Development of a low cost digital energy meter

This paper presents a versatile low cost equipment that allows simultaneous display of usually required measurements in electric circuits, like true RMS (Root Mean Square) values of mains voltage and current, line frequency, power factor, active, reactive and apparent power, and energy. The equipment is based on a microcontroller that interfaces current and voltage transducers through 16 bits sigma-delta ADCs (Analog to Digital Converters). The microcontroller controls the periodic acquisition of the measured signal waveforms, makes the respective calculations and presents the results on an alphanumeric display. The equipment also provides a serial port that enables the communication with other devices allowing the interface through a SCADA (Supervisory Control and Data Acquisition) system

Automatic pre-bended customized prosthesis for pectus excavatum minimal invasive surgery correction

Pectus excavatum is the most common deformity of the thorax. A minimally invasive surgical correction is commonly carried out to remodel the anterior chest wall, by employing an intrathoracic convex prosthesis in substernal position. The process of prosthesis modeling and bending still remains an area of improvement. The authors developed a new system, i3DExcavatum, which can automatically model and bend the bar preoperatively based on a thoracic CT-scan. This paper presents a comparison between automatic and manual bending. The i3DExcavatum was used to personalize prosthesis for 41 patients who underwent pectus excavatum surgical correction between 2007 and 2012. Regarding the anatomic variations, the soft tissue thicknesses external to the ribs show that symmetric or asymmetric patients have always asymmetric variations by comparing both patients’ sides. It highlighted that the prosthesis bar should be modeled according to each patient ribs position and dimension. The average differences between the skin and costal line curvature lengths were 84±4 mm and 96±11mm, for male and female patients, respectively. On the other hand, the i3DExcavatum ensured a smooth curvature of the surgical prosthesis and was capable to predict and simulate a virtual shape and size of the bar for asymmetric or symmetric patients. In conclusion, the i3DExcavatum allows preoperative personalization according to the thoracic morphology of each patient. It reduces surgery time and minimizes the margin error induced by the manual bended bar shape that only uses a template that copies the chest wall curvature

Single-phase series active conditioner for the compensation of voltage harmonics, sags, swell and flicker

Simulation and experimental results shown on this paper describes the performance of a developed Single-Phase Series Active Conditioner that regulates the voltage being delivered to a load. This Custom Power device is a solution for power quality issues related with voltage amplitude variations, which are responsible for innumerous flaws in industrial processes which brings with it high financial losses. The Single-Phase Series Active Conditioner is a back-to-back converter, composed by two power converters sharing a common DC link. One of the converters is series connected to the electrical grid, whereas the other one is shunt connected. The first is used to compensate load voltage, and the second to regulate the DC link voltage. This paper shows the results obtained with the Series Active Conditioner in Sag, Swell and Flicker events, and also Voltage Harmonics compensation, in order to deliver to the load a sinusoidal voltage, at nominal amplitude.Fundação para a Ciência e Tecnologia (FCT

Condicionadores ativos de potência para mitigação de problemas de qualidade de energia elétrica em instalações industriais

Os condicionadores ativos são equipamentos baseados em eletrónica de potência que permitem mitigar de forma dinâmica diversos problemas nas tensões e nas correntes do sistema elétrico, contribuindo efetivamente para a melhoria da produtividade das indústrias, reduzindo os prejuízos provocados pelos problemas de Qualidade de Energia Elétrica.Fundação para a Ciência e a Tecnologia (FCT

New generation of nitric oxide-releasing porous materials: assessment of their potential to regulate biological functions

Nitric oxide (NO) presents innumerable biological roles, and its exogenous supplementation for therapeutic purposes has become a necessity. Some nanoporous materials proved to be potential vehicles for NO with high storage capacity. However, there is still a lack of information about their efficiency to release controlled NO and if they are biocompatible and biologically stable. In this work, we address this knowledge gap starting by evaluating the NO release and stability under biological conditions and their toxicity with primary keratinocyte cells. Titanosilicates (ETS-4 and ETS-10 types) and clay-based materials were the materials under study, which have shown in previous studies suitable NO gas adsorption/release rates. ETS-4 proved to be the most promising material, combining good biocompatibility at 180 μg/mL, stability and slower NO release. ETS-10 and ETAS-10 showed the best biocompatibility at the same concentration and, in the case of clay-based materials, CoOS is the least toxic of those tested and the one that releases the highest NO amount. The potentiality of these new NO donors to regulate biological functions was assessed next by controlling the mitochondrial respiration and the cell migration. NO-loaded ETS-4 regulates O2 consumption and cell migration in a dose-dependent manner. For cell migration, a biphasic effect was observed in a narrow range of ETS-4 concentration, with a stimulatory effect becoming inhibitory just by doubling ETS-4 concentration. For the other materials, no effective regulation was achieved, which highlights the relevance of the new assessment presented in this work for nanoporous NO carriers that will pave the way for further developments.publishe

