Non INESC TEC publications - Indexed Articles in Conferences

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    Spanish coal royal decree: An energy security measure
    ( 2013) Diaz,CA ; José Villar ; Campos,FA ; Gonzalez,P ; Webster,M
    National governments sometimes introduce policies that modify energy markets to achieve other social and political goals. These policies, created with the best of intentions, often have unintended consequences. Here we present a case study of one such policy, the Royal Decree in Spain that mandates the use of the Spanish-Indigenous Coal (IC). © 2013 IEEE.
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    Design lessons from deploying NFC mobile payments
    ( 2013) Jose,R ; Rodrigues,H ; Melro,A ; Coelho,A ; Marta Campos Ferreira
    The adoption of mobile payment systems is known to face multiple concerns regarding security, usability and value proposition. In this work, we start from the assumption that initial acceptance will always be weak because of the lack of an established usage frame. Instead, we focus on understanding how we can leverage upon the real contact with the technology to create a solid path for gradual acceptance through the development of new practices and the increasing perception of value. In this study, we report on our findings with a real-world prototype of a NFC-based payment system. We identify a set of design lessons that may help to improve the initial phases of NFC-based payment deployments and provide a path for the adoption that focuses on positive initial user experiences and early adoption scenarios. © Springer International Publishing 2013.
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    Lane Background Removal for the Classification of Thin-Layer Chromatography Images
    ( 2013) Moreira,BM ; Sousa,AV ; Ana Maria Mendonça ; Aurélio Campilho
    This paper describes a methodology to remove the background of the lanes in Thin Layer Chromatography (TLC) images, aiming at improving band detection and classification. The storage of the biological samples to be analyzed by TLC is usually done via plastic containers. Filter paper is an alternative that allows reduced costs and higher portability, but it increases the complexity of the image analysis stage due to lane background alteration. In order to overcome this problem, a negative control lane is included in every chromatographic plate. After image preprocessing and lane detection stages, a background profile is generated by processing the negative control lane using the Discrete Wavelet Transform (DWT). This profile is then subtracted to the profiles of all other sample lanes in order to overcome the data degradation introduced by filter paper usage. For assessing the proposed background removal process, 105 TLC lanes, with and without background, were used as input for three one-class classifiers. In all cases, the best results were achieved for the lanes after background removal.
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    Automatic Classification of Retinal Vessels Using Structural and Intensity Information
    ( 2013) Dashtbozorg,B ; Ana Maria Mendonça ; Aurélio Campilho
    This paper presents an automatic approach for artery/vein (A/V) classification based on the analysis of a graph representing the structure of the retinal vasculature. The entire vascular tree is classified by deciding on the type of each intersection point (graph node) and assigning one of two classes to each vessel segment (graph link). The final label for each vessel segment is accomplished by a combination of structural information taken from the graph (link class) with intensity features measured in the original color image. An accuracy of 88.0% was achieved for the 40 images of the INSPIRE-AVR dataset, thus demonstrating that our method outperforms state-of-the-art approaches for A/V classification.
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    Hourly energy and reserve joint dispatch with a hydro-thermal technological based representation
    ( 2013) Gonzalez,P ; José Villar ; Diaz,CA ; Campos,FA
    Intermittent technologies are enhancing both the economic and technological value of ancillary services in the electric power system. Some of these services commonly denoted as reserves have been liberalized and are offered in the balancing markets in the European Union countries, or in the regulation markets in the USA. This paper presents a deterministic single-node centralized energy and secondary reserve dispatch that outputs hourly scheduled energies and reserves, and both commodities prices. In this model, units of each generation company are simplified into technologies and sub-technologies for faster performance, but still considering inter temporal constraints such as ramps and responding time for reserves, and unit commitment decisions such as start-up and shut-down costs. Detailed short-term hydro-thermal constraints (topology, efficiency, etc.) have been simplified by means of weekly constraints based on historical data (inflows, installed capacity, productions). The model has been validated by comparing its output prices and productions with the real ones occurred during 2010 in the Spanish market with satisfactory results. Furthermore, a study-case on high penetration of solar generation in the Spanish system reveals strong interactions between the energy and reserve markets and points out the importance of hydro technologies in the system. © 2013 IEEE.
