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Publicações

2017

PLineD: Vision-based Power Lines Detection for Unmanned Aerial Vehicles

Autores
Santos, T; Moreira, M; Almeida, J; Dias, A; Martins, A; Dinis, J; Formiga, J; Silva, E;

Publicação
2017 IEEE INTERNATIONAL CONFERENCE ON AUTONOMOUS ROBOT SYSTEMS AND COMPETITIONS (ICARSC)

Abstract
It is commonly accepted that one of the most important factors for assuring the high performance of an electrical network is the surveillance and the respective preventive maintenance. From a long time ago that TSOs and DSOs incorporate in their maintenance plans the surveillance of the grid, where is included the aerial power lines inspection. Those inspections started by human patrol, including structure climbing when needed and later were substituted by helicopters with powerful sensors and specialised technicians. More recently the Unmanned Aerial Vehicles (UAV) technology has been used, taking advantage of its numerous advantages. This paper addresses the problem of improving the real-time perception capabilities of UAVs for endowing them with capabilities for safe and robust autonomous and semi-autonomous operations. It presents a new vision based power line detection algorithm denoted by PLineD, able to improve the detection robustness even in the presence of image with background noise. The algorithm is tested in real outdoor images of a dataset with multiple backgrounds and weather conditions. The experimental results demonstrate that the proposed approach is effective and able to implemented in real-time image processing pipeline.

2017

FEMALE ENTREPRENEURSHIP AND ACCESS TO BANK LOANS IN TANZANIA: A DOUBLE-HURDLE MODEL APPROACH

Autores
Teixeira, AAC; Sharifu, HA;

Publicação
JOURNAL OF DEVELOPMENTAL ENTREPRENEURSHIP

Abstract
The present study assesses the perceptions of female entrepreneurs in Tanzania regarding the access to bank loans and the difficulties experienced in the process of financing their businesses. Focusing on small-scale businesses, face-to-face interviews were conducted with 75 female entrepreneurs from the Dar es Salaam area. Resorting to double-hurdle estimation models, we conclude that: 1) women who perceive higher discrimination and/or inequality in accessing bank loans, but who also recognize that female entrepreneurs often lack relevant business skills, tend to apply more often for bank loans; 2) women running larger business, operating in the tailoring industry, face fewer difficulties; 3) although highly educated female entrepreneurs apply less for bank loans, formal education acts as a shield to the difficulties faced by women when applying to bank loans; 4) more autonomous and money seeking female entrepreneurs are less likely to report difficulties during the bank loan application process.

2017

Fabrication and characterization of TiO2 coated cone shaped nano-fiber pH sensor

Autores
Pathak, AK; Bhardwaj, V; Gangwar, RK; De, M; Singh, VK;

Publicação
Optics Communications

Abstract
In the present paper a novel cone shaped nano-fiber (CSNF) pH sensor using multi-mode fiber (MMF) has been fabricated and demonstrated. Three different pH indicators, chlorophenol red, bromothymol blue and cresol red with precursor tetraethyl orthosilicate (TEOS) have been used for fabrication of pH sensing layer. A significant enhancement in sensing properties of pH sensor with TiO2 thin film has been observed. The pH sensor with TiO2 thin film shows the quite high sensitivity (1.16 dBm/pH) as compared to sensor with simple pH coating (0.81 dBm/pH) at 1550 nm with a good linear response. Moreover, the sensor with TiO2 film exhibits fast response time of ~ 25 s for pH values ranging from 4 to 11 with excellent stability and durability. © 2016 Elsevier B.V.

2017

Learning with Imbalanced Domains: Preface

Autores
Torgo, L; Krawczyk, B; Branco, P; Moniz, N;

Publicação
First International Workshop on Learning with Imbalanced Domains: Theory and Applications, LIDTA@PKDD/ECML 2017, 22 September 2017, Skopje, Macedonia

Abstract

2017

Weightless neural networks for open set recognition

Autores
Cardoso, DO; Gama, J; França, FMG;

Publicação
MACHINE LEARNING

Abstract
Open set recognition is a classification-like task. It is accomplished not only by the identification of observations which belong to targeted classes (i.e., the classes among those represented in the training sample which should be later recognized) but also by the rejection of inputs from other classes in the problem domain. The need for proper handling of elements of classes beyond those of interest is frequently ignored, even in works found in the literature. This leads to the improper development of learning systems, which may obtain misleading results when evaluated in their test beds, consequently failing to keep the performance level while facing some real challenge. The adaptation of a classifier for open set recognition is not always possible: the probabilistic premises most of them are built upon are not valid in a open-set setting. Still, this paper details how this was realized for WiSARD a weightless artificial neural network model. Such achievement was based on an elaborate distance-like computation this model provides and the definition of rejection thresholds during training. The proposed methodology was tested through a collection of experiments, with distinct backgrounds and goals. The results obtained confirm the usefulness of this tool for open set recognition.

2017

Simultaneous Measurement of Temperature and Refractive Index Based on Microfiber Knot Resonator Integrated in an Abrupt Taper Mach-Zehnder Interferometer

Autores
Gomes, AD; Frazao, O;

Publicação
THIRD INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
A microfiber knot resonator integrated in an abrupt taper-based Mach-Zehnder interferometer was used for simultaneous measurement of temperature and refractive index. This compact structure was fabricated using only CO2 laser processing. The transmission spectrum is the combination of the microfiber knot resonator and the Mach-Zehnder interferometer responses. The two different components of the transmission spectrum (the microfiber knot resonator and the MachZehnder interferometer components) present different sensitivities when subjected to physical or chemical parameters. A characterization in temperature, refractive index, and sodium chloride (NaCl) concentration was performed. A simple matrix method was used for simultaneous measurement of temperature and refractive index.

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