Rapid zonation of abrupt mass movement hazard: Part I. General principles     

J.R. Ni  R.Z. Liu  Onyx W.H. Wai  Alistair G.L. Borthwick  X.D. Ge   《Geomorphology》2006,80(3-4):214-225

Hazards caused by mass movement cost many human lives and cause severe damage to property. Accurate zonation of such hazards provides an important tool for preventive measures. Previous approaches for mass movement hazard zonation are costly because they require large amounts of data, time and labor, and are only applicable to specific local areas. In this paper, a Rapid Zonation of Abrupt Mass-movement Hazard (RZAMH), applicable to large regions, is proposed. It involves the selection of appropriate zonation principles, routes, units, and indexes that can be used for the classification of reference groups, identification of matching groups of test sites, evaluation of blank test sites, and coalescence of sub-regions into specified zonation areas. The K-means clustering method is used in the classification processes. The applicability of the RZAMH approach to a large area implies that the number of reference sites required to build the reference groups is not of primary importance as long as the reference sites are representative. Therefore, for large areas, the RZAMH approach would be more economical than other conventional methods. The RZAMH approach is probably applicable to all abrupt mass movement hazards including rock falls, landslides, and debris flows.  相似文献   

The Effect of Spatial Heterogeneity in Soil Properties on Erosion Pattern: A Conceptual Model and Computer Simulations     

Alistair Smith  Vladimir Nikora 《Mathematical Geology》2006,38(8):1011-1016

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A sample of 6C radio sources designed to find objects at redshift z > 4 — I. The radio data     

Katherine M.Blundell  SteveRawlings  Stephen A.Eales  Gregory B.Taylor  Alistair D.Bradley 《Monthly notices of the Royal Astronomical Society》1998,295(2):265-279

We describe the selection of a sample of 34 radio sources from the 6C survey from a region of sky covering 0.133 sr. The selection criteria for this sample, hereafter called 6C*, were chosen to optimize the chances of finding radio galaxies at redshift z  > 4. Optical follow-up observations have already led to the discovery of the most distant known radio galaxy at z  = 4.41. We present VLA radio maps and derive radio spectra for all the 6C* objects.  相似文献   

Viewing Highland Scotland: ideology, representation and the 'natural heritage'     

Fraser MacDonald 《Area》1998,30(3):237-244

Summary This paper reconsiders the role of conservation within the cultural politics of Highland Scotland. The crofting version of the natural heritage debate is regarded as counter-hegemonic to dominant discourses of conservation and the sporting estate. That view is given precedence in defining the ecology and landscape of the Highlands.  相似文献   

Monitoring Biotic And Abiotic Processes Across The Hyporheic/Groundwater Interface   总被引：2，自引：0，他引：2  

Brian G. Fraser  D. Dudley Williams  Ken W.F. Howard 《Hydrogeology Journal》1996,4(2):36-50

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Address of the president of the international hydrographic Bureau     

Rear Admiral F. L. Fraser 《Ocean Dynamics》1986,39(6):266-266

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Kinetics of the reactions of hydroxyl radicals with alkyl nitrates and with some oxygen-containing organic compounds studied under simulated atmospheric conditions   总被引：1，自引：0，他引：1  

J. Alistair Kerr  David W. Stocker 《Journal of Atmospheric Chemistry》1986,4(2):253-262

Rate constants have been measured for the reactions of hydroxyl radicals with alkyl nitrates and with some oxygen-containing organic compounds by a competitive technique. Mixtures of synthetic air containing a few ppm of nitrous acid, ethylene and the organic substrate were photolysed in a Teflon bag smog chamber. Based on the value k _HO+C2H₄}=8.1×10^-12 cm³ molecule^-1 s^-1 the following rate constants were obtained for the hydroxyl radical reactions at 750 Torr and at 303 K in units of 10^-12 cm³ molecule^-1: CH₃ONO₂, 0.37±0.09; C₂H₅ONO₂, 0.48±0.20; n-C₃H₇ONO₂, 0.70±0.22; C₂H₅OH, 3.6±0.4; CH₃COCH₃, 0.26±0.08; CH₃CO₂ i-C₃H₇, 3.0±0.8; CH₃CO₂ n-C₃H₇, 2.4±0.2. The results are discussed in relation to the available literature data and the implications of the results are considered in terms of the smog reactivity of these molecules.  相似文献   

Methane,carbon monoxide and methylchloroform in the southern hemisphere   总被引：1，自引：0，他引：1  

P. J. Fraser  P. Hyson  R. A. Rasmussen  A. J. Crawford  M. A. K. Khalil 《Journal of Atmospheric Chemistry》1986,4(1):3-42

New observational data on CH₄, CO and CH₃CCl₃ in the southern hemisphere are reported. The data are analysed for long term trends and seasonal cycles. CH₃CCl₃ data are used to scale the OH fields incorporated in a two dimensional model, which in turn, is used to constrain the magnitude of a global CH₄ source function. The possible causes of observed seasonality of CH₃CCl₃, CH₄ and CO are identified, and several other aspects of observed CH₄ variability are discussed.Possible future research directions are also given.  相似文献   

Wave packet structure and phase jumps in low latitude Pc3 geomagnetic pulsation     

I A Ansari  B J Fraser  K J McLean 《Journal of Earth System Science》1986,95(1):13-24

An array of four low latitude induction coil magnetometer stations has been used to study the spatial and temporal characteristics of Pc3 pulsations over a longitudinal range of 17° atL=1·8 to 2·7 in south-east Australia. A preliminary study of individual Pc3 wave packet structure at the azimuthal stations has established the existence of phase jumps between wave packets at low latitudes similar to those observed at synchronous orbit and at higher latitude ground stations. However there did not appear to be any obvious pattern in phase jump occurrences between stations or signal components.  相似文献   

Spectral characteristics of low latitude Pc3 geomagnetic pulsations in south-east Australia     

I A Ansari  B J Fraser  K J McLean 《Journal of Earth System Science》1986,95(1):25-45

Geomagnetic pulsations in the Pc3 period range (10–45 sec) were recorded simultaneously in south-east Australia using an array of four low latitude induction coil magnetometers over a longitudinal range of 17° atL=1·8 to 2·7. Geomagnetic data from March 25 to September 21, 1982 were digitized and spectral studies were carried out from Grey scale digital (GSD) dynamic spectra and contour sonagrams. Similar wave spectra were generally seen at the three stationsWM, BH andNC in the same latitude with Pc3 waves mostly being observed in the 40–45 mHz band. In addition the higher latitude station (LN) also showed lower frequency Pc4 bands (≈ 10mHz) on some days but higher frequency bands (60–80mHz) on others. Sometimes completely different wave frequencies were observed on theX andY components with the stations in the same latitude generally showing similar spectra on the corresponding components. Dynamic spectra also indicated that wave energy often turned off and on abruptly over short intervals of time implying solar wind control and Pc3 pulsation activity. A band harmonic structure was occasionally seen in wave spectra at the azimuthal stations mainly on theX component during the local afternoon with a harmonic spacing (Δf) of ≈ 10 mHz.  相似文献