912 resultados para Parallels (Geometry)
Resumo:
Braking or traction torque is regarded as an important source of wheelset skid and a potential source of derailment risk that adversely affects the safety levels of train operations; therefore, this research examines the effect of braking/traction torque to the longitudinal and lateral dynamics of wagons. This paper reports how train operations safety could be adversely affected due to various braking strategies. Sensitivity of wagon dynamics to braking severity is illustrated through numerical examples. The influence of wheel/rail interface friction coefficient and the effects of two types of track geometry defects on wheel unloading ratio and wagon pitch are also discussed in the paper.
Resumo:
Purpose: The purpose of this paper is to report the resistance of plasma-sprayed titanium dioxide (TiO2) nanostructured coatings in a corrosive environment.----- Design/methodology/approach: Weight loss studies are performed according to ASTM G31 specifications in 3.5?wt% NaCl. Electrochemical polarization resistance measurements are made according to ASTM G59-91 specifications. Corrosion resistance in a humid and corrosive environment is determined by exposing the samples in a salt spray chamber for 100?h. Microstructural studies are carried out using an atomic force microscope and scanning electron microscope.----- Findings: The nanostructured TiO2 coatings offer good resistance to corrosion, as shown by the results of immersion, electrochemical and salt spray studies. The corrosion resistance of the coating is dictated primarily by the geometry of splat lamellae, density of unmelted nanoparticles, magnitude of porosity and surface homogeneity.----- Practical implications: The TiO2 nanostructured coatings show promising potential for use as abrasion, wear-resistant and thermal barrier coatings for service in harsh environments.----- Originality/value: The paper relates the corrosion resistance of nanostructured TiO2 coatings to their structure and surface morphology.
Resumo:
This article explores the contributions of two unique Australian women, Annette Kellerman and Florence Broadhurst, to global fashion and aesthetics through subverting and challenging female gender roles of the early twentieth century. These two women are brought together here as a means of highlighting their markedly contrasting social tactics: undressing versus layering. Kellerman's body became an instrument in her quest for global fame, engaging in daring public "undress" in swimming and diving performances around the world that served to show case her innovative swimwear design. In contrast, Broadhurst, through repeated reconstructions of her persona and constant relayering of identities, concocted versions of herself in order to pass through Shanghai, London, and Sydney societies. Their lives exist as binaristic parallels, expressing contrasting values of un-Australianness - the disavowal of national identity; and Australianness - the promotion of national identity. Both Kellerman and Broadhurst tested the limits of body, dress and national identity as vehicles for global recognition. The recent interest in their historical roles is evidenced in the films "The original Mermaid"( 2004) and "Unfolding Florence" (2005) in addition to numerous books and journal articles. Despite this resurgent public recognition of their lives and achievements, scholarly analysis of their legacies in the fields of fashion and design are still relatively neglected. This article explores their contributions to celebrity and modernity, fashion and gender as modern un-Australian women.
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This correspondence presents a microphone array shape calibration procedure for diffuse noise environments. The procedure estimates intermicrophone distances by fitting the measured noise coherence with its theoretical model and then estimates the array geometry using classical multidimensional scaling. The technique is validated on noise recordings from two office environments.
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Near-infrared spectroscopy is a somewhat unutilised technique for the study of minerals. The technique has the ability to determine water content, hydroxyl groups and transition metals. In this paper we show the application of NIR spectroscopy to the study of selected minerals. The structure and spectral properties of two Cu-tellurite minerals graemite and teineite are compared with bismuth containing tellurite mineral smirnite by the application of NIR and IR spectroscopy. The position of Cu2+ bands and their splitting in the electronic spectra of tellurites are in conformity with octahedral geometry distortion. The spectral pattern of smirnite resembles graemite and the observed band at 10855 cm-1 with a weak shoulder at 7920 cm-1 is identified as due to Cu2+ ion. Any transition metal impurities may be identified by their bands in this spectral region. Three prominent bands observed in the region of 7200-6500 cm-1 are the overtones of water whilst the weak bands observed near 6200 cm-1in tellurites may be attributed to the hydrogen bonding between (TeO3)2- and H2O. The observation of a number of bands centred at around 7200 cm-1 confirms molecular water in tellurite minerals. A number of overlapping bands in the low wavenumbers 4500-4000 cm-1 is the result of combinational modes of (TeO3)2−ion. The appearance of the most intense peak at 5200 cm-1 with a pair of weak bands near 6000 cm-1 is a common feature in all the spectra and is related to the combinations of OH vibrations of water molecules, and bending vibrations ν2 (δ H2O). Bending vibrations δ H2O observed in the IR spectra shows a single band for smirnite at 1610 cm-1. The resolution of this band into number of components is evidenced for non-equivalent types of molecular water in graemite and teineite. (TeO3)2- stretching vibrations are characterized by three main absorptions at 1080, 780 and 695 cm-1.
