Contribuições à estratégia de controle sem detecção de harmônicos aplicada a um filtro ativo de potência paralelo

The conventional control schemes applied to Shunt Active Power Filters (SAPF) are Harmonic extractor-based strategies (HEBSs) because their effectiveness depends on how quickly and accurately the harmonic components of the nonlinear loads are identified. The SAPF can be also implemented without the use of the load harmonic extractors. In this case, the harmonic compensating term is obtained from the system active power balance. These systems can be considered as balanced-energy-based schemes (BEBSs) and their performance depends on how fast the system reaches the equilibrium state. In this case, the phase currents of the power grid are indirectly regulated by double sequence controllers with two degrees of freedom, where the internal model principle is employed to avoid reference frame transformation. Additionally the DSC controller presents robustness when the SAPF is operating under unbalanced conditions. Furthermore, SAPF implemented without harmonic detection schemes compensate simultaneously harmonic distortion and reactive power of the load. Their compensation capabilities, however, are limited by the SAPF power converter rating. Such a restriction can be minimized if the level of the reactive power correction is managed. In this work an estimation scheme for determining the filter currents is introduced to manage the compensation of reactive power. Experimental results are shown for demonstrating the performance of the proposed SAPF system.

Detecção e diagnostico de agarramento em válvulas posicionadoras

Valve stiction, or static friction, in control loops is a common problem in modern industrial processes. Recently, many studies have been developed to understand, reproduce and detect such problem, but quantification still remains a challenge. Since the valve position (mv) is normally unknown in an industrial process, the main challenge is to diagnose stiction knowing only the output signals of the process (pv) and the control signal (op). This paper presents an Artificial Neural Network approach in order to detect and quantify the amount of static friction using only the pv and op information. Different methods for preprocessing the training set of the neural network are presented. Those methods are based on the calculation of centroid and Fourier Transform. The proposal is validated using a simulated process and the results show a satisfactory measurement of stiction.

Análise de métodos para detecção de mudanças estruturais em séries temporais climáticas

The time series analysis has played an increasingly important role in weather and climate studies. The success of these studies depends crucially on the knowledge of the quality of climate data such as, for instance, air temperature and rainfall data. For this reason, one of the main challenges for the researchers in this field is to obtain homogeneous series. A time series of climate data is considered homogeneous when the values of the observed data can change only due to climatic factors, i.e., without any interference from external non-climatic factors. Such non-climatic factors may produce undesirable effects in the time series, as unrealistic homogeneity breaks, trends and jumps. In the present work it was investigated climatic time series for the city of Natal, RN, namely air temperature and rainfall time series, for the period spanning from 1961 to 2012. The main purpose was to carry out an analysis in order to check the occurrence of homogeneity breaks or trends in the series under investigation. To this purpose, it was applied some basic statistical procedures, such as normality and independence tests. The occurrence of trends was investigated by linear regression analysis, as well as by the Spearman and Mann-Kendall tests. The homogeneity was investigated by the SNHT, as well as by the Easterling-Peterson and Mann-Whitney-Pettit tests. Analyzes with respect to normality showed divergence in their results. The von Neumann ratio test showed that in the case of the air temperature series the data are not independent and identically distributed (iid), whereas for the rainfall series the data are iid. According to the applied testings, both series display trends. The mean air temperature series displays an increasing trend, whereas the rainfall series shows an decreasing trend. Finally, the homogeneity tests revealed that all series under investigations present inhomogeneities, although they breaks depend on the applied test. In summary, the results showed that the chosen techniques may be applied in order to verify how well the studied time series are characterized. Therefore, these results should be used as a guide for further investigations about the statistical climatology of Natal or even of any other place.

Desenvolvimento e validação de testes de fluxo lateral para a detecção de cultivares geneticamente modificados e de aflatoxinas em produtos agrícolas

