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81.
Despite a significant period of strong economic and jobs growth nationally, there is well-established evidence in Australia that the proceeds of this growth have not been shared equally, either between places or between individuals. Empirically, it is well known that particular socioeconomic groups have a higher risk of unemployment and it has become equally well established that there are particular geographic patterns of labour market disadvantage that suggest that local geographic context is also important. What is not well understood are the ways in which phenomena at the geographic level are associated with individual-level characteristics and other social contexts in ways that negatively impact on a range of social outcomes, including unemployment. The present paper specifically addresses this issue by using a multi-scalar approach and using survey data from the Housing, Income and Labour Force Dynamics Australia (HILDA) survey and aggregate level census data to model unemployment risk. The paper argues that to better understand unemployment and to add to sound policy development, approaches that incorporate a variety of contexts, including the impact of local geographies, are important. 相似文献
82.
Xinya Li Bill X. Hu Juxiu Tong 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(6):1741-1755
There are many factors affecting submarine groundwater discharge (SGD). However, systematic study of the influences of these factors is still limited. In this study, numerical modeling is performed to quantitatively explore the influences of various factors on SGD in a coastal aquifer. In such locations, tidal and terrestrial hydraulic gradients are the primary forces driving fresh and salt water movement. Unlike steady-state flow, dynamic fresh and salt water mixing at the near-shore seafloor may form an intertidal mixing zone (IMZ) near the surface. By constructing a general SGD model, the effects of various model components such as boundary conditions, model geometry and hydraulic parameters are systematically studied. Several important findings are obtained from the study results: (1) Previous studies have indicated there will be a freshwater discharge tube between the classic transition zone and the IMZ. However, this phenomenon may become unclear with the increase of heterogeneity and anisotropy of the medium’s conductivity field. (2) SGD and IMZ are both more sensitive to the vertical anisotropy ratio of hydraulic conductivity (Kx/Kz) than to the horizontal ratio (Kx/Ky). (3) Heterogeneity of effective porosity significantly affects SGD and IMZ. (4) Increase of the storage coefficient decreases fresh water discharge but increases mixing salt water discharge and total SGD. The increase will also change the shape of the IMZ. (5) Variation of dispersivities does not affect SGD, but significantly changes the distributions of the IMZ and the whole mixing zone. These findings will be helpful to the sampling design of field studies of SGD and to the application of dynamic SGD models to field sites for model development and calibration. 相似文献
83.
Juxiu Tong Bill X. Hu Hai Huang Luanjin Guo Jinzhong Yang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(3):729-741
With growing importance of water resources in the world, remediations of anthropogenic contaminations due to reactive solute transport become even more important. A good understanding of reactive rate parameters such as kinetic parameters is the key to accurately predicting reactive solute transport processes and designing corresponding remediation schemes. For modeling reactive solute transport, it is very difficult to estimate chemical reaction rate parameters due to complex processes of chemical reactions and limited available data. To find a method to get the reactive rate parameters for the reactive urea hydrolysis transport modeling and obtain more accurate prediction for the chemical concentrations, we developed a data assimilation method based on an ensemble Kalman filter (EnKF) method to calibrate reactive rate parameters for modeling urea hydrolysis transport in a synthetic one-dimensional column at laboratory scale and to update modeling prediction. We applied a constrained EnKF method to pose constraints to the updated reactive rate parameters and the predicted solute concentrations based on their physical meanings after the data assimilation calibration. From the study results we concluded that we could efficiently improve the chemical reactive rate parameters with the data assimilation method via the EnKF, and at the same time we could improve solute concentration prediction. The more data we assimilated, the more accurate the reactive rate parameters and concentration prediction. The filter divergence problem was also solved in this study. 相似文献
84.
