1,721,211 research outputs found
Autostrada ferroviaria e trasporto stradale lungo la direttrice del Frejus: analisi di scenari mediante un modello di rete
Full text linkIn questo lavoro ci si propone di valutare, mediante l'adozione di un modello di rete, l'influenza delle caratteristiche del sistema di offerta del modo stradale e ferroviario, relativo al transito alpino tra l'Italia e la Francia, sulla ripartizione del trasporto merci. Si analizza, in particolare, un nuovo servizio disponibile e si stima se le sue caratteristiche siano in grado d'influenzare la scelta operata da parte delle aziende di trasporto merci, rispetto al tradizionale percorso stradale. Il sistema è riprodotto ed analizzato mediante un modello di rete, che considera in modo esplicito il fenomeno della congestione nelle parti significative del sistema; esso riproduce pertanto quei fenomeni di interazione tra i flussi di traffico lungo i percorsi della rete. L'utilizzo del sistema, nei vari scenari, è stato valutato in configurazioni di "ottimo di sistema", che rendono minimi i costi complessivi sulla rete, e di "equilibrio per l'utente", al fine di stimare le scelte spontanee degli operatori di trasporto merci e logistica. Il modello ipotizzato è di tipo stazionario durante il periodo di analisi, data la distribuzione giornaliera del traffico, ed i risultati ottenuti sono riportati come media oraria nel periodo
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Planning and optimization methods for advanced urban logistics systems at tactical level
No full textVehicle routing problems for city logistics
No full textThis paper surveys the vehicle routing problems met in cities for good distribution. It applies the following methodology. First, it gives an overview of the literature devoted to vehicle route optimization in cities. Then, it classifies and analyses urban logistic flows. As a result, it identifies the principal scientific challenges that need to be addressed: time-dependency, multi-level and multi-trip organization of the distribution, dynamic information. Finally, it focuses on each one of these challenges, analyses the main difficulties they imply and how they are treated in the literature
A Business Model Assessment and Evaluation Framework for City Logistics Collaborative Strategic Decision Support
Full text linkSeveral City Logistics (CL) initiatives have emerged in the last two decades with the aim to reduce the negative externalities of freight distribution in urban areas. Such initiatives can be public and/or private but need to not break or impeach current operations efficiency so to not hinder their profitability. In order to provide business value to CL initiatives and thus fostering their long-term success, it is necessary to understand the decision-making of private companies operating in the urban freight ecosystem. This paper proposes an ex-ante assessment and evaluation framework built around the concept of an ecosystem business modelling that includes the decision-making by CL stakeholders. A theoretical framework previously developed is extended to evaluate a collaborative business model of an Urban Consolidation Centre (UCC). Cost-Benefit analysis (CBA is used estimate the impact of the business model configuration. Finally, research and practice implications are also addressed
Potential of zero total charge of platinum single crystals: a local approach to stepped surfaces vicinal to Pt(111)
No full textThe electrochemical behavior of platinum single-crystal electrodes is revisited, with special emphasis on the determination of the potential of zero charge. We show that the measure of the charge displaced during CO adsorption allows the determination of the potential of zero total charge (PZTC). The estimation of the potential of zero free charge (PZFC) is discussed, with different degrees of approximation. The application of this methodology to the study of the PZTC of platinum stepped surfaces vicinal to Pt(111) reveals a marked decrease of the PZTC due to the introduction of surface steps. This effect is interpreted as the result of the existence of markedly smaller surface potentials localized on step sites. The importance of considering local aspects of the interface is emphasized with the use of N2O reduction as a sensitive probe to the local structure of the surface. It is proposed that the different local maxima observed in the absolute value of the reduction current correspond to the local values of PZTC. It is shown that there is, in general, good agreement between the overall PZTC, obtained from the CO displacement, and that calculated from the local values inferred from the N2O reduction. Further insight is obtained with the application of the laser-induced temperature jump method. This technique is useful to calculate the potential of maximum entropy of the double-layer formation. The resulting value of this potential for Pt(111) is discussed in the light of the PZFC value obtained from different approaches. For stepped surfaces vicinal to Pt(111), two local maxima in the entropy of the double layer are observed that are close to the local PZTC values estimated from the N2O reduction. This result suggests the existence of cooperative effects in the organization of the water dipoles close to the electrode surfac
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