1,720,952 research outputs found
Determining the Required Storage Capacity of an Import Dry Bulk Terminal
No full textCargo transport is important for supplies of goods and food worldwide. The goods and food are transported by inland transport modes, like road, railway and inland waterway transport. Due to a growth in world population the demand of goods and food increase, which results in an increase in cargo transport. More transport leads to more traffic on roads, railway and inland waterways. Roads and railways are at their limits of capacity, while inland waterways have the ability for an increase of waterway traffic. The European waterway network for inland transport is wide and connects sea ports and the European hinterland with each other. While inland waterway transport is cheaper and slower compared to road and railway transport, it is also less reliable than the other transport modes. The reliability is the ability to perform and maintain the agreements made between actors involved in the cargo transport during normal circumstances, as well as during unexpected circumstances, like delays. A disadvantage for inland waterway navigation is the locks in the waterway network. Locks maintain the water on a certain level, so that inland vessels can navigate without the risk of grounding. Locks also cause congestions when the lock capacity is lower than the amount of vessels that want to pass the lock during a certain time. These congestions cause delays for the vessels, which do not increase the reliability of the waterway transport mode. To stimulate the inland waterway transport, so that cargo transport over water will become more compatible with road and railway transport, the reliability for inland waterway transport must be increased. This can be done by decreasing the waiting times at the locks in the waterways. The interarrival times of inland vessels have an influence on the waiting times for vessels at locks. So when the arrival times of vessels at a lock are controlled, the waiting times can be controlled. A simulation model is designed to simulate what the effect of controlled arrivals of vessels is on the waiting time at locks. The simulation model is able to adjust the velocities of all vessels that navigate on the waterway towards the lock. With the adjustments in velocity of a vessels, the arrival time of that vessel is controlled by the model. The adjustment in velocity can let the vessel navigate faster and slower. When a vessel slows down it´s travel time on the waterway increases. A lower velocity and a longer travel time means that the fuel costs decrease and the operation time increases. That could result in a higher total travel costs. Therefore the simulation model can minimize the waiting times or the travel costs. With the minimization of costs the waiting time is minimized as well, due to the fixed operating costs a vessel has, which are the travel costs without fuel costs. Variables in the simulation model are the length of the controlled waterway, the service time of the lock and the lock capacity. The length of the controlled waterway determines the size of the system and the area where the vessels are controlled, the service time is the time it takes to pass the lock and the lock capacity determines the maximum number of vessels that can enter the lock chamber during one service run. As an input for the simulation model each vessel has its own entering velocity and entering time during a day. The entering velocities of the vessel are between 10 and 20 km/h and can be adjusted between 5 km/h and 110% of the entering velocity of the vessel. The entering time is distributed by a Weibull distribution. Since inland waterway transport is not yet a full 24/7 industry, the distribution is in such way that the majority of the daily vessels that pass the lock will enter the system between 06:00 and 20:00 hour. The settings used for the variables in the simulations are based on situations at four locks between the two largest sea ports in Europe, which are Rotterdam and Antwerp. The locks are the Volkerak, Krammer, Hansweert and Kreekrak lock and the waiting times at those lock are expected to be as long as 3 hours in the next decade. The output of the simulation model are waiting times at the lock and the total travel costs for each vessel in an optimized situation, which is a situation with minimized waiting time or travel costs. Optimized results of the simulation model are compared with the simulations that represent the four locks with the expected waiting times. The simulation model shows a reduction in waiting times of more than 80% compared to the expected waiting times for the next decade. If this can be achieved in reality the inland waterway transport mode can be stimulated due to smaller unexpected delays and an increased reliability.Mechanical, Maritime and Materials EngineeringMarine and Transport TechnologyTransport Engineering and Logistics2012.PEL.772
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
A nuclear ribosomal DNA phylogeny of Acer inferred with maximum likelihood, splits graphs, and motif analysis of 606 sequences
Get PDF The multi-copy internal transcribed spacer (ITS) region of nuclear ribosomal DNA is widely used to infer phylogenetic relationships among closely related taxa. Here we use maximum likelihood (ML) and splits graph analyses to extract phylogenetic information from ~ 600 mostly cloned ITS sequences, representing 81 species and subspecies of Acer, and both species of its sister Dipteronia. Additional analyses compared sequence motifs in Acer and several hundred Ana-cardiaceae, Burseraceae, Meliaceae, Rutaceae, and Sapindaceae ITS sequences in GenBank. We also assessed the effects of using smaller data sets of consensus sequences with ambiguity coding (accounting for within-species variation) instead of the full (partly redundant) original sequences. Neighbor-nets and bipartition networks were used to visualize conflict among character state patterns. Species clusters observed in the trees and networks largely agree with morphology-based classifications; of de Jong's (1994) 16 sections, nine are supported in neighbor-net and bipartition networks, and ten by sequence motifs and the ML tree; of his 19 series, 14 are supported in networks, motifs, and the ML tree. Most nodes had higher bootstrap support with matrices of 105 or 40 consensus sequences than with the original matrix. Within-taxon ITS divergence did not differ between diploid and polyploid Acer, and there was little evidence of differentiated parental ITS haplotypes, suggesting that concerted evolution in Acer acts rapidly. </jats:p
Morphological character evolution of Amorphophallus (Araceae) based on a combined phylogenetic analysis of trnL, rbcL, and LEAFY second intron sequences
No full textSequences of three different genes in 69 taxa of Amorphophallus were combined to reconstruct the molecular phylogeny of this species-rich Aroid genus. The data set was analyzed by three different methods, Maximum Parsimony, Maximum Likelihood and Bayesian analysis, producing slightly different tree topologies. Three major clades identified in all analyses reflect the biogeographical distribution of Amorphophallus. Some clades were supported by morphological characters such as sessile/nonsessile stigma, pollen opening mechanism, shape of the main segments of the lamina, growth cycle, and berry colour. When optimised, a nonsessile stigma may have evolved from a sessile one with several reversals. Pollen opening by connective rupturing evolved from pollen opening by pores. Unequally shaped segments of the lamina evolved from equally shaped segments. Simultaneously existing leaf and inflorescences evolved from alternating leaves and inflorescences. Blue, purple, green, and yellow berries evolved from red/orange/white ones
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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