Comparisons of Snowfall Measurements in Complex Terrain Made During the 2010 Winter Olympics in Vancouver 总被引:1,自引:0,他引:1
Faisal S. Boudala George A. Isaac Roy Rasmussen Stewart G. Cober Bill Scott 《Pure and Applied Geophysics》2014,171(1-2):113-127
Solid precipitation (SP) intensity ( $ R_{\text{s}} $ ) using four automatic gauges, Pluvio, PARSIVEL (PArticle, SIze and VELocity), FD12P and POSS, and radar reflectivity factor ( $ Z $ ) using the POSS and PARSIVEL were measured at a naturally sheltered station (VOA) located at high level (1,640 m) on the Whistler Mountain in British Colombia, Canada. The R s and other standard meteorological parameters were collected from March 2009, and from November 2009, to February 2010. The wind speed (ws) measured during this period ranged from 0 to 4.5 ms?1, with a mean value of 0.5 ms?1. The temperature varied from 4 to ?17 °C. The SP amount reported by the PARSIVEL was higher than that reported by the Pluvio by more than a factor of 2, while the FD12P and POSS measured relatively smaller amounts, but much closer to that reported by the Pluvio and manual measurements. The dependence of R s from the PARSIVEL on wind speed was examined, but no significant dependence was found. The PARSIVEL’s precipitation retrieval algorithm was modified and tested using three different snow density size relationships (ρ s–D) reported in literature. It was found that after modification of the algorithm, the derived R s amounts using the raw data agreed reasonably well with the Pluvio. Statistical analysis shows that more than 95 % of $ Z_{{h_{\text{poss}} }} $ data measured by POSS appears to correlates well with the reflectivity factors determined using the three ρ s–D relationships. The automated Pluvio accumulation and manually determined daily SP amount (SPm) measured during five winter months were compared. The mean ratio (MR) and the mean difference (MD), and the correlation coefficient (r) calculated using the data collected using the two methods, were found to be 0.96, 0.4 and 0.6 respectively, indicating respectable agreement between these two methods, with only the Pluvio underestimating the amount by about 4 %. 相似文献
85.
Ruping Mo Paul Joe George A. Isaac Ismail Gultepe Roy Rasmussen Jason Milbrandt Ron McTaggart-Cowan Jocelyn Mailhot Melinda Brugman Trevor Smith Bill Scott 《Pure and Applied Geophysics》2014,171(1-2):157-183
A comprehensive study of mid-mountain clouds and their impacts on the Vancouver 2010 Winter Olympics and Paralympics is presented. Mid-mountain clouds were frequently present on the Whistler alpine venue, as identified in an extensive archive of webcam images over a 45-day period from February 5 to March 21, 2010. These clouds posed serious forecast challenges and had significant impacts on some Olympic and Paralympic alpine skiing competitions. Under fair weather conditions, a diurnal upslope (anabatic) flow can work in concert with a diurnal temperature inversion aloft to produce a localized phenomenon known as “Harvey’s Cloud” at Whistler. Two detailed case studies in this paper suggest that mid-mountain clouds can also develop in the area as a result of a moist valley flow interacting with a downslope flow descending from the mountaintop. A southerly inflow through the Sea-to-Sky corridor can be channeled by the local topography into a westerly upslope flow toward Whistler Mountain, resulting in orographic clouds on the alpine venue. Under favorable circumstances, these clouds are trapped to the mid-mountain zone by the leeward subsidence of an elevated southerly flow. The presence of the downslope subsidence was manifested by a distinguished dry layer observed on the top of the mid-mountain clouds in both cases. It is the subsidence-induced adiabatic warming that imposes a strong buoyant suppression to trap the mid-mountain cloud. On the other hand, the subsidence-induced dry layer has the potential to trigger evaporative instability to periodically breakup the mid-mountain cloud. 相似文献
86.
Based on this preliminary study, existing sand and gravel mining regulations (in Maine, USA) can be inferred to provide some
protection to water resources. Sand and gravel deposits are important natural resources that have dual uses: mining for construction material and pumping for drinking water. How the mining of sand and gravel affects aquifers and change aquifer vulnerability to contamination
is not well documented. Mining regulations vary greatly by state and local jurisdiction. This study test metrics to measure
the effectiveness of mining regulations. The sand and gravel aquifer system studied is covered with former and active gravel
pits to nearly 25% of its areal extent. Data from homeowner interviews and field measurements found scant evidence of changes
in water quantity. Water quality analyses collected from springs, streams, ponds and wells indicate that the aquifer was vulnerable
to contamination by chloride and nitrate. However, water quality changes can not be related directly to mining activities. 相似文献
87.
