1,720,965 research outputs found
Stochastic capacitated dispersion problems in disaster preparedness for mass casualty incident
No full textRecent disasters that cause mass casualty incidents --such as the 2020 Beirut explosion or the 2023 Turkey-Syria earthquake-- have shown that critical facilities, which are meant to help the casualties, could be damaged by them. Therefore, it is critical to increase the resiliency of critical facilities by dispersing their locations. This paper proposes a stochastic capacitated dispersion model that considers a scenario in which a disaster can cause mass casualty incidents and damage critical facilities. The extent of damage is modeled as a function of the distance between the site locations of the facility and the epicenter of the disaster, as well as the level of severity of the disaster. The model incorporates a chance constraint to account for supply uncertainty. To solve this stochastic optimisation problem, we propose a new simheuristic algorithm that combines simulation and heuristic optimisation. Experiments show that our algorithm produces solutions that match the quality of the best deterministic solutions reported in the literature. In the stochastic disaster scenario, our algorithm produces solutions that can meet demand 90\% of the time, while deterministic solutions fail to meet this demand
On the scarcity of observations when modelling random inputs and the quality of solutions to stochastic optimisation problems
No full textMost of the literature on supply chain management assumes that the demand distributions and their parameters are known with certainty. However, this may not be the case in practice since decision makers may have access to limited amounts of historical demand data only. In this case, treating the demand distributions and their parameters as the true distributions is risky, and it may lead to sub-optimal decisions. To demonstrate this, this paper considers an inventory-routing problem with stochastic demands, in which the retailers have access to limited amounts of historical demand data. We use simheuristic method to solve the optimisation problem and investigate the impact of the limited amount of demand data on the quality of the simheuristic solutions to the underlying optimisation problem. Our experiment illustrates the potential impact of input uncertainty on the quality of the solution provided by a simheuristic algorithm.</p
Simulating interaction behaviors in bi-directional shared corridor with real case study
Full text linkMicroscopic traffic simulation tools are able to evaluate possible impacts induced by automated shuttles under various conditions. However, automated shuttles operate more and more often in shared space areas and few microscopic traffic simulation tools are able to handle networks with shared space infrastructure. Interaction behaviors between road users and automated shuttles are addressed only seldom as well. In this paper, we propose the concept of bi-directional edges in the open source microscopic traffic simulation suite SUMO to simulate road users’ interactions in a bi-directional shared-space corridor. A case study, where automated shuttles and cyclists share the bike path, and the related data collection were conducted to examine the performance of the proposed concept and understand the usage of the shared corridor. The simulation results are promising. Further refinement of the proposed concept is planned for properly reflecting complex interaction behaviors among diverse road users, and their surrounding environment
An inventory-routing problem with stochastic demand and stock-out: a solution and risk analysis using Simheuristics
No full textSupply chain operations have become more complex. Hence, in order to optimise supply chain operations, we often need to simplify the optimisation problem in such a way that it can be solved efficiently using either exact methods or metaheuristics. One common simplification is to assume all model inputs are deterministic. However, for some management decisions, considering the uncertainty in model inputs (e.g., demands, travel times, processing times) is essential. Otherwise, the results may be misleading and might lead to an incorrect decision. This paper considers an example of a complex supply chain operation that can be viewed as an Inventory-Routing Problem with stochastic demands. We demonstrate how a simheuristic framework can be employed to solve the problem. Further, we illustrate the risks of not considering input uncertainty. The results show that simheuristics can produce a good result, and ignoring the uncertainty in the model input may lead to sub-optimal results
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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