The expansion of cultivated areas with genetically modified crops (GM) is a worldwide phenomenon, stimulating regulatory authorities to implement strict procedures to monitor and verify the presence of GM varieties in agricultural crops. With the constant growing of plant cultivating areas all over the world, consumption of aflatoxin-contaminated food also increased. Aflatoxins correspond to a class of highly toxic contaminants found in agricultural products that can have harmful effects on human and animal health. Therefore, the safety and quality evaluation of agricultural products are important issues for consumers. Lateral flow tests (strip tests) is a promising method for the detection both proteins expressed in GM crops and aflatoxins-contaminated food samples. The advantages of this technique include its simplicity, rapidity and cost-effective when compared to the conventional methods. In this study, two novel and sensitive strip tests assay were developed for the identification of: (i) Cry1Ac and Cry8Ka5 proteins expressed in GM cotton crops and; (ii) aflatoxins from agricultural products. The first strip test was developed using a sandwhich format, while the second one was developed using a competitive format. Gold colloidal nanoparticles were used as detector reagent when coated with monoclonal antibodies. An anti-species specific antibody was sprayed at the nitrocellulose membrane to be used as a control line. To validate the first strip test, GM (Bollgard I® e Planta 50- EMBRAPA) and non-GM cotton leaf (Cooker 312) were used. The results showed that the strip containing antibodies for the identification of Cry1Ac and Cry8Ka5 proteins was capable of correctly distinguishing between GM samples (positive result) and non-GM samples (negative result), in a high sensitivity manner. To validate the second strip test, artificially contaminated soybean with Aspergillus flavus (aflatoxin-producing fungus) was employed. Food samples, such as milk and soybean, were also evaluated for the presence of aflatoxins. The strip test was capable to distinguish between samples with and without aflatoxins samples, at a sensitivity concentration of 0,5 μg/Kg. Therefore, these results suggest that the strip tests developed in this study can be a potential tool as a rapid and cost-effective method for detection of insect resistant GM crops expressing Cry1Ac and Cry8Ka5 and aflatoxins from food samples.

Desenvolvimento e validação de testes de fluxo lateral para a detecção de cultivares geneticamente modificados e de aflatoxinas em produtos agrícolas

The expansion of cultivated areas with genetically modified crops (GM) is a worldwide phenomenon, stimulating regulatory authorities to implement strict procedures to monitor and verify the presence of GM varieties in agricultural crops. With the constant growing of plant cultivating areas all over the world, consumption of aflatoxin-contaminated food also increased. Aflatoxins correspond to a class of highly toxic contaminants found in agricultural products that can have harmful effects on human and animal health. Therefore, the safety and quality evaluation of agricultural products are important issues for consumers. Lateral flow tests (strip tests) is a promising method for the detection both proteins expressed in GM crops and aflatoxins-contaminated food samples. The advantages of this technique include its simplicity, rapidity and cost-effective when compared to the conventional methods. In this study, two novel and sensitive strip tests assay were developed for the identification of: (i) Cry1Ac and Cry8Ka5 proteins expressed in GM cotton crops and; (ii) aflatoxins from agricultural products. The first strip test was developed using a sandwhich format, while the second one was developed using a competitive format. Gold colloidal nanoparticles were used as detector reagent when coated with monoclonal antibodies. An anti-species specific antibody was sprayed at the nitrocellulose membrane to be used as a control line. To validate the first strip test, GM (Bollgard I® e Planta 50- EMBRAPA) and non-GM cotton leaf (Cooker 312) were used. The results showed that the strip containing antibodies for the identification of Cry1Ac and Cry8Ka5 proteins was capable of correctly distinguishing between GM samples (positive result) and non-GM samples (negative result), in a high sensitivity manner. To validate the second strip test, artificially contaminated soybean with Aspergillus flavus (aflatoxin-producing fungus) was employed. Food samples, such as milk and soybean, were also evaluated for the presence of aflatoxins. The strip test was capable to distinguish between samples with and without aflatoxins samples, at a sensitivity concentration of 0,5 μg/Kg. Therefore, these results suggest that the strip tests developed in this study can be a potential tool as a rapid and cost-effective method for detection of insect resistant GM crops expressing Cry1Ac and Cry8Ka5 and aflatoxins from food samples.

Utilização da transformada de wavelet para detecção de variações anormais de tensão em sistemas elétricos com geração distribuída

The increasing demand in electricity and decrease forecast, increasingly, of fossil fuel reserves, as well as increasing environmental concern in the use of these have generated a concern about the quality of electricity generation, making it well welcome new investments in generation through alternative, clean and renewable sources. Distributed generation is one of the main solutions for the independent and selfsufficient generating systems, such as the sugarcane industry. This sector has grown considerably, contributing expressively in the production of electricity to the distribution networks. Faced with this situation, one of the main objectives of this study is to propose the implementation of an algorithm to detect islanding disturbances in the electrical system, characterized by situations of under- or overvoltage. The algorithm should also commonly quantize the time that the system was operating in these conditions, to check the possible consequences that will be caused in the electric power system. In order to achieve this it used the technique of wavelet multiresolution analysis (AMR) for detecting the generated disorders. The data obtained can be processed so as to be used for a possible predictive maintenance in the protection equipment of electrical network, since they are prone to damage on prolonged operation under abnormal conditions of frequency and voltage.

