Implementation and comparison of different switching techniques for shunt active power filters

This paper presents a comparison between three switching techniques that can be used in three-phase four-wire Shunt Active Power Filters (SAPFs). The implemented switching techniques are: Periodic-Sampling (PS), Triangular Carrier Pulse-Width Modulation (TC-PWM) and Space Vector PWM (SVPWM). The comparison between them is made in terms of the compensated currents THD%, implementation complexity, necessary CPU time and SAPF efficiency. To perform this comparison are presented and analyzed several experimental results, obtained with a 20 kVA Shunt Active Power Filter prototype, specially developed for this purpose. The control system of the developed SAPF is based in the p-q Theory with a grid synchronization algorithm p-PLL.

Análise da qualidade do serviço numa empresa transportadora

Dissertação de mestrado integrado em Engenharia e Gestão Industrial

Methanogens, sulphate and heavy metals: a complex system

Anaerobic digestion (AD) is a well-established technology used for the treatment of wastes and wastewaters with high organic content. During AD organic matter is converted stepwise to methane-containing biogasa renewable energy carrier. Methane production occurs in the last AD step and relies on methanogens, which are rather sensitive to some contaminants commonly found in wastewaters (e.g. heavy metals), or easily outcompeted by other groups of microorganisms (e.g. sulphate reducing bacteria, SRB). This review gives an overview of previous research and pilot-scale studies that shed some light on the effects of sulphate and heavy metals on methanogenesis. Despite the numerous studies on this subject, comparison is not always possible due to differences in the experimental conditions used and parameters explained. An overview of the possible benefits of methanogens and SRB co-habitation is also covered. Small amounts of sulphide produced by SRB can precipitate with metals, neutralising the negative effects of sulphide accumulation and free heavy metals on methanogenesis. Knowledge on how to untangle and balance sulphate reduction and methanogenesis is crucial to take advantage of the potential for the utilisation of biogenic sulphide as a metal detoxification agent with minimal loss in methane production in anaerobic digesters.

Effect of the acoustic impedance in ultrasonic emitter transducers using digital modulations

In an underwater environment it is difficult to implement solutions for wireless communications. The existing technologies using electromagnetic waves or lasers are not very efficient due to the large attenuation in the aquatic environment. Ultrasound reveals a lower attenuation, and thus has been used in underwater long-distance communications. The much slower speed of acoustic propagation in water (about 1500 m/s) compared with that of electromagnetic and optical waves, is another limiting factor for efficient communication and networking. For high data-rates and real-time applications it is necessary to use frequencies in the MHz range, allowing communication distances of hundreds of meters with a delay of milliseconds. To achieve this goal, it is necessary to develop ultrasound transducers able to work at high frequencies and wideband, with suitable responses to digital modulations. This work shows how the acoustic impedance influences the performance of an ultrasonic emitter transducer when digital modulations are used and operating at frequencies between 100 kHz and 1 MHz. The study includes a Finite Element Method (FEM) and a MATLAB/Simulink simulation with an experimental validation to evaluate two types of piezoelectric materials: one based on ceramics (high acoustic impedance) with a resonance design and the other based in polymer (low acoustic impedance) designed to optimize the performance when digital modulations are used. The transducers performance for Binary Amplitude Shift Keying (BASK), On-Off Keying (OOK), Binary Phase Shift Keying (BPSK) and Binary Frequency Shift Keying (BFSK) modulations with a 1 MHz carrier at 125 kbps baud rate are compared.

Marine origin polysaccharides in drug delivery systems

Oceans are a vast source of natural substances. In them, we find various compounds with wide biotechnological and biomedical applicabilities. The exploitation of the sea as a renewable source of biocompounds can have a positive impact on the development of new systems and devices for biomedical applications. Marine polysaccharides are among the most abundant materials in the seas, which contributes to a decrease of the extraction costs, besides their solubility behavior in aqueous solvents and extraction media, and their interaction with other biocompounds. Polysaccharides such as alginate, carrageenan and fucoidan can be extracted from algae, whereas chitosan and hyaluronan can be obtained from animal sources. Most marine polysaccharides have important biological properties such as biocompatibility, biodegradability, and anti-inflammatory activity, as well as adhesive and antimicrobial actions. Moreover, they can be modified in order to allow processing them into various shapes and sizes and may exhibit response dependence to external stimuli, such as pH and temperature. Due to these properties, these biomaterials have been studied as raw material for the construction of carrier devices for drugs, including particles, capsules and hydrogels. The devices are designed to achieve a controlled release of therapeutic agents in an attempt to fight against serious diseases, and to be used in advanced therapies, such as gene delivery or regenerative medicine.

