FAO's EEZ programme: Assisting a new era in fisheries     

Tony Loftas 《Marine Policy》1981,5(3):229-239

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The demise of the Aral Sea – an environmental disaster     

Tony Waltham  Ihsan Sholji 《Geology Today》2001,17(6):218-228

The shrinkage of the Aral Sea ranks as one of the world's greatest man-made environmental disasters. While there is some hope for a separated northern part, the main sea is doomed  相似文献   

Physical and compositional studies of Comet 81P/Wild 2 at multiple apparitions     

Tony L. Farnham  David G. Schleicher 《Icarus》2005,173(2):533-558

We present analyses and results from both narrowband photometry and CCD imaging of Comet 81P/Wild 2 from multiple apparitions, obtained in support of the Stardust mission. These data include photometric measurements from 12 days before the encounter and imaging from 3 days after. Using narrowband photometry from the different apparitions, we analyzed the dust and gas production rates as a function of heliocentric distance, finding a substantial seasonal effect where the production of OH, NH, and dust peaks 11-12 weeks before perihelion. The CN, C₂, and C₃ production show no such asymmetry, suggesting that there may be heterogeneities among different sources on the nucleus. The water production peaked at a level of approximately in 1997. A comparison of the relative abundances of minor gas species places Wild 2 in the “depleted” category in the A'Hearn et al. (1995, Icarus 118, 223) taxonomic classifications. Continuum measurements at multiple wavelengths indicate that the comet has a low dust-to-gas ratio, with moderately reddened dust. In our images we see a dust tail, an anti-tail and two well-defined jets. The primary jet, which persists for several months and is roughly aligned with the spin axis, has a source latitude >+75°, while the secondary jet is located on the opposite hemisphere between −37° and −62°. We used the apparent position angle of the primary jet to determine the pole orientation, α=281±5°, δ=+13±7°, and surmise that the nucleus is likely in a state of simple rotation. The primary source is continuously illuminated when Wild 2 is inbound and turns away from the Sun at about the time that the comet reaches perihelion, explaining the seasonal effects in the production rates. We measured lightcurves on several observing runs but saw no significant modulation, so no constraints can be set on the rotation rate. Images at different wavelengths show that the jets have the same colors as the dust in other regions in the coma and tail, indicating that the grain properties are similar throughout the coma. Radial profiles of the coma were measured in various directions on a number of different observing runs, and we discuss the findings from these measurements. Finally, we compare our results with other published data and attempt to predict future times at which observations should be obtained to help constrain additional properties.  相似文献   

The pinning of Lyme Regis     

Tony Waltham 《Geology Today》2001,17(5):175-176

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Decade of the oceans     

Tony Loftas 《Marine Policy》1977,1(1):2

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Laboratory simulation of the salt weathering of schist: 1. Weathering of schist blocks in a seasonally wet tropical environment     

Tony Wells  Philip Binning  Garry Willgoose  Greg Hancock 《地球表面变化过程与地形》2006,31(3):339-354

Data describing sediment generation focusing on the temporal evolution of size gradation are required for the prediction of long‐term landform evolution. This paper presents such data for the salt weathering of a quartz‐chlorite schist obtained from the Ranger Uranium Mine in northern Australia. Rock fragment samples are subjected to three different climate regimes: (1) a dry season climate; (2) a wet season climate (both based on observations at the Ranger site); and (3) an oven‐drying sequence designed to test the sensitivity of the weathering process by exposing the rocks to more extreme temperatures. Two MgSO₄ salt solutions are applied, one being typical of wet season runoff and the other a more concentrated solution. Salt solution is applied daily in the wet season experiments and once only at the beginning of the dry season experiments. Results of the experiments reveal four stages of weathering. The kinetics of each stage are described and related to the formation of sediment of different sizes. Wet season climate conditions are shown to produce greater moisture variability and lead to faster weathering rates. However, salt concentrations in the wet season are typically lower and so when climate is combined with observed salt concentrations, the dry and wet season experiments weather at approximately equal rates. Finally, small variations in rock properties were shown to have a large impact on weathering rates, leading to the conclusion that rock weathering experiments need to be carefully designed if results are to be used to help predict weathering behaviour at the landscape scale. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Study on the suitability of New Zealand coals for hydrogen production   总被引：4，自引：0，他引：4  

