45 research outputs found
Prediction of late/early arrivals in container terminals - A qualitative approach
Vessel arrival uncertainty in ports has become a very common problem worldwide. Although ship operators have to notify the Estimated Time of Arrival (ETA) at predetermined time intervals, they frequently have to update the latest ETA due to unforeseen circumstances. This causes a series of inconveniences that often impact on the efficiency of terminal operations, especially in the daily planning scenario. Thus, for our study we adopted a machine learning approach in order to provide a qualitative estimate of the vessel delay/advance and to help mitigate the consequences of late/early arrivals in port. Using data on delays/advances at the individual vessel level, a comparative study between two transshipment container terminals is presented and the performance of three algorithmic models is evaluated. Results of the research indicate that when the distribution of the outcome is bimodal the performance of the discrete models is highly relevant for acquiring data characteristics. Therefore, the models are not flexible in representing data when the outcome distribution exhibits unimodal behavior. Moreover, graphical visualisation of the importance-plots made it possible to underline the most significant variables which might explain vessel arrival uncertainty at the two European ports
Port Pricing. Considerations on Economic Principles and Marginal Costs
Pricing by ports and operators within ports is considered quite a complex and untransparant matter, and as such it is sometimes perceived as archaic. This often results in debates about subsidies, captive markets and the dredging and deepening of maritime access routes, raising questions concerning potential distortion of competition and/or abuse of monopolistic power. This paper starts from the most important scientific literature on port pricing (and port competition), and adds new empirical results while calculating the marginal cost of a port call. A distinction is made between four elements of marginal costs in port operations, being costs for provision of infrastructure, costs associated with the use of the transport mode, costs for supplying port services, and external costs. This material may constitute the basis for a meaningful debate on the implementation of a pricing approach that is grounded on the marginal cost principle
Settlement of Macoma balthica larvae in response to benthic diatom films
The role of multi-species benthic diatom films (BDF) in the settlement of late pediveliger larvae of the bivalve Macoma balthica was investigated in still-water bioassays and multiple choice flume experiments. Axenic diatom cultures that were isolated from a tidal mudflat inhabited by M. balthica were selected to develop BDF sediment treatments characterized by a different community structure, biomass, and amount of extracellular polymeric substances (EPS). Control sediments had no added diatoms. Although all larvae settled and initiated burrowing within the first minute after their addition in still water, regardless of treatment, only 48-52% had completely penetrated the high diatom biomass treatments after 5 min, while on average 80 and 69% of the larvae had settled and burrowed into the control sediments and BDF with a low diatom biomass (<3.5 mu g Chl a g(-1) dry sediment), respectively. The percentage of larvae settling and burrowing into the sediment was negatively correlated with the concentration of Chl a and EPS of the BDF. This suggests higher physical resistance to bivalve penetration by the BDF with higher diatom biomass and more associated sugar and protein compounds. The larval settlement rate in annular flume experiments at flow velocities of 5 and 15 cm s(-1) was distinctly lower compared to the still-water assays. Only 4.6-5.8% of the larvae were recovered from BDF and control sediments after 3 h. Nonetheless, a clear settlement preference was observed for BDF in the flume experiments; i.e., larvae settled significantly more in BDF compared to control sediments irrespective of flow speed. Comparison with the settlement of polystyrene mimics and freeze-killed larvae led to the conclusion that active selection, active secondary dispersal and, at low flow velocities (5 cm s(-1)), passive adhesion to the sediment are important mechanisms determining the settlement of M. balthica larvae in estuarine biofilms
Value migration: digitalization of shipping as a mechanism of industry dethronement
In this conceptual paper, we review latest developments related to unmanned vessels and sketch potential scenarios that implicate with the existing maritime industry structure. On the one hand, we isolate a range of challenges that make the imminent realization of unmanned vessels seem like a rather utopian pursuit. On the other hand, we explain the reasons that may catalyse their emergence. Inspired by these opposing tensions, we highlight that the digital transformation of the shipping industry has the potential to enhance value within the industryâs ecosystem. However, we also contend that unmanned vessels -if realized- pose a very particular threat to the identity of the shipping industry as we know it. In particular, we build upon the concept of value migration and we highlight the drastic existential changes that may likely stem from a shift to non-seafarer-centric shipping. We conclude with questions that matter for industry dethronement purposes i.e., the possibility that existing industry structures may be substantially reconfigured following a removal of the seafarer as the nucleus of value creation in shipping
Bottom trawl fishing footprints on the worldâs continental shelves
Bottom trawlers land around 19 million tons of fish and invertebrates annually, almost one-quarter of wild marine landings. The extent of bottom trawling footprint (seabed area trawled at least once in a specified region and time period) is often contested but poorly described. We quantify footprints using high-resolution satellite vessel monitoring system (VMS) and logbook data on 24 continental shelves and slopes to 1,000-m depth over at least 2 years. Trawling footprint varied markedly among regions: from 50% in some European seas. Overall, 14% of the 7.8 million-km2 study area was trawled, and 86% was not trawled. Trawling activity was aggregated; the most intensively trawled areas accounting for 90% of activity comprised 77% of footprint on average. Regional swept area ratio (SAR; ratio of total swept area trawled annually to total area of region, a metric of trawling intensity) and footprint area were related, providing an approach to estimate regional trawling footprints when high-resolution spatial data are unavailable. If SAR was â€0.1, as in 8 of 24 regions, there was >95% probability that >90% of seabed was not trawled. If SAR was 7.9, equal to the highest SAR recorded, there was >95% probability that >70% of seabed was trawled. Footprints were smaller and SAR was â€0.25 in regions where fishing rates consistently met international sustainability benchmarks for fish stocks, implying collateral environmental benefits from sustainable fishing
Bottom trawl fishing footprints on the worldâs continental shelves
Publication history: Accepted - 23 August 2018; Published online - 8 October 2018.Bottom trawlers land around 19 million tons of fish and invertebrates
annually, almost one-quarter of wild marine landings. The extent of
bottom trawling footprint (seabed area trawled at least once in a
specified region and time period) is often contested but poorly
described. We quantify footprints using high-resolution satellite vessel
monitoring system (VMS) and logbook data on 24 continental shelves
and slopes to 1,000-m depth over at least 2 years. Trawling footprint
varied markedly among regions: from <10% of seabed area in Australian
and New Zealand waters, the Aleutian Islands, East Bering Sea,
South Chile, and Gulf of Alaska to >50% in some European seas.
