2012
Autores
Pacheco, H; Cunha, A;
Publicação
Theory and Practice of Model Transformations - 5th International Conference, ICMT 2012, Prague, Czech Republic, May 28-29, 2012. Proceedings
Abstract
Lenses are one of the most popular approaches to define bidirectional transformations between data models. However, writing a lens transformation typically implies describing the concrete steps that convert values in a source schema to values in a target schema. In contrast, many XML-based languages allow writing structure-shy programs that manipulate only specific parts of XML documents without having to specify the behavior for the remaining structure. In this paper, we propose a structure-shy bidirectional two-level transformation language for XML Schemas, that describes generic type-level transformations over schema representations coupled with value-level bidirectional lenses for document migration. When applying these two-level programs to particular schemas, we employ an existing algebraic rewrite system to optimize the automatically-generated lens transformations, and compile them into Haskell bidirectional executables. We discuss particular examples involving the generic evolution of recursive XML Schemas, and compare their performance gains over non-optimized definitions. © 2012 Springer-Verlag.
2012
Autores
Lopes, A; Mendes Moreira, J; Gama, J;
Publicação
CEUR Workshop Proceedings
Abstract
Predicting activities from data gathered with sensors gained importance over the years with the objective of getting a better understanding of the human body. The purpose of this paper is to show that predicting activities on an Android phone is possible. We take into consideration different classifiers, their accuracy using different approaches (hierarchical and one step classification) and limitations of the mobile itself like battery and memory usage. A semi-supervised learning approach is taken in order to compare its results against supervised learning. The objective is to discover if the application can be adapted to the user providing a better solution for this problem. The activities predicted are the most usual in everyday life: walking, running, standing idle and sitting. An android prototype, embedding the software MOA, was developed to experimentally evaluate the ideas proposed here.
2012
Autores
Queiros, RB; Noronha, JP; Marques, PVS; Sales, MGF;
Publicação
26TH EUROPEAN CONFERENCE ON SOLID-STATE TRANSDUCERS, EUROSENSOR 2012
Abstract
Microcystin-LR (MC-LR) is a dangerous toxin found in environmental waters, quantified by high performance liquid chromatography and/or enzyme-linked immunosorbent assays. Quick, low cost and on-site analysis is thus required to ensure human safety and wide screening programs. This work proposes label-free potentiometric sensors made of solid-contact electrodes coated with a surface imprinted polymer on the surface of Multi-Walled Carbon NanoTubes (CNTs) incorporated in a polyvinyl chloride membrane. The imprinting effect was checked by using non-imprinted materials. The MC-LR sensitive sensors were evaluated, characterized and applied successfully in spiked environmental waters. The presented method offered the advantages of low cost, portability, easy operation and suitability for adaptation to flow methods. (C) 2012 Elsevier Ltd....Selection and/or peer-review under responsibility of the Symposium Cracoviense Sp. z.o.o.
2012
Autores
Allender, E; Buhrman, H; Friedman, L; Loff, B;
Publicação
Mathematical Foundations of Computer Science 2012 - 37th International Symposium, MFCS 2012, Bratislava, Slovakia, August 27-31, 2012. Proceedings
Abstract
This paper is motivated by a conjecture [All12, ADF+13] that BPP can be characterized in terms of polynomial-time nonadaptive reductions to the set of Kolmogorov-random strings. In this paper we show that an approach laid out in [ADF+13l] to settle this conjecture cannot succeed without significant alteration, but that it does bear fruit if we consider time-bounded Kolmogorov complexity instead. We show that if a set A is reducible in polynomial time to the set of time-t-bounded Kolmogorov random strings (for all large enough time bounds t), then A is in P/poly, and that if in addition such a reduction exists for any universal Turing machine one uses in the definition of Kolmogorov complexity, then A is in PSPACE. © E. Allender, H. Buhrman, L. Friedman, and B. Loff.
2012
Autores
Pires, A; Putnik, G; Avila, P;
Publicação
JOURNAL OF APPLIED RESEARCH AND TECHNOLOGY
Abstract
In this work, a survey is made of the analysis of the resource selection process. We approach the process also from the point of view of conventional enterprises but with particular emphasis on the existent models in Agile/Virtual Enterprises in order to identify the main limitations and shortcomings of the process. This analysis was focused in the global process of the resource selection, namely in terms of the pre-selection and selection phases, requisites, mathematical models, tools and other relevant areas in the existent models. It is concluded that the resource pre-selection is an area that is not adequately explored in a systematic way. The value concept is not incorporated in the selection process. As a result, a reasoned analysis is not performed of the decision-making process for creating an Agile/Virtual Enterprise. These conclusions were made to envision a future approach that allows the incorporation of new areas that contribute to the improvement of the resource selection process.
2012
Autores
Migueis, VL; Van den Poel, D; Camanho, AS; Falcao e Cunha, JFE;
Publicação
EXPERT SYSTEMS WITH APPLICATIONS
Abstract
Retaining customers has been considered one of the most critical challenges among those included in Customer Relationship Management (CRM), particularly in the grocery retail sector. In this context, an accurate prediction whether or not a customer will leave the company, i.e. churn prediction, is crucial for companies to conduct effective retention campaigns. This paper proposes to include in partial churn detection models the succession of first products' categories purchased as a proxy of the state of trust and demand maturity of a customer towards a company in grocery retailing. Motivated by the importance of the first impressions and risks experienced recently on the current state of the relationship, we model the first purchase succession in chronological order as well as in reverse order, respectively. Due to the variable relevance of the first customer-company interactions and of the most recent interactions, these two variables are modeled by considering a variable length of the sequence. In this study we use logistic regression as the classification technique. A real sample of approximately 75,000 new customers taken from the data warehouse of a European retail company is used to test the proposed models. The area under the receiver operating characteristic curve and 1%, 5% and 10% percentiles lift are used to assess the performance of the partial-churn prediction models. The empirical results reveal that both proposed models outperform the standard RFM model.
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