Norio Honjo Bill Bonnichsen William P Leeman John C Stormer Jr 《Bulletin of Volcanology》1992,54(3):220-237
Voluminous mid-Miocene rhyolitic ash-flow tuffs and lava flows are exposed along the northern and southern margins of the central and western Snake River Plain. These rhyolites are essentially anhydrous with the general mineral assemblage of plagioclase ±sanidine ± quartz + augite + pigeonite ± hypersthene ± fayalitic olivine + Fe-Ti oxides + apatite + zircon which provides an opportunity to compare feldspar, pyroxene, and Fe-Ti oxide equilibration temperatures for the same rocks. Estimated pyroxene equilibration temperatures (based on the geothermometers of Lindsley and coworkers) range from 850 to 1000°C, and these are well correlated with whole-rock compositions. With the exception of one sample, agreement between the two-pyroxene thermometers tested is well within 50°C. Fe-Ti oxide geothermometers applied to fresh magnetite and ilmenite generally yield temperatures about 50 to 100°C lower than the pyroxene temperatures, and erratic results are obtained if these minerals exhibit effects of subsolidus oxidation and exsolution. Results of feldspar thermometry are more complicated, and reflect uncertainties in the thermometer calibrations as well as in the degree of attainment of equilibrium between plagioclase and sanidine. In general, temperatures obtained using the Ghiorso (1984) and Green and Usdansky (1986) feldspar thermometers agree with the pyroxene temperatures within the respective uncertainties. However, uncertainties in the feldspar temperatures are the larger of the two (and exceed ±60°C for many samples). The feldspar thermometer of Fuhrman and Lindsley (1988) produces systematically lower temperatures for many of the samples studied. The estimated pyroxene temperatures are considered most representative of actual magmatic temperatures for these rhyolites. This range of temperatures is significantly higher than those for rhyolites from many other suites, and is consistent with the hypothesis that the Snake River Plain rhyolitic magmas formed by partial fusion of relatively dry (e.g. granulitic) crustal lithologies. 相似文献
88.
R. Holt I. G. Egbuniwe W. R. Fitches J. B. Wright 《International Journal of Earth Sciences》1978,67(2):631-646
The rocks of the Maru and Anka regions of northwestern Nigeria comprise a polycyclic, migmatite-gneiss, basement sequence with an infolded cover of low grade metasediments. Both basement and cover are intruded by a suite of syn-tectonic to latetectonic granites and granodiorites.Evidence from contrasting lithologies and geochronological data suggest that at least three depositional cycles may be represented in the Anka and Maru Belts of low-grade metasediments. An attempt is made to correlate these three cycles with the Kibaran (c. 1100 m. y.) and Pan-African (c. 550 m. y.) events.Structural similarities between the two belts are explained by continued reactivation of Kibaran basement structures during Pan-African times.Calc-alkaline volcanics of late Pan-African age are restricted to the Anka Belt. Recent work shows that volcanism in the Anka Belt is not all of late-orogenic type: a volcano-sedimentary pile, containing possible crystal tuff units, being intruded by acid-intermediate dykes and sills, and deformed during the Pan-African event. Syenitic plutonism restricted to the Maru Belt is shown to be post-tectonic.The recognition of a significant Kibaran event in the basement of northwestern Nigeria is in accord with workers who record a similar event in other parts of the Nigerian basement and in the Precambrian basements of Mali and the Ahaggar.
Zusammenfassung Die Gesteine der Maru- und Anka-Region im nordwestlichen Nigeria umfassen eine Grundgebirgsserie mit Migmatit-Gneisen, in die eine schwach metamorphe Metasedimentserie eingefaltet ist. Beide Serien werden von synbis spättektonischen Graniten und Granodioriten durchdrungen.Aus der abweichenden Lithologie und den Altersdatierungen folgt, da mindestens 3 sedimentäre Zyklen in den Metasedimenten von Anka und Maru vorliegen. Es wird versucht, diese 3 Zyklen mit der Kibaran (ca. 1100 m. y.) und der Pan African Orogenese (ca. 550 m. y.) zu korrelieren.Strukturelle Ähnlichkeiten zwischen den beiden Regionen erklären sich aus einer Reaktivierung des Kibaran-Grundgebirges während der Pan-African-Orogenese.Kalkalkali-Vulkanite von Pan-African-Alter sind auf die Anka-Region beschränkt. Der Vulkanismus der Anka-Region ist nicht nur von einer spätorogenen Phase geprägt, es liegen vielmehr vulkano-sedimentäre Serien vor, die von sauren bis intermediären Gängen durchdrungen werden, die wiederum von der Pan-African Orogenese erfaßt werden. Ein syemitischer Plutonismus ist auf die Maru-Region beschränkt und dort als posttektonisch anzusehen.Das Auftreten einer Kibaran-Orogenese im Grundgebirge von NW-Nigeria steht im Einklang mit Beobachtungen aus anderen Teilen Nigerias, Malis und Ahaggars.