Modelagem molecular voltada para a construção de um nanobiossensor para detecção do herbicida Imazaquin

In this study, our goal was develop and describe a molecular model of the enzyme-inhibiting interaction which can be used for an optimized projection of a Microscope Force Atomic nanobiosensor to detect pesticides molecules, used in agriculture, to evaluate its accordance with limit levels stipulated in valid legislation for its use. The studied herbicide (imazaquin) is a typical member of imidazolinone family and is an inhibitor of the enzymatic activity of Acetohydroxiacid Synthase (AHAS) enzyme that is responsible for the first step of pathway for the synthesis of side-chains in amino acids. The analysis of this enzyme property in the presence of its cofactors was made to obtain structural information and charge distribution of the molecular surface to evaluate its capacity of became immobilized on the Microscopy Atomic Force tip. The computational simulation of the system, using Molecular Dynamics, was possible with the force-field parameters for the cofactor and the herbicides obtained by the online tool SwissParam and it was implemented in force-field CHARMM27, used by software GROMACS; then appropriated simulations were made to validate the new parameters. The molecular orientation of the AHAS was defined based on electrostatic map and the availability of the herbicide in the active site. Steered Molecular Dynamics (SMD) Simulations, followed by quantum mechanics calculations for more representative frames, according to the sequential QM/MM methodology, in a specific direction of extraction of the herbicide from the active site. Therefore, external harmonic forces were applied with similar force constants of AFM cantilever for to simulate herbicide detection experiments by the proposed nanobiosensor. Force value of 1391 pN and binding energy of -14048.52 kJ mol-1 were calculated.

A descoberta do elétron como tema gerador de um ensino de física mediado por experimentação remota

In this work, we have proposed and applied a methodology for teaching electromagnetism, based on an experimental activity and designed in an investigative teaching model, and containing a high degree of dialogism among teachers and students. We have used the discovery of the electron as a generator theme and a remote experiment to determine the charge-to-mass ratio of the electron as an educational resource. Our analyses indicate favorably towards the promotion of ways of appropriation of knowledge by the student, very different from those perceived in traditional expositive classes. Similarly, we find that the presence of a technological resource and an experimental activity create new posture of the teacher in the classroom, probably caused by the unpredictability of the results from the use of such resources. A challenge that we still need to solve is how to engage students in extra classroom tasks, since learning is not only effective in time for classes. We also present the weaknesses detected in our methodological proposal as well as implementations necessary in order to continue the validation process of this methodology.

Avaliação do AAM - Active Appearance Model para detecção de regiões de interesse em radiografias carpais na estimativa da idade óssea através do método TW

In several areas of health professionals (pediatricians, nutritionists, orthopedists, endocrinologists, dentists, etc.) are used in the assessment of bone age to diagnose growth disorders in children. Through interviews with specialists in diagnostic imaging and research done in the literature, we identified the TW method - Tanner and Whitehouse as the most efficient. Even achieving better results than other methods, it is still not the most used, due to the complexity of their use. This work presents the possibility of automation of this method and therefore that its use more widespread. Also in this work, they are met two important steps in the evaluation of bone age, identification and classification of regions of interest. Even in the radiography in which the positioning of the hands were not suitable for TW method, the identification algorithm of the fingers showed good results. As the use AAM - Active Appearance Models showed good results in the identification of regions of interest even in radiographs with high contrast and brightness variation. It has been shown through appearance, good results in the classification of the epiphysis in their stages of development, being chosen the average epiphysis finger III (middle) to show the performance. The final results show an average percentage of 90% hit and misclassified, it was found that the error went away just one stage of the correct stage.

