1,340 research outputs found
Inter-cluster Filaments of Galaxies Programme: Abundance and Distribution of Filaments in the 2dFGRS Catalogue
Filaments of galaxies are known to stretch between galaxy clusters at all
redshifts in a complex manner. In this Letter, we present an analysis of the
frequency and distribution of inter-cluster galaxy filaments selected from the
2dF Galaxy Redshift Survey. Out of 805 cluster-cluster pairs, we find at least
40 per cent have bone-fide filaments. We introduce a filament classification
scheme and cast the filaments into several types according to their visual
morphology: straight (lying on the cluster-cluster axis; 37 per cent), warped
or curved (lying off the cluster-cluster axis; 33 per cent), sheets (planar
configurations of galaxies; 3 per cent), uniform (1 per cent) and irregular (26
per cent). We find that straight filaments are more likely to reside between
close cluster pairs and they become more curved with increasing cluster
separation. This curving is toward a larger mass concentration in general. We
also show that the more massive a cluster is, the more likely it is to have a
larger number of filaments. Our results are found to be consistent with a
Lambda cold dark matter cosmology.Comment: 6 pages, 3 figures, accepted for publication in MNRAS letter
Some aspects of electro-chemical grid-marking
Introduction
The value of fine grids, electromarked (1) on to metal sheets
before pressing, so that the type and magnitude of the strain developed
in the critical region of the pressing can be assessed, is undisputed.
Keeler (2), Meyer and Newby (3), and Goodwin (4), have all discussed
practical applications of this technique and Palmer (5) has reviewed
the field and introduced the concept of a relative safety factor (MSF).
However it may be useful to see what this 'mark' consists of, how the
marking affects the subsequent metal performance, what the limitations
of the process are and other peripherical issues. It is these aspects
of the process which is the concern of this paper
SOURCES OF PRODUCTIVITY GROWTH DURING THE TRANSITION TO ALTERNATIVE CROPPING SYSTEMS
Traditional measures of productivity growth may not fully account for all sources of growth during the transition from conventional to alternative cropping systems. This paper treats soil quality as part of the production process and incorporates it directly into rotational measures of productivity growth. An application to data from an experimental cropping system in Pennsylvania suggests that both experimental learning and soil-quality improvements were important sources of growth during the system's transition.Productivity Analysis,
Public Release of 2dF data from the Fornax Cluster Spectroscopic Survey
Thanks to the 2dF spectrograph on the Anglo-Australian Telescope, we have
recently completed the first stage of a complete spectroscopic survey more than
one order of magnitude larger than any previous study, measuring 7000 spectra
in a 6 sq.deg. area as part of our study of the Fornax Cluster. In this article
we describe the public release of 3600 spectra from our first field. We hope
that this public release will encourage colleagues making surveys for rare
objects to choose these fields, as much of the follow-up spectroscopy that
might be required is available from our data.Comment: To appear in the AAO Newsletter. Data online at
http://astro.ph.unimelb.edu.au/data
Total focussing method for volumetric imaging in immersion non destructive evaluation
This paper describes the use of a 550 (25x22) element 2MHz 2D piezoelectric composite array in immersion mode to image an aluminum test block containing a collection of artificial defects. The defects included a 1mm diameter side-drilled hole, a collection of 1mm slot defects with varying degrees of skew to the normal and a flat bottomed hole. The data collection was carried out using the full matrix capture; a scanning procedure was developed to allow the operation of the large element count array through a conventional 64-channel phased array controller. A 3D TFM algorithm capable of imaging in a dual media environment was implemented in MATLAB for the offline processing the raw scan data. This algorithm facilitates the creation of 3D images of defects while accounting for refraction effects at material boundaries. In each of the test samples interrogated the defects, and their spatial position, are readily identified using TFM. Defect directional information has been characterized using VTFM for defect exhibiting angles up to and including 45o of skew
Wind-tunnel and Piloted Flight Simulator Investigation of a Deflected-slipstream VTOL Airplane, the Ryan VZ-3RY
No abstract availabl
Interactive manipulation of microparticles in an octagonal sonotweezer
An ultrasonic device for micro-patterning and precision manipulation of micrometre-scale particles is demonstrated. The device is formed using eight piezoelectric transducers shaped into an octagonal cavity. By exciting combinations of transducers simultaneously, with a controlled phase delay between them, different acoustic landscapes can be created, patterning micro-particles into lines, squares, and more complex shapes. When operated with all eight transducers the device can, with appropriate phase control, manipulate the two dimensional acoustic pressure gradient; it thus has the ability to position and translate a single tweezing zone to different locations on a surface in a precise and programmable manner
Multi-criteria decision support for drought security
The recently completed Lower Hunter Water Plan identified a portfolio of drought response measures to ensure that the region does not run out of water under severe drought conditions. A multi-criteria decision analysis (MCDA) process was developed to guide the assessment of the drought response options against multiple criteria (both quantitative and qualitative), and for the assembly and analysis of drought response portfolios. The process guided stakeholders in considering a wide range of alternative supply and demand side options, and allowed for the transparent trade-off between options or portfolios of options. The MCDA process integrated the assessment of social, environmental and risk/resilience criteria with cost effectiveness analysis. The process also included the analysis of contextual uncertainties and risk to determine the flexibility of the options under different future situations. The outcome of this process revealed a portfolio of drought response options that best met the weighted critieria and satisfied the drought response objectives
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