1,720,980 research outputs found
Bundles generation and pricing in crowdshipping
No full textCrowdshipping is a new delivery paradigm that exploits the capacity of ordinary people who offer their own vehicles and free time to perform deliveries against compensation. In this work, we consider a peer-to-peer logistic platform where a company receives orders from its customers and assigns them to occasional drivers (ODs), or crowdshippers, who perform the delivery operations. We first investigate the problem of deciding how the orders should be partitioned into bundles, where a bundle is a set of orders assigned to the same OD. Then, we focus on the problem of determining the compensation associated with each bundle, with the purpose of minimizing the total delivery costs. The pricing scheme is based on the assumption that each OD is associated with a willingness-to-serve function, which is modeled as a random variable that gives the probability that the OD accepts to deliver the bundle given the compensation value. This random variable captures the estimation of the willingness-to-serve function that the company has elaborated, for example on the basis of historical data. If the compensation offered by the company is greater than or equal to the willingness-to-serve value, the OD performs the delivery, otherwise she/he refuses. In case no OD is available to deliver a bundle, then all packages in the bundle are offered to a third-party delivery company. We simulate two auction systems for the assignment of bundles to ODs: a static and a dynamic auction. In exhaustive simulation tests, we compare different pricing schemes as well as the two auction systems, and outline several managerial insights
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
Lagrangian Approaches for QoS Scheduling in Computer Networks
Full text linkWe study a routing problem arising in computer networks where stringent Quality of Service (QoS) scheduling requirements ask for a routing of the packets with controlled worst-case “end-to-end” delay. With widely used delay formulæ, this is a shortest-path-type problem with a nonlinear constraint depending in a complex way on the reserved rates on the chosen arcs. However, when the minimum reserved rate in the path is fixed, the Lagrangian problem obtained by relaxing the delay constraint presents a special structure and can be solved efficiently. We exploit this property and present an effective method that provides both upper and lower bounds of very good quality in extremely short computing times
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
Solution approaches for the vehicle routing problem with occasional drivers and time windows
No full textThe efficient management of last-mile delivery is one of the main challenges faced by on-line retailers and logistic companies. The main aim is to offer personalized delivery services, that meet speed, flexibility, and control requirements and try to reduce environmental impacts as well. Crowd-sourced shipping is an emerging strategy that can be used to optimize the last-mile delivery process. The main idea is to deliver packages to customers with the aid of non-professional couriers, called occasional drivers. In this paper, we address the vehicle routing problem with occasional drivers, time window constraints and multiple deliveries. To handle this problem, we design some greedy randomized adaptive search procedures (GRASP). In order to assess the behaviour of the proposed algorithms, computational experiments are carried out on benchmark instances and new generated test sets. A comparison with previous published approaches, tailored for the problem at hand, is also provided. The numerical results are very encouraging and highlight the superiority, in terms of both efficiency and effectiveness, of the proposed GRASP algorithms
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