3,473 research outputs found

    Decentralized event-triggered control over wireless sensor/actuator networks

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    In recent years we have witnessed a move of the major industrial automation providers into the wireless domain. While most of these companies already offer wireless products for measurement and monitoring purposes, the ultimate goal is to be able to close feedback loops over wireless networks interconnecting sensors, computation devices, and actuators. In this paper we present a decentralized event-triggered implementation, over sensor/actuator networks, of centralized nonlinear controllers. Event-triggered control has been recently proposed as an alternative to the more traditional periodic execution of control tasks. In a typical event-triggered implementation, the control signals are kept constant until the violation of a condition on the state of the plant triggers the re-computation of the control signals. The possibility of reducing the number of re-computations, and thus of transmissions, while guaranteeing desired levels of performance makes event-triggered control very appealing in the context of sensor/actuator networks. In these systems the communication network is a shared resource and event-triggered implementations of control laws offer a flexible way to reduce network utilization. Moreover reducing the number of times that a feedback control law is executed implies a reduction in transmissions and thus a reduction in energy expenditures of battery powered wireless sensor nodes.Comment: 13 pages, 3 figures, journal submissio

    The Dynamics of International Trade Patterns

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    This paper introduces new dynamic measures for examining changes in international trade patterns. Using data for 20 OECD countries over the 1980-2000 period, we show that inter-industry trade changes contrary to countries' previous specialisation are frequently the dominant form of trade expansion. The econometric analysis indicates that the observed changes in trade patterns were explained by initial endowments of human-capital and industry-specific changes in labour productivity and labour costs. The results also suggest that trade liberalisation induced an increase in the previous specialisation of larger OECD economies in industries with increasing returns to scale.Dynamics of international specialisation, trade liberalisation, technology transfers.

    Governance and City Regeneration – A New Methodological Approach for Design and Evaluation

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    Governance has become a central topic among policymakers. There is an international consensus that policymaking is evolving from a traditional top-down government approach towards a system of governing that focuses on engaging the citizens within an area (Cabus, 2003). New forms of governance targeting urban competitiveness are increasingly oriented to vertical (between lower and high levels of government and cooperation forms between entities and firms along the production chain) and horizontal (between firms or different municipalities or public and private entities) cooperation (OEDC, 2005). Urban renewal policies underwent significant changes in recent decades. Synthetically, the following periods can be distinguished: 1970s: ñ€Ɠhardñ€ urban renewal – extensive physical interventions; 1980s: ñ€Ɠsoftñ€ urban renewal - efforts to keep the original population in place; 1990s: ñ€Ɠintegrated urban renewalñ€ - combining physical, economic and social interventions (Tosics, 2010). And over the last few years there has been a gradual shift in the understanding of what should be the tools and objectives of urban regeneration policies, with a greater emphasis on process-related and ‘soft’ issues of stakeholder engagement, partnership formation, leadership development, ‘institutional capacity’ development, knowledge and learning (Magalhães, 2004). This shift in the understanding of urban regeneration processes accomplishes the growing importance in literature of concepts like urban governance, institutional relational density, creativity, social capital, city branding and place marketing. The main purpose of this paper is to propose a new methodology for territorial analysis and planning focused on urban regeneration processes and its governance mechanisms. A new methodology that seeks, for each specific urban context, contribute to the following results: 1) Help select the most appropriate governance model to be adopted for each process of urban regeneration, 2) Monitor the partnership process and help promote the partnership guidance; 3) Support the design process and the definition of the strategic approach and projects, 4) Monitor the process of implementing the strategy and support multidimensional and multiscale evaluation of its results; 5) Evaluate the socio-economic and territorial impacts of urban regeneration processes.

    Governance and Creativity on Urban Regeneration Processes

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    Governance has become a central topic among policymakers. There is an international consensus that policymaking is evolving from a traditional top-down government approach towards a system of governing that focuses on engaging the citizens within an area (Cabus, 2003). New forms of governance targeting urban competitiveness are increasingly oriented to vertical (between lower and high levels of government and cooperation forms between entities and firms along the production chain) and horizontal (between firms or different municipalities or public and private entities) cooperation (OEDC, 2005). Based on a study research methodology, this article seeks to contribute to answer to the following research questions: i) what is the role of governance in the processes of urban regeneration?; ii) what is the role of governance in the development of creative processes for urban regeneration? and iii) what is the potential of governance to support urban regeneration strategies based on creativity and creative industries?Territorial governance, Creativity, Urban regeneration.

