induction period for apatite nucleation on the surface of the silica was largely decreased with the addition of a small amount of the calcium or phosphate ions to the SBF and with an increase in pH, but increased with the addition of magnesium ion. Bioactivity of bioactive materials like Bioglass® and glass-ceramic A-W was well interpreted in terms of the rate of apatite formation reflected in these results. Moreover, the results provide the basic knowledge for designing new bioactive materials. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770040303
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  • 4
    Electronic Resource
    Electronic Resource
    The bone-bonding polymer Polyactive® 80/20 induces hydroxycarbonate apatite formation in vitro (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 34 (1997), S. 79-86 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The bone-bonding polymer known as Polyactive® is a block copolymer composed of a polyethylene oxide (PEO) soft segment and a polybutylene terephthalate (PBT) hard segment. This study focuses on the in vitro induction of hydroxyapatite by Polyactive®. Our results show that Polyactive® is capable of inducing hydroxycarbonate apatite (HCAp) formation from a metastable calcium phosphate solution analogous to a physiological solution. In a 4-day incubation, the HCAp formation extended approximately 100 μm deep from the surface. A great number of globules about 1 μm large were found in the calcified Polyactive®. These globules were composed of HCAp crystals embedded in the polymer matrix. There were so many globules in the surface that they connected with each other and formed a calcified layer. Next to the calcified layer was a zone where the globules were scattered. The calcified surface may have acted to promote HCAp growth from the solution, bringing about the formation of a HCAp layer on top of the calcified layer. The transition of solid Polyactive® into a Polyactive® hydro-gel in calcium phosphate solution permitted HCAp formation within the polymer. It is proposed that the COOH groups produced during hydrolysis of Polyactive® play an important role in nucleating hydroxyapatite. A remarkable affinity of the PEO segment of the polymer for calcium ions may facilitate moving calcium and phosphate from the solution into the polymer for the growth of HCAp. © 1997 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 5
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    Spatial distribution of mercury deposition fluxes in Wanshan Hg mining area, Guizhou province, China (2012)
    Copernicus
    Details
    Publication Date: 2012-07-18
    Description: The legacy of long-term mining activities in Wanshan mercury (Hg) mining area (WMMA), Guizhou, China including a series of environmental issues related to Hg pollution. The spatial distribution of gaseous elemental mercury (Hg0) concentrations in ambient air were monitored using a mobile RA-915+ Zeeman Mercury Analyzer during daytime and night time in May 2010. The data imply that calcines and mine wastes piles located at Dashuixi and on-going artisanal Hg mining activities at Supeng were major sources of atmospheric mercury in WMMA. For a full year (May 2010 to May 2011), sampling of precipitation and throughfall were conducted on a weekly basis at three sites (Shenchong, Dashuixi, and Supeng) within WMMA. Hg in deposition was characterized by analysis of total Hg (THg) and dissolved Hg (DHg) concentrations. The corresponding data exhibit a high degree of variability, both temporarily and spatially. The volume-weighted mean THg concentrations in precipitation and throughfall samples were 502.6 ng l−1 and 977.8 ng l−1 at Shenchong, 814.1 ng l−1and 3392.1 ng l−1 at Dashuixi, 7490.1 ng l−1and 9641.5 ng l−1 at Supeng, respectively. THg was enhanced in throughfall compared to wet deposition samples by up to a factor of 7. The annual wet Hg deposition fluxes were 29.1, 68.8 and 593.1 μg m−2 yr−1 at Shenchong, Dashuixi and Supeng, respectively, while the annual dry Hg deposition fluxes were estimated to be 378.9, 2613.6 and 6178 μg m−2 yr−1 at these sites, respectively. Dry deposition played a dominant role in total atmospheric Hg deposition in WMMA since the dry deposition fluxes were 10.4–37.9 times higher than the wet deposition fluxes during the whole sample period. Our data showed that air deposition was still an important pathway of Hg contamination to the local environment in WMMA.
