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The monitoring and management of species depends on reliable population estimates, and this can be both difficult and very costly for cryptic large vertebrates that live in forested habitats. Recently developed camera trapping techniques have already been shown to be an effective means of making mark-recapture estimates of individually identifiable animals (e.g. tigers). Camera traps also provide a new method for surveying animal abundance. Through computer simulations, and an analysis of the rates of camera trap capture from 19 studies of tigers across the species' range, we show that the number of camera days/tiger photograph correlates with independent estimates of tiger density. This statistic does not rely on individual identity and is particularly useful for estimating the population density of species that are not individually identifiable. Finally, we used the comparison between observed trapping rates and the computer simulations to estimate the minimum effort required to determine that tigers, or other species, do not exist in an area, a measure that is critical for conservation planning.

This paper considers the problem of determining the inviscid, subsonic compressible (or incompressible) blade-to-blade flow field through a turbomachine blade row, and presents two computer solutions, known as the ‘matrix’ and ‘streamline curvature’ methods, for solving this elliptic problem. In the former method the equations of motion are formulated in terms of a stream function and the numerical solution is based on finite difference approximations; in the latter, the equations of motion are solved in conjunction with the equation of continuity by an iterative process starting from a guess for the streamline pattern. Solutions for several blade profiles, giving flow patterns and blade surface velocity distributions, are included.

This paper shows how analytic surfaces can be used to define the vanes of an impeller of a centrifugal compressor. The analysis has been given of a cubic-linear patch for representing three-dimensional geometries. An example has shown how this type of patch can be successfully used to model the geometry of centrifugal or mixed flow impellers having 'swept back vanes at the outlet. The analysis has been programmed for the Atlas computer at the Computer Aided Design Centre (CADC), Cambridge and set up in such a way that the designer can examine systematically a range of impeller shapes.

In the last few years considerable progress has been made in calculating the three-dimensional flows through turbomachines. The two methods which appear to be widely used are what have come to be known as the “Streamline Curvature” and the “Matrix Through Flow” methods. At the National Gas Turbine Establishment, these advanced methods have been applied to existing turbomachines and this paper presents some of the calculated and experimental results for four axial flow machines. By making use of fairly simple loss distributions it has been found that these methods can assist towards the understanding of observed phenomena and, in the case of the axial compressor, they offer some prospect of being able to calculate the onset of surge. Also included is a brief report of work in progress to generate a computer program for the solution of the compressible velocity distribution around the surfaces of turbomachine blades, together with an indication of possible future experimental work.Copyright © 1968 by ASME