999 resultados para wheel-rail contact


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Investigates the relationship between painting and photography, with a special focus on techniques using large contact negatives and digital applications. The thesis is comprised of a written exegesis that contextualises and informs upon an exhibition of photographic and digital inkjet montages. It discusses the theoretical and structural issues underpinning the conceptual basis of the research and elaborates upon the applications and processes involved in producing each exhibited image.

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The experiments reported in this thesis investigated the visual information used by observers to judge the time-to-contact (TTC) of approaching objects. The results provide support for the proposition that TTC judgements are based on retinal image expansion rate and observers' prior experience with the objects.

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This research investigated the benefits of children's contact with nature as perceived by adult educators. It was found that contact with nature is perceived to: increase self-confidence and self-esteem; provide opportunities to experience mystery, privacy, and sensory engagement; connect children with school; and accommodate different learning styles and abilities.

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Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to investigate correlations between the molecular changes and postcuring reaction on the surface of a diglycidyl ether of bisphenol A and diglycidylether of bisphenol F based epoxy resin cured with two different amine-based hardeners. The aim of this work was to present a proof of concept that ToF-SIMS has the ability to provide information regarding the reaction steps, path, and mechanism for organic reactions in general and for epoxy resin curing and postcuring reactions in particular. Contact-angle measurements were taken for the cured and postcured epoxy resins to correlate changes in the surface energy with the molecular structure of the surface. Principal components analysis (PCA) of the ToFSIMS positive spectra explained the variance in the molecular information, which was related to the resin curing and postcuring reactions with different hardeners and to the surface energy values. The first principal component captured information related to the chemical phenomena of the curing reaction path, branching, and network density based on changes in the relative ion density of the aliphatic hydrocarbon and the C7H7O+ positive ions. The second principal component captured information related to the difference in the surface energy, which was correlated to the difference in the relative intensity of the CxHyNz+ ions of the samples. PCA of the negative spectra provided insight into the extent of consumption of the hardener molecules in the curing and postcuring reactions of both systems based on the relative ion intensity of the nitrogen-containing negative ions and showed molecular correlations with the sample surface energy.

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This paper presents a novel optical fibre based micro contact probe system with high sensitivity and repeatability. In this optical fibre probe with a fused spherical tip, a fibre Bragg grating has been utilized as a strain sensor in the probe stem. When the probe tip contacts the surface of the part, a strain will be induced along the probe stem and will produce a Bragg wavelength shift. The contact signal can be issued once the wavelength shift signal is produced and demodulated. With the fibre grating sensor element integrated into the probe directly, the probe system shows a high sensitivity. In this work, the strain distributions along the probe stem with the probe under axial and lateral load are analysed. A simulation of the strain distribution was performed using the finite element package ANSYS 11. Performance tests using a piezoelectric transducer stage with a displacement resolution of 1.5 nm yielded a measurement resolution of 60 nm under axial loading.

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This paper uses information contributed by ACM-W Ambassadors from nine countries to build a picture of women working to improve the gender balance in IT around the world. The focus on women’s participation in education, the workforce and the political arena is presented using Hofstede and Hofstede’s (2005) dimensions of cultural masculinity, power distribution and individuality for each of the ACM-W Ambassador countries to set the scene. It is apparent from this compilation of information that different social and cultural climates in many parts of the world will necessitate different actions by ACM-W Ambassadors in their respective countries. While the ACM-W Ambassador program provides a forum for ideas, support and strategies to deal with the under-representation of women in IT, many of the current Ambassadors have more pressing issues to deal with, and indeed a ‘one size for all’ model for programs to promote IT to women will not be suitable. Exploring the network from an Australian perspective this work demonstrates that much is to be gained from increasing international networks to share the strategies and support required to encourage more women into IT.

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Internet-based interventions with therapist support have proven effective for treating a range of mental health conditions. This study examined whether frequency of therapist contact affected treatment outcomes. Fifty-seven people with panic disorder (including 32 with agoraphobia) were randomly allocated to an 8-week Internet-based cognitive behavioural treatment intervention (Panic Online) with either frequent (three e-mails per week) or infrequent (one e-mail per week) support from a psychologist. Posttreatment, intention-to-treat analyses revealed that both treatments were effective at improving panic disorder and agoraphobia severity ratings, panicrelated cognitions, negative affect, and psychological and physical quality of life domains, with no differences between conditions. High end-state functioning was achieved by 28.6% of the frequent and infrequent participants, respectively. Therapist alliance, treatment credibility, and satisfaction also did not differ between groups, despite significantly greater therapist time invested in the frequent contact condition. The results provide evidence that the effectiveness of Internet-based mental health interventions may be independent of the frequency of therapist support and may, therefore, be more cost-effective than previously reported.

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The boundary films generated on a series of inorganic compounds, typical of native films on metal and ceramic surfaces, when exposed to various ionic liquids (ILs) based on the trihexyl(tetradecyl)phosphonium cation have been characterized using multinuclear solid-state NMR. The NMR results indicate that SiO2 and Mg(OH)2 interact strongly with the anion and cation of each IL through a mechanism of adsorption of the anion and subsequent close proximity of the cation in a surface double layer (as observed through 1H−29Si cross polarization experiments). In contrast, Al2O3, MgO, ZnO, and ZrO2 appear less active, strongly suggesting the necessity of hydroxylated surface groups in order to enhance the generation of these interfacial films. Using solid-state NMR to characterize such interfaces not only has the potential to elucidate mechanisms of wear resistance and corrosion protection via ILs, but is also likely to allow their rapid screening for such durability applications.

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This paper directly examines the contact sliding distance experienced during a typical sheet metal stamping process-an area that has largely been neglected in the literature. A method to numerically quantify the sliding distance is proposed. The sliding distance predicted from this method, and the contact pressure obtained from numerical simulation, allow the recently identified time-dependent contact conditions on the die and blank surfaces to be completely characterized. Consequently, a new insight into the wear/galling that occurs at the die radius in sheet metal stamping is gained. The results show that the region close to zero degrees on the die radius is likely to experience the most wear, with the identified transient stage contributing to a large proportion of the total wear. Additionally, the region on the blank surface often observed to be heavily burnished - the die impact line - is estimated to experience the highest wear severity due to the transient contact conditions. The proposed method to numerically quantify the sliding contact conditions can be applied as a general approach to study any other two-body sliding contact situations.

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This paper addresses the leader-follower tracking problem of a four-wheel-steering robot subjected to nonlinear uncertainties. Two control laws have been developed, based on the adaptive sliding mode method and the adaptive input-output feedback linearization method. The proposed control schemes have been tested by means of simulations.

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As the portable entertainment and mobility technologies migrate into the car, driver distraction has become recognized as a major factor in road crashes around the world. To help alert drivers to their distraction, active safety technologies such as lane departure warning systems and collision avoidance systems are being implemented. One issue with the implementation of yet another technology into the vehicle is how to cut through the competing demands of the mobile phone, navigation systems and other technologies. Haptic alerts present just such a method that may enable the system to short-circuit the normal auditory or visual communication channels. This paper presents a low cost haptic steering wheel controller that has been designed developed and tested and may be used as a communication device by a lane departure, collision avoidance, or other type of safety system.