Exploring the potential of using Marine-Derived Ingredients: From the extraction to Cutting-Edge Cosmetics

The growing understanding and knowledge of the potential of marine species, as well as the application of “blue biotechnology” have been motivating new innovative solutions in cosmetics. It is widely noted that that marine species are important sources of compounds with several biological activities that are yet to be discovered. This review explores various biological properties of marine-derived molecules and briefly outlines the main extraction methods. Alongside these, it is well known the legislative and normative framework of cosmetics is increasingly being developed. In this research segment, there is a growing concern with sustainability. In this sense, “blue biotechnology”, together with the use of invasive species or marine waste products to obtain new active ingredients, haven been emerging as innovative and sustainable solutions for the future’s cosmetics industry. This review also examines the regulatory framework and focus on the recent advancements in “blue biotechnology” and its relevance to the sustainable development of innovative cosmetics.info:eu-repo/semantics/publishedVersio

Analysis of the features of a UPQC to improve power quality in smart grids

An UPQC (Unified Power Quality Conditioner) is an equipment composed by two active conditioners operating in a combined way. One of the active conditioners is connected in series with the electrical power system, allowing the compensation of problems in the system voltages. The other active conditioner is connected in parallel with the electrical system, and allows the compensation of current harmonics, current unbalances and power factor. In three-phase four-wire systems the parallel connected active conditioner also compensates the zero sequence current components, eliminating the neutral wire current. The UPQC operates in an automatic way, adjusting itself dynamically to the variations of the load and of the electrical system, keeping high levels of power quality in the voltages delivered to the load. At the same time, it only consumes from the electrical system the active power necessary to the load operation, in a balanced way through the three phases, and with sinusoidal currents. The compensation capabilities of the UPQC can be very useful to ensure high levels of power quality in the future Smart Grids, which are not characterized as a single technology or device, but rather as a vision of a distributed electrical system, supported by reference technologies, as Power Electronics Devices, Renewable Energy Resources, Energy Storage Systems (ESS), Advanced Metering Infrastructures (AMI), and Information and Communication Technologies (ICT).This work is financed by FEDER Funds, through the Operational Program for Competitiveness Factors – COMPETE, and by National Funds through the Foundation for Science and Technology of Portugal, under projects: PTDC/EEAEEL/104569/2008 and FCOMP-01-0124-FEDER-022674.info:eu-repo/semantics/publishedVersio

A comparative analysis of ex-ante credit spreads: structured finance versus straight debt finance

info:eu-repo/semantics/submittedVersio

A flexible infrastructure for dynamic power control of electric vehicle battery chargers

This paper proposes a Flexible Infrastructure for Dynamic Power Control (FIDPC) of Electric Vehicle (EV) Battery Chargers. This infrastructure dynamically adjusts the EV battery charger current, according to the power demand of the home wherein the vehicle is plugged. An infrastructure was implemented to validate this proposal. Such infrastructure is composed by an EV battery charger and a communication system based on a Radio Frequency interface. The battery charger has nominal power of 3.6 kVA and operates with sinusoidal current and unitary total power factor, while the RF interface provides continuous data flow to the battery charger with information about the home total current consumption (rms value). Experimental tests were performed under realistic conditions to validate the concept behind the proposed FIDPC. These tests served to assess the behavior of the EV battery charger with dynamic power control on a single-phase, 230 V, 16 A, 50 Hz residential electrical installation. The experimental results confirm the quick time response of the FIDPC even when working under heavy home load variations.This work was supported by the Fundacao para a Ciencia e Tecnologia (FCT) through Project PEst-UID/CEC/00319/2013. The work of V. Monteiro was supported by the FCT agency through a doctoral scholarship under Grant SFRH/BD/80155/2011. The review of this paper was coordinated by Dr. D. Cao

Field results on developed three-phase four-wire shunt active power filters

Abstract-This paper presents three-phase four-wire Shunt Active Power Filters with ability to compensate current harmonics, power factor, and current unbalance. The power stage of the Active Power Filters is based on a two-level four-leg inverter. The switching technique is based on an optimized periodic sampling strategy, and the digital controller uses the Theory of Instantaneous Reactive Power (p-q Theory) expanded for three- phase four-wire systems. The presented Active Power Filters were successfully demonstrated in four different facilities. The presented experimental results show the performance of the Active Power Filters in operation with very different load profiles