    The Innovation Public Policies and the Firms’ adoption of Innovative Processes - A New Methodological Approach for Evaluation

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    Today, innovation is present in the discourse of politicians and business leaders. They see innovation as a positive value and as a solution to solve social problems and company’s competitiveness, so organizations are encouraged to adopt innovative practices through incentives and innovation policies. Several economic and sociological studies have shown that Portuguese companies adopt more easily technological innovations (with short-term effects) then organizational and social innovations. In this sense, we will consider innovation public policies effects at Portuguese companies and how they take available opportunities for innovation. The aim is to know if the concept of innovation spread by these policies is multidimensional (eg social, economic and technological) or restricted. We propose to study the factors (internal and external) that affect innovation processes in enterprises through case studies methodology. This research strategy will show us the processes of innovation from within the organizations and analyze the socio-economic context in which organizations operate through a new methodological approach for evaluation.Innovation, Innovation Systems, Public Policies, Enterprises, Territory.

    Review of the genus Bursaphelenchus Fuchs, 1937 (Nematoda, Aphelenchida) with some conclusions on the host-parasite and vector-parasite evolution.

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    INTRODUCTION AND GOALS: Genus Bursaphelenchus includes several pests of the world importance for the rural economy, the most dangerous are the Bursaphelenchus xylophilus (the pinewood nematode caused decline of the pine trees in south Asia and in one spot area in Europe, Portugal, Peninsula de Setubal) and the Bursaphelenchus cocophilus, causing the decline of coco-palm plantations in Carribean and Latin American regions. The peculiarity of the host-parasite association of the genus that the nematode life cycle includes three trophic components: plant (mostly a tree), insect vector and a fungus. Goals of the presentation is to list all species of the world fauna and all efficient diagnostic characters, then create the identification tool and analyze the similarity of species and possible ways and causes of the host-parasite evolution of the group. RESULTS: Complete list of species with synonymy and a catalogue of all efficient diagnostic characters with their states, selected from papers of the most experienced taxonomists of the genus, are given for the genus Bursaphelenchus. List of known records of Bursaphelenchus species with names of natural vectors and plants and their families is given (for world pests the most important groups of trees and insects are listed). The tabular, traditional and computer-aided keys are presented. Dendrograms of species relationships (UPGMA, standard distance: mean character difference) based on all efficient taxonomic characters and separately on the spicule characters only, are given. Discussion whether the species groups are natural or purely diagnostic ones is based on the relationships dendrograms and the vector and associated plant ranges of Bursaphelenchus species; the xylophilus species group (B. xylophilus, B. abruptus, B. baujardi, B. conicaudatus, B. eroshenkii, B. fraudulentus, B. kolymensis, B. luxuriosae; B. mucronatus), the hunti group (B. hunti, B. seani, B. kevini and B. fungivorus) are probably the natural ones. CONCLUSIONS: The parasitic nematode association includes three trophic components: plant, insect vector and fungus. The initial insect-plant complex Scolytidae-Pinaceae is changeable and only in rare occasions the change of the preferred vector to Cerambycidae (the xylophilus group), Hymenoptera (the hunti group) led to formation of the natural species-groups. From the analysis it is clear that although the vector range is changeable it is comparatively more important for the evolution of the genus Bursaphelenchus than associations with plants at the family level. Data on the fungi species (3rd component in natural Bursaphelenchus associations) are insufficient for the detailed comparative analysis

    Computerized key to the genus Bursaphelenchus Fuchs, analysis of species clusters based on morphology, using information of insect vectors and associated plants, with a revision of the genus.

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    The genus Bursaphelenchus includes B. xylophilus (Steiner et Buhrer, 1934) Nickle, 1981, which is of world economic and quarantine importance. Distinction among several species of the pinewood nematodes species complex (PWNSC) is often difficult. Besides standard morphology, morphometrics and molecular biology, new tools are welcome to better understand this group. The computerized (or e-) key of this genus, presented in this communication, includes 74 species (complete list of valid species of the world fauna) and 35 characters, that were used by the taxonomic experts of this group, in the original descriptions. Morphology of sex organs (male spicules and female vulval region) was digitized and classified to distinguish alternative types. Several qualitative characters with overlapping character states (expressions) were transformed into the morphometric indices with the discontinuous ranges (characters of ratios of the spicule dimensions). Characters and their states (expressions) were illustrated in detail and supplied by brief user-friendly comments. E-key was created in the BIKEY identification system (Dianov & Lobanov, 1996-2004). The system has built-algorithm ranging characters depending on their diagnostic values at each step of identification. Matrix of species and the character states (structural part of the e-key database) may be easily transformed using statistical packages into the dendrograms of general phenetic similarities (UPGMA, standard distance: mean character difference). It may be useful in the detailed analysis of taxonomy and evolution of the genus and in its splitting to the species groups based on morphology. The verification of the dendrogram using the information on the species links with insect vectors and their associated plants, provided an opportunity to recognize the five clusters (xylophilus, hunti, eremus sensu stricto, tusciae and piniperdae sensu stricto), which seem to be the natural species groups. The hypothesis about the origin and the first stages of the genus evolution is proposed. A general review of the genus Bursaphelenchus is presented
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