    Print ISSN: 1680-7316
    Electronic ISSN: 1680-7324
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 6
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    A study on the aerosol extinction-to-backscatter ratio with combination of micro-pulse LIDAR and MODIS over Hong Kong (2006)
    Copernicus
    Details
    Publication Date: 2006-08-07
    Description: The aerosol extinction-to-backscatter ratio is an important parameter for inverting LIDAR signals in the LIDAR equation. It is a complicated function of the aerosol microphysical characteristics. In this paper, a method to retrieve the column-averaged aerosol extinction-to-backscatter ratio by constraining the aerosol optical depths (AOD) from a Micro-pulse LIDAR (MPL) by the AOD measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) is presented. Both measurements were taken on cloud free days between 1 May 2003 and 30 June 2004 over Hong Kong, a coastal city in south China. Simultaneous measurements of aerosol scattering coefficients with a forward scattering visibility sensor are compared with the LIDAR retrieval of aerosol extinction coefficients. The data are then analyzed to determine seasonal trends of the aetrosol extinction-to-backscatter ratio. In addition, the relationships between the extinction-to-backscatter ratio and wind conditions as well as other aerosol microphysical parameters are presented. The mean aerosol extinction-to-backscatter ratio for the whole period was found to be 29.1±5.8 sr, with a minimum of 18 sr in July 2003 and a maximum of 44 sr in March 2004. The ratio is lower in summer because of the dominance of oceanic aerosols in association with the prevailing southwesterly monsoon. In contrast, relatively larger ratios are noted in spring and winter because of the increased impact of local and regional industrial pollutants associated with the northerly monsoon. The extended LIDAR measurements over Hong Kong provide not only a more accurate retrieval of aerosol extinction coefficient profiles, but also significant substantial information for air pollution and climate studies in the region.
    Print ISSN: 1680-7316
    Electronic ISSN: 1680-7324
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 7
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    Emissions of air-borne mercury from five municipal solid waste landfills in Guiyang and Wuhan, China (2010)
    Copernicus
    Details
    Publication Date: 2010-04-09
    Description: China disposes of bulk Municipal Solid Waste (MSW) by landfilling, resulting in a large quantity of mercury that enters landfills through waste. A detailed study on atmospheric mercury emissions from MSW landfills in China is necessary to understand mercury behavior from this source. Between 2003 and 2006, mercury airborne emissions through different pathways, as well as mercury speciation in Landfill Gas (LFG) were measured at 5 MSW landfills in Guiyang and Wuhan, China. The results showed that mercury content in the substrate increased the magnitude of mercury emissions, with the highest emission rate measured at the working face and in uncovered waste areas, and the lowest measured near soil covers and vegetated areas. Meteorological parameters, especially solar radiation, influenced the diurnal pattern of mercury surface-air emissions. Total Gaseous Mercury (TGM) in LFG varied from 2.0 to 1406.0 ng m−3, Monomethyl Mercury (MMHg) and Dimethyl Mercury (DMHg) in LFG averaged at 1.93 and 9.21 ng m−3, and accounted for 0.51% and 1.79% of the TGM in the LFG, respectively. Total mercury emitted from the five landfills ranged from 17 to 3300 g yr−1, with the highest from the working face, then soil covering, and finally the vent pipes.
    Print ISSN: 1680-7316
    Electronic ISSN: 1680-7324
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 8
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    In-situ measurements of atmospheric hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) at the Shangdianzi regional background station, China (2012)
    Copernicus
    Details
    Publication Date: 2012-11-05
    Description: Atmospheric hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) were measured in-situ at the Shangdianzi (SDZ) Global Atmosphere Watch (GAW) regional background station, China, from May 2010 to May 2011. The time series for five HFCs and three PFCs showed occasionally high-concentration events while background conditions occurred for 36% (HFC-32) to 83% (PFC-218) of all measurements. The mean mixing ratios during background conditions were 24.5 ppt (parts per trillion, 10−12, molar) for HFC-23, 5.86 ppt for HFC-32, 9.97 ppt for HFC-125, 66.0 ppt for HFC-134a, 9.77 ppt for HFC-152a, 79.1 ppt for CF4, 4.22 ppt for PFC-116, and 0.56 ppt for PFC-218. The background mixing ratios for the compounds at SDZ are consistent with those obtained at mid to high latitude sites in the Northern Hemisphere. North-easterly winds were associated with negative contributions to atmospheric HFC and PFC loadings (mixing ratio anomalies weighted by time associated with winds in a given sector), whereas south-westerly advection (urban sector) showed positive loadings. Chinese emissions estimated by a tracer ratio method using carbon monoxide as tracer were 3.6 ± 3.2 kt yr−1 for HFC-23, 4.3 ± 3.6 kt yr−1 for HFC-32, 2.7 ± 2.3 kt yr−1 for HFC-125, 6.0 ± 5.6 kt yr−1 for HFC-134a, 2.0 ± 1.8 kt yr−1 for HFC-152a, 2.4 ± 2.1 kt yr−1 for CF4, 0.27 ± 0.26 kt yr−1 for PFC-116, and 0.061 ± 0.095 kt yr−1 for PFC-218. The lower HFC-23 emissions compared to earlier studies may be a result of the HFC-23 abatement measures taken as part of Clean Development Mechanism (CDM) projects that started in 2005.