Resumo:
Residents, businesses, local, state and national government stakeholders all want to have their say when airports expand or develop. While stakeholder engagement is increasingly a strategy employed for managing the tensions attracted to airport development, different stakeholders have different expectations and demands of airports. This requires different approaches to stakeholder engagement. Identifying the public interests that are at stake in developing airports provides an initial step towards building a platform for selecting and applying stakeholder engagement strategies in airport and more general infrastructure contexts. This paper uses the existing literature of public interests and values to build a general typology of public values for the stakeholders of airport development. A range of semi-privatised and state owned airport case studies from Europe have been used to demonstrate the universal nature of the identified values. The result is a framework that identifies both the substantive and procedural values, separated into local, state/regional and national levels of interest. The typology provides a generalised view of public interests in airport development; however, the public interests identified may be limited to more western oriented societies due to the skew of airport cases reviewed. Contributions are made to the literature with a typology of public values derived from existing knowledge and explored using empirical case examples. The provided typology enables research of airport development decision-making to delineate public interests both within and between stakeholder groups, and helps to explain the different perspectives that stakeholders have towards airport development. Future research may focus on refining the typology for different types of airport governance structures, such as differences between public values in state and market-led airport development; include more airport cases from eastern societies to draw parallels or differences between western and eastern societies; or utilise the typology as a framework for analysing changes in public interests of airports over time.
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Because aesthetics can have a profound effect upon the human relationship to the non-human environment the importance of aesthetics to ecologically sustainable designed landscapes has been acknowledged. However, in recognition that the physical forms of designed landscapes are an expression of the social values of the time, some design professionals have called for a new aesthetic ― one that reflects these current ecological concerns. To address this, some authors have suggested various theoretical design frameworks upon which such an aesthetic could be based. Within these frameworks there is an underlying theme that the patterns and processes of natural systems have the potential to form a new aesthetic for landscape design —an aesthetic based on fractal rather than Euclidean geometry. Perry, Reeves and Sim (2008) have shown that it is possible to differentiate between different landscape forms by fractal analysis. However, this research also shows that individual scenes from within very different landscape forms can possess the same fractal properties. Early data, revealed by transforming landscape images from the spatial to the frequency domain, using the fast Fourier transform, suggest that fractal patterning can have a significant effect within the landscape. In fact, it may be argued that any landscape design that includes living processes will include some design element whose ultimate form can only be expressed through the mathematics of fractal geometry. This paper will present ongoing research into the potential role of fractal geometry as a basis for a new form language – a language that may articulate an aesthetic for landscape design that echoes our ecological awakening.
Resumo:
Natural iowaite, magnesium–ferric oxychloride mineral having light green color originating from Australia has been characterized by EPR, optical, IR, and Raman spectroscopy. The optical spectrum exhibits a number of electronic bands due to both Fe(III) and Mn(II) ions in iowaite. From EPR studies, the g values are calculated for Fe(III) and g and A values for Mn(II). EPR and optical absorption studies confirm that Fe(III) and Mn(II) are in distorted octahedral geometry. The bands that appear both in NIR and Raman spectra are due to the overtones and combinations of water and carbonate molecules. Thus EPR, optical, and Raman spectroscopy have proven most useful for the study of the chemistry of natural iowaite and chemical changes in the mineral.
