Melody L. Hoffmann,Bike lanes are white lanes: bicycle advocacy and urban planning     

Amy Lubitow  Dillon Mahmoudi 《Urban geography》2017,38(6):951-952

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Back analysis of the Kanowna Belle stope filling case history     

《Computers and Geotechnics》2016

A fully coupled multi-physics finite element model has been used to conduct a back-analysis of a stope filling case history at the Kanowna Belle (KB) mine in Western Australia. The model captures a number of important characteristics of mine backfill behaviour, including the evolution of strength and consolidation properties with cement hydration, the impact of chemical shrinkage (self-desiccation) and de-saturation. Material parameters for the constitutive model have been calibrated using published laboratory test data. A reasonable match between ideal and actual elements of response as revealed through in-situ measurements of total stress and pore pressure was obtained using these initial parameters. A parametric study was then performed which showed that the backfill strength parameters (friction angle, dilation and cohesion), the chemical volume shrinkage, the rate of cement hydration and the water retention properties all have a significant influence on the calculated states of stress within the stope.  相似文献   

THE ROLE OF ATMOSPHERIC CIRCULATION PATTERNS IN AGROCLIMATE VARIABILITY IN FINLAND, 1961–2011          下载免费PDF全文

MASOUD IRANNEZHAD  DELIANG CHEN  BJØRN KLØVE 《Geografiska Annaler: Series A, Physical Geography》2016,98(4):287-301

This study evaluates interannual variations and trends in growing season daily temperature sum and daily precipitation sum in Finland during 1961–2011, and their connections to well known atmospheric circulation patterns. Changes in summer (June–August) climate partially explain changes in growing season daily temperature sum and daily precipitation sum over Finland, which naturally decreased from south to north. On a national scale, growing season warmed and became wetter during 1961–2011, as growing season daily temperature sum and daily precipitation sum significantly (p < 0.05) increased by 5.01 ± 3.17°C year^–1 and 1.39 ± 0.91 mm year^–1, respectively. The East Atlantic pattern was the most influential atmospheric circulation pattern for variations in growing season daily temperature sum (rho = 0.40) across Finland and the East Atlantic/West Russia pattern was most influential for growing season daily precipitation sum variability (rho = –0.54). There were significant (p < 0.05) increasing trends in growing season daily temperature sum and daily precipitation sum throughout Finland during 1961–2011. Increased growing season daily temperature sum was mainly observed in northern, central, western, eastern and coastal areas of south‐western Finland. This warming was positively associated with the East Atlantic pattern in the north, centre and south, but negatively associated with the East Atlantic/West Russia pattern in eastern Finland. Increased GSP mostly occurred in southern, eastern, western, central, northern and north‐western Finland. These wetting trends were positively correlated with the East Atlantic pattern in the north and negatively correlated with the Polar pattern in the south and the East Atlantic/West Russia pattern in the east, west, centre and north‐east of Finland. The overall agroclimatic year‐to‐year variability in Finland between 1961 and 2011 was mostly linked to variations in the East Atlantic and East Atlantic/West Russia patterns.  相似文献   

The effects of fisheries management on the Icelandic demersal fish value chain     

《Marine Policy》2016

Iceland׳s fishing industry has outperformed fishing industries in neighboring countries in recent years. This paper identifies key factors in market structure in recent decades that contribute to long run profitability of the Icelandic fishing (and fish processing) industry using semi-structured interviews with industry participants, and compares those with similar results from Norway. Further, the development of profitability in the Icelandic and Norwegian demersal fishing industries is used to assess the long run effects of different management systems on quality, product focus and profitability. The results indicate that three key changes in Icelandic regulation during the 1980s were important to the development of long run profitability within the fishing industry: the abolition of export barriers, the introduction of an individual transferable quota (ITQ) system and the establishment of fish auctions. A large and growing literature supports the role of ITQs in ensuring long run profitability. The importance of market structure for profitability has only recently been identified, affecting the ability of value chains to become market oriented and supply homogenous product flow from heterogeneous raw material. Comparison with Norway indicates that while individual transferable quota management does improve profitability in fishing to a certain extent, management systems must facilitate a strong market connection from consumers, through the stages of retail and processing, to fishers for the full realization of profit potential in the fishing industry.  相似文献   

Simplified uncertainties analysis of continuous buried steel pipes on an elastic foundation in the presence of low stiffness zones     

《Computers and Geotechnics》2013

In conventional design, continuous buried steel pipes are designed based on their transverse behavior where low stiffness zones of soil, uncertainties in soil and structure properties are not considered. Winkler’s analytical model and the FOSM method are used to estimate uncertainties in terms of the coefficient of variation in the differential settlement (CV_Δ) and the bending moment (CV_M) as the function of the uncertainties in the subgrade reaction modulus (k_s) and the low stiffness zone length beneath the pipe. Results show that the values of CV_Δ and CV_M are very different depending on the uncertainties of k_s and the length of the low stiffness zone.  相似文献   