    Print ISSN: 1680-7316
    Electronic ISSN: 1680-7324
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 9
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    In-situ measurements of atmospheric hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) at the Shangdianzi regional background station, China (2012)
    Copernicus
    Details
    Publication Date: 2012-05-02
    Description: In-situ measurements of atmospheric hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) have been conducted at the Shangdianzi (SDZ) Global Atmosphere Watch (GAW) regional background station, China, from May 2010 to May 2011. The time series for 5 HFCs and 4 PFCs periodically showed high concentration events while background conditions occurred for 36% (HFC-32) to 83% (PFC-218) of all measurements. The mean mixing ratios during background conditions for HFC-23, HFC-32, HFC-125, HFC-134a, HFC-152, CF4, PFC-116, PFC-218 and PFC-318 were 24.5, 5.86, 9.97, 66.0, 9.77, 79.1, 4.22, 0.56, 1.28 ppt (parts per trillion, 10−12, molar), respectively. The background mixing ratios for the compounds at SDZ are consistent with those obtained at mid to high latitude sites in the Northern Hemisphere, except for HFC-32 and PFC-318 for which background mixing ratios were not reported in recent years. All HFCs and PFCs show positive trends at rates of 0.7, 1.4, 1.6, 4.1, 1.1, 0.43, 0.05, 0.01, 0.04 ppt yr−1 for HFC-23, HFC-32, HFC-125, HFC-134a, HFC-152, CF4, PFC-116, PFC-218 and PFC-318, respectively. North-easterly winds were connected with small contributions to atmospheric HFCs and PFCs loadings, whereas south-westerly advection (urban sector) showed increased loadings. Chinese emissions were estimated by a tracer ratio method using CO as tracer with rather well known emissions. The emissions, as derived from our measurement period, were 4.4 ± 0.7, 6.9 ± 0.9, 2.5 ± 0.3, 9.0 ± 1.3, 2.2 ± 0.4, 2.1 ± 0.3, 0.24 ± 0.06, 0.07 ± 0.04, 0.45 ± 0.09 kt yr−1 for HFC-23, HFC-32, HFC-125, HFC-134a, HFC-152, CF4, PFC-116, PFC-218, and PFC-318, respectively. The lower HFC-23 emissions compared to earlier studies may be a result of the HFC-23 abatement measures taken as part of the Clean Development Mechanism (CDM) project that started in 2005.
    Electronic ISSN: 1680-7375
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 10
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    The relative contributions of forest growth and areal expansion to forest biomass carbon sinks in China (2015)
    Copernicus
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    Publication Date: 2015-06-30
    Description: Forests play a leading role in regional and global terrestrial carbon (C) cycles. Changes in C sequestration within forests can be attributed to areal expansion (increase in forest area) and forest growth (increase in biomass density). Detailed assessment of the relative contributions of areal expansion and forest growth to C sinks is crucial to reveal the mechanisms that control forest C sinks and is helpful for developing sustainable forest management policies in the face of climate change. Using the Forest Identity concept and forest inventory data, this study quantified the spatial and temporal changes in the relative contributions of forest areal expansion and increased biomass growth to China's forest C sinks from 1977 to 2008. Over the last 30 years, the areal expansion of forests was a larger contributor to C sinks than forest growth for all forests and planted forests in China (74.6 vs. 25.4 % for all forests, and 62.4 vs. 37.8 % for plantations). However, for natural forests, forest growth made a larger contribution than areal expansion (60.4 vs. 39.6 %). The relative contribution of forest growth of planted forests showed an increasing trend from an initial 25.3 to 61.0 % in the later period of 1998 to 2003, but for natural forests, the relative contributions were variable without clear trends owing to the drastic changes in forest area and biomass density over the last 30 years. Our findings suggest that afforestation can continue to increase the C sink of China's forests in the future subject to persistently-increasing forest growth after establishment of plantation.
    Print ISSN: 1810-6277
    Electronic ISSN: 1810-6285
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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