Resumo:
In this paper, the problems of three carrier phase ambiguity resolution (TCAR) and position estimation (PE) are generalized as real time GNSS data processing problems for a continuously observing network on large scale. In order to describe these problems, a general linear equation system is presented to uniform various geometry-free, geometry-based and geometry-constrained TCAR models, along with state transition questions between observation times. With this general formulation, generalized TCAR solutions are given to cover different real time GNSS data processing scenarios, and various simplified integer solutions, such as geometry-free rounding and geometry-based LAMBDA solutions with single and multiple-epoch measurements. In fact, various ambiguity resolution (AR) solutions differ in the floating ambiguity estimation and integer ambiguity search processes, but their theoretical equivalence remains under the same observational systems models and statistical assumptions. TCAR performance benefits as outlined from the data analyses in some recent literatures are reviewed, showing profound implications for the future GNSS development from both technology and application perspectives.
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Research in services has long recognized the need for managers to focus internally on employees as well as externally on customers. This internal focus is the domain of internal marketing. Despite over 2 decades of discussion of internal marketing, most operationalizations of marketing are grounded in ideas of product markets and remain resolutely focused on the external market, ignoring the internal focus necessary in services markets. Such operationalizations of marketing are outdated in modern markets where most purchases involve a combination of product and service elements, and, in the long term, service quality may be more important than product quality to the consumer. This paper reconceptualizes marketing and develops a new construct, ‘internal market orientation’ (IMO), which closely parallels and complements existing models of external market orientation. The relationship between internal and external market orientations is explored, and the performance implications of IMO are discussed. A second model of these proposed relationships is presented with implications for managers and recommendations for future research.
Resumo:
Foam-filled conical tubes have recently emerged as efficient energy absorbing devices to mitigate the adverse effects of impacts. The primary aim of this thesis was to generate research and design information on the impact and energy absorption response of empty and foam-filled conical tubes, and to facilitate their application in energy absorbing systems under axial and oblique loading conditions representative of those typically encountered in crashworthiness and impact applications. Finite element techniques supported by experiments and existing results were used in the investigation. Major findings show that the energy absorption response can be effectively controlled by varying geometry and material parameters. A useful empirical formula was developed for providing engineering designers with an initial estimate of the load ratio and hence energy absorption performances of these devices. It was evident that foam-filled conical tubes enhance the energy absorption capacity and stabilise the crush response for both axial and oblique impact loading without a significant increase in the initial peak load. This is practically beneficial when higher kinetic energy needs to be absorbed, thus reducing the impact force transmitted to the protected structure and occupants. Such tubes also increase and maintain the energy absorption capacity under global bending as well as minimise the reduction of energy absorption capacity with increasing load angle. Furthermore, the results also highlight the feasibility of adding a foam-filled conical tube as a supplementary device in energy absorbing systems, since the overall energy absorption performance of such systems can be favourably enhanced by only including a relatively small energy absorbing device. Above all, the results demonstrate the superior performance of foam-filled conical tube for mitigating impact energy in impact and crashworthiness applications.
