Binary cavitation in a transparent three hole GDI nozzle

[EN] A more or less real size three hole (0.1 mm diameter) transparent injection nozzle was made with 120° between the orifices and an inclination of 20° to the injector axis. The geometry is similar to that of a multi hole GDI injector. Experiments are performed using n-pentane and -methyl-naphtalene mixtures in varying composition. The flow in the orifices is observed under submerged injection conditions from downstream looking in direction of the injector using a beam splitter plate for illumination with the light from a Minilite NdYag laser that was made incoherent by fluorescence in a cuvette filled with a dilute rhodamine-ethanol mixture. The images show the appearance of cavitation depending on the cavitation number as well as on the composition of the mixture. The behaviour is not what can be expected from equilibrium thermodynamics. Due to the transient nature of the flow the n-pentane concentration cannot attain the equilibrium value one would expect and cavitation occurs at higher cavitation values. Diffusion appears to play a role in the onset appearance of cavitation for binary mixtures.Chaves, H.; Donath, S. (2017). Binary cavitation in a transparent three hole GDI nozzle. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 1035-1042. https://doi.org/10.4995/ILASS2017.2017.5051OCS1035104

Analysis of the confined spaces atmospheres in a wastewater drainage network

There is an underground technical infrastructure for the disposal of wastewater in most of urban areas, which is periodically targeted for maintenance and rehabilitation by specialized workers, or even used more specifically by authorities or emergency forces. Each entry point can be considered a separate confined space, where there are hazardous atmospheres to the physical integrity of the workers. To understand the hazards to which all subjects are exposed, a systematic and exhaustive analysis was carried out in the interior atmosphere of the manholes in the wastewater drainage network, in the entire eastern zone of the city of Beja, the gases produced and at those facilities. The collection of the data was performed when the network was its normal state of exploration, had minimum flows. The flow rates were classified as minimum, after analyzing the readings of recording of the flow meters installed in the zones of measurement and control of the water distribution network, in two very distinct periods

Drenažna mreža otpadnih voda: analiza radnog okruženja

In the city of Beja, Portugal, there is an infrastructure for the conduction of wastewater for treatment, this infrastructure is subject to periodic and systematic rehabilitation and maintenance and can still be used by authorities and even by other companies. Each manhole is a potential confined space with all the constraints and problems that they usually present. A thorough and systematic analysis of the atmosphere inside the manholes of the wastewater drainage system was made to know the respective risks and hazards to all subjects exposed, throughout the East part of the city, from the gases produced and in these installations. The data collection was carried out in two different periods when the network presented minimum flows in normal operation. The flows were considered minimum after the reading of the flowmeters installed in the measurement areas indicated it.Grad Beja u Portugalu ima infrastrukturu za odvođenje otpadnih voda na daljnju obradu. Ta se infrastruktura povremeno obnavlja i održava a radove obavlja gradska uprava ili druge tvrtke. Svaki šaht je potencijalno ograničen prostor koji predstavlja razne teškoće. U istočnom dijelu grada učinjena je sustavna analiza zraka u šahtovima odvodnog sustava kako bi se utvrdili rizici i opasnosti za osobe izložene plinovima u takvim instalacijama. Podaci su prikupljani u dva navrata kad je mreža normalno radila i bila najmanje opterećena protokom. Protoci su se smatrali minimalnima kad su mjerni instrumenti za bilježenje protoka tako pokazali

Química computacional aplicada ao estudo de mecanismos de reacções químicas

Tese de doutoramento, especialidade em "Química Orgânica", Faculdade de Ciências e Tecnologia. Universidade Nova de Lisboa.1998Este trabalho reporta-se ao estudo de várias reacções químicas por modelação computacional das espécies intervenientes: reagentes, intermediários, estados de transição e produtos. Na primeira parte da dissertação estuda-se a reacção de equilíbrio entre uma O-acil- hidroxilamina e o respectivo ácido hidroxâmico. As O-acil-hidroxilaminas são mais estáveis do que os correspondentes ácidos hidroxâmicos, se tiverem substituintes aromáticos ligados ao átomo de azoto, sendo a energia de activação necessária para passar ao ácido hidroxâmico maior do que se tiverem substituintes alifáticos no átomo de azoto. No casos dos ácidos hidroxâmicos, é precisamente o oposto: são mais estáveis se tiverem substituintes alifáticos ligados ao átomo de azoto. O mesmo se passa quando o ácido hidroxâmico e a O-acil-hidroxilamina estão ionizados em meio básico. Os estados de transição aniónicos têm valores de calores de formação mais baixos relativamente às correspondentes espécies neutras. Na segunda parte da dissertação são estudados dois possíveis mecanismos para a reacção de aziridinação de alcenos com O-acil-hidroxilaminas. Verificou-se que a reacção é energeticamente mais favorável se se postular em primeiro lugar a transformação da hidroxilamina numa oxaziridina, que reaja subsequentemente com o alceno. O outro mecanismo menos favorável é a reacção directa da hidroxilamina com o alceno. Verificou-se também, que a reacção é mais favorável se for feita em meio básico, o que está de acordo com os resultados experimentais referidos na literatura. Na terceira parte do trabalho, confirma-se a influência de um ácido de Lewis e de um grupo que constitua impedimento estereoquímico numa reacção de Diels-Alder, fazendo com que praticamente apenas um isómero se produza (anti-endo). Este estudo foi feito através da determinação dos estados de transição da reacção envolvendo a variação das três ligações críticas determinantes para a reacção. Por último, estuda-se a estereoquímica da oxidação de ditianos com periodato e ácido perfórmico, calculando-se os calores de formação e as distâncias das ligações críticas, nomeadamente da ligação S-O do produto, para os estados de transição respectivos. Os valores calculados para a reacção com periodato e ácido perfórmico justificam teoricamente o resultado experimental encontrado para a mono-oxidação de 1,3-ditianos que dá origem a um sulfóxido em posição equatorial, mas não explicam claramente a segunda oxidação que origina o 1,3-dissulfóxido com o último oxigénio em posição axial. Contudo, cálculos ab initio realizados permitem racionalizar a estereoquímica da reacção em ambos os átomos de enxofre, nomeadamente a introdução preferencial do segundo oxigénio em posição axial

