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Publicações

2016

Localization and Navigation of an Omnidirectional Mobile Robot: The Robot@Factory Case Study

Autores
Costa, PJ; Moreira, N; Campos, D; Goncalves, J; Lima, J; Costa, PL;

Publicação
IEEE REVISTA IBEROAMERICANA DE TECNOLOGIAS DEL APRENDIZAJE-IEEE RITA

Abstract
The Robot@Factory competition was recently included in Robotica, the main Portuguese Robotics Competition. This robot competition takes place in an emulated factory plant, where automatic guided vehicles (AGVs) must cooperate to perform tasks. To accomplish their goals, the AGVs must deal with localization, navigation, scheduling, and cooperation problems that must be solved autonomously. This robot competition can play an important role in education due to its inherent multidisciplinary approach, which can motivate students to bridge different technological areas. It can also play an important role in research and development, because it is expected that its outcomes will later be transferred to real-world problems in manufacturing or service robots. By presenting a scaled-down factory shop floor, this competition creates a benchmark that can be used to compare different approaches to the challenges that arise in this kind of environment. The ability to alter the environment, in some restricted areas, can usually promote the test and evaluation of different localization mechanisms, which is not possible in other competitions. This paper presents one of the possible approaches to build a robot capable of entering this competition. It can be used as a reference to current and new teams.

2016

Tensor-based anomaly detection: An interdisciplinary survey

Autores
Fanaee T, H; Gama, J;

Publicação
KNOWLEDGE-BASED SYSTEMS

Abstract
Traditional spectral-based methods such as PCA are popular for anomaly detection in a variety of problems and domains. However, if data includes tensor (multiway) structure (e.g. space-time-measurements), some meaningful anomalies may remain invisible with these methods. Although tensor-based anomaly detection (TAD) has been applied within a variety of disciplines over the last twenty years, it is not yet recognized as a formal category in anomaly detection. This survey aims to highlight the potential of tensor-based techniques as a novel approach for detection and identification of abnormalities and failures. We survey the interdisciplinary works in which TAD is reported and characterize the learning strategies, methods and applications; extract the important open issues in TAD and provide the corresponding existing solutions according to the state-of-the-art.

2016

High Resolution Trichromatic Road Surface Scanning with a Line Scan Camera and Light Emitting Diode Lighting for Road-Kill Detection

Autores
Lopes, G; Ribeiro, AF; Sillero, N; Goncalves Seco, L; Silva, C; Franch, M; Trigueiros, P;

Publicação
SENSORS

Abstract
This paper presents a road surface scanning system that operates with a trichromatic line scan camera with light emitting diode (LED) lighting achieving road surface resolution under a millimeter. It was part of a project named Roadkills-Intelligent systems for surveying mortality of amphibians in Portuguese roads, sponsored by the Portuguese Science and Technology Foundation. A trailer was developed in order to accommodate the complete system with standalone power generation, computer image capture and recording, controlled lighting to operate day or night without disturbance, incremental encoder with 5000 pulses per revolution attached to one of the trailer wheels, under a meter Global Positioning System (GPS) localization, easy to utilize with any vehicle with a trailer towing system and focused on a complete low cost solution. The paper describes the system architecture of the developed prototype, its calibration procedure, the performed experimentation and some obtained results, along with a discussion and comparison with existing systems. Sustained operating trailer speeds of up to 30 km/h are achievable without loss of quality at 4096 pixels' image width (1 m width of road surface) with 250 mu m/pixel resolution. Higher scanning speeds can be achieved by lowering the image resolution (120 km/h with 1 mm/pixel). Computer vision algorithms are under development to operate on the captured images in order to automatically detect road-kills of amphibians.

