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Publications

2015

Performance of state space and ARIMA models for consumer retail sales forecasting

Authors
Ramos, P; Santos, N; Rebelo, R;

Publication
ROBOTICS AND COMPUTER-INTEGRATED MANUFACTURING

Abstract
Forecasting future sales is one of the most important issues that is beyond all strategic and planning decisions in effective operations of retail businesses. For profitable retail businesses, accurate demand forecasting is crucial in organizing and planning production, purchasing, transportation and labor force. Retail sales series belong to a special type of time series that typically contain trend and seasonal patterns, presenting challenges in developing effective forecasting models. This work compares the forecasting performance of state space models and ARIMA models. The forecasting performance is demonstrated through a case study of retail sales of five different categories of women footwear: Boots, Booties, Flats, Sandals and Shoes. On both methodologies the model with the minimum value of Akaike's Information Criteria for the in-sample period was selected from all admissible models for further evaluation in the out-of-sample. Both one-step and multiple-step forecasts were produced. The results show that when an automatic algorithm the overall out-of-sample forecasting performance of state space and ARIMA models evaluated via RMSE, MAE and MAPE is quite similar on both one-step and multi-step forecasts. We also conclude that state space and ARIMA produce coverage probabilities that are close to the nominal rates for both one-step and multi-step forecasts.

2015

From project's information management to project-based organizational learning: The role of knowledge sharing

Authors
Vaz Almeida, M; Soares, AL;

Publication
Handbook of Research on Effective Project Management through the Integration of Knowledge and Innovation

Abstract
Project-based organizations have characteristics that raise additional barriers to information management, knowledge sharing, and to organizational learning. The main causes of this are inadequate information architectures and governance, poor collaborative culture, and lack of organization-wide information management strategies. This chapter presents a comprehensive basis to understand the information and knowledge-sharing practices in PBO, as well as the methods and tools that information professionals and project managers should have in mind when performing their tasks. For that, literatures are reviewed focusing on the explanation of the processes of knowledge creation and sharing leading to organizational learning. The main conclusion is that a knowledge-sharing strategy in a PBO should include a set of mechanisms that address a customized mix of the codification and personalization dimensions and that strategies for collaborative information management should be used as enablers for embedding knowledge sharing within the organizational practices and culture.

2015

Abstract Timers and their Implementation onto the ARM Cortex-M family of MCUs

Authors
Lindgren, P; Fresk, E; Lindner, M; Lulea, AL; Pereira, D; Pinho, LM;

Publication
CEUR Workshop Proceedings

Abstract
Real-Time For the Masses (RTFM) is a set of languages and tools being developed to facilitate embedded software development and provide highly efficient implementations geared to static verification. The RTFM-kernel is an architecture designed to provide highly efficient and predicable Stack Resource Policy based scheduling, targeting bare metal (singlecore) platforms. We contribute beyond prior work by introducing a platform independent timer abstraction that relies on existing RTFM-kernel primitives. We develop two alternative implementations for the ARM Cortex-M family of MCUs: a generic implementation, using the ARM defined SysTick- /DWT hardware; and a target specific implementation, using the match compare/free running timers. While sacrificing generality, the latter is more exible and may reduce overall overhead. Invariants for correctness are presented, and methods to static and run-time verification are discussed. Overhead is bound and characterized. In both cases the critical section from release time to dispatch is less than 2us on a 100MHz MCU. Queue and timer mechanisms are directly implemented in the RTFM-core language and can be included in system-wide scheduling analysis.

2015

Novel Methods for Pulse Wave Velocity Measurement

Authors
Pereira, T; Correia, C; Cardoso, J;

Publication
JOURNAL OF MEDICAL AND BIOLOGICAL ENGINEERING

Abstract
The great incidence of cardiovascular (CV) diseases in the world spurs the search for new solutions to enable an early detection of pathological processes and provides more precise diagnosis based in multi-parameters assessment. The pulse wave velocity (PWV) is considered one of the most important clinical parameters for evaluate the CV risk, vascular adaptation, and therapeutic efficacy. Several studies were dedicated to find the relationship between PWV measurement and pathological status in different diseases, and proved the relevance of this parameter. The commercial devices dedicate to PWV estimation make a regional assessment (measured between two vessels), however a local measurement is more precise evaluation of artery condition, taking into account the differences in the structure of arteries. Moreover, the current devices present some limitations due to the contact nature. Emerging trends in CV monitoring are moving away from more invasive technologies to non-invasive and non-contact solutions. The great challenge is to explore the new instrumental solutions that allow the PWV assessment with fewer approximations for an accurately evaluation and relatively inexpensive techniques in order to be used in the clinical routine.

2015

Editorial

Authors
Pinho, LM;

Publication
Ada User Journal

Abstract

2015

Arterial pulse pressure waveform monitoring by novel optical probe

Authors
Pereira, T; Pereira, TS; Santos, H; Correia, C; Cardoso, J;

Publication
INTERNATIONAL JOURNAL OF CARDIOLOGY

Abstract

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