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    Telenursing in colorectal cancer patient follow-up and treatment assessment: a mixed methods evaluation study
    ( 2013) Dias,MJ ; Fragoso,M ; Lara Santos,L ; Pedro Pereira Rodrigues
    The incidence of colorectal cancer cases in the Portuguese Institute of Oncology of Porto created the need of a telenursing program in the Gastro-Intestinal Cancer Unit. After staging, treatment may involve surgery radio and chemotherapy (either oral or IV). Patients with no treatment after surgery are scheduled for medical exams every 3 months in the first 2 years. Patients on chemotherapy need to be compliant and to have a close monitoring of adverse events. The GI Cancer Unit uses a telenursing information system to help assess colorectal cancer patients' follow-up after surgery, medical treatment compliance and adverse events. A mixed-methods evaluation was done to a) describe the target population, b) detect problems in the telenursing information system, and c) suggest changes to meet users' requirements. From 181 outbound phone calls, representing 67 patients (49 in treatment and 18 in follow-up), patients' main characteristics were extracted and system's problems were identified by the intervening nurses. Recommendations will be useful for a further development of the system.
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    Enhancing traffic sampling scope and efficiency
    ( 2013) João Marco ; Carvalho,P ; Lima,SR
    Traffic Sampling is a crucial step towards scalable network measurements, enclosing manifold challenges. The wide variety of foreseeable sampling scenarios demands for a modular view of sampling components and features, grounded on a consistent architecture. Articulating the measurement scope, the required information model and the adequate sampling strategy is a major design issue for achieving an encompassing and efficient sampling solution. This is the main focus of the present work, where a layered architecture, a taxonomy of existing sampling techniques distinguishing their inner characteristics and a flexible framework able to combine these characteristics are introduced. In addition, a new multiadaptive technique proposal, based on linear prediction, allows to reduce the measurement overhead significantly, while assuring that traffic samples reflect the statistical behavior of the global traffic under analysis. © 2013 IEEE.
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    Automatic Estimation of the Arteriolar-to-Venular Ratio in Retinal Images Using a Graph-Based Approach for Artery/Vein Classification
    ( 2013) Dashtbozorg,B ; Ana Maria Mendonça ; Aurélio Campilho
    The Arteriolar-to-Venular Ratio (AVR) is a well known index for the diagnosis of diseases such as diabetes, hypertension or cardiovascular pathologies. This paper presents a fully automatic AVR estimation method which uses a graph-based artery/vein classification approach to classify the retinal vessels by a combination of structural information taken from the vasculature graph with intensity features from the original color image. This method was evaluated on the images of the INSPIRE-AVR dataset. The mean error and the correlation coefficient of obtained results with respect to the reference AVR values were identical to the ones obtained by the second observer using a semi-automated system, which demonstrate the potential of the herein proposed solution for clinical application.
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    Correction of Geometrical Distortions in Bands of Chromatography Images
    ( 2013) Moreira,BM ; Sousa,AV ; Ana Maria Mendonça ; Aurélio Campilho
    This paper presents a methodology for correcting band distortions in Thin-Layer Chromatography (TLC) images. After the segmentation of image lanes, the intensity profile of each lane column is spatially aligned with a reference profile using a modified version of the Correlation Optimized Warping (COW) algorithm. As the initial partition of the profile into equal length segments proposed by COW can result in the separation of a single band between two segments to be disjointedly aligned, in the proposed method the warping function is only applied to selected profile regions containing groups of adjacent bands. The proposed band correction methodology was assessed using 105 profiles of 105 TLC lanes. A set of features for band characterization was extracted from each lane profile, before and after band distortion correction, and was used as input for three distinct one-class classifiers aiming at band identification. In all cases, the best results of band classification were obtained for the set lanes after band distortion correction.
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    Enhancing Scaling Exponents in Heart Rate by means of Fractional Integration
    ( 2013) Argentina Leite ; Rocha,AP ; Silva,ME
    The characterization of heart rate variability (HRV) series has become important for clinical diagnosis. These series are non-stationary and exhibit long and short-range correlations. The non-parametric methodology detrended fluctuation analysis (DFA) has become widely used for the detection of these correlations. The standard procedure is to apply DFA to the RR series, estimating the desired scaling exponents. In this work we pursue an alternative approach which consists in applying DFA to the fractionally differenced RR series, Delta(RR)-R-d, where 0 < d < 1 is the long-range correlation parameter. Both methodologies are applied to 24 hour HRV series from the Noltisalis data base. We conclude that changes in HRV are better quantified by DFA scaling exponents calculated over fractionally differenced RR series than by the standard procedure. The results indicate that the scaling exponent corresponding to high frequencies obtained from Delta(RR)-R-d increases the discriminatory power among the groups: from 60% to 87% during the day period and 57% to 77% during the night period.