Public awareness of marine environmental issues in the UK     

Stephen Fletcher  Jonathan S. Potts  Carolyn Heeps  Kate Pike 《Marine Policy》2009

This paper presents the results of a survey of public awareness of marine environmental issues within the context of the UK's National Maritime Museum. It was found that public interest in marine environmental issues is significant, but that gaps exist in terms of issue-specific awareness and that the availability of independent information on marine issues is limited. It is concluded that there are significant opportunities to develop the Museum's role in raising public awareness of marine environmental issues that build on its current activities and that of the Museum's partners.  相似文献   

High‐resolution monitoring reveals dissolved oxygen dynamics in an Antarctic cryoconite hole     

E. A. Bagshaw  M. Tranter  J. L. Wadham  A. G. Fountain  M. Mowlem 《水文研究》2011,25(18):2868-2877

This study presents the first high‐resolution dataset of dissolved oxygen (DO) measurements in an ice‐lidded cryoconite hole on Canada Glacier, McMurdo Dry Valleys, Antarctica. Fibre optic DO minisensors were installed in a cryoconite hole prior to seasonal internal melting and hydrological connection to the subsurface drainage system. Oxygen air saturation in the cryoconite hole typically ranged from 50 to 80%, in broad agreement with previous single measurements, indicating net respiration (R). This is consistent with results of simple incubation experiments performed in the field. Simultaneous time series for electrical conductivity, water temperature, and DO over the four‐week study period provide information regarding the connectivity of cryoconite holes with the near‐surface drainage system. The main driver of the observed variations in DO is likely to be periodic melt‐freeze cycles. We conclude that automated sensing techniques, such as those described here, when used in conjunction with physical measurements, have great potential for high‐resolution monitoring of the factors that perturb biogeochemical processes in cryospheric surface aquatic ecosystems. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Confidence levels for tsunami-inundation limits in northern Oregon inferred from a 10,000-year history of great earthquakes at the Cascadia subduction zone   总被引：1，自引：1，他引：0  

George R. Priest  Chris Goldfinger  Kelin Wang  Robert C. Witter  Yinglong Zhang  António M. Baptista 《Natural Hazards》2010,54(1):27-73

To explore the local tsunami hazard from the Cascadia subduction zone we (1) evaluate geologically reasonable variability of the earthquake rupture process, (2) specify 25 deterministic earthquake sources, and (3) use resulting vertical coseismic deformations for simulation of tsunami inundation at Cannon Beach, Oregon. Maximum runup was 9–30 m (NAVD88) from earthquakes with slip of ~8–38 m and M _w ~8.3–9.4. Minimum subduction zone slip consistent with three tsunami deposits was 14–15 m. By assigning variable weights to the source scenarios using a logic tree, we derived percentile inundation lines that express the confidence level (percentage) that a Cascadia tsunami will not exceed the line. Ninety-nine percent of Cascadia tsunami variation is covered by runup ≤30 m and 90% ≤16 m with a “preferred” (highest weight) value of ~10 m. A hypothetical maximum-considered distant tsunami had runup of ~11 m, while the historical maximum was ~6.5 m.  相似文献   

Comparative petrology of silicates in the Udei Station (IAB) and Miles (IIE) iron meteorites: Implications for the origin of silicate-bearing irons     

