Abstract

Abstract
This paper intends to highlight the importance of the maintenance activity for all kind of companies in general and for the water treatment companies in particular. To attain this objective, a literature review on the evolution of the maintenance concept, the relation between the production function and the total productive maintenance (TPM) and the factors that influence the success of TPM is performed. To demonstrate the contribution of the maintenance activity for the improvement of the performance of companies especially for the water treatment companies, a case study of a Portuguese company belonging to the water treatment sector is performed. The water company considered in the case study, regarding management and maintenance activities, has an annual capacity of treatment and distribution of 41 million m3 of drinking water to approximately 438,000 inhabitants spread over a geographic area that represents 15% of the Portuguese territory. Copyright © 2017 Inderscience Enterprises Ltd.

Abstract
In this paper a modified Newton type algorithm (NTA) is analysed to estimate the electrical signal spectral composition. As core of this study, it is given attention to the accuracy and sensitivity of the algorithm for base frequency and harmonic content characterization under noisy measurements. Convergence speed, stability issues and computational complexity of the implementation are detailed and compared using clean and noisy test signals. Conclusions are duly drawn.

Abstract
The energy demand of the residential sector and the adjacent option for fossil fuels has negative consequences by both greenhouse gases (GHG), CO2 and other air pollutants emissions. The home energy demand consists mainly of energy requirements for space and water heating along with the energy dedicated for appliances. Therefore, different strategies that aim to stimulate an efficient use of energy need to be reinforced at all levels of human activity. In this paper a comparison is made between a Model Predictive Control (MPC) model, the ON/OFF and proportional-integral-derivative (PID) control models of an air conditioning unit AC system controlling the temperature of a room. The model of the house with local Photovoltaic (PV) solar microgeneration is assumed to be located in a Portuguese city. The household of the case study is subject to the local solar irradiance, temperature and electricity tariff of a summer day.

Abstract
The advent of wearable technology is fundamental to the dissemination of wearable personal health monitoring devices. Recent developments of biomedical sensors have decreased the form factor and power consumption that can be worn on a permanent basis. This paper discusses a low cost reflective photoplethysmography (PPG) system using a dedicated integrated circuit (IC) solution as the core of a wearable health monitoring device. The measurement of two physiological indicators is performed, namely the pulse rate (HR) and the blood oxygen saturation (SpO(2)). The paper analyses in depth the PPG signals sensing architecture, guaranteeing high resolution measurements due to a delta-sigma analog to digital conversion unit. Post-processing digital filter operations are implemented to enhance low noise PPGs acquisition for physiological signals extraction. A complete system design is presented and a detailed evaluation is made in a real-time processing scenario. The test platform is completed with a PC based graphics application for on-line and off-line data analysis. Minimizing power dissipation is the main challenge in,a wearable design. However, it restrains PPG signal measurement sensitivity by lowering signal quality. Using the developed prototype power consumption, studies concerning the characterization of power consumption and signal quality over various working conditions are performed. Next, a performance merit figure is proposed as the main research contribution, which addresses the power consumption and signal quality trade-off subject. It aims to be used as an analysis for trade-offs between these two conflicting design criteria.

Abstract
The growing need for the clean and renewable energy has led to the fast development of grid-connected tidal stream power generation systems all over the world. These large scale tidal stream power generation systems are going to be connected to power systems and one of the important subjects that should be investigated is its impacts on power system stability. Hence, this paper investigates the possibility of tidal stream power generation system on damping inter-area oscillations, as a new contribution to earlier studies. As tidal farms are mostly installed far from conventional power plants, local signals do not include good quality to alleviate inter-area oscillations. To overcome the problem, a novel damping controller is developed by employing wide-area measurement system and added to base controllers of doubly-fed induction generator through tidal stream power generation system. The proposed wide area damping controller includes efficient means to compensate for the incompatible performances of wide area measurement based delayed signals. Robustness of the designed damping controller has been demonstrated by facing the study system with faults leading to enough shifts in power system operating point, and tidal farm generation.