New Zealand Journal of Marine and Freshwater Research Dec 2010     

Doug Mountfort 《新西兰海洋与淡水研究杂志》2013,47(4)

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Evaluation of a low‐cost temperature measurement system for environmental applications     

Jason Hubbart  Timothy Link  Colin Campbell  Doug Cobos 《水文研究》2005,19(7):1517-1523

Thermochron iButtons incorporate the latest in digital technology, making them smaller, less expensive, durable and potentially more reliable than many other temperature logging devices. The objective of this study was to test the accuracy of an inexpensive air temperature measurement system, composed of a Thermochron iButton and radiation shield. Sixty‐one iButtons were subjected to a sequence of two water baths (0 °C and 24·9 °C) to assess the absolute accuracy of the sensors. Five solar radiation shields were tested in a greenhouse setting to evaluate the reduction in radiative heating. Significant differences (p < 0·05) were detected between instruments subsequent to both water‐bath treatment analyses. The accuracy of the sensors was well within the manufacturer's stated specification of ±1·0 °C with a collective temperature variance of ±0·21 °C. Temperature responses generated by the Thermochron iButtons in different radiation shields were consistent, but varied significantly (p < 0·05) from 28 to 44 °C based on diurnal temperature ranges. Results indicate that the Thermochron iButton is an accurate, inexpensive alternative to more expensive temperature data‐logging systems, and is well suited for obtaining quality spatially distributed data for hydrologic and water quality investigations. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

An Integrated Numerical Modelling–Discrete Fracture Network Approach Applied to the Characterisation of Rock Mass Strength of Naturally Fractured Pillars     

Davide Elmo  Doug Stead 《Rock Mechanics and Rock Engineering》2010,43(1):3-19

Naturally fractured mine pillars provide an excellent example of the importance of accurately determining rock mass strength. Failure in slender pillars is predominantly controlled by naturally occurring discontinuities, their influence diminishing with increasing pillar width, with wider pillars failing through a combination of brittle and shearing processes. To accurately simulate this behaviour by numerical modelling, the current analysis incorporates a more realistic representation of the mechanical behaviour of discrete fracture systems. This involves realistic simulation and representation of fracture networks, either as individual entities or as a collective system of fracture sets, or a combination of both. By using an integrated finite element/discrete element–discrete fracture network approach it is possible to study the failure of rock masses in tension and compression, along both existing pre-existing fractures and through intact rock bridges, and incorporating complex kinematic mechanisms. The proposed modelling approach fully captures the anisotropic and inhomogeneous effects of natural jointing and is considered to be more realistic than methods relying solely on continuum or discontinuum representation. The paper concludes with a discussion on the development of synthetic rock mass properties, with the intention of providing a more robust link between rock mass strength and rock mass classification systems.  相似文献   

TSDS: high-performance merge, subset, and filter software for time series-like data     

Robert S. Weigel  Doug M. Lindholm  Anne Wilson  Jeremy Faden 《Earth Science Informatics》2010,3(1-2):29-40

Time Series Data Server (TSDS) is a software package for implementing a server that provides fast super-setting, sub-setting, filtering, and uniform gridding of time series-like data. TSDS was developed to respond quickly to requests for long time spans of data. Data may be served from a fast database, typically created by aggregating granules (e.g., data files) from a remote data source and storing them in a local cache that is optimized for serving time series. The system was designed specifically for time series data, and is optimized for requests where the longest dimension of the requested data structure is time. Scalar, vector, and spectrogram time series types are supported. The user can interact with the server by requesting a time series, a date range, and an optional filter to apply to the data. Available filters include strides, block average/minimum/maximum, exclude, and inequality. Constraint expressions are supported, which allow such operations as a request for data from one time series when a different time series satisfied a specified relationship. TSDS builds upon DAP (Data Access Protocol), NcML (netCDF Mark-up language) and related software libraries. In this work, we describe the current design of this server, as well as planned features and potential implementation strategies.  相似文献   

Impacts of changes in the flue-cured tobacco sector on farmers in Ontario, Canada     

Doug Ramsey  Barry Smit 《Applied geography (Sevenoaks, England)》2001,21(4)

Impacts of the forces and processes of agricultural restructuring are described in this paper through an analysis of farmers’ ‘lived experience’ in the tobacco sector of Ontario, Canada. The paper argues that the political and economic changes in the 1980s fundamentally altered tobacco farming and the broader rural community. The analysis is based upon a survey of farmers and former farmers, and includes examples of individual case histories. The results show the ways in which farmers’ well-being was affected and provides insights into coping mechanisms.  相似文献   

Structural and engineering geology of the East Gate Landslide, Purcell Mountains, British Columbia, Canada   总被引：3，自引：0，他引：3  

Marc-Andr Brideau  Doug Stead  Rjean Couture 《Engineering Geology》2006,84(3-4):183-206