Alex Ruzicka  Melinda Hutson 《Geochimica et cosmochimica acta》2010,74(1):394-433

The textures and mineral chemistries of silicate inclusions in the Udei Station (IAB) and Miles (fractionated IIE) iron meteorites were studied using optical and electron microscopy, SEM, EMPA, and LA-ICP-MS techniques to better understand the origin of silicate-bearing irons. Inclusions in Udei Station include near-chondritic, basaltic/gabbroic, feldspathic orthopyroxenitic, and harzburgitic lithologies. In Miles, most inclusions can be described as feldspathic pyroxenite or pyroxene-enriched basalt/gabbro. The trace-element compositions of both orthopyroxene and plagioclase grains are similar in different lithologies from Udei Station; whereas in different inclusions from Miles, the compositions of orthopyroxene grains are similar, while those of clinopyroxene, plagioclase, and especially Cl-apatite are variable. Orthopyroxene in Miles tends to be enriched in REE compared to that in Udei Station, but the reverse is true for plagioclase and clinopyroxene.The data can be explained by models involving partial melting of chondritic protoliths, silicate melt migration, and redox reactions between silicate and metal components to form phosphate. The extent of heating, melt migration, and phosphate formation were all greater in Miles. Silicates in Miles were formed from liquids produced by ∼30% partial melting of a chondritic precursor brought to a peak temperature of ∼1250 °C. This silicate melt crystallized in two stages. During Stage 1, crystallizing minerals (orthopyroxene, clinopyroxene, chromite, and olivine) were largely in equilibrium with an intercumulus melt that was evolving by igneous fractionation during slow cooling, with a residence time of ∼20 ka at ∼1150 °C. During Stage 2, following probable re-melting of feldspathic materials, and after the silicate “mush” was mixed with molten metal, plagioclase and phosphate fractionally crystallized together during more rapid cooling down to the solidus. In Udei Station, despite a lower peak temperature (<1180 °C) and degree of silicate partial melting (∼3-10%), silicate melt was able to efficiently separate from silicate solid to produce melt residues (harzburgite) and liquids or cumulates (basalt/gabbro, feldspathic orthopyroxenite) prior to final metal emplacement. Olivine was generally out of equilibrium with other minerals, but orthopyroxene and plagioclase largely equilibrated under magmatic conditions, and clinopyroxene in basalt/gabbro crystallized from a more evolved silicate melt.We suggest that a model involving major collisional disruption and mixing of partly molten, endogenically heated planetesimals can best explain the data for IAB and fractionated IIE silicate-bearing irons. The extent of endogenic heating was different (less for the IABs), and the amount of parent body disruption was different (scrambling with collisional unroofing for the IAB/IIICD/winonaite body, more complete destruction for the fractionated IIE body), but both bodies were partly molten and incompletely differentiated at the time of impact. We suggest that the post-impact secondary body for IAB/IIICD/winonaite meteorites was mineralogically zoned with Ni-poor metal in the center, and that the secondary body for fractionated IIE meteorites was a relatively small melt-rich body that had separated from olivine during collisional break-up.  相似文献   

Relations between sinkhole density and anthropogenic contaminants in selected carbonate aquifers in the eastern United States   总被引：2，自引：1，他引：1  

Bruce D. Lindsey  Brian G. Katz  Marian P. Berndt  Ann F. Ardis  Kenneth A. Skach 《Environmental Earth Sciences》2010,60(5):1073-1090

The relation between sinkhole density and water quality was investigated in seven selected carbonate aquifers in the eastern United States. Sinkhole density for these aquifers was grouped into high (>25 sinkholes/100 km²), medium (1–25 sinkholes/100 km²), or low (<1 sinkhole/100 km²) categories using a geographical information system that included four independent databases covering parts of Alabama, Florida, Missouri, Pennsylvania, and Tennessee. Field measurements and concentrations of major ions, nitrate, and selected pesticides in samples from 451 wells and 70 springs were included in the water-quality database. Data were collected as a part of the US Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program. Areas with high and medium sinkhole density had the greatest well depths and depths to water, the lowest concentrations of total dissolved solids and bicarbonate, the highest concentrations of dissolved oxygen, and the lowest partial pressure of CO₂ compared to areas with low sinkhole density. These chemical indicators are consistent conceptually with a conduit-flow-dominated system in areas with a high density of sinkholes and a diffuse-flow-dominated system in areas with a low density of sinkholes. Higher cave density and spring discharge in Pennsylvania also support the concept that the high sinkhole density areas are dominated by conduit-flow systems. Concentrations of nitrate-N were significantly higher (p < 0.05) in areas with high and medium sinkhole density than in low sinkhole-density areas; when accounting for the variations in land use near the sampling sites, the high sinkhole-density area still had higher concentrations of nitrate-N than the low sinkhole-density area. Detection frequencies of atrazine, simazine, metolachlor, prometon, and the atrazine degradate deethylatrazine indicated a pattern similar to nitrate; highest pesticide detections were associated with high sinkhole-density areas. These patterns generally persisted when analyzing the detection frequency by land-use groups, particularly for agricultural land-use areas where pesticide use would be expected to be higher and more uniform areally compared to urban and forested areas. Although areas with agricultural land use and a high sinkhole density were most vulnerable (median nitrate-N concentration was 3.7 mg/L, 11% of samples exceeded 10 mg/L, and had the highest frequencies of pesticide detection), areas with agricultural land use and low sinkhole density still were vulnerable to contamination (median nitrate-N concentration was 1.5 mg/L, 8% of samples exceeded 10 mg/L, and had some of the highest frequencies of detections of pesticides). This may be due in part to incomplete or missing data regarding karst features (such as buried sinkholes, low-permeability material in bottom of sinkholes) that do not show up at the scales used for regional mapping and to inconsistent methods among states in karst feature delineation.  相似文献