Natural Hazards - Acknowledging the devastating consequences of past earthquakes, current research efforts focus on the development of tools for assessing and controlling the risk and losses... 相似文献
The urban fringe is usually portrayed as a location of unrelieved adversity for farmers. It is rare for the costs of the urban fringe to be counterbalanced by an assessment of the opportunities that are also found there. This paper presents the results of a large scale farm survey in Essex which sought to examine the effects of urban proximity on farm management practices.The paper examines the nature and spatial extent of the following: conversion of farm land to urban uses (with special emphasis on the role of compulsory purchase orders); changes in farm labour; part time farming and the location of part time farmers jobs; vandalism and trespass damage and farmers response to this hazard; farm-based recreation and the sale of produce direct to the public. In general it is shown that the disadvantages of farming in the urban fringe have been overrated while the advantages have been underrated. 相似文献
1 INTRODUCTION The transport of sediment in rivers with active floodplains is a two-dimensional process because the main channel and the floodplain can have very different transport capacities. Therefore, two-dimensional (2D) models are often used to simulate the streamwise and transverse variations of sediment erosion and deposition. Many 2D numerical models have been presented to simulate sediment transport in floodplains (James, 1985; Pizzuto, 1987; Howard, 1992; Nicholas and Walli… 相似文献
A search for gravitational waves from the millisecond pulsar PSR 0437-4715 has been initiated using the bar detector NIOBE which is located at the University of Western Australia. We present a detailed report on the data analysis algorithm, called phase plane rotation , which will be used in this search. A discussion of the actual implementation of the algorithm is presented. The data analysis algorithm mentioned above has the advantage that it requires minimal changes to the already-existing data acquisition facility of NIOBE but, at the same time, it is as efficient as optimal filtering in detecting a signal. This search involves a very long coherent integration of the bar output which may stretch over a few years. With some planned improvements in the detector, a three-year integration should be able to put an upper limit of h ∼ 10−26 on the signal amplitude. 相似文献
An updated linear computer model for meandering rivers with incision has been developed. The model simulates the bed topography, flow field, and bank erosion rate in an incised meandering channel. In a scenario where the upstream sediment load decreases (e.g., after dam closure or soil conservation), alluvial river experiences cross section deepening and slope flattening. The channel migration rate might be affected in two ways: decreased channel slope and steeped bank height. The proposed numerical model combines the traditional one-dimensional (1D) sediment transport model in simulating the channel erosion and the linear model for channel meandering. A non-equilibrium sediment transport model is used to update the channel bed elevation and gradations. A linear meandering model was used to calculate the channel alignment and bank erosion/accretion, which in turn was used by the 1D sediment transport model. In the 1D sediment transport model, the channel bed elevation and gradations are represented in each channel cross section. In the meandering model, the bed elevation and gradations are stored in two dimensional (2D) cells to represent the channel and terrain properties (elevation and gradation). A new method is proposed to exchange information regarding bed elevations and bed material fractions between 1D river geometry and 2D channel and terrain. The ability of the model is demonstrated using the simulation of the laboratory channel migration of Friedkin in which channel incision occurs at the upstream end. 相似文献
THE DICTIONARY OF HUMAN GEOGRAPHY edited by R. J. Johnston. 20 x 13 cm, xix and 411 pages. Blackwell: Oxford 1983 (ISBN 0 631 13465 4) $A13.95 (limp).
THE GEOGRAPHY OF AUSTRALIAN CORPORATE POWER edited by Michael Taylor. 22 x 14 cm, ix and 230 pages. Croom Helm Australia: Sydney 1984 (ISBN 0 949614 06 8) $A24.95 (cloth).
MULTINATIONALS AS MUTUAL INVADERS: Intra‐industry Direct Foreign Investment edited by A. Erdilek. 14 x 22 cm, xii and 217 pages. Croom Helm: London 1985 (ISBN 0 7099 0935 7) $A39.95 (cloth).
UNEVEN DEVELOPMENT: Nature, Capital and the Production of Space by N. Smith. 15 x 22 cm, xv and 198 pages. Basil Blackwell: Oxford 1984 (ISBN 0 631 13564 2) $A59.95 (cloth); (ISBN 0 631 13685 1) $A18.95 (limp).
SOCIAL THEORY AND THE AUSTRALIAN CITY (Studies in Society No. 26) by L. Kilmartin, D. Thorns and T. Burke. 14 x 21 cm, ix and 218 pages. George Allen and Unwin: Sydney 1985 (ISBN 0 86861 405) $A24.95 (cloth); (ISBN 0 86861 413 0) $A12.95 (limp).
THE FUTURE OF URBAN FORM: The Impact of New Technology edited by J. Brotchie, P. Newton, P. Hall and P. Nijkamp. 14 x 22 cm, xiii and 374 pages. Croom Helm: London 1985 (ISBN 0 7099 3255 3) $A44.95 (cloth). 相似文献
The characteristics of a reflected spherical wave at a free surface are investigated by numerical methods; in particular, the polarization angles and amplitude coefficients of a reflected spherical wave are studied. The classical case of the reflection of a plane P wave from a free surface is revisited in order to establish our terminology, and the classical results are recast in a way which is more suited for the study undertaken. The polarization angle of a plane P wave, for a given angle of incidence, is shown to be 90° minus twice the angle of reflection of the reflected S wave. For a Poisson's ratio less than 1/3, there is a non-normal incident angle for which both amplification coefficients are 2 precisely; for this incident angle the direction of the particle motion at the free surface is also the direction of the incident wave. For a wave emanating from a spherical source, the polarization angle, for all angles of incidence, is always less than, or equal to, the polarization angle of a plane P wave. The vector amplification coefficient of a spherical wave, for all angles of incidence, is always greater than the vector amplification coefficient of a plane P wave. As expected, the results for a spherical wave approach the results for a plane P wave in the far field. Furthermore, there was a good agreement between the theoretical modelling and the numerical modelling using the dynamic finite element method (DFEM). 相似文献