The East Gate Landslide is a prehistoric landslide that was reactivated in January 1997. The slope failure took place in the lower greenschist metasedimentary units of the Precambrian Horsethief Creek Group. The Grizzly Creek Thrust is a regional overturned fault that coincides with the location of the headscarp of the East Gate Landslide. Four discontinuity sets were recognised from detailed engineering geological mapping of the headscarp and surrounding area. The main scarp of the section reactivated in 1997 was sub-divided into three structural domains based on its position within the landslide, lithology, and orientation of the discontinuity sets. Limit-equilibrium techniques, finite-difference (FLAC) and distinct-element (UDEC) codes were used to investigate the failure mechanism of the 1997 event. The results of the field observations and numerical models suggest that the 1997 failure involved a complex mechanism incorporating components of rock-slumping, bi-planar, and pseudo-circular failure that was controlled by both the orientation of the discontinuity sets and reduced rock-mass quality due to tectonic deformation.  相似文献   

Example of a debris-flow risk analysis from Vancouver Island,British Columbia,Canada     

Ron Arksey  Doug VanDine 《Landslides》2008,5(1):121-126

In July 2005, a debris flow and a water flood occurred on two adjacent gullies in the White River area, on northern Vancouver Island in British Columbia, Canada. The 16,000 m³ debris flow buried approximately 7.5 ha of second-growth trees, buried approximately 500 m of a forestry road, and reached two fish-bearing streams. The water flood eroded approximately 240 m of the same forestry road and plugged four culverts before overtopping and inundating the road. To better plan for future events, risk analyses of debris flows, debris floods, and water floods were carried out for the two gullies involved, plus a third adjacent gully. The elements at risk that were analyzed included, in order of priority: users of the forestry road, the fish-bearing streams, the forestry road itself, and a timber bridge. Using a series of qualitative, but defined, relative-risk matrices, the following components of specific risk were estimated for each of the three types of events on each of the three gullies for each of the four elements at risk: probability of occurrence, probability that the event will reach or otherwise affect the site of the element at risk, the probability that the element at risk will be at the site when the event occurs, and the probability of loss or damage resulting from the element being at the site when the event occurs.  相似文献   

Morphogenetische Betrachtung über die oberitalienische Schwemmlandküste     

Dr. Walter Geisler 《International Journal of Earth Sciences》1920,11(1-4):1-18

Ohne Zusammenfassung  相似文献   

High spatial resolution ion microprobe measurements refine chronology of carbonate formation in Orgueil     

Peter Hoppe  Doug MacDougall  Günter W. Lugmair 《Meteoritics & planetary science》2007,42(7-8):1309-1320

Abstract— Aqueous activity on meteorite parent bodies is indicated by the presence of carbonates. High spatial resolution ion microprobe analyses of nine individual carbonate grains (four dolomites, five breunnerites) from the Orgueil meteorite reveal linear correlations between ⁵³Cr excesses and Mn/Cr ratios in all grains, indicative of in situ decay of radioactive ⁵³Mn (half‐life 3.7 million years). The well‐defined isochrons appear to have chronological significance. If this is the case, then ⁵³Mn/⁵⁵Mn ratios between 2.1 and 4.7 × 10^?6 are inferred for the time of carbonate formation and absolute ages of between 4561 and 4565 Ma are calculated (systematic uncertainty of ±2 Ma). Dolomites tend to have formed slightly earlier than the breunnerites. Our data imply extensive aqueous activity on the Orgueil parent body over a period of several million years, starting ～3–4 Myr after formation of the solar system, that most likely was the result of impact heating and latent heat from the decay of radioactive ²⁶Al and ⁶⁰Fe.  相似文献   

Ages and metallicities of five intermediate-age star clusters projected towards the Small Magellanic Cloud     

Andrés E. Piatti  João F. C. SantosJr  Juan J. Clariá  Eduardo Bica  Ata Sarajedini  Doug Geisler 《Monthly notices of the Royal Astronomical Society》2001,325(2):792-802

Colour–magnitude diagrams are presented for the first time for L32, L38, K28 (L43), K44 (L68) and L116, which are clusters projected on to the outer parts of the Small Magellanic Cloud (SMC). The photometry was carried out in the Washington system C and T ₁ filters, allowing the determination of ages by means of the magnitude difference between the red giant clump and the main-sequence turn-off, and metallicities from the red giant branch locus. The clusters have ages in the range 2–6 Gyr , and metallicities in the range −1.65<[Fe/H]<−1.10, increasing the sample of intermediate-age clusters in the SMC. L116, the outermost cluster projected on to the SMC, is a foreground cluster, and somewhat closer to us than the Large Magellanic Cloud. Our results, combined with those for other clusters in the literature, show epochs of sudden chemical enrichment in the age–metallicity plane, which favour a bursting star formation history as opposed to a continuous one for the SMC.  相似文献