Caracterização de Particulas de Desgaste do Rolamentos por Ferrografia e Ferrometria

Avarias em rolamentos são causas comuns de falhas em máquinas e equipamentos industriais. Portanto, é importante a aplicação de técnicas que permitam a deteção e a identificação do problema o mais cedo possível a fim de evitar a destruição do rolamento e consequente paragem da máquina. Logo, o processo de monitorização do estado dos rolamentos deve receber uma atenção especial no plano de manutenção de qualquer indústria. Este trabalho tem, assim, como principal objetivo a caracterização das partículas de desgaste provenientes de rolamentos através da análise dos seus lubrificantes por ferrometria e ferrografia analítica. Estas técnicas permitem identificar e caracterizar as várias partículas de desgaste presentes numa amostra de lubrificante, permitindo não só avaliar o grau de severidade do desgaste mas também identificar o tipo de desgaste predominante (fadiga, abrasão, corrosão,etc.), e até identificar os diferentes materiais das partículas que se podem associar a componentes específicos com falhas. A criação de uma base de dados para armazenar os resultados, os comentários e as informações mais importantes obtidos nos ensaios experimentais, assim como a análise de alguns casos práticos, foram também realizados no âmbito deste trabalho. Para desenvolver um conhecimento mais profundo sobre as técnicas utilizadas foi importante fazer uma análise aos diversos tipos de rolamentos, a sua lubrificação e as causas e tipos principais de avarias encontradas.

Myoelectric Signal Monitoring System

The Electromyography (EMG) is an important tool for gait analyzes and disorders diagnoses. Traditional methods involve equipment that can disturb the analyses, being gradually substituted by different approaches, like wearable and wireless systems. The cable replacement for autonomous systems demands for technologies capable of meeting the power constraints. This work presents the development of an EMG and kinematic data capture wireless module, designed taking into account power consumption issues. This module captures and converts the analog myoeletric signal to digital, synchronously with the capture of kinetic information. Both data are time multiplexed and sent to a PC via Bluetooth link. The work carried out comprised the development of the hardware, the firmware and a graphical interface running in an external PC. The hardware was developed using the PIC18F14K22, a low power family of microcontrollers. The link was established via Bluetooth, a protocol designed for low power communication. An application was also developed to recover and trace the signal to a Graphic User Interface (GUI), coordinating the message exchange with the firmware. Results were obtained which allowed validating the conceived system in static and with the subject performing short movements. Although it was not possible to perform the tests within more dynamic movements, it is shown that it is possible to capture, transmit and display the captured data as expected. Some suggestions to improve the system performance also were made.

Run-time Monitoring Architecture for RealTime Systems

Presented at INForum - Simpósio de Informática (INFORUM 2015). 7 to 8, Sep, 2015. Portugal.

Resultado do Obstétrico de Gravidezes Gemelares Resultantes de Fecundação in Vitro, Microinjeção e Estimulação da Ovulação em Comparação com Espontâneas

Introduction: Uncontrolled studies suggest that twins conceived by in vitro fertilization have increased rates of preterm birth and low birth weight and would warrant increased antenatal monitoring. The objective of this study was to compare the obstetric outcome of twin pregnancies conceived by in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) and ovulation induction with those conceived spontaneously. Methods: All twin deliveries achieved by IVF/ICSI (n=235) and ovulation induction (n=68) from September 1994 through December 2010 were evaluated. Both groups and an additional control group who conceived spontaneously (n=997) and was delivered during the same time period were compared with each other. Results: In univariate analysis, patients who conceived with the assistance of IVF/ICSI had a significantly higher risk of being older (p=0.01), nulliparous (p=0.01), having hypertensive disorders (p=0.012), gestational diabetes mellitus (p=0.031), cesarean section (p=0.008) and lower gestational age at birth, compared with the control group. Newborns had similar birthweights in all groups (2229±544g; 2102±619g; 2251±553g). Spontaneous pregnancies had a higher risk of being monochorionic 38.4% versus 16.2% and 10.2% (p=0.01). Multivariate analysis however showed that patients who conceived with the assistance of IVF/ICSI only had a higher risk of gestational diabetes (OR=1.91,95%CI 1.168-3.120; p=0.01). Conclusions: Our study shows that twin pregnancies conceived with the assistance of IVF/ICSI had a higher risk of gestacional diabetes and a lower gestacional age at birth. Birthweights were similar, as was the incidence of perinatal death, low birth weight infants, and congenital malformations.