Resumo:
Analytical and computational models of the intervertebral disc (IVD) are commonly employed to enhance understanding of the biomechanics of the human spine and spinal motion segments. The accuracy of these models in predicting physiological behaviour of the spine is intrinsically reliant on the accuracy of the material constitutive representations employed to represent the spinal tissues. There is a paucity of detailed mechanical data describing the material response of the reinforcedground matrix in the anulus fibrosus of the IVD. In the present study, the ‘reinforcedground matrix’ was defined as the matrix with the collagen fibres embedded but not actively bearing axial load, thus incorporating the contribution of the fibre-fibre and fibre-matrix interactions. To determine mechanical parameters for the anulus ground matrix, mechanical tests were carried out on specimens of ovine anulus, under unconfined uniaxial compression, simple shear and biaxial compression. Test specimens of ovine anulus fibrosus were obtained with an adjacent layer of vertebral bone/cartilage on the superior and inferior specimen surface. Specimen geometry was such that there were no continuous collagen fibres coupling the two endplates. Samples were subdivided according to disc region - anterior, lateral and posterior - to determine the regional inhomogeneity in the anulus mechanical response. Specimens were loaded at a strain rate sufficient to avoid fluid outflow from the tissue and typical stress-strain responses under the initial load application and under repeated loading were determined for each of the three loading types. The response of the anulus tissue to the initial and repeated load cycles was significantly different for all load types, except biaxial compression in the anterior anulus. Since the maximum applied strain exceeded the damage strain for the tissue, experimental results for repeated loading reflected the mechanical ability of the tissue to carry load, subsequent to the initiation of damage. To our knowledge, this is the first study to provide experimental data describing the response of the ‘reinforcedground matrix’ to biaxial compression. Additionally, it is novel in defining a study objective to determine the regionally inhomogeneous response of the ‘reinforcedground matrix’ under an extensive range of loading conditions suitable for mechanical characterisation of the tissue. The results presented facilitate the development of more detailed and comprehensive constitutive descriptions for the large strain nonlinear elastic or hyperelastic response of the anulus ground matrix.
Resumo:
Residents, businesses, local, state and national government stakeholders all want to have their say when airports expand or develop. While stakeholder engagement is increasingly a strategy employed for managing the tensions attracted to airport development, different stakeholders have different expectations and demands of airports. This requires different approaches to stakeholder engagement. Identifying the public values that are at stake in developing airports provides an initial step towards building a platform for selecting and applying stakeholder engagement strategies in airport and more general infrastructure contexts. -------- This paper uses the existing literature of public values to build a general typology of public values for the stakeholders of airport development. A range of semi-privatised and state owned airport case studies from Europe have been used to demonstrate the universal nature of the identified values. The result is a framework that identifies both the substantive and procedural values, separated into local, state/regional and national levels of interest. The typology provides a generalised view of public values in airport development; however, the public values identified may be limited to more western oriented societies due to the skew of airport cases reviewed. --------- Contributions are made to the literature with a typology of public values derived from existing knowledge and explored using empirical case examples. The provided typology enables research of airport development decision-making to delineate public values both within and between stakeholder groups, and helps to explain the different perspectives that stakeholders have towards airport development. Future research may focus on refining the typology for different types of airport governance structures, such as differences between public values in state and market-led airport development; include more airport cases from eastern societies to draw parallels or differences between western and eastern societies; or utilise the typology as a framework for analysing changes in public values of airports over time.
Resumo:
This paper describes the real time global vision system for the robot soccer team the RoboRoos. It has a highly optimised pipeline that includes thresholding, segmenting, colour normalising, object recognition and perspective and lens correction. It has a fast ‘paint’ colour calibration system that can calibrate in any face of the YUV or HSI cube. It also autonomously selects both an appropriate camera gain and colour gains robot regions across the field to achieve colour uniformity. Camera geometry calibration is performed automatically from selection of keypoints on the field. The system achieves a position accuracy of better than 15mm over a 4m × 5.5m field, and orientation accuracy to within 1°. It processes 614 × 480 pixels at 60Hz on a 2.0GHz Pentium 4 microprocessor.
Resumo:
A pragmatic method for assessing the accuracy and precision of a given processing pipeline required for converting computed tomography (CT) image data of bones into representative three dimensional (3D) models of bone shapes is proposed. The method is based on coprocessing a control object with known geometry which enables the assessment of the quality of resulting 3D models. At three stages of the conversion process, distance measurements were obtained and statistically evaluated. For this study, 31 CT datasets were processed. The final 3D model of the control object contained an average deviation from reference values of −1.07±0.52 mm standard deviation (SD) for edge distances and −0.647±0.43 mm SD for parallel side distances of the control object. Coprocessing a reference object enables the assessment of the accuracy and precision of a given processing pipeline for creating CTbased 3D bone models and is suitable for detecting most systematic or human errors when processing a CT-scan. Typical errors have about the same size as the scan resolution.