34 resultados para Printed strip monopole antenna

em Deakin Research Online - Australia


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The performance of a strip search by a police officer is a serious interference with the liberty and dignity of an individual. However, it is considered by police to be an important part of their law enforcement armory and one that is increasingly necessary to utilise to assist in the investigation and prosecution of drug-related crimes. This article considers the troublesome issue of whether and in what circumstances the common law may extend to police the power to conduct a strip search. In addition, there is an examination of the statutes and regulations that purportedly give police in Victoria the power to strip search with particular attention given to ss 81 and 82 of the Drugs, Poisons and Controlled Substances Act 1981 (Vic).

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Galvanneal is a form of zinc-coated sheet steel, where steel is dipped in molten zinc, and then heat treated in a furnace to produce a complex iron-zinc coating. Many industries, such as automotive, use galvanneal for components fabricated from sheet steel. The microstructural properties of galvanneal have a significant influence on how well the sheet metal changes shape on stamping. By means of optical microscopy, scanning electron microscopy, and glow-discharge optical emission spectrometry, we present a study of the microstructure of several galvanneal samples, both stamped and unformed, relating the phases and morphology of the coatings to performance in stamping operations. Samples of galvanneal were subjected to different heat-treatment temperatures. The frequency of defects in stamped components was found to be related to the average alloy content in the coatings, which varied with furnace temperature. An increased average iron content in the coatings was related to increased powdering defects in stamping operations that use galvanneal coated sheet steel.

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This paper is about challenges to the hegemony of printed books in Australian tertiary education and the potential demise of that hegemony. Not because the book in its traditional form is considered by some to be outdated and not because ofcompeting products that might put the use of the traditional book under threat - our Australian 'book-industry' might well rise to such challenges given that competitiveness is a driving feature of business. This paper is about challenges to the hegemony of printed books in tertiary education because of forces entirely outside the 'book-industry's' control.

The function of traditional printed books within tertiary education is changing. Education is a user-pays product, and competitive pressures ensure students are given greater voice in the types of learning resources provided, with the evolution of electronic and communication technologies allowing student learning resources to be made available in a myriad of ways. Thus a traditional printed book may be an inflexible tool in a dynamic environment.

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This paper addresses the problem of the design of a precoder for multiple transmit antenna communication systems with spatially and temporally correlated fading channels. Using the theories of matrix differential calculus, the paper derives a precoder for unitary space-time codes that can exploit the spatio-temporal correlation in the time-varying fading channels. The design criterion is based on minimizing the mean square error of the channel estimates. Computer simulation results show that a significant performance gain can be achieved by using the designed precoder.

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Differential space-time modulation (DSTM) techniques developed for multi-antenna systems allow the receiver to detect the transmitted signal without the knowledge of the fading channels. It can be viewed as an extension of differential phase-shift keying (DPSK) in single antenna systems. In this paper, we derived the pairwise error probability upper bound of differential space-time coded systems with spatially correlated Rayleigh fading channels. Based on the performance analysis, we develop a novel DSTM scheme which can exploit the spatial correlation in the fading channels. It is found that by carefully designing the initial transmitted signal matrix, the performance of the differential space-time coded systems can be significantly improved.

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A novel single-pass hot strip rolling process has been developed in which ultra-fine (<2 μm) ferrite grains form at the surface of hot rolled strip in two low carbon steels with average austenite grain sizes above 200 μm. Two experiments were performed on strip that had been re-heated to 1250°C for 300 s and air-cooled to the rolling temperatures. The first involved hot rolling a sample of 0.09 wt.%C–1.68Mn–0.22Si–0.27Mo steel (steel A) at 800°C, which was just above the Ar3 of this sample, while the second involved hot rolling a sample of 0.11C–1.68Mn–0.22Si steel (steel B) at 675°C, which is just below the Ar3 temperature of the sample. After air cooling, the surface regions of strip of both steel A and B consisted of ultra-fine ferrite grains which had formed within the large austenite grains, while the central regions consisted of a bainitic microstructure. In the case of steel B, a network of allotriomorphic ferrite delineated the prior-austenite grain boundaries throughout the strip cross-section. Based on results from optical microscopy and scanning/transmission electron microscopy, as well as bulk X-ray texture analysis and microtextural analysis using Electron Back-Scattered Diffraction (EBSD), it is shown that the ultra-fine ferrite most likely forms by a process of rapid intragranular nucleation during, or immediately after, deformation. This process of inducing intragranular nucleation of ferrite by deformation is referred to as strain-induced transformation.