Résumé Les roches des régions de Maru et d'Anka du nord-ouest de la Nigérie comprennent une série de socle polycyclique avec gneiss migmatitiques, au sein de laquelle une couverture de métasédiments faiblement métamorphiques est impliquée par plissement. Socle et couverture sont recoupés par une série d'intrusions granitiques et granodioritiques, snytectoniques á tardi-tectoniques.Le contraste des lithologies et les données géochronologiques permettent de penser qu'au moins 3 périodes de dépôt pourraient être représentées parmi les métasédiments peu métamorphiques de la région de Maru et d'Anka. Un essai est tenté de corréler ces 3 cycles avec de Kibarien (c. 1100 M.) et le Panafricain (c. 550 M.).On peut expliquer les ressemblances structurales entre les deux zones par une réactivation des structures du socle kibarien pendant l'époque panafricaine.Les volcanites cale-alcalines du Panafricain tardif se limitent à la zone d'Anka. Les travaux récents montrent que le volcanisme de la zone d'Anka n'est pas du tout d'un type orogénique tardif; il s'agit d'en ensemble volcano-sédimentaire pouvant renfermer des tuffs cristalins, récoupé par des filons et des sills acides à intermédiaires, et déformé au cours du Panafricain. Le plutonisme syénitique confiné à la zone de Maru apparaît comme post-tectonique.L'enregistrement d'un évènement kibarien dans le socle du nord-ouest de la Nigérie est en accord avec les résultats des recherches mentionnant un évènement semblable dans d'autres parties du socle nigérien et dans les socles précambriens du Mali et d'Ahaggar.
- - . , - - . . — 1100 — — 550 . - .- - . , - : - , , - . - . - , .相似文献
89.
R. G. Bill Jr. L. H. Allen Jr. T. Audunson B. Gebhart E. Lemon 《Boundary-Layer Meteorology》1976,10(2):199-220
Hot-wire anemometers were used to measure air temperature and the three velocity components of the wind within and above a maize canopy. From digitized anemometer outputs, correlation coefficients for vertical heat flux and turbulent momentum transfer were calculated. A comparison of these coefficients with profiles of mean wind speed and mean temperature indicates that the main features of the turbulence may be explained in terms of the usual mixing-length theory. Instantaneous records of heat and momentum flux, however, indicate the existence of other competing turbulent mechanisms due to the unsteady, non-equilibrium nature of the turbulent flow. Regimes of flow dominated by mechanical and/or thermal mixing are indicated. Spectral results show that high shear and turbulent intensity levels as well as the presence of the maize leaves and stalks as vortex-shedding surfaces complicate the energy transfer mechanism. An energy balance between radiation and convection reveals that the energy budget is primarily a balance between solar radiation and the flux of latent heat.Contribution of the Sibley School of Mechanical and Aerospace Engineering, Cornell University, in cooperation with the Agricultural Research Service, U.S. Department of Agriculture, Ithaca, N.Y., U.S.A. and the Cornell University Agricultural Experiment Station. Department of Agronomy Series No. 1116.Sibley School of Mechanical and Aerospace Engineering, Cornell University; U.S. Department of Agriculture, Gainesville, Florida Section for Estuary and Fjord Studies, River and Harbour Laboratory, Technical University of Norway, Trondheim, Norway; State Univ. of New York at Buffalo; and U.S. Department of Agriculture and Cornell University; respectively. 相似文献
90.
J.C. Briden W.R. Fitches M.W. McElhinny 《Physics of the Earth and Planetary Interiors》1973,7(2):217-218
From a collection of 39 oriented hand-samples at 16 sites, total N.R.M. directions at 12 sites from the Elmina Sandstone (Devonian or possibly Carboniferous) of the Ghana coast fall in a group. Their in-situ mean (D = 334°, ) is significantly divergent from the local geomagnetic field, and does not correlate with expected Palaeozoic remanence directions. A bedding-tilt test suggests that the magnetisation is secondary, and comparison with other African data suggests a Mesozoic (possibly Cretaceous) age. The remanence is only partially stable against thermal demagnetisation. The observations are consistent with a remanence originating at the time of faulting, tilting and uplift which marked the beginning of rifting of South America from Africa. 相似文献