299 research outputs found

    Assessing the ability of rural areas to fulfill multiple societal demands

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    Rural areas are changing through a process of multifunctional transition. New societal expectations, including countryside consumption and protection, increasingly determine the way rural space is used. There is a pressing need to grasp the new relative balance between these drivers of the rural space, in each particular area, in order to target public intervention. Tackling differentiation within rural space will definitely contribute to developing the potential and vocation of each area while supporting territorial cohesion. In this context, sound analytical knowledge that reveals and characterizes this differentiation is required and novel analytical approaches are needed for this knowledge to be obtained. Based on the conceptual framework proposed by Holmes (2006, 2012), this paper presents two methodological pathways for defining a typology of European regions that considers the multifunctionality of rural areas today and the relative weight of the dimensions of production, protection and consumption. The classification is produced at Nomenclature Territorial Unit NUTS 2 level, using information derived from European statistical datasets compiling different cartographic sources. One of the methods used to develop a typology was a clustering approach while the other method used was an expert-based analytical procedure. Even when the limitations stemming from the data available for the whole of Europe are considered, the results are encouraging. The results show two different regional distributions in Europe. These distributions, which have some similarities but also certain differences, both reveal the general characteristics of NUTS 2 regions and shed new light on the ways in which societal expectations for production, protection and consumption might be spatially reconciled. The expert-based approach seems to produce a more faithful classification. Both typologies result in most regions being classified as pluri-active, or complex or multifunctional, which may indicate that multiple modes of rural occupancy are widely found in each region and therefore that a more detailed scale of analysis would be more likely to enable evidence-based decisions to be made

    A one-phase interior point method for nonconvex optimization

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    The work of Wachter and Biegler suggests that infeasible-start interior point methods (IPMs) developed for linear programming cannot be adapted to nonlinear optimization without significant modification, i.e., using a two-phase or penalty method. We propose an IPM that, by careful initialization and updates of the slack variables, is guaranteed to find a first-order certificate of local infeasibility, local optimality or unboundedness of the (shifted) feasible region. Our proposed algorithm differs from other IPM methods for nonconvex programming because we reduce primal feasibility at the same rate as the barrier parameter. This gives an algorithm with more robust convergence properties and closely resembles successful algorithms from linear programming. We implement the algorithm and compare with IPOPT on a subset of CUTEst problems. Our algorithm requires a similar median number of iterations, but fails on only 9% of the problems compared with 16% for IPOPT. Experiments on infeasible variants of the CUTEst problems indicate superior performance for detecting infeasibility. The code for our implementation can be found at https://github.com/ohinder/OnePhase .Comment: fixed typo in sign of dual multiplier in KKT syste

    Joint Carrier-Phase Estimation for Digital Subcarrier Multiplexing Systems With Symbol-Rate Optimization

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    Digital subcarrier multiplexing (SCM) has recently emerged as a promising solution for next-generation ultra-high-baudrate coherent optical communication systems. Among its distinctive advantages over traditional single-carrier modulation, SCM enables the exploitation of symbol-rate optimization (SRO), which has been shown to enable the passive mitigation of the nonlinear interference noise (NLIN) that is generated during propagation over dispersion-unmanaged optical fiber systems. However, the full exploitation of SRO-based NLIN mitigation is severely hindered by the uncompensated distortion caused by laser phase noise (LPN) and non-linear phase noise (NLPN), whose impact is magnified by the use of low-baudrate subcarriers. Resorting to low-complexity carrier phase estimation (CPE) algorithms, in this paper we experimentally demonstrate that it is possible to overcome the hurdles posed by LPN and NLPN in SCM systems, provided that adequate joint-subcarrier CPE processing is employed. A dual-stage joint-processing approach composed of a pilot-based CPE optionally followed by a blind phase search (BPS)-based estimator is implemented and experimentally assessed, enabling to effectively optimize the symbol-rate per subcarrier down to 3 GBaud, in accordance with the theoretical SRO predictions for the system under test. In addition, we demonstrate that signal-to-noise ratio (SNR) gains of more than 1 dB can be achieved through joint-subcarrier CPE processing in shorter-reach links, while this gain tends to progressively reduce with increasing propagation distance, down to about 0.5 dB gain after 3000 km propagation

    Urban population looking for rural landscapes: Different appreciation patterns identified in Southern Europe