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An austenitic Ni-30 wt pct Fe alloy, with a stacking-fault energy and deformation characteristics similar to those of austenitic low-carbon steel at elevated temperatures, has been used to examine the defect substructure within austenite deformed by single-pass strip rolling and to identify those features most likely to provide sites for intragranular nucleation of ultrafine ferrite in steels. Samples of this alloy and a 0.095 wt pct C-1.58Mn-0.22Si-0.27Mo steel have been hot rolled and cooled under similar conditions, and the resulting microstructures were compared using transmission electron microscopy (TEM), electron diffraction, and X-ray diffraction. Following a single rolling pass of ∼40 pct reduction of a 2mm strip at 800 °C, three microstructural zones were identified throughout its thickness. The surface zone (of 0.1 to 0.4 mm in depth) within the steel comprised a uniform microstructure of ultrafine ferrite, while the equivalent zone of a Ni-30Fe alloy contained a network of dislocation cells, with an average diameter of 0.5 to 1.0 µm. The scale and distribution and, thus, nucleation density of the ferrite grains formed in the steel were consistent with the formation of individual ferrite nuclei on cell boundaries within the austenite. In the transition zone, 0.3 to 0.5 mm below the surface of the steel strip, discrete polygonal ferrite grains were observed to form in parallel, and closely spaced “rafts” traversing individual grains of austenite. Based on observations of the equivalent zone of the rolled Ni-30Fe alloy, the ferrite distribution could be correlated with planar defects in the form of intragranular microshear bands formed within the deformed austenite during rolling. Within the central zone of the steel strip, a bainitic microstructure, typical of that observed after conventional hot rolling of this steel, was observed following air cooling. In this region of the rolled Ni-30Fe alloy, a network of microbands was observed, typical of material deformed under plane-strain conditions.

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The Victorian Environment Protection Authority (EPA) has identified Alcoa’s Point Henry aluminium smelter as being a major source of recognized pollutant input due to its disposal of effluent into Corio Bay. Historically, the water quality parameters that have most often exceeded Point Henry’s EPA limits have been pH and suspended solids from the smelter’s discharge points. These waste water discharges also experience high nitrogen and phosphorus concentrations which result in algal blooms that occur at the onset of warm weather. The main hypothesis of this study was that “prevention of algal blooming with the onset of warm weather by removal of nutrients during the cooler months, and continued removal thereafter, is better than curing the problems chemically”. Biofilms have been used to remove nutrients from waste waters, but not under the conditions experienced at Point Henry. The aim of this study, therefore, was to determine if significant biofilm growth would be observed on floating structures suspended in the Point Henry waste water stream during the cooler, winter months of the year. Statistically significant biofilm growth occurred on all suspended structures in all discharge ponds during the winter and early spring of 2000. The use of suspended structures, such as AquaMatTM, as an artificial substrate to attract and support periphyton and bacterial communities (biofilms), which are then able to out-compete phytoplankton communities for available nutrients, is therefore a viable option for the Point Henry smelter. However, further research on the competitive performance of biofilms in the Point Henry ponds during the summer months is required before adequate biofilm management strategies can be developed.

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The metal strip used in roll forming has often been preprocessed by (tension or roller) leveling or by skin-pass rolling, and as a consequence, may contain residual stresses. These stresses are not well observed by the tensile test, but could have a significant effect on the bending and springback behavior. With the advent of improved process design techniques for roll forming, including advanced finite element techniques, the need for precise material property data has become important. The major deformation mode of roll forming is that of bending combined with unloading and reverse bending, and hence property data derived from bend tests could be more relevant than that from tensile testing.

This work presents a numerical study on the effect of skin passing on the material behavior of stainless steel strip in pure bending and tension. A two dimensional (2-D) numerical model was developed using Abaqus Explicit to analyze the affect of skin passing on the residual stress profile across a section for various working conditions. The deformed meshes and their final stress fields were then imported as pre-defined fields into Abaqus Standard, and the post-skin passing material behavior in pure bending was determined. The results show that a residual stress profile is introduced into the steel strip during skin passing, and that its shape and stress level depend on the overall thickness reduction as well as the number of rolling passes used in the skin passing process. The material behavior in bending and the amount of springback changed significantly depending on the skin pass condition.

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The research addressed performance issues for wireless signal transmission and has shown that performance improves with the help of relays due to increased diversity. Further, the areas of antenna selection and channel estimation and modelling has been investigated for improved cost and complexity and has shown to further enhance the performance of the wireless relay systems.