1,720,966 research outputs found
Location of Active Sensor on Traffic Network
No full textSensors are used to monitor traffic in networks. For example, in transportation networks, they may be used to measure traffic volumes on given arcs and paths of the network. This paper refers to an
active sensor when it reads identifications of vehicles, including their routes in the network, that the vehicles
actively provide when they use the network. On the other hand, the conventional inductance loop detectors
are passive sensors that mostly count vehicles at points in a network to obtain traffic volumes (e.g., vehicles
per hour) on a lane or road of the network.
This paper introduces a new set of network location problems that determine where to locate active
sensors in order to monitor or manage particular classes of identified traffic streams. In particular, it focuses
on the development of two generic locational decision models for active sensors, which seek to answer these
questions: (1) “How many and where should such sensors be located to obtain sufficient information on
flow volumes on specified paths?”, and (2) “Given that the traffic management planners have already located
count detectors on some network arcs, how many and where should active sensors be located to get the
maximum information on flow volumes on specified paths?”
The problem is formulated and analyzed for three different scenarios depending on whether there are
already count detectors on arcs and if so, whether all the arcs or a fraction of them have them. Location of an
active sensor results in a set of linear equations in path flow variables, whose solution provide the path flows.
The general problem, which is related to the set-covering problem, is shown to be NP-Hard, but special cases
are devised, where an arc may carry only two routes, that are shown to be polynomially solvable. New graph
theoretic models and theorems are obtained for the latter cases, including the introduction of the generalized
edge-covering by nodes problem on the path intersection graph for these special cases. An exact algorithm
for the special cases and an approximate one for the general case are presented
Computational Complexity Analysis of the Sensor Location Flow Observability Problem
No full textThe sensor location flow observability problem is studied from the computational complexity point of view. Although the general problem is shown to be NP-complete, by studying the special cases of input matrix structures and data where the corresponding problems are polynomially solvable, the boundary between NP-complete and polynomial solvable problems is delineated
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
Delivery itineraries and distribution capacity of a freight network with time slots
No full textThe paper focuses on the distribution problem of delivering goods to medium size stores in a Central Business District (CBD) having limited off-street parking which can accommodate only restricted space and time for parking, loading/unloading operations. In this scenario, freight distribution can be addressed from two perspectives: (i) from the viewpoint of delivery/pick-up firms, delivery itineraries need to be coordinated with consideration of the delivery capacities and times at store sites for parking, and loading/unloading operations; (ii) from the viewpoint of transportation and city planners, the “distribution capacity” in the CBD must be determined, including the average cost of distribution routes, the maximum number of routes that can be simultaneously coordinated, the total number of stores that can be served, etc., much in the way traffic engineers are interested in the “traffic capacity” of a transportation network under which the vehicles move efficiently. Both the above viewpoints are addressed in this paper by solving the following problem: what delivery itineraries are available so that parking loading/unloading capacities and associated time windows are respected and the itineraries are “balanced” in a way that costs and number of deliveries fall in given ranges. This problem is studied and a mathematical programming formulation is developed. To evaluate exactly the freight distribution capacity, a branch-and-bound approach is developed, where the relaxation of the formulation provides good bounds. Subsequently, a heuristic is presented that is useful from an operational point of view. In fact, the latter algorithm exploits the results provided by the exact approach and maximizes the efficiency of the system
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
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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