Development of Monoolein-based lipofection vectors for therapeutic siRNA delivery

Tese de Doutoramento em Biologia Molecular e Ambiental - Especialidade em Biologia Celular e Saúde

Development of a poly(L-Lactic acid) based drug release system

Dissertação de mestrado em Biofísica e Bionanossistemas

Lipid based nanocarriers for the delivery of the bioactive compound resveratrol

Dissertação de mestrado em Biofísica e Bionanossistemas

Development of nanohydrogels as a vehicle for the release of bioactive compounds in food matrices

PhD in Chemical and Biological Engineering

Perceção e produção de sons consonânticos do português europeu por aprendentes chineses

Dissertação de mestrado em Português Língua Não Materna (PLNM): Português Língua Estrangeira (PLE) Português Língua Segunda (PL2)

Caracterización de péptidos circulantes en sangre activadores e inhibidores de linfocitomas

El presente proyecto es continuación de una línea de investigación iniciada en colaboración con el Instituto de Investigaciones de Péptidos de la Universidad de Hannover, Alemania. En el mismo estudiaremos la actividad biológica de un péptido que aislamos y caracterizamos recientemente a partir del hemofiltrado de pacientes renales dializados. Este péptido, compuesto por una doble cadena de 70 aminoácidos unidos por puentes disulfuros en posición paralela, aparece en su forma postranscripcional con 1 a 3 metioninas oxidadas y tiene capacidad de ligar xenobióticos y productos naturales. Por su actividad proliferativa sobre las células de linfoma Nb2, utilizadas como bioanálisis, lo hemos denominado LPAP; péptido activador de la proliferación de linfocitoma. El efecto proliferativo sobre células de linfocitoma y posiblemente sobre otras especies celulares, representa una actividad biológica cuyas implicancias son imponderables. Dada su capacidad de fijar péptidos bioactivos no se puede descartar que el LPAP sea un transportador (o carrier), en cuyo caso la actividad proliferativa debe ser atribuida a otro compuesto firmemente ligado a la molécula secuenciada por nosotros. (...) Los siguientes objetivos son propuestos para los próximos 3 años: 1. Producción de anticuerpos específicos contra LPAP para determinar las células productoras del mismo en el organismo por un mapeo inmunocitoquímico. 2. Desarrollo de un método cuantitativo para valorar las concentraciones del péptido en diferentes fluidos corporales en sujetos en condiciones normales y patológicas. 3. Síntesis parcial o total de la molécula para establecer definitivamente la actividad biológica observada. 4. Caracterización de péptidos inhibitorios de la proliferación del Linfoma. 5. Determinación de prolactina en el hemofiltrado y correlación de su contenido con otras moléculas proliferativas o inhibidoras de las células Nb2.

Implementation of Reed-Solomon RS (255,239) Code

In this paper the construction of Reed-Solomon RS(255,239) codeword is described and the process of coding and decoding a message is simulated and verified. RS(255,239), or its shortened version RS(224,208) is used as a coding technique in Low-Power Single Carrier (LPSC) physical layer, as described in IEEE 802.11ad standard. The encoder takes 239 8-bit information symbols, adds 16 parity symbols and constructs 255-byte codeword to be transmitted through wireless communication channel. RS(255,239) codeword is defined over Galois Field GF and is used for correcting upto 8 symbol errors. RS(255,239) code construction is fully implemented and Simulink test project is constructed for testing and analyzing purposes.

