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Publications

2014

Monitoring the shape parameter of a Weibull distribution

Authors
Figueiredo, F; Gomes, M; Figueiredo, A;

Publication
Proceedings of COMPSTAT 2014 - 21st International Conference on Computational Statistics

Abstract
A control chart based on the quantile function to monitor the shape parameter of a Weibull distribution is proposed and its performance is analyzed by Monte Carlo simulation. The importance of monitoring the shape parameter even when the other parameters of the Weibull distribution are assumed known is further enhanced, together with motivating examples. © 2014 Proceedings of COMPSTAT 2014 - 21st International Conference on Computational Statistics. All rights reserved.

2014

Fast and accurate solution for the SCUC problem in large-scale power systems using adapted binary programming and enhanced dual neural network

Authors
Shafie khah, M; Moghaddam, MP; Sheikh El Eslami, MK; Catalao, JPS;

Publication
ENERGY CONVERSION AND MANAGEMENT

Abstract
This paper presents a novel hybrid method for solving the security constrained unit commitment (SCUC) problem. The proposed formulation requires much less computation time in comparison with other methods while assuring the accuracy of the results. Furthermore, the framework provided here allows including an accurate description of warmth-dependent startup costs, valve point effects, multiple fuel costs, forbidden zones of operation, and AC load flow bounds. To solve the nonconvex problem, an adapted binary programming method and enhanced dual neural network model are utilized as optimization tools, and a procedure for AC power flow modeling is developed for including contingency/security issues, as new contributions to earlier studies. Unlike classical SCUC methods, the proposed method allows to simultaneously solve the unit commitment problem and comply with the network limits. In addition to conventional test systems, a real-world large-scale power system with 493 units has been used to fully validate the effectiveness of the novel hybrid method proposed.

2014

Reply to: Comments on "Particle Swarm Optimization with Fractional-Order Velocity"

Authors
Tenreiro Machado, JAT; Solteiro Pires, EJS; Couceiro, MS;

Publication
NONLINEAR DYNAMICS

Abstract

2014

Characterization of an Acoustic Based Device for Local Arterial Stiffness Assessment

Authors
Pereira H.C.; Contente M.; Almeida V.; Pereira T.; Simões J.B.; Simões J.B.; Cardoso J.; Correia C.; Pereira H.C.; 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.

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