A multi-objective optimization of the active and reactive resource scheduling at a distribution level in a smart grid context

In the traditional paradigm, the large power plants supply the reactive power required at a transmission level and the capacitors and transformer tap changer were also used at a distribution level. However, in a near future will be necessary to schedule both active and reactive power at a distribution level, due to the high number of resources connected in distribution levels. This paper proposes a new multi-objective methodology to deal with the optimal resource scheduling considering the distributed generation, electric vehicles and capacitor banks for the joint active and reactive power scheduling. The proposed methodology considers the minimization of the cost (economic perspective) of all distributed resources, and the minimization of the voltage magnitude difference (technical perspective) in all buses. The Pareto front is determined and a fuzzy-based mechanism is applied to present the best compromise solution. The proposed methodology has been tested in the 33-bus distribution network. The case study shows the results of three different scenarios for the economic, technical, and multi-objective perspectives, and the results demonstrated the importance of incorporating the reactive scheduling in the distribution network using the multi-objective perspective to obtain the best compromise solution for the economic and technical perspectives.

A multi-objective model for scheduling of short-term incentive-based demand response programs offered by electricity retailers

In this paper, we formulate the electricity retailers’ short-term decision-making problem in a liberalized retail market as a multi-objective optimization model. Retailers with light physical assets, such as generation and storage units in the distribution network, are considered. Following advances in smart grid technologies, electricity retailers are becoming able to employ incentive-based demand response (DR) programs in addition to their physical assets to effectively manage the risks of market price and load variations. In this model, the DR scheduling is performed simultaneously with the dispatch of generation and storage units. The ultimate goal is to find the optimal values of the hourly financial incentives offered to the end-users. The proposed model considers the capacity obligations imposed on retailers by the grid operator. The profit seeking retailer also has the objective to minimize the peak demand to avoid the high capacity charges in form of grid tariffs or penalties. The non-dominated sorting genetic algorithm II (NSGA-II) is used to solve the multi-objective problem. It is a fast and elitist multi-objective evolutionary algorithm. A case study is solved to illustrate the efficient performance of the proposed methodology. Simulation results show the effectiveness of the model for designing the incentive-based DR programs and indicate the efficiency of NSGA-II in solving the retailers’ multi-objective problem.

Análise da interoperabilidade aplicada ao projeto BIM de Estruturas Metálicas

O BIM – Building Information Modeling – é um conceito de controlo e gestão de informação desenvolvida, entre diferentes especialidades e intervenientes envolventes, durante o ciclo de vida das construções. A utilização das tecnologias BIM, no ramo da Engenharia Mecânica e Civil, tem sido uma aposta constante, e cada vez mais concisa, nos projetos de construção. A justificação para a adoção destas metodologias mais eficientes, em substituição dos processos convencionais, prende-se com o facto desses processos convencionais, ainda hoje, apresentarem muitas dificuldades e problemas associados, por exemplo, à falta de comunicação entre os intervenientes e ao ineficiente controlo na gestão de projetos. O objetivo desta dissertação centra-se na análise da interoperabilidade de softwares BIM, ou seja, na verificação da viabilidade de exportação de dados dos modelos produzidos, entre as ferramentas BIM. Para este campo de ação contribuirá a análise da passagem de informação, relativa ao modelo de uma Nave Industrial modelada, em alguns dos softwares BIM, correntemente mais utilizados. O conhecimento adquirido com a modelação do caso de estudo do presente trabalho irá permitir identificar algumas lacunas existentes ao nível da falta de recomendações práticas que sirvam de orientação na modelação recorrendo a ferramentas informáticas BIM-compatíveis. Assim, a base deste trabalho consiste na criação de uma série de recomendações ou de um roteiro de modelação em específico para a disciplina de estruturas enquanto área de aplicação concreta do estudo efetuado. Nesse sentido, a proposta deste trabalho é de apresentar alguns critérios de modelação onde são definidos os elementos a modelar em cada fase do projeto.

