Antonio J. Reinoso

Temporal Characterization of the Requests to Wikipedia

This chapter presents an empirical study about the temporal patterns characterizing the requests submitted by users to Wikipedia. The study is based on the analysis of the log lines registered by the Wikimedia Foundation Squid servers after having sent the appropriate content in response to users’ requests. The analysis has been conducted regarding the ten most visited editions of Wikipedia and has involved more than 14,000 million log lines corresponding to the traffic of the entire year 2009. The conducted methodology has mainly consisted in the parsing and filtering of users’ requests according to the study directives. As a result, relevant information fields have been finally stored in a database for persistence and further characterization. In this way, we, first, assessed, whether the traffic to Wikipedia could serve as a reliable estimator of the overall traffic to all the Wikimedia Foundation projects. Our subsequent analysis of the temporal evolutions corresponding to the different types of requests to Wikipedia revealed interesting differences and similarities among them that can be related to the users’ attention to the Encyclopedia. In addition, we have performed separated characterizations of each Wikipedia edition to compare their respective evolutions over time.

Quantitative analysis and characterization of Wikipedia requests

Our poster describes the quantitative analysis carried out to study the use of the Wikipedia system by its users with special focus on the identification of time and kind-of-use patterns, characterization of traffic and workload, and comparative analysis of different language editions. By filtering and classifying a large sample of the requests directed to the Wikimedia systems over 7 days we have been able to identify important information such us the targeted namespaces, the visited resources or the requested actions. The results found include the identification of weekly and daily patterns, and several correlations between different actions on the articles. In summary, the study shows an overall picture of how the most visited language editions of the Wikipedia are being accessed by their users.

Behavioral Aspects in the Interaction Between Wikipedia and its Users

Wikipedia continues to be the most well-known on-line encyclopedia and receives the visits of millions of users on a daily basis. Its contents correspond to almost all the knowledge areas and are altruistically contributed by individuals and organizations. In addition, users are encouraged to add their own contributions according to the Wikipedia’s own supporting paradigm. Its progression to a mass phenomenon has propitiated many studies and research initiatives. Therefore, topics such as the quality of the published contents or the authoring of its contributions have been widely developed. However, very few attention has been paid to the behavioral aspects characterizing the interaction between Wikipedia and its users. Henceforth, this chapter aims to determine the habits exhibited by users when browsing the Wikipedia pages. Particularly, we will focus on visits and contributions, as they constitute the two most common forms of interaction. Our study is based on a sample of the requests submitted to Wikipedia, and its results are twofold: on the one hand, it provides different metrics concerning users’ behavior and, on the other, presents particular comparisons among different Wikipedia editions.

Design of a dynamic positioning system for a moored floating platform using QFT robust control

This paper describes the design of a dynamic positioning system for a moored floating platform by using robust control techniques, particularly Quantitative Feedback Theory (QFT). The goal is to minimize the drift resulting from the wave action by appropriate thrusters control. The model of the platform is a SIMO (single-input multiple-output) system, therefore an interesting question is that the plant has less degree of freedom for actuation and is difficult to control. The control problem of the underactuated system is solved by an iterative multi-stage sequential procedure. Simulation results are presented to demonstrate that the control achieves efficiently the dynamic positioning system. Therefore robust techniques based on QFT methodology constitute attractive alternatives in the application of positioning control of an underactuated marine system.

Applications of QFT robust control techniques to marine systems

In this work an overview of the application of the Quantitative Feedback Theory (QFT) technique to different marine systems is presented. Namely the problems of the stabilization of a high-speed craft, the dynamic positioning of a moored platform and the tracking control of a hovercraft are studied. An interesting question is that the plants have less degree of freedom for actuation and is more difficult to control. The three multivariable nonlinear problems are tackled by different procedures. Performance evaluation analyses and simulations in different conditions are carried out. It is shown that robust techniques based on QFT methodology result feasible and very suitable; and therefore they constitute attractive alternatives in the application of stabilization, dynamic positioning and tracking control of advanced marine systems.