Problemática ambiental do biodiesel: uma perspetiva química

Provas Públicas de Avaliação da Competência Pedagógica e Técnico-Científica na área disciplinar de Química, para efeitos de admissão à categoria de Professor Coordenador, Instituto Politécnico de Beja, 2017.A presente lição, subordinada ao tema “Problemática ambiental do biodiesel: uma perspetiva química”, surge no âmbito das Provas Públicas de Avaliação da Competência Pedagógica e Técnico-Científica para acesso à categoria de Professor Coordenador, no disposto nos n.os 8 a 11 do artigo 6.º do Decreto-Lei n.º 207/2009, de 31 de agosto na redação dada pela Lei n.º 7/2010, de 13 de maio, da carreira docente do ensino Superior Politécnico.O tema selecionado é justificado pela sua atualidade e pela controvérsia que tem gerado no meio científico e social, em que a Química pode dar uma resposta sustentável a um problema ambiental que, sendo uma área transversal recebe apoio de várias outras áreas. Além do conhecimento técnico e científico pretende-se também incutir aos alunos um espírito critico sobre este tema

A Smart Approach to Harvest Date Forecasting

The concept of grape ripeness depends not only on the degree of enrichment of the chemical compounds in the grape and the volume of the berries, but also on the possible production purposes. The different types of maturation in individual cases are not sufficient for the decision on the harvest date. Taken together, however, they define oenological maturation times and help to harvest them. However, there are no consistent studies that correlate the chemical parameters obtained from must analysis and oenological maturation due to the nonlinearity of these two types of variables. Therefore, this work seeks to create a self-explanatory model that allows for the prediction of ideal harvest time, based on eneological parameters related to practices in new developments in knowledge acquisition and management in relational databases

Wine Quality Assessment under the Eindhoven Classification Method

The identification, classification and recording of events leading to deterioration of wine quality is essential for developing appropriate strategies to avoid them. This work introduces an adverse event reporting and learning system that can help preventing hazards and ensure the quality of the wines. The Eindhoven Classification Method (ECM) has been extended and adapted to the incidents of the wine industry. Logic Programming (LP) was used for Knowledge Representation and Reasoning (KRR) in order to model the universe of discourse, even in the presence of incomplete data, information or knowledge. On the other hand, the evolutionary process of the body of knowledge is to be understood as a process of energy devaluation, enabling the automatic extraction of knowledge and the generation of reports to identify the most relevant causes of errors that can lead to a poor wine quality. In addition, the answers to the problem are object of formal evidence through theorem proving

Assessment of Water Consumers Literacy

Nowadays, an increasing amount of water is used without the awareness that this resource is not inexhaustible. In fact, pollution, environmental degradation and/or climate change caused by human activities lead to the degradation of the quality of available water. In 2015, the United Nations warned about the risk of reaching a water deficit of 40%, in 2030, if consumption patterns are not changed. Indeed, population growth is one of the main causes for this deficit. The protection and sustainable consumption of water is one of the United Nations’ Sustainable Development Goals, to ensure that the world’s population has access to clean water, free from pollution and managed responsibly. Thus, governments and non-governmental organizations must promote the conscious and informed use of water by the population. It is mandatory that the population becomes aware of the need for efficient management of water resources, ensuring their quality and preventing their degradation, in order to not compromise/jeopardize their future availability. The knowledge of the population’s literacy on water issues and on water quality—health interconnections is essential to design plans leading to the implementation of eco-sustainable practices. The goal of this research was to evaluate the literacy of water consumers and to establish a forecast model for water literacy managing. The collection of information was conducted through the inquiry by questionnaire technique and applied on a cohort encompassing 453 participants. The questionnaire includes three main dimensions (Water Quality, Disease Prevention and Sustainability/Public Health Promotion) and in each dimension, four competencies were evaluated (obtain, understand, assess and apply information regarding water consumption). The results obtained allow to assert that in the two first dimensions, the competence in which participants show more difficulty is assess. Regarding the Sustainability/Public Health Promotion,the participants show more difficulty in the competence apply. The model presented in this research, grounded on the connectionist paradigm, has shown great efficiency in the forecast of the target variable. The key contribution of the present research is to present an integrated and systematic approach that can give a contribution to the increase of water literacy, which allows the implementation of eco-sustainable practices

Draw on Artificial Neural Networks to Assess and Predict Water Quality

Water is one of the important vehicles for diseases of an infectious nature, which makes it essential to assess its quality. However, the assessment of water quality in reservoirs is a complex problem due to geographic limitations, sample collection and respective transport, the number of parameters to be studied and the financial resources spent to obtain analytical results. In addition, the period between sampling and analysis results must be added. This work describes the development of an Artificial Neural Network (ANN) to predict the biochemical and chemical oxygen demand based on the water pH value, the dissolved oxygen, the conductivity and its temperature. The models were trained and tested using experimental data (N=605) obtained from superficial water samples used to irrigate and produce water for public use, collected between September 2005 and December 2017. To evaluate the performance of the ANN models, the determination coefficient, the mean absolute error, the mean square error and the bias were calculated. It was determined that an ANN with topology 4-6-5-2 could be used successfully to predict the variables’ output. Indeed, good agreement was observed between the observed and predicted values, with the values of the coefficient of determination ranging from 0.813 to 0.979