1,720,956 research outputs found
Modeling the empty container flow: An application of system dynamics
No full textThe volume of container traffic has increased many folds during the last two decades owing to increased globalization of trade. The imbalance of trade has also increased along with the increase in global trade. Presently, trade imbalance exists along all the major trading routes in the world. The increased trade imbalance has resulted in significant cost to the marine industry for handling and repositioning of empty containers. Although trade imbalance is the major cause, many other factors like tariffs, cost of repositioning, cost of new containers and dynamics in leasing industry also impact the flow of empty containers. Detailed analysis of the factors and the dynamics affecting this flow has been made in the relevant literature. However, no attempt has been made so far to model and simulate this system. The purpose of the present study is to model the dynamics of empty container flow using system dynamics. System dynamics gives the user an ability to model relationship among multiple interacting factors, and study the resultant behavior of the system, which precisely, is the purpose of this study. As such the use of system dynamics as the modeling tools seems justified. A simple two port container port system is developed. The model is validated through comparison of actual and simulated container flow for the Port of Los Angeles for a specified time span. Such a model would provide a tool to the decision makers to evaluate various what-if scenarios, which would give them better visibility of the system and assist them in taking the appropriate decisions, from policy point of view
Monte Carlo simulation: Remanufacturing or not -A newsvendor perspective
No full textThe concept of random yields or uncertain supply is not new in inventory management. While this aspect has been extensively studied in the literature over several decades, the factors impacting uncertain supply have been largely been limited to quality defects, uncertain capacity and sourcing issues. The concept of random yields is very much applicable to the reverse logistics and remanufacturing activities that has received increased attention in recent years. The purpose of this paper is to demonstrate the modeling of the newsvendor problem with uncertain supply via spreadsheet based simulation as a managerial tool for optimizing the performance of a remanufacturing operation
Modeling the empty container flow: An application of system dynamics
No full textThe volume of container traffic has increased many folds during the last two decades owing to increased globalization of trade. The imbalance of trade has also increased along with the increase in global trade. Presently, trade imbalance exists along all the major trading routes in the world. The increased trade imbalance has resulted in significant cost to the marine industry for handling and repositioning of empty containers. Although trade imbalance is the major cause, many other factors like tariffs, cost of repositioning, cost of new containers and dynamics in leasing industry also impact the flow of empty containers. Detailed analysis of the factors and the dynamics affecting this flow has been made in the relevant literature. However, no attempt has been made so far to model and simulate this system. The purpose of the present study is to model the dynamics of empty container flow using system dynamics. System dynamics gives the user an ability to model relationship among multiple interacting factors, and study the resultant behavior of the system, which precisely, is the purpose of this study. As such the use of system dynamics as the modeling tools seems justified. A simple two port container port system is developed. The model is validated through comparison of actual and simulated container flow for the Port of Los Angeles for a specified time span. Such a model would provide a tool to the decision makers to evaluate various what-if scenarios, which would give them better visibility of the system and assist them in taking the appropriate decisions, from policy point of view
Modeling and simulating the economic and demographic impact of transport infrastructure investment
No full textInvestment in transportation infrastructure has been widely utilized as an instrument for inducing economic growth in a country or region. Such investment usually leads to job creation and an increase in per capita income that, in turn, encourages an increase in population through migration. The increased spending of these newly migrated populations leads to secondary job creation and further economic development. However, this increased economic activity corresponds with increased utilization of the transport infrastructure resulting in high levels of congestion. This congestion may negatively impact the attractiveness of the region for further new investment since the level of congestion in a transportation network is known to affect the productivity of the workforce. Thus, congestion has a direct impact on the region's GRP (Gross Regional Product). Often, calls are made to alleviate this congestion through added investment in the transport infrastructure. This, again, further spurs economic activity, migration, and congestion. The present study employs a system dynamics approach for modeling the cyclic relationships observed between the economic impact of transportation infrastructure and regional development. Our approach uses a common platform wherein the interconnected factors of demography, transportation infrastructure, and economic activity are jointly modeled and simulated. This model aspires to be utilized as a decision support and consensus building tool in the process of better understanding the impact of investment in transport infrastructure. © 2011 Simulation Councils, Inc
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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