Monitoring morphisms to support sustainable interoperability of enterprise systems

Dissertation to obtain the Master degree in Electrical Engineering and Computer Science

Electrochemical sensor for simultaneous determination of herbicide MCPA and its metabolite 4-chloro-2-methylphenol. Application to photodegradation environmental monitoring

The development and application of a polyaniline/carbon nanotube (CNT) cyclodextrin matrix (PANI-β-CD/MWCNT)-based electrochemical sensor for the quantitative determination of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) and its main transformation product 4-chloro-2-methylphenol in natural waters are described. A simple cyclic voltammetry-based electrochemical methodology, in phosphate buffer solution at pH 6.0, was used to develop a method to determine both MCPA and 4-chloro-2-methylphenol, without any previous extraction or derivatization steps. A linear concentration range (10 to 50 μmol L−1) and detection limits of 1.1 and 1.9 μmol L−1, respectively, were achieved using optimized cyclic voltammetric parameters. The proposed method was successfully applied to the determination of MCPA and 4-chloro-2-methylphenol in natural water samples with satisfactory recoveries (94 to 107 %) and in good agreement with the results obtained by an established high-performance liquid chromatography technique, no significant differences being found between the methods. Interferences from ionic species and other herbicides used for broad-leaf weed control were shown to be small. The newly developed methodology was also successfully applied to MCPA photodegradation environmental studies.

Distribution of hepatitis B virus genotypes and viral load levels in Brazilian chronically infected patients in São Paulo city

The objective of the present study was to evaluate the serum viral load in chronically infected Hepatitis B virus (HBV) patients and to investigate the distribution of HBV genotypes in São Paulo city. Quantitative HBV-DNA assays and HBV genotyping have gained importance for predicting HBV disease progression, have been employed for assessing infectivity, for treatment monitoring and for detecting the emergence of drug resistance. Twenty-nine Brazilian patients with suspected chronic hepatitis B were studied, using real time PCR for viral load determination and direct DNA sequencing for the genotyping. The serology revealed chronic HBV infection in 22 samples. The HBV-DNA was positive in 68% samples (15/22). The phylogenetic analysis disclosed that eleven patients were infected with HBV genotype A, two with genotype F and two with genotype D. Thus, the genotype A was the most prevalent in our study.

ezGo: A voice operated wheelchair with biosignal monitoring for home environments

In this paper we present ezGo, an electric powered wheelchair with a speech based interface and biosignal monitoring instrumentation. The user can use the voice, a natural communication method, for controlling the chair movement and obtain information about his health. Additionally a set of semi-autonomous modes with macro recording enable the execution of navigation tasks with little effort and improved precision. The main purpose of the system is to provide severely disabled persons with an assistive device that can improve their confidence and daily independence. The obtained results on usability tests showed that users consider ezGo a valuable help on their daily tasks and a very desirable addition to standard wheelchairs.

Serological monitoring of a Toxoplasma infection after hematopoietic stem cell transplantation

We report a primary response to Toxoplasma gondii following a hematopoietic stem cell transplantation in a patient with multiple myeloma. The primary response to T. gondii was supported by IgM, IgG and IgA seroconversion. The patient was promptly treated and there were no complications related to toxoplasmosis in the subsequent months.

The monitoring of hematopoietic stem cell transplant donors and recipients from endemic areas for malaria

Malaria is an unusual complication after hematopoietic stem cell transplantation in non-endemic countries. However, transplant candidates, recipients and donors living in endemic regions frequently report previous episodes of malaria. This fact could represent an important risk for immunosuppressed recipients that could develop severe malaria cases. We report a case of hematopoietic stem cell transplant (HSCT) in which the donor had a history of previous malaria, and close monitoring was performed before and after procedure by parasitological and molecular tests. The donor presented Plasmodium vivax in thick blood smears one month after transplant and was treated according to Brazilian Health Ministry guidelines. The polymerase chain reaction (PCR) was able to detect malaria infection in the donor one week earlier than thick blood film. Even without positive results, the recipient was pre-emptively treated with chloroquine in order to prevent the disease. We highlight the importance of monitoring recipients and donors in transplant procedures with the aim of reducing the risk of malaria transmission.

Transoesophageal Echocardiography for Monitoring Liver Surgery: Data from a Pilot Study

A pilot study aimed to introduce intraoperative monitoring of liver surgery using transoesophageal echocardiography (TEE) is described. A set of TEE measurements was established as a protocol, consisting of left atrial (LA) dimension at the aortic valve plane; mitral velocity flow integral, calculation of stroke volume and cardiac output (CO); mitral annular plane systolic excursion; finally, right atrial area. A total of 165 measurements (on 21 patients) were performed, 31 occurring during hypotension. The conclusions reached were during acute blood loss LA dimension changed earlier than CVP, and, in one patient, a dynamic left ventricular (LV) obstruction was observed; in 3 patients a transient LV systolic dysfunction was documented. The comparison between 39 CO paired measurements obtained by TEE and PiCCO2 revealed a statistically significant correlation (P < 0.001, r = 0.83). In this pilot study TEE successfully answered the questions raised by the anesthesiologists. Larger cohort studies are needed to address this issue.