Hur planerar lärare sin undervisning i NO? : Tänker de på de olika lärstilarna och använder de sig av närliggande naturområden

Syftet med denna undersökning är att ta reda på hur lärare planerar och varierar undervisningen, hur de olika lärstilarna täcks in samt användningen av den närliggande naturen/skogen/grönområden. De frågor som denna studie sökte svar på var:   Hur planerar lärare sin undervisning i de naturorienterande ämnena? Använder sig lärare av den närliggande naturen/skogen/grön områden? Varieras undervisningen så de olika lärstilarna täcks in?   I denna studie har jag använt mig av en fallstudie för att få djupgående kunskap som man sedan undersöker ”på djupet” till detaljerade kunskaper. Det som kännetecknar fallstudien är att den fokuserar på ett fenomen, som i detta fall är lektionsplaneringen och variationen för lektionerna.   Resultatet har visat på att samtliga lärare planerar och varierar sin undervisning men de gör inte ett medvetet val för att täcka in de fyra olika lärstilarna. De använder sig av den närliggande naturen/skogen/grön områden samt skolgården i stor utsträckning. De använder dessa mest under de varmare årstiderna men några använder dessa året runt. 

Sean Banan och Frost-Elsa sjunger sig in i förskolan : En kvalitativ studie om hur förskollärare resonerar kring populärmusikens betydelse för barn gällande lärande och identitetsskapande.

Vårt syfte är att få syn på hur förskollärare resonerar kring populärmusikens betydelse för barn gällande lärande och identitetsskapande. Vi har valt att utgå ifrån förskollärares perspektiv på fenomenet. Som metod valde vi att göra en kvalitativ studie där vi intervjuade förskollärare från olika slumpmässigt utvalda förskolor. Det insamlade materialet har vi analyserat med hjälp av ett sociokulturellt perspektiv. Studiens resultat visar på att förskollärarna anser att populärmusiken har en stor betydelse för barnet som lärande och identitetsskapande. Den spelar enligt förskollärarna en betydelsefull roll i skapandet av sociala möten i förskolan. Även populärmusikens möjligheter som pedagogiskt redskap lyftes fram i intervjuerna. Slutligen diskuterades populärmusiken som ett verktyg i arbetet med normer och värderingar i förskolan.

”De leker de här lekarna som är förbjudna av vuxna – för att skapa sig en egen värld.”

Syftet med denna studie är att ta reda på om det finns lekar som förskollärare upplever som problematiska, icke önskvärda eller rent av förbjuder i sin verksamhet, vilka regler som finns för lek i deras verksamhet, samt vilka diskurser kring lek i förskolan som ligger till grund för dessa uppfattningar. Vi vill även undersöka hur förskollärarna själva ser på hur faktorer som genus och egna lekerfarenheter i barndomen har påverkat deras synsätt. Metoden för studien är enskilda intervjuer av semistrukturerad karaktär, samt analys av respondenternas utsagor utifrån ett poststrukturalistiskt perspektiv. Studiens resultat visar att det bland de intervjuade förskollärarna finns föreställningar om lek som bygger på diskurser om lek som lärande, utveckling och bearbetning. När det gäller reglering av lek så ges här uttryck för ståndpunkter som vilar på diskurser om att leken ska vara säker och bygga på samtycke och ömsesidighet mellan de som leker och att ingen får bli kränkt. En slutsats av studien är att det inom svensk förskoleverksamhet både existerar förhållningssätt om totalförbud mot vissa typer av lekar, till exempel vapenlek, men även förhållningssätt som accepterar sådana lekar. En annan slutsats är att pedagoger i förskolan kan uppleva att den pedagogiska miljön begränsar deras möjligheter att tillåta vissa typer av lekar. 

Att 'bilda sig' eller att 'bilda sig'? : Om religionslärarens frirum som medborgarbildare i den nya ämnesplanen för religionskunskap på gymnasiet

 I den här texten lyfter jag fram den nya ämnesplanen i religionskunskap på gymnasiet. Syftet med detta är att sätta denna ämnesplan i relation till religionslärarens medborgarbildande uppgift. Med utgångspunkt i bildningsbegreppet diskuteras denna uppgift som en fråga om att se till religionslärarens frirum. Diskussionen utmynnar i ett resonemang om betydelsen av att läraren inte ensidigt ser till vissa bildningsmål i ämnesundervisningen på bekostnad av andra.

