988 resultados para descriptions


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The role of polarisation in late time complex resonance based target identification is investigated numerically for the case of an L-shaped wire. While repeated extraction of the resonances for varying polarisation allows for better signal-to-noise immunity, it is also found that there are preferred polarisations for each complex resonance. The first few of these polarisations are extracted for the sample target.

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Cephalosphaera Enderlein is a nearly cosmopolitan genus of big-headed flies (Pipunculidae) which was previously unknown from Australia. Four species have now been found in Australia, all of them undescribed. New species in the subgenus Neocephalosphaera include: C. eukrenaina, C. parthenopipis and C. petila. Only one new species occurs in the nominate subgenus: C. prionotaina. Descriptions and a key to these species are presented.

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Context information is used by pervasive networking and context-aware programs to adapt intelligently to different environments and user tasks. As the context information is potentially sensitive, it is often necessary to provide privacy protection mechanisms for users. These mechanisms are intended to prevent breaches of user privacy through unauthorised context disclosure. To be effective, such mechanisms should not only support user specified context disclosure rules, but also the disclosure of context at different granularities. In this paper we describe a new obfuscation mechanism that can adjust the granularity of different types of context information to meet disclosure requirements stated by the owner of the context information. These requirements are specified using a preference model we developed previously and have since extended to provide granularity control. The obfuscation process is supported by our novel use of ontological descriptions that capture the granularity relationship between instances of an object type.

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This research seeks to generate and foster new descriptions and understandings of processes underlying the internationalisation experienced by small- and medium-sized, knowledge-intensive enterprises. The longitudinal study centres on the growth and internationalisation of a cluster of small- and medium-sized enterprises (SMEs) in the most southern state of Australia, of which a number were 'bom global.' It draws on both retrospective data such as corporate archives, as well as observations and interviews as events unfolded over a period of eighteen months to garner insights into processes underlying the SMEs' internationalisation. The approach to inquiry is influenced by an epistemology of social constructionism, interpretive narrative, sensemaking and dramaturgical theoretical perspectives, and elements of cultural anthropology. Exploratory in the early stages, a funnel approach characteristic of ethnographic enquiry was used whereby the study became progressively focused over time. The extended period of fieldwork led to observations and interpretations that cast the retrospective data in new light, and the use of the construct 'legitimacy' as a lens through which to view activities and events infusing the firms' internationalisation. A generic narrative scheme that offers a temporal ordering of actions, context and meaning attributions in relation to legitimation behaviours and internationalisation processes is developed. This narrative scheme is then used to garner a deeper understanding of three activities that were central to the firms' internationalisation over time: the choice of geographic export markets, strategic participation in international standard-setting committees, and portfolio entrepreneurship. In addition, the study offers a rich story of the growth and internationalisation of the cluster of knowledge-intensive SMEs. The tale of growth and internationalisation pursued by the cluster of knowledgeintensive SMEs spans the period from 1975 to mid 1997, and may prove a useful resource for the theorising of others.

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We present in this paper ideas to tackle the problem of analysing and forecasting nonstationary time series within the financial domain. Accepting the stochastic nature of the underlying data generator we assume that the evolution of the generator's parameters is restricted on a deterministic manifold. Therefore we propose methods for determining the characteristics of the time-localised distribution. Starting with the assumption of a static normal distribution we refine this hypothesis according to the empirical results obtained with the methods anc conclude with the indication of a dynamic non-Gaussian behaviour with varying dependency for the time series under consideration.

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A preliminary study by Freeman et al (1996b) has suggested that when complex patterns of motion elicit impressions of 2-dimensionality, odd-item-out detection improves given targets can be differentiated on the basis of surface properties. Their results can be accounted for, it if is supposed that observers are permitted efficient access to 3-D surface descriptions but access to 2-D motion descriptions is restricted. To test the hypothesis, a standard search technique was employed, in which targets could be discussed on the basis of slant sign. In one experiment, slant impressions were induced through the summing of deformation and translation components. In a second theory were induced through the summing of shear and translation components. Neither showed any evidence of efficient access. A third experiment explored the possibility that access to these representations may have been hindered by a lack of grouping between the stimuli. Attempts to improve grouping failed to produce convincing evidence in support of life. An alternative explanation is that complex patterns of motion are simply not processed simultaneously. Psychophysical and physiological studies have, however, suggested that multiple mechanisms selective for complex motion do exist. Using a subthreshold summation technique I found evidence supporting the notion that complex motions are processed in parallel. Furthermore, in a spatial summation experiment, coherence thresholds were measured for displays containing different numbers of complex motion patches. Consistent with the idea that complex motion processing proceeds in parallel, increases in the number of motion patches were seen to decrease thresholds, both for expansion and rotation. Moreover, the rates of decrease were higher than those typically expected from probability summation, thus implying mechanisms are available, which can pool signals from spatially distinct complex motion flows.

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We study how the spatial distribution of inertial particles evolves with time in a random flow. We describe an explosive appearance of caustics and show how they influence an exponential growth of clusters due to smooth parts of the flow, leading in particular to an exponential growth of the average distance between particles. We demonstrate how caustics restrict applicability of Lagrangian description to inertial particles.

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Four bar mechanisms are basic components of many important mechanical devices. The kinematic synthesis of four bar mechanisms is a difficult design problem. A novel method that combines the genetic programming and decision tree learning methods is presented. We give a structural description for the class of mechanisms that produce desired coupler curves. Constructive induction is used to find and characterize feasible regions of the design space. Decision trees constitute the learning engine, and the new features are created by genetic programming.

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The project “Reference in Discourse” deals with the selection of a specific object from a visual scene in a natural language situation. The goal of this research is to explain this everyday discourse reference task in terms of a concept generation process based on subconceptual visual and verbal information. The system OINC (Object Identification in Natural Communicators) aims at solving this problem in a psychologically adequate way. The system’s difficulties occurring with incomplete and deviant descriptions correspond to the data from experiments with human subjects. The results of these experiments are reported.

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Earlier the authors have suggested a logical level description of classes which allows to reduce a solution of various pattern recognition problems to solution of a sequence of one-type problems with the less dimension. Here conditions of the effectiveness of the use of such a level descriptions are proposed.

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A verification task of proving the equivalence of two descriptions of the same device is examined for the case, when one of the descriptions is partially defined. In this case, the verification task is reduced to checking out whether logical descriptions are equivalent on the domain of the incompletely defined one. Simulation-based approach to solving this task for different vector forms of description representations is proposed. Fast Boolean computations over Boolean and ternary vectors having big sizes underlie the offered methods.

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* The research presented here is partially supported by the project KT-DigiCult-Bg (FP6) and by the ICT Agency in Bulgaria.