603 research outputs found

    Modeling an offshore container terminal: the Venice case study

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    In order to reduce marine transportation times and related costs, as well as the environmental impacts, an alternative multimodal route to the current Suez-Gibraltar-North Sea corridor for the containers shipped from Far and Middle East was identified as potentially very effective. A key operational problem to achieve this result is the capacity and the effectiveness of the terminals within the concerned new logistic chain. In this framework, the Venice Port Authority is developing a project aimed to improve relevantly the potential of its container terminals to al-low loading/unloading of containers to and from the Central Europe. The project includes a new offshore terminal for mooring huge ships (up to 18.000 TEU) in the Adriatic Sea and a link operated by barges with an onshore terminal in Venice to overcome the constraints for the navigation of the containers ships in the Venetian lagoon. This innovative operational scheme requires a deep functional analysis to ensure the full capacity operation, assess the reachable performances and correspondingly dimensioning the required equipment (cranes, barges, quays, etc.). For this purpose, the authors developed a specific discrete-events simulation model. The paper includes the presentation of the model and the results of its application to Venice case study, by identifying the benefits achievable with this approach and the potential wider application fields

    Inferring Synaptic Structure in presence of Neural Interaction Time Scales

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    Biological networks display a variety of activity patterns reflecting a web of interactions that is complex both in space and time. Yet inference methods have mainly focused on reconstructing, from the network's activity, the spatial structure, by assuming equilibrium conditions or, more recently, a probabilistic dynamics with a single arbitrary time-step. Here we show that, under this latter assumption, the inference procedure fails to reconstruct the synaptic matrix of a network of integrate-and-fire neurons when the chosen time scale of interaction does not closely match the synaptic delay or when no single time scale for the interaction can be identified; such failure, moreover, exposes a distinctive bias of the inference method that can lead to infer as inhibitory the excitatory synapses with interaction time scales longer than the model's time-step. We therefore introduce a new two-step method, that first infers through cross-correlation profiles the delay-structure of the network and then reconstructs the synaptic matrix, and successfully test it on networks with different topologies and in different activity regimes. Although step one is able to accurately recover the delay-structure of the network, thus getting rid of any \textit{a priori} guess about the time scales of the interaction, the inference method introduces nonetheless an arbitrary time scale, the time-bin dtdt used to binarize the spike trains. We therefore analytically and numerically study how the choice of dtdt affects the inference in our network model, finding that the relationship between the inferred couplings and the real synaptic efficacies, albeit being quadratic in both cases, depends critically on dtdt for the excitatory synapses only, whilst being basically independent of it for the inhibitory ones

    Analytical methods and simulation models to assess innovative operational measures and technologies for rail port terminals: the case of Valencia Principe Felipe terminal

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    The topic of freight transport by rail is a complex theme and, in recent years, a main issue of European policy. The legislation evolution and the White Paper 2011 have demonstrated the European intention to re-launch this sector. The challenge is to promote the intermodal transport system to the detriment of road freight transport. In this context intermodal freight terminals, play a primary role for the supply chain, they are the connection point between the various transport nodes and the nodal points where the freight are handled, stored and transferred between different modes to final customer. To achieve the purpose, it is strengthen the improvement of existing intermodal freight terminals and the development of innovative intermodal freight terminals towards higher performance (ERRAC, 2012). Many terminal performances improvements have been proposed and sometime experimented. They are normally basing on combinations of operational measures and innovative technologies (e.g. automatic horizontal and parallel storage and handling, automated gate and sensors for tracking systems data exchange) tested in various terminals, with often-contradictory results. The research work described in this paper (developed within the Capacity4Rail EU project) focusses on the assessment of effects that these innovations can have in the intermodal freight terminals combined in various alternative consistent effective scenarios. The methodological framework setup to assess these innovations is basing on a combination of analytical methods based on sequential algorithms and discrete events simulation models. The output of this assessment method are key performance indicators (KPIs) selected according to terminals typologies and related to different aspects (e.g. management, operation and organization). The present paper illustrates the application of the methodological framework, tuned on the operation of various intermodal terminals, for the validation on today operation and the assessment of possible future scenarios to the case study of the Principe Felipe sea-rail terminal in Valencia

