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Publications

2016

User-friendly imaging algorithms for interferometry

Authors
Young, J; Thiebaut, E; Duvert, G; Vannier, M; Garcia, P; Mella, G;

Publication
OPTICAL AND INFRARED INTERFEROMETRY AND IMAGING V

Abstract
OPTICON currently supports a Joint Research Activity (JRA) dedicated to providing easy to use image reconstruction algorithms for optical/IR interferometric data. This JRA aims to provide state-of-the-art image reconstruction methods with a common interface and comprehensive documentation to the community. These tools will provide the capability to compare the results of using different settings and algorithms in a consistent and unified way. The JRA is also providing tutorials and sample datasets to introduce the principles of image reconstruction and illustrate how to use the software products. We describe the design of the imaging tools, in particular the interface between the graphical user interface and the image reconstruction algorithms, and summarise the current status of their implementation.

2016

High-Level Synthesis

Authors
Cardoso, JMP; Weinhardt, M;

Publication
FPGAs for Software Programmers

Abstract
The compilation of high-level languages, such as software programming languages, to FPGAs is of paramount importance for the mainstream adoption of FPGAs. An efficient compilation process will improve designer productivity and will make the use of FPGA technology viable for software programmers. When targeting the hardware resources provided by FPGAs, a compilation process usually requires a stage known as High-Level Synthesis (HLS) which is responsible for generating application specific hardware architectures from the input source code or from an intermediate representation of the input application. This chapter briefly describes HLS and its main processing stages. The chapter provides the indispensable knowledge for readers who want to follow the remaining chapters of this book. © Springer International Publishing Switzerland 2016.

2016

Curvature and Vibration Sensing Based on Core Diameter Mismatch Structures

Authors
Fernandes, CS; Giraldi, MTMR; de Sousa, MJ; Costa, JCWA; Gouveia, C; Jorge, P; Franco, MAR;

Publication
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT

Abstract
Core diameter mismatch structures are proposed and experimentally investigated for curvature and vibration sensing. Two configurations are suggested, one approach uses a structure formed by splicing an uncoated short section of multimode fiber between two standard single-mode fibers (SMFs) single-mode-multimode-single-mode (SMS), combined to a fiber optical mirror at its end, and the other approach uses a structure made by splicing a section of SMF between two multimode fibers (SMSMS). In the curvature analysis, the proposed SMS sensor generates the destructive interference patterns when it is bent, varying only the attenuation of the optical signal without wavelength shifts. The SMSMS vibration sensor proved to be suitable to monitor very low frequencies such as 0.1 Hz. The configuration of the proposed sensors presents several interesting features, such as easy fabrication, low cost, high efficiency, and high sensitivity. These advantages make such sensors very useful in a wide range of applications, for instance, structural health monitoring.

2016

An Overview of Concept Drift Applications

Authors
Žliobaite I.; Pechenizkiy M.; Gama J.;

Publication
Studies in Big Data

Abstract
In most challenging data analysis applications, data evolve over time and must be analyzed in near real time. Patterns and relations in such data often evolve over time, thus, models built for analyzing such data quickly become obsolete over time. In machine learning and data mining this phenomenon is referred to as concept drift. The objective is to deploy models that would diagnose themselves and adapt to changing data over time. This chapter provides an application oriented view towards concept drift research, with a focus on supervised learning tasks. First we overview and categorize application tasks for which the problem of concept drift is particularly relevant. Then we construct a reference framework for positioning application tasks within a spectrum of problems related to concept drift. Finally, we discuss some promising research directions from the application perspective, and present recommendations for application driven concept drift research and development.

2016

Automatic Segmentation of Extensor Tendon of the MCP Joint in Ultrasound Images

Authors
Sultan, MS; Martins, N; Veiga, D; Ferreira, M; Coimbra, MT;

Publication
Proceedings of the 9th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2016) - Volume 2: BIOIMAGING, Rome, Italy, February 21-23, 2016.

Abstract
Rheumatoid arthritis (RA) is a chronic inflammatory disease that primarily affects the small joints of the hand. High frequency ultrasound imaging is used to measure the inflammatory activity in the joint capsule region of Metacarpophalangeal (MCP) joint. In our previous work, the problem of bones and joint capsule segmentation was addressed and in this work we aim to automatically identify the tendon using previously segmented structures. The extensor tendon is located above the metacarpal and phalange bone and the joint capsule. Tendon and bursal involvement are frequent and often clinically dominant in early RA. Ridge-like structures are enhanced and pre-processed to reduce speckle noise using a Log-Gabor filter. These regions are then simplified using medial axis transform and vertically connected lines are removed. Adjacent lines are connected using morphological operators and short lines are filtered by thresholding. Physiological information is used to create a distance map for all the lines using prior knowledge of the bone and capsule region location. Based on this distance map, the tendon is finally segmented and its shape refined by using active contours. The segmentation algorithm was tested on 90 images and experimental results demonstrate the accuracy of the proposed algorithm. The automatic segmentation was compared with an expert manual segmentation, and a mean error of 3.7 pixels and a standard deviation of 2 pixels were achieved, which are interested results for integration into future computer-assisted decision systems.

2016

Performance-driven instrumentation and mapping strategies using the LARA aspect-oriented programming approach

Authors
Cardoso, JMP; Coutinho, JGF; Carvalho, T; Diniz, PC; Petrov, Z; Luk, W; Goncalves, F;

Publication
SOFTWARE-PRACTICE & EXPERIENCE

Abstract
The development of applications for high-performance embedded systems is a long and error-prone process because in addition to the required functionality, developers must consider various and often conflicting nonfunctional requirements such as performance and/or energy efficiency. The complexity of this process is further exacerbated by the multitude of target architectures and mapping tools. This article describes LARA, an aspect-oriented programming language that allows programmers to convey domain-specific knowledge and nonfunctional requirements to a toolchain composed of source-to-source transformers, compiler optimizers, and mapping/synthesis tools. LARA is sufficiently flexible to target different tools and host languages while also allowing the specification of compilation strategies to enable efficient generation of software code and hardware cores (using hardware description languages) for hybrid target architectures - a unique feature to the best of our knowledge not found in any other aspect-oriented programming language. A key feature of LARA is its ability to deal with different models of join points, actions, and attributes. In this article, we describe the LARA approach and evaluate its impact on code instrumentation and analysis and on selecting critical code sections to be migrated to hardware accelerators for two embedded applications from industry. Copyright (c) 2014 John Wiley & Sons, Ltd.

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