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    Criteria for Lipid layer pattern evaluation. Pli-marker database
    ( 2013) Garcia Resua,C ; Pena Verdeal,H ; Beatriz Remeseiro López ; Penedo,MG ; Jesus Giraldez,MJ ; Yebra Pimentel,E
    The purpose of this study is to establish the procedure of acquisition and evaluate the Lipid layer pattern (LLP) by Tearscope in order to enhance this useful technique. To aid this purpose, we present a new broad LLP images database (included in a web application called Pli-marker) The tear film lipid layer was examined using a Tearscope-plus (Keeler, Windsor, UK). To capture LLPs videos a Topcon DV-3 digital camera was used and attached to the slit lamp. All videos were stored in a computer via Topcon IMAGEnet i-base software and LLP images were obtained and uploaded at Pli-marker web application, which offers the manual selection of regions associated to a specific LLP. 50 images were analysed by 4 experienced optometrists. Each of them marked (using Pli-marker) those areas in the 50 images that corresponded with some of the 5 LLP: open meshwork (OM), closed meshwork, (CM), wave (W), amorphous (AM) and color fringe (CO). From the 50 images we obtained 25 areas of OM, 22 areas of CM, 20 areas of W, 46 areas of AM and 17 areas of CO that 4 observers were in accordance. We present an example of 4 pictures for each area of concordance together with the description of the features used for categorizing the LLP in our study. This work describes the methodology used in our research project, including settings for capture image, and the criteria for subjective categorization of the LLP accomplished by a set of images.
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    An Automatic Method for the Estimation of Arteriolar-to-Venular Ratio in Retinal Images
    ( 2013) Dashtbozorg,B ; Ana Maria Mendonça ; Aurélio Campilho
    This paper presents an automatic approach for the estimation of Arteriolar-to-Venular Ratio (AVR) in retinal images. The method was assessed using the images of the INSPIRE-AVR database. A mean error of 0.05 was obtained when the method's results were compared with reference AVR values provided with this dataset, thus demonstrating the adequacy of the proposed solution for AVR estimation.
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    Compaction Management: Results of a Demonstration Project
    ( 2013) Manuel Afonso Parente ; Correia,AG
    Compaction management, also referred to as intelligent compaction (IC), is a real time automatic operation adjustment and continuous compaction control technology of soils or asphalt layers. It is essentially a technology for optimization and evaluation of the compaction process, being capable of adjusting the compaction energy applied to the material, increasing or decreasing compaction efficiency in the necessary areas according to an acceptance target value, thus attaining maximum stiffness, while preventing overcompaction and minimizing the total number of passes. This study seeks to assess in a case study the IC performance, in comparison with conventional compaction methods in terms of efficiency in compaction of a sandy soil. For this purpose, a specific experimental section was carried out in which the performance of an IC compactor was compared with a conventional heavier class compactor. Data was obtained and analysed by the IC continuous information, as well as by the application of several different conventional compaction control tests and methods. Results show that the IC technology presents a superior performance, as well as various advantages when compared to conventional compactors.
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    LogicObjects: Enabling logic programming in Java through linguistic symbiosis
    ( 2013) Castro,S ; Mens,K ; Paulo Moura
    While object-oriented programming languages are good at modelling real-world concepts and benefit from rich libraries and developer tools, logic programming languages are well suited for declaratively solving computational problems that require knowledge reasoning. Non-trivial declarative applications could take advantage of the modelling features of object-oriented programming and of the rich software ecosystems surrounding them. Linguistic symbiosis is a common approach to enable complementary use of languages of different paradigms. However, the problem of concepts leaking from one paradigm to another often hinders the applicability of such approaches. This issue has mainly been reported for object-oriented languages participating in a symbiotic relation with a logic language. To address this issue, we present LogicObjects, a linguistic symbiosis framework for transparently and (semi-) automatically enabling logic programming in Java, that aims to solve most of the problems of paradigm leaking reported in other works. © 2013 Springer-Verlag.
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    Multi-criteria evaluation of class binarization and feature selection in tear film lipid layer classification
    ( 2013) Mendez,R ; Beatriz Remeseiro López ; Peteiro Barral,D ; Penedo,MG
    Dry eye is an increasingly popular syndrome in modern society which can be diagnosed through an automatic technique for tear film lipid layer classification. Previous studies related to this multi-class problem lack of analysis focus on class binarization techniques, feature selection and artificial neural networks. Also, all of them just use the accuracy of the machine learning algorithms as performance measure. This paper presents a methodology to evaluate different performance measures over these unexplored areas using the multiple criteria decision making method called TOPSIS. The results obtained demonstrate the effectiveness of the methodology proposed in this research.