    AmI Systems as Agent-Based Mirror Worlds: Bridging Humans and Agents through Stigmergy

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    In this chapter we introduce a vision of agent-oriented AmI systems that is extended to integrate ideas inspired by MirrorWorlds as introduced by Gelernter at the beginning of the eighties. In this view, AmI systems are actually a digital world mirroring but also augmenting the physical world with capabilities, services and functionalities.We then discuss the value of stigmergy as background reference conceptual framework to define and understand interactions occurring between the physical environments and its digital agent-based extension. The digital world augments the physical world so that traces left by humans acting in the physical world are represented in the digital one in order to be perceived by software agents living there and, viceversa, actions taken by software agents in the mirror can have an effect on the connected physical counterpart

    A non-invariance result for the spatial AK model

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    This paper deals with the positivity condition of an infinite-dimensional evolutionary equation, associated with a control problem for the optimal consumption over space. We consider a spatial growth model for capital, with production generating endogenous growth and technology of the form AK. We show that for certain initial data, even in the case of heterogeneous spatial distribution of technology and population, the solution to an auxiliary control problem that is commonly used as a candidate for the original problem is not admissible. In particular, we show that initial conditions that are non-negative, under the auxiliary optimal consumption strategy, may lead to negative capital allocations over time

    Capturing impacts of Leader and of measures to improve Quality of Life in rural areas

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    The Helpdesk of European Evaluation Network for Rural Development supported by a group of external experts has prepared a Working Paper on ”Capturing the impacts of Leader and measures to improve the Quality of life (QoL) in rural areas”. The working paper provides methodological support for evaluators, managing authorities and other interested parties. The main evaluation challenges include: assessing the “double scope” of Leader (it is both a process and generates impacts); the need to adequately define what is QoL in the context of Rural Development Programmes (RDPs); tackling the qualitative nature of the effects; identifying contributions from small-scale interventions; and the fact that the EU’s Common Monitoring and Evaluation Framework (CMEF) requires assessment of impacts ultimately at programme level. The working paper is targeted primarily at practitioners involved in the evaluation of the current RDPs (2007-2013). It proposes a framework of reference which provides a conceptual model in order to assess Quality of Life around four dimensions – environment, socio-culture, economy and governance.Rural development, impact evaluation, leader, quality of life, Agricultural and Food Policy, Q18,

    Dependence of the Ce(III)/Ce(IV) ratio on intracellular localization in ceria nanoparticles internalized by human cells

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    CeO2 nanoparticles (CNPs) have been investigated as promising antioxidant agents with significant activity in the therapy of diseases involving free radicals or oxidative stress. However, the exact mechanism responsible for CNP activity has not been completely elucidated. In particular, in situ evidence of modification of the oxidative state of CNPs in human cells and their evolution during cell internalization and subsequent intracellular distribution has never been presented. In this study we investigated modification of the Ce(iii)/Ce(iv) ratio following internalization in human cells by X-ray absorption near edge spectroscopy (XANES). From this analysis on cell pellets, we observed that CNPs incubated for 24 h showed a significant increase in Ce(iii). By coupling on individual cells synchrotron micro-X-ray fluorescence (μXRF) with micro-XANES (μXANES) we demonstrated that the Ce(iii)/Ce(iv) ratio is also dependent on CNP intracellular localization. The regions with the highest CNP concentrations, suggested to be endolysosomes by transmission electron microscopy, were characterized by Ce atoms in the Ce(iv) oxidation state, while a higher Ce(iii) content was observed in regions surrounding these areas. These observations suggest that the interaction of CNPs with cells involves a complex mechanism in which different cellular areas play different roles
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