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Publications

2014

Characterization of an Acoustic Based Device for Local Arterial Stiffness Assessment

Authors
Pereira, HC; Contente, M; Almeida, V; Pereira, T; Simoes, JB; Cardoso, J; Correia, C; Pereira, HC; Simoes, JB; Maldonado, J; Pereira, T;

Publication
BIOMEDICAL ENGINEERING SYSTEMS AND TECHNOLOGIES (BIOSTEC 2013)

Abstract
Arterial stiffness, recognized as an independent predictor of cardiovascular events, can be assessed non-invasively by regional and local methods. The present work proposes and describes a novel and low-cost device, based on a double-headed acoustic probe (AP), to assess local arterial stiffness, by means of pulse wave velocity (PWV) measurements. Local PWV is measured over the carotid artery and relies on the determination of the time delay between the signals acquired simultaneously by both acoustic sensors, placed at a fixed distance. The AP was characterized with dedicated test setups, in order to evaluate its performance concerning waveform analysis, repeatability, crosstalk effect and time resolution. Results show that AP signals are repeatable and crosstalk effect do not interfere with its time resolution, when the cross-correlation algorithm for time delay estimation is used. The AP's effectiveness in measuring higher PWV (14 m/s), with a relative error less than 5 %, when using two uncoupled APs, was also demonstrated. Finally, its clinical feasibility was investigated, in a set of 17 healthy subjects, in which local PWV and other hemodynamic parameters were measured. Carotid PWV yielded a mean value of 2.96 +/- 1.08 m/s that is in agreement with the values obtained in other reference studies.

2014

How to publish privately

Authors
Bettencourt, N; Silva, N; Barroso, J;

Publication
CEUR Workshop Proceedings

Abstract
In a world overwhelmed by constant data creation and manipulation, where privacy is becoming a real concern, topics like data usage control, accountability, provenance, protected sharing of resources and trustworthiness of knowledge sources are becoming main topics of discussion among communities of interest. In this paper enhancements are proposed for an existing framework that tackles some of the afore mentioned issues namely data provenance, usage control and accountability. Such proposals consist of providing means for publishing resources in a private manner hereby making websites behave like meshes of hyperlinked resources from different domains, not only for resources publicly published but also for the ones protected by access policies. © 2014, Society, Privacy and the Semantic Web Policy and Technology.

2014

Single minute exchange of die and organizational innovation in seven small and medium-sized firms

Authors
Carrizo Moreira, A;

Publication
Lean Manufacturing in the Developing World: Methodology, Case Studies and Trends from Latin America

Abstract
Innovation plays a very important role in businesses competitiveness. As Small and Medium-sized Enterprises (SMEs) stem for more than 95 % of the industrial fabric in the developed world, the improvement of the industrial production or the provision of a service are key to increase their productivity and competitiveness. The Single Minute Exchange of Die (SMED) is a Japanese process-based innovative methodology that involves the separation and conversion of internal setup operations into external ones. The SMED makes it possible for firms to reduce their lead times and to eliminate wastefulness during changeover activities. Although organizational innovation is a very important tool, it plays a silent role in productivity improvement, as it is less tangible than product or process innovation. Moreover, studies about SMED implementation and how teams have managed to achieve their results are still very limited among SMEs. The main objective of this chapter is to provide the results of seven projects involving business-university partnerships addressing this understudied topic: SMED implementation and organizational innovation in SMEs. The main finding of this study is that all firms managed to improve their setup times, although the results vary extensively. From the organizational innovation point of view, only one firm failed to intertwine the initiation and the implementation stages. Although all firms have initiation-implementation routines, there are clear differences among them. As a result, although it is possible to claim that all SMEs analyzed are ambidextrous organizations, their initiation-implementation routines, deserve deeper comprehension. © Springer International Publishing Switzerland 2014. All rights are reserved.

2014

INTERROGATION AND MULTIPLEXING SYSTEM FOR FIBER LOOP MIRROR COUPLED INTENSITY SENSORS USING OTDR

Authors
Rocco Giraldi, MTMR; Fernandes, CS; Ferreira, MS; de Sousa, MJ; Jorge, P; Costa, JCWA; Santos, JL; Frazao, O;

Publication
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS

Abstract
In this article, it is proposed an interrogation and multiplexing system based on optical time domain reflectometer for fiber loop mirror coupled intensity sensors. Pulse width of approximately 100 ns enabled to attain a dynamic range of approximately 18 dB. Good linearity was achieved with a -13.3 dB/mm slope. The resolution of the sensing head was 0.027 mm. The proposed interrogation system showed to be an alternative technique for multiplexing and remote sensing. (C) 2014 Wiley Periodicals, Inc.

2014

SECURITY VULNERABILITIES AND RISKS IN INDUSTRIAL USAGE OF WIRELESS COMMUNICATION

Authors
Plosz, S; Farshad, A; Tauber, M; Lesjak, C; Ruprechter, T; Pereira, N;

Publication
2014 IEEE EMERGING TECHNOLOGY AND FACTORY AUTOMATION (ETFA)

Abstract
Due to its availability and low cost, the use of wireless communication technologies increases in domains beyond the originally intended usage areas, e.g. M2M communication in industrial applications. Such industrial applications often have specific security requirements. Hence, it is important to understand the characteristics of such applications and evaluate the vulnerabilities bearing the highest risk in this context. We present a comprehensive overview of security issues and features in existing WLAN, NFC and ZigBee standards, investigating the usage characteristics of these standards in industrial environments. We apply standard risk assessment methods to identify vulnerabilities with the highest risk across multiple technologies. We present a threat catalogue, conclude in which direction new mitigation methods should progress and how security analysis methods should be extended to meet requirements in the M2M domain.

2014

Control Strategy for the Stable Operation of Multilevel Converter Topologies in DG Technology

Authors
Pouresmaeil, E; Mehrasa, M; Catalao, JPS;

Publication
2014 POWER SYSTEMS COMPUTATION CONFERENCE (PSCC)

Abstract
A control technique of multilevel converter topologies based on Direct Lyapunov Control method is presented in this paper for integration of Distributed Generation (DG) resources into the power grid. The compensation of instantaneous variations in the reference current components in ac-side and dc-voltage variations of cascaded capacitors in dc-side of the interfacing system are considered properly, which is the main contribution and novelty of this work in comparison with other control strategies. The proposed control technique provides the continuous injection of active power in fundamental frequency from DG sources to the grid. In addition, reactive power and harmonic current components of loads are provided with a fast dynamic response; thereby, achieving sinusoidal grid currents in phase with load voltages, while the required power from load side is more than the maximum capacity of interfaced converter, is possible. Simulation results confirm the effectiveness of the proposed control strategy in DG technology during dynamic and steady-state operating conditions.

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