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    In the context of the peripheral European rural landscapes, the role of the urban population, generally referred to as the ‘outsiders’, has shown to be influential in the dynamics of rural space. This influence occurs namely through the demand for non-productive functions leading to the emergence of new modes of occupancy. In addition, the emerging policy framework concerning policies and planning in rural landscapes call for an improved understanding of the diversified social demands for these landscapes. We argue that a more profound knowledge on the urban demand for rural landscape is needed to better integrate the urban interests into rural policy and planning. The present paper aims to gain greater insight on this demand by identifying landscape preferences of urban users, framed by the multifunctional transition theory, and using a photo-based survey with contrasting land covers derived from CORINE Land Cover classes. Furthermore, the use of land cover classes as the main landscape component, and thereby relating preferences to specific land covers, offers a sound basis for a territorial approach, able to integrate landscape into rural policy and land use planning practice. A case-study in Southern Portugal was developed at the regional scale and results showed different appreciation patterns for rural landscapes varying from humanised and more naturalised landscapes according to the different functions sought by urban users. Another prominent result is that urban demand for rural landscapes, even if driven by consumption, is strongly influenced by both protection and production values. A deeper knowledge on the interests of urban population can be a step forward for rural communities, land managers, and sectoral policy decision-makers to better define investment strategies in rural-urban partnerships facing the growing urban demand over rural space

    Estado actual dos Montados e necessidades de intervenção

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    Os Montados constituem uma das áreas arborizadas mais extensas da Europa, sendo particularmente importantes pela sua riqueza em termos ambientais. A Floresta, sempre foi reconhecida como uma riqueza nacional, cuja necessidade de preservação e de desenvolvimento é estratégica para o progresso do país. No entanto, apesar de reconhecida, a sua importância ambiental, económica e social, e de lhe serem destinados recursos públicos ao longo dos últimos anos, é importante que o investimento na floresta e nos espaços florestais se mantenha e que seja encarado como uma prioridade. Estes recursos têm permitido a existência de medidas de apoio às florestas no âmbito dos diversos Quadros Comunitários de Apoio, dos quais Portugal tem beneficiado, e permitiu o aumento da área arborizada e a beneficiação dos espaços florestais existentes. Nesta fase de preparação de novos projetos, e considerando essencial promover a discussão entre produtores, técnicos, investigadores e decisores, para que os mecanismos financeiros a disponibilizar, através do Portugal 2020, vão de encontro às necessidades de intervenção que o setor precisa foi realizado o Colóquio “Medidas de Apoio ao setor florestal” onde for apresentado o “ Estado actual dos Montados e necessidades de intervenção” (Teresa Pinto Correia, Sérgio Godinho, Nuno Guiomar) sobre a complexidade da representação espacial do Montado, suas dinâmicas, registos históricos, a relação azinheira/sobreiro, os efeitos da perda de árvores - temperatura e pastoreio

    Adaptive Stokes-Based Polarization Demultiplexing for Long-Haul Multi-Subcarrier Systems

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    We experimentally evaluate the performance of the adaptive Stokes polarization demultiplexing (PolDemux) algorithm over a long-haul optical link considering the propagation of 31 × 192 Gb/s channels modulated as PM-16QAM multisubcarrier (MSC) signals. Initially, we consider 1 × 24 Gbaud channel under test, and subsequently, we assess the performance of the algorithm on an increasing number of subcarriers (up to 12 × 2 Gbaud) while keeping the same aggregate symbol rate. Taking advantage of the higher robustness of MSC signals toward chromatic dispersion (CD), we demonstrate that the memoryless Stokes-based PolDemux algorithm, originally designed for short reach links, can also be used for low-complexity and modulation transparent polarization demultiplexing in long-haul systems. In addition, we demonstrate that the PolDemux rotation matrix for the MSC signals can be estimated over a restricted group of Nref subcarriers and seamlessly applied to all Nsc subcarriers, thereby significantly reducing the overall complexity by a factor of ∼Nsc/Nref

    Real-Time Demonstration of Low-Complexity Time-Domain Chromatic Dispersion Equalization

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    We demonstrate real-time CD equalization (CDE) for coherent optical transmission systems using a low complexity time-domain (TD) multiplierless finite-impulse response (FIR)-based equalizer, based on a field-programmable gate array (FPGA) implementation. The real-time operation is performed for a single-channel 2.5 Gb/s QPSK optical signal with a performance penalty of only 0.15 dB with respect to the maximum performance. The hardware complexity is also evaluated in terms of occupation in a Virtex-6 FPGA-XC6VLX240T, revealing the high efficiency of the proposed CDE algorithm

    Dealing with highly fuzzy landscapes: how to assess High Nature Value Farmland in Mediterranean silvo-pastoral systems

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    The 9th IALE world congress a joint meeting between the International Association of Landscape Ecology World Congress (WC) and the US chapter of IALE (US-IALE). The Meeting Theme was Crossing Scales, Crossing Borders: Global Approaches to Complex Challenges. Teresa Pinto Correia was co-organizer of the symposium S45 “Shaping landscape ecology approaches in different regional contexts” and presenter of “Dealing with highly fuzzy landscapes: how to assess High Nature Value Farmland in Mediterranean silvo-pastoral systems”- The MONTADO: Mediterranean silvo-pastoral system with extensive land use, several layers, functional complexity, high spatial fuzziness, the effect of farm management shift in High Nature Value farmland
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