2016

Male breast cancer: Looking for better prognostic subgroups

Autores
Abreu, MH; Afonso, N; Abreu, PH; Menezes, F; Lopes, P; Henrique, R; Pereira, D; Lopes, C;

Publicação
BREAST

Abstract
Purpose: Male Breast Cancer (MBC) remains a poor understood disease. Prognostic factors are not well established and specific prognostic subgroups are warranted. Patients/methods: Retrospectively revision of 111 cases treated in the same Cancer Center. Blinded-central pathological revision with immunohistochemical (IHQ) analysis for estrogen (ER), progesterone (PR) and androgen (AR) receptors, HER2, ki67 and p53 was done. Cox regression model was used for uni/multivariate survival analysis. Two classifications of Female Breast Cancer (FBC) subgroups (based in ER, PR, HER2, 2000 classification, and in ER, PR, HER2, ki67, 2013 classification) were used to achieve their prognostic value in MBC patients. Hierarchical clustering was performed to define subgroups based on the six-IHQ panel. Results: According to FBC classifications, the majority of tumors were luminal: A (89.2%; 60.0%) and B (7.2%; 35.8%). Triple negative phenotype was infrequent (2.7%; 3.2%) and HER2 enriched, non-luminal, was rare (<= 1% in both). In multivariate analysis the poor prognostic factors were: size >2 cm (HR: 1.8; 95% CI: 1.0-3.4years, p = 0.049), absence of ER (HR: 4.9; 95% CI: 1.7-14.3years, p = 0.004) and presence of distant metastasis (HR: 5.3; 95% CI: 2.2-3.1years, p < 0.001). FBC subtypes were independent prognostic factors (p = 0.009, p = 0.046), but when analyzed only luminal groups, prognosis did not differ regardless the classification used (p > 0.20). Clustering defined different subgroups, that have prognostic value in multivariate analysis (p = 0.005), with better survival in ER/PR+, AR-, HER2- and ki67/p53 low group (median: 11.5 years; 95% CI: 6.2-16.8 years) and worst in PR-group (median: 4.5 years; 95% CI: 1.6 -7.8 years). Conclusion: FBC subtypes do not give the same prognostic information in MBC even in luminal groups. Two subgroups with distinct prognosis were identified in a common six-IHQ panel. Future studies must achieve their real prognostic value in these patients.

2016

Separating Degrees of Freedom for Object Manipulation in VR

Autores
Relvas, F; Mendes, D; Ferreira, A; Jorge, J;

Publicação
2016 23RD PORTUGUESE MEETING ON COMPUTER GRAPHICS AND INTERACTION (EPCGI)

Abstract
Manipulating objects is an essential aspect in virtual environments. Nonetheless, object positioning in immersive virtual environments relying in direct and natural approaches is still difficult. Previous research concluded that degrees-of-freedom separation in mouse and touch interfaces led to positive results. In this document we present a user evaluation to assess if explicit separation of degrees-of-freedom also benefits mid-air manipulation tasks. We implemented a virtual widget based technique that allows users to control a single DOF, and compared it against a direct approach and the PRISM technique, which adjusts the ratio between the hand and object movement. The results of our assessment suggest that full DOF separation benefits precision in spatial manipulations, at the expense of additional time for complex tasks. From these results we proposed a new technique that combines different aspects from the three techniques compared in our assessment.

2016

A Novel DC-Bus Sensor-less MPPT Technique for Single-Stage PV Grid-Connected Inverters

Autores
Elsaharty, MA; Ashour, HA; Rakhshani, E; Pouresmaeil, E; Catalao, JPS;

Publicação
ENERGIES

Abstract
Single-stage grid connected inverters are considered as an economic, compact and simple topology compared with multi-stage inverters. In photovoltaic (PV) grid connected systems, the major requirement is to achieve maximum output power from the source. Maximum Power Point Tracking (MPPT) techniques require measurements on the DC side of the inverter connected to the PV in order to determine the current operating point on the power characteristics. Typically this is achieved by perturbing the reference output power and observe the change in the PV voltage, current or both. Based on the observation, it could be determined whether the current operating point is beyond or below maximum power. This paper presents an MPPT technique for a single-stage PV grid connected inverter where the MPPT algorithm determines the current operating point at different operating conditions based upon observing the inverter controller action. Such approach eliminates the requirement of sensing elements to be added to the converter which aids the advantages of the single-stage converter. Design of the utilized PV system is derived based on filter parameters, PV panel selection and controller parameters. Using simulation and practical implementation, the performance of the proposed MPPT technique is evaluated for the PV grid connected system.

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