Tony Clemens  Desmond Gong  Steven Pearce 《International Journal of Coal Geology》2006,65(3-4):235-242

Internationally there is considerable interest in utilizing hydrogen as an energy carrier. The use of hydrogen offers considerable potential benefits such as reducing greenhouse emissions, reducing urban pollution, increased energy security and increased efficiencies from the use of advanced energy conversion technologies.One of the most important questions when considering the development of a hydrogen economy is “where will the hydrogen come from?” Possible answers include electrolysis of water, steam reforming of methane and the gasification of coal. Given the high costs associated with electrolysis of water, and the increase in the cost of methane predicted over time, the gasification of coal is viewed by many as being the cheapest method of hydrogen production in the foreseeable future. These considerations are particularly relevant to New Zealand where gas supplies are dwindling but where there is sufficient coal to last for many centuries at present utilization rates. This, along with the current high international interest in hydrogen energy, has been recognized by the New Zealand Government in the form of a six-year [2002–2008] research project “Hydrogen Energy for the Future of New Zealand”.One important coal property that, in particular, determines the suitability of a particular coal for use in a fluidised bed gasifier is its reactivity towards the gasification reaction. It was found that a high percentage of New Zealand's coal resource is particularly well-suited towards fluidised bed gasification, reacting at anywhere between 0.9 to 1.75 times the rate of Australian brown coals. It was found the New Zealand lignites contained significant levels of organically bound calcium, which was shown to be responsible for not only the high reactivity of the New Zealand lignites, but also a product gas composition with higher than expected hydrogen concentrations. These findings are discussed along with their implications for the gasifier and gas clean-up design.  相似文献   

GML for Representing Data from Spatio-Historical Databases: A Case Study     

Fang Siyuan  Tony Griffiths  Norman W Paton 《Transactions in GIS》2007,11(2):233-253

Many applications, in areas such as land use, traffic management and location aware services, involve the storage, analysis and sharing of spatio‐temporal data. The need to represent such data in a way that eases sharing across applications, has led to the development of the Geography Markup Language (GML), which provides a rich collection of constructs for representing spatial and associated aspatial data as XML documents. However, although there are a growing number of applications and tools that make use of GML, there are surprisingly few experience reports on the representation of data from existing applications or models using GML constructs. This paper provides one such report, describing the use of GML as an exchange format for the Tripod spatio‐historical database. This in turn involves identifying mappings between Tripod and GML constructs, and the development of a generic architecture for carrying out such mappings. The experience demonstrates that even though GML provides rich modelling facilities, the development of mappings from pre‐existing models can be challenging, as related constructs often provide semantically distinct capabilities.  相似文献   

The flooding of New Orleans     

Tony Waltham 《Geology Today》2005,21(6):225-231

With its man-made defences, New Orleans is at best only a marginally stable city, and it was destined to suffer as more powerful natural processes evolved. The aftermath of the August 2005 hurricane was the disaster that had been waiting to happen.  相似文献   

Inversion of nuclear well-logging data using neural networks   总被引：1，自引：1，他引：1  

Elsa Aristodemou  Christopher Pain  Cassiano de Oliveira  Tony Goddard  Christopher Harris 《Geophysical Prospecting》2005,53(1):103-120

This work looks at the application of neural networks in geophysical well‐logging problems and specifically their utilization for inversion of nuclear downhole data. Simulated neutron and γ‐ray fluxes at a given detector location within a neutron logging tool were inverted to obtain formation properties such as porosity, salinity and oil/water saturation. To achieve this, the forward particle‐radiation transport problem was first solved for different energy groups (47 neutron groups and 20 γ‐ray groups) using the multigroup code EVENT. A neural network for each of the neutron and γ‐ray energy groups was trained to re‐produce the detector fluxes using the forward modelling results from 504 scenarios. The networks were subsequently tested on unseen data sets and the unseen input parameters (formation properties) were then predicted using a global search procedure. The results obtained are very encouraging with formation properties being predicted to within 10% average relative error. The examples presented show that neural networks can be applied successfully to nuclear well‐logging problems. This enables the implementation of a fast inversion procedure, yielding quick and reliable values for unknown subsurface properties such as porosity, salinity and oil saturation.  相似文献