Skolan i livet - livet i skolan : Några illitterata invandrarkvinnor lär sig tala, läsa och skriva på svenska som andraspråk

Many immigrants in Sweden have not had the chance to learn to read and write, for various reasons. In Sweden, literacy is a prerequisite to being able to function in the cultural community, and for many immigrants this is the first time that they experience their inability to read and write as a handicap or see themselves as “illiterate”. The aim of this study is to use a socio-cultural, second language and gender approach to describe, analyse and understand how a number of adult, illiterate, immigrant women experience their situation when they are expected to simultaneously learn to speak, read and write Swedish. The study focuses on two literacy groups in two Swedish municipalities. In one of the groups I act as both teacher and researcher. The thesis is a case study of the learning process of five illiterate immigrant women in Sweden. The results are based on interviews, carried out with the help of an interpreter, and observation of teaching and texts ritten by the students. The study is based on the assumption that human learning is an activity that takes place in a cultural community in a social context. When learning a language, the language is simultaneously the tool that facilitates social communication and the object of the learning process. The study shows that cultural communities influence the women in different ways. Gender structures are firmly planted in a patriarchal value system, which means that women are seen as inferior to men, and women are expected to “meet the demands of others”. The women have no time to study at home, as their household duties are prioritised. However, there are subtle indications that there is a wish to change the situation in accordance with Swedish values and norms. This can be seen in the Swedish for Immigrants (SFI) lessons. As they have little contact with Swedes, school is the only arena in which they have a chance to use Swedish. They are positive towards teaching and school as an institution. Here they are able to develop an alternative identity. The study also shows that teaching in the literacy groups is to a great extent based on a technical approach, in which the teacher tries to elicit a correct answer from the students. Social interaction involving contemplation and negotiation is either not included or not prioritised. the women’s experience and knowledge is not made use of. There are,however, occasions when collaborative discussions take place between the teacher and students. On these occasions an exchange of experiences takes place. Learning is based on the students’ own experiences and thoughts. Linguistic concepts gain meaning in the collaborative discussion. Initially the concepts may be unclear, but the group works on them together, adapting and adjusting them until they finally make sense. Finally, I conclude that women immigrants bring their own socio-cultural values and experience to the school situation, which affects their learning process to varying degrees. Furthermore, immigrant women need more time at school, as it is the only arena in which they can spend time on studying and personal development. another conclusion is that the school must become a learning community that recognises the immigrants’ cultures, makes use of the students’ experience and allows the students to participate in collaborative discussions, so that they can develop their ability to speak, read and write Swedish.

Vi vill, vi kan men hur? : Att använda sig av anpassade verktyg för cheferna inom vård och omsorg för att förmedla sitt ledarskap till sina medarbetare

Vårt syfte med denna studie är att belysa de verktyg som kan erfordras för att enhetschefer ska kunna förmedla sitt ledarskap till sina medarbetare. Detta på grund av att medarbetarna inom kommunen inte är helt belåtna med ledarskapet från kommun eller sina chefer, vilket framgår i den medarbetarundersökning som genomfördes 2014 av kommunen. I samma medarbetarundersökning framkom det likaså att sjukskrivningar bland medarbetarna i kommunen kan beror på ledarskapet. Därför har vi valt att undersöka en del av kommunens enhetschefer och hur de ser på sitt eget ledarskap samt vad de kan göra för att få sina medarbetare att må bättre och förebygga sjukskrivningar. Då tiden inte fanns till att undersöka alla enhetschefer inom den valda kommunen, valdes vård och omsorgsförvaltningens enhetschefer ut för vår egen enkätundersökning. Resultatet av vår enkätundersökning utföll sig på så sätt att enhetscheferna erfordrar mer tid att ägna sig åt sina medarbetare och att administrativt stöd fordras för att underlätta enhetschefernas arbetsmiljö. Om enhetscheferna erhåller mer tid till att spendera med sina medarbetare kan det skapa ett starkare psykologiskt band emellan dem, vilket gör att tilliten från medarbetarna till enhetscheferna stärks. När tilliten stärks vågar medarbetarna vända sig till sina enhetschefer för att berätta hur de mår. Genom att plocka bort de administrativa uppgifterna och i stället ge dem till en assistent får enhetscheferna mer tid till att spendera med sin personal och utifrån detta kan de eventuellt få en översikt av hur verksamheten fungerar. Översikten gör att de kan fatta bättre strategiska beslut för deras verksamhet och medarbetare.