504 research outputs found

    The Sources of Economic Energy.

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    The time and space so loved by philosophers and poets, burden and delight of physicists and astronomists, for a long time have been more for economists elements of inconvenience than of analysis. All this finds a justification in the mechanistic logic which also regulates the great economic theories. But the “Newtonian†general economic theory, fascinating though it is and irreplaceable in conferring rigour to theoretical formulations and reducing to a simplified form the apparently (or real) chaos of the great systems, in its necessarily high flying it is unsuitable to interpreting the local level where, instead, it is indispensable to keep one’s feet on the ground, to move in the territory following the infinite combinations of the surrounding countryside, to worm oneself into the maze of economic and social interrelations which make it unique and unrepeatable.The long journey began with the Solow type neoclassical growth models, characterised by the production function with decreasing returns and with perfect market forms, passing through endogenous growth models, now reaches territorialised forms, which have the advantage of being less abstract than neoclassical models, in that they operate in imperfect markets, but which do not manage to keep the growth rate under control, which is always given as positive. From “implosive†models we pass to “explosive†models.Forceably including local interrelations into classical production functions is not successful in overcoming the basic contradictions between Newtonian determinism and localistic indeterminism, with the result that the classical elegance is lost without acquiring localistic concreteness Now the new physicists are trying again with the String Theory, above all in the M version or the Theory of Everything. But this fascinating theory does not yet allow us to understand some fundamental things, for example it does not tell us why particles align in a certain way, in a certain order and with a certain potential. Adapting concepts and paths elaborated by post-Newtonian physics, the economist could do much less and a bit more. Much less because he is not required to solve in any way the mysteries of the universe, a bit more because, perhaps, he can describe without contradictions, using known economic science, what physicists, in their field, are not able to describe: he can tell us, using formal models why at a certain point in time and space a determined productive set composed of a well defined number of “economics quanta†relative to material and immaterial elements, of which is known the magnitude, order and force, behaves like a string and begins to “vibrate†setting off the chain reaction of economic development.

    Unsupervised clustering of IoT signals through feature extraction and self organizing maps

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    This thesis scope is to build a clustering model to inspect the structural properties of a dataset composed of IoT signals and to classify these through unsupervised clustering algorithms. To this end, a feature-based representation of the signals is used. Different feature selection algorithms are then used to obtain reduced feature spaces, so as to decrease the computational cost and the memory demand. Thus, the IoT signals are clustered using Self-Organizing Maps (SOM) and then evaluatedope

    Learning object behaviour models

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    The human visual system is capable of interpreting a remarkable variety of often subtle, learnt, characteristic behaviours. For instance we can determine the gender of a distant walking figure from their gait, interpret a facial expression as that of surprise, or identify suspicious behaviour in the movements of an individual within a car-park. Machine vision systems wishing to exploit such behavioural knowledge have been limited by the inaccuracies inherent in hand-crafted models and the absence of a unified framework for the perception of powerful behaviour models. The research described in this thesis attempts to address these limitations, using a statistical modelling approach to provide a framework in which detailed behavioural knowledge is acquired from the observation of long image sequences. The core of the behaviour modelling framework is an optimised sample-set representation of the probability density in a behaviour space defined by a novel temporal pattern formation strategy. This representation of behaviour is both concise and accurate and facilitates the recognition of actions or events and the assessment of behaviour typicality. The inclusion of generative capabilities is achieved via the addition of a learnt stochastic process model, thus facilitating the generation of predictions and realistic sample behaviours. Experimental results demonstrate the acquisition of behaviour models and suggest a variety of possible applications, including automated visual surveillance, object tracking, gesture recognition, and the generation of realistic object behaviours within animations, virtual worlds, and computer generated film sequences. The utility of the behaviour modelling framework is further extended through the modelling of object interaction. Two separate approaches are presented, and a technique is developed which, using learnt models of joint behaviour together with a stochastic tracking algorithm, can be used to equip a virtual object with the ability to interact in a natural way. Experimental results demonstrate the simulation of a plausible virtual partner during interaction between a user and the machine

    Biometric signals compression with time- and subject-adaptive dictionary for wearable devices

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    This thesis work is dedicated to the design of a lightweight compression technique for the real-time processing of biomedical signals in wearable devices. The proposed approach exploits the unsupervised learning algorithm of the time-adaptive self-organizing map (TASOM) to create a subject-adaptive codebook applied to the vector quantization of a signal. The codebook is obtained and then dynamically refined in an online fashion, without requiring any prior information on the signal itsel

    Artificial Intelligence in geospatial analysis: applications of self-organizing maps in the context of geographic information science.

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    A thesis submitted in partial fulfillment of the requirements for the degree of Doctor in Information Management, specialization in Geographic Information SystemsThe size and dimensionality of available geospatial repositories increases every day, placing additional pressure on existing analysis tools, as they are expected to extract more knowledge from these databases. Most of these tools were created in a data poor environment and thus rarely address concerns of efficiency, dimensionality and automatic exploration. In addition, traditional statistical techniques present several assumptions that are not realistic in the geospatial data domain. An example of this is the statistical independence between observations required by most classical statistics methods, which conflicts with the well-known spatial dependence that exists in geospatial data. Artificial intelligence and data mining methods constitute an alternative to explore and extract knowledge from geospatial data, which is less assumption dependent. In this thesis, we study the possible adaptation of existing general-purpose data mining tools to geospatial data analysis. The characteristics of geospatial datasets seems to be similar in many ways with other aspatial datasets for which several data mining tools have been used with success in the detection of patterns and relations. It seems, however that GIS-minded analysis and objectives require more than the results provided by these general tools and adaptations to meet the geographical information scientist‟s requirements are needed. Thus, we propose several geospatial applications based on a well-known data mining method, the self-organizing map (SOM), and analyse the adaptations required in each application to fulfil those objectives and needs. Three main fields of GIScience are covered in this thesis: cartographic representation; spatial clustering and knowledge discovery; and location optimization.(...

    Machine Learning

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    Machine Learning can be defined in various ways related to a scientific domain concerned with the design and development of theoretical and implementation tools that allow building systems with some Human Like intelligent behavior. Machine learning addresses more specifically the ability to improve automatically through experience

    Autonomy in the real real-world: A behaviour based view of autonomous systems control in an industrial product inspection system

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    The thesis presented in this dissertation appears in two sequential parts that arose from an exploration of the use of Behaviour Based Artificial Intelligence (BBAI) techniques in a domain outside that of robotics, where BBAI is most frequently used. The work details a real-world physical implementation of the control and interactions of an industrial product inspection system from a BBAI perspective. It concentrates particularly on the control of a number of active laser scanning sensor systems (each a subsystem of a larger main inspection system), using a subsumption architecture. This industrial implementation is in itself a new direction for BBAI control and an important aspect of this thesis. However, the work has also led on to the development of a number of key ideas which contribute to the field of BBAI in general. The second part of the thesis concerns the nature of physical and temporal constraints on a distributed control system and the desirability of utilising mechanisms to provide continuous, low-level learning and adaptation of domain knowledge on a sub-behavioural basis. Techniques used include artificial neural networks and hill-climbing state-space search algorithms. Discussion is supported with examples from experiments with the laser scanning inspection system. Encouraging results suggest that concerted design effort at this low level of activity will benefit the whole system in terms of behavioural robustness and reliability. Relevant aspects of the design process that should be of value in similar real-world projects are identified and emphasised. These issues are particularly important in providing a firm foundation for artificial intelligence based control systems
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