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    Learner's satisfaction within a breast imaging eLearning course for radiographers
    ( 2013) Moreira,IC ; Ventura,SR ; Ramos,I ; Pedro Pereira Rodrigues
    Background: An asynchronous eLearning system was developed for radiographers in order to promote a better knowledge about senology and mammography. Objectives: to assess the learners' satisfaction. Methods: Target population included radiographers and radiography students, in order to assess eLearning satisfaction according to different experience levels in breast imaging. Satisfaction was measured through a questionnaire developed especially for eLearning systems, using a seven-point Likert scale. Main topics related are content, interface, personalization and learning community. Results: Overall, 85% of learners were satisfied with the course and 87,5% considered that the course is successful. Main areas that were evaluated by most learners in a positive way were interface and content (between six and seven-point); on the other hand, learning community presented a wider distribution of answers. Conclusions: The course provides an overall high degree of learner satisfaction, thus providing more effective knowledge gain on breast imaging for radiographers.
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    Pressure Sensor based on an all-fiber Fabry-Perot interferometer for different gaseous environments
    ( 2013) Susana Oliveira Silva ; Luís Carlos Coelho ; Orlando Frazão
    This work describes an all-fiber Fabry-Perot interferometer (FFPI) that is sensitive to gas pressure variations. The geometry of the air cavity consists on splicing a small section of silica rod with a large offset in between two singlemode fibers. It is shown that the FFPI sensor is sensitive to gas pressure variation and when submitted to different gaseous environments, namely carbon dioxide, nitrogen and oxygen, it presented different sensitivities of 6.2, 4.1 and 3.6 nm/MPa, respectively. This result is obtained due to refractive index difference between gases. The refractive index change on nitrogen environment by means of the gas pressure variation resulted in a sensitivity of 1526 nm/RIU. The response of the sensing device to temperature in air was also determined and a sensitivity of -14 pm/degrees C was attained.
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    Dark knowledge and graph grammars in automated software design
    ( 2013) Batory,D ; Rui Carlos Gonçalves ; Marker,B ; Siegmund,J
    Mechanizing the development of hard-to-write and costly-to-maintain software is the core problem of automated software design. Encoding expert knowledge (a.k.a. dark knowledge) about a software domain is central to its solution. We assert that a solution can be cast in terms of the ideas of language design and engineering. Graph grammars can be a foundation for modern automated software development. The sentences of a grammar are designs of complex dataflow systems. We explain how graph grammars provide a framework to encode expert knowledge, produce correct-by-construction derivations of dataflow applications, enable the generation of high-performance code, and improve how software design of dataflow applications can be taught to undergraduates. © 2013 Springer International Publishing.
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    Predicting visualization of hospital clinical reports using survival analysis of access logs from a virtual patient record
    ( 2013) Pedro Pereira Rodrigues ; Dias,CC ; Rocha,D ; Boldt,I ; Teixeira Pinto,A ; Ricardo Correia
    The amount of data currently being produced, stored and used in hospital settings is stressing information technology infrastructure, making clinical reports to be stored in secondary memory devices. The aim of this work was to develop a model that predicts the probability of visualization, within a certain period after production, of each clinical report. We collected log data, from January 2013 till May 2011, from an existing virtual patient record, in a tertiary university hospital in Porto, Portugal, with information on report creation and report first-time visualization dates, along with contextual information. The main factors associated with visualization were defined using logistic regression. These factors were then used as explanatory variables for predicting the probability of a piece of information being accessed after production, using Kaplan-Meier analysis and the Weibull probability distribution. Clinical department, type of encounter and report type were found significantly associated with time-to-visualization and probability of visualization.
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    Colour Texture Segmentation of Tear Film Lipid Layer Images
    ( 2013) Beatriz Remeseiro López ; Ramos,L ; Rodríguez,NB ; González,AM ; Pimentel,EY
    Dry eye is a symptomatic disease which can be diagnosed by several clinical tests. One of them is the evaluation of the interference lipid pattern and its classification into one of the Guillon categories. Previous researches have automatised this manual test, saving time for experts and providing unbiased results. However, the heterogeneity of the tear film lipid layer makes its classification into a single category per eye impossible. For this reason, this paper presents a first approximation to segment tear film images into the Guillon categories, in order to detect several categories in each patient. The adequacy of the methodology was demonstrated since it achieves reliable results in comparison with the annotations done by optometrists. © 2013 Springer-Verlag Berlin Heidelberg.