Overall, 14% of the 7.8 million-km2 study area was trawled, and
86% was not trawled. Trawling activity was aggregated; the most
intensively trawled areas accounting for 90% of activity comprised
77% of footprint on average. Regional swept area ratio (SAR; ratio
of total swept area trawled annually to total area of region, a metric
of trawling intensity) and footprint area were related, providing an
approach to estimate regional trawling footprints when highresolution
spatial data are unavailable. If SAR was â€0.1, as in 8 of
24 regions, therewas >95% probability that >90%of seabed was not
trawled. If SAR was 7.9, equal to the highest SAR recorded, there
was >95% probability that >70% of seabed was trawled. Footprints
were smaller and SAR was â€0.25 in regions where fishing rates consistently
met international sustainability benchmarks for fish stocks,
implying collateral environmental benefits from sustainable fishing.Funding for meetings of the study group and salary
support for R.O.A. were provided by the following: David and Lucile Packard
Foundation; the Walton Family Foundation; the Alaska Seafood Cooperative;
American Seafoods Group US; Blumar Seafoods Denmark; Clearwater Seafoods
Inc.; Espersen Group; Glacier Fish Company LLC US; Gortons Seafood; Independent
Fisheries Limited N.Z.; Nippon Suisan (USA), Inc.; Pesca Chile S.A.;
Pacific Andes International Holdings, Ltd.; San Arawa, S.A.; Sanford Ltd. N.Z.;
Sealord Group Ltd. N.Z.; South African Trawling Association; Trident Seafoods;
and the Food and Agriculture Organisation of the United Nations. Additional
funding to individual authors was provided by European Union Project
BENTHIS EU-FP7 312088 (to A.D.R., O.R.E., F.B., N.T.H., L.B.-M., R.C., H.O.F.,
H.G., J.G.H., P.J., S.K., M.L., G.G.-M., N.P., P.E.P., T.R., A.S., B.V., and M.J.K.); the
Instituto PortuguĂȘs do Mar e da Atmosfera, Portugal (C.S.); the International
Council for the Exploration of the Sea Science Fund (R.O.A. and K.M.H.); the
Commonwealth Scientific and Industrial Research Organisation (C.R.P. and
T.M.); the National Oceanic and Atmospheric Administration (R.A.M.); New
Zealand Ministry for Primary Industries Projects BEN2012/01 and DAE2010/
04D (to S.J.B. and R.F.); the Institute for Marine and Antarctic Studies, University
of Tasmania and the Department of Primary Industries, Parks, Water and
Environment, Tasmania, Australia (J.M.S.); and UK Department of Environment,
Food and Rural Affairs Project MF1225 (to S.J.)
Integrale evaluatie van de band tussen ruimtelijk-economische structuur en infrastructuur voor goederenvervoer
Dit onderzoek kadert binnen een ruimere studie rond duurzame mobiliteit, meer bepaald gericht op de economische en ruimtelijke effecten van toenemend goederenvervoer, in opdracht van de Federale Diensten voor Wetenschappelijke, Technische en Culturele Aangelegenheden. Dit globale onderzoek omvat drie hoofdcomponenten. Eén hoofdcomponent heeft als doel de economische effecten van een toenemend goederenvervoer na te gaan. Daarbij wordt vooral aandacht besteed aan modale keuze en prijszetting op geaggregeerd bedrijfsniveau. Een andere hoofdcomponent bekijkt het transportnetwerk voor goederenvervoer op Europees niveau, met bijzondere aandacht voor toedeling van het gegenereerde transport aan de verschillende verbindingen op het netwerk. De derde hoofdcomponent, waarvan dit onderzoek deel uitmaakt, zoekt de band tussen de economische en de ruimtelijke aspecten van toenemend goederenvervoer, die in de andere twee delen afzonderlijk behandeld worden. Een deel van het onderzoek binnen de derde hoofdcomponent gebeurt door medewerkers van UCL (Université Catholique de Louvain). In dit deel ligt de klemtoon op de efficiënte ruimtelijke werking van het transportnetwerk en optimale locatie van multimodale overslagpunten. Voor de beoordeling van de kwaliteit van het transportnetwerk grijpen de onderzoekers terug naar de bevolking (gezien als consumenten van goederen) als determinerende factor. Het deel dat op UFSIA wordt onderzocht, en waarvan de voorliggende tekst de neerslag is, bekijkt de kwaliteit van het transportnetwerk in relatie tot omliggende activiteitenplaatsen. Hierbij wordt de productiezijde als uitgangspunt genomen: de bedrijvigheid van industriële of distributieve aard, als generator van transportactiviteit en gebruiker van de transportinfrastructuur. Een eerste deel van dit werk omvat de uitgangspunten die tot het uiteindelijke onderzoek hebben geleid. In het tweede deel wordt het eigenlijke onderzoek aangevat met een literatuuroverzicht op het gebied van kwaliteitsbeoordeling van transportnetwerken. In het derde deel passen we dan met de resultaten van de literatuurstudie de kwaliteitsbeoordeling toe.