Verificação, em condiçoes naturais, da infecção de mais três hematófagos (Anophelineos, Flebótomos e Simulídeos) em leprosos

The A. went last August to the State of Minas Gerais to continue his studies on transmission of leprosy by insects. He selected ten lepers (all L3 cases) for his experiments. It happened in the middle of August, a few day after freezing temperature. Practically there were no day mosquitoes, even near a river where in March there were very many. Bringing the patients to a wood, near the Peixe River (Fish River), at the dawn they were attacked by very many Anopheles, some flebotomus, a few Simulium and very rare Culex scapularis. All these insects became infected, in different degrees, by biting such patients. CONCLUSIONS. 1. Two species of Anopheles (A. albitarsis and A. tarsimaculatus) became strongly infected by Hansen bacilli. 2. By dissection done by Dr. Oliveira Castro were found lepra bacilli in various points of the proboscis of two Flebotomus (F. intermedius) and in their stomachs. 3. By smearing were found lepra bacilli in two specimens of Simulium sp. (probably pertinax). 4. It was confirmed also the verification done last March, at the same Leper Colony, that Phthirius pubis can be also a carrier of lepra bacillus. 5. There was confirmed also natural infection of nymphs of Amblyomma cajennense in lepers. Dr. Oliveira Castro is dissecting the Anopheles to locate the bacilli in their organisms and he started, with the cooperation of the Director of Colonia Santa Fé, Dr. José Mariano, attenpts to re-infect a group of negative-nerve cases of leprosy with infected mosquitoes.

Contribuição ao estudo das doenças hereditárias

Em revisão de conhecimentos sobre doenças hereditárias foi verificada em várias dessas heredopatias (anemia de hemátias em alvo, icterícia hemolítica heredo-familiar. anemia ovalocítica, anemia perniciosa de BIERMER, trombopatia constitucional, distrofia miotônica — compreendendo a doença de TNOMSEN e paramiotonia -, doença de FRIEDREICH, doença de CHARCOT-MARIE, epilepsia, keratosis follicularis ou doença de DARIER. braquidactilia, e câncer gástrico) a existência de indivíduos de comportamento semelhante ao siclêmico na anemia drepanocítica. Tais indivíduos são identificáveis por apresentarem precocemente algum dos sinais clínicos da doença. Provas especiais para cada entidade mórbida são necessárias para essa identificação.Essas verificações indicam a possibilidade de se identificarem os portadores de caráter patogênico hereditário na fase de latência (indivíduos “aparentemente sãos" ou "carrier") e que a existência de tais indivíduos é uma das características das doenças hereditárias, talvez excetuadas, as deformidades congênitas. Sugerem também que se deve relacionar o fenômeno de salteamento de gerações (skipping) na incidência das heredopatias com êsses portadores. E' sugerido o recenseamento e exames periódicos dêsses indivíduos no sentido da aquisição de dados sôbre os fatores responsáveis pela passagem da condição de "latente" para a de doente. Possivelmente, êsses conhecimentos forneceriam as bases de eventual profilaxia das doenças acima mencionadas. Na anemia perniciosa a hepatoterapia, como aconselha ASKEY, deve ser aplicada aos acloridricos, como medida preventiva.

Subsídio ao melhor conhecimento do tifo exantemático neotrópico no Brasil: presença do virus no leite

In articles, already published, we have proved that the strain V. B. of Brazilian virus, goes through the placenta (Macacus rhesus) (1) and the apparently normal gastro-intestinal tube (1934-1937) (Canis familiaris) (2). Today we present the idea that the Brazilian virus can reach the milk of an animal even when the latter has only the unapparent disease. In former articles (**), we have shown that the goat (Capra hircus) can be an excellent reservoir of Brazilian virus, having the strain V. B. in its blood and presenting a Weil Felix reaction high and in “group”, with the disease unapparent. When the goats are bred in the laboratory, and even in some foci of the disease, they give a negative Weil Felix, being zero for all the nine strains of Proteus. In the interior of Brazil, in many localities, goats substitute cows, in supplying milk for children and adults, and in some districts goat’s milk is considered superior to cow’s milk, possessing marvellous qualities for men, women an children. Having proved, now, that goat’s milk can contain the virus even when the animal presents nothing clinically, and having also shown that this virus goes through the digestive tube apparently sound, it is easy to understand how infants-in-arms, that is, only a few months old, living in strictly domestic surroundings, can contract the disease; we have many such cases on record. Protocol of the experiments: Goat nº 2, white, January 1948. This animal had been inoculated with the V. B. strain of the Brazilian virus in June 1947, via intra-peritoneal, presenting nothing then, not even a feverish reaction. On that occasion it was not possible to isolate the virus of the blood, although the Weil Felix reaction was positive, high and in “group”. Now January 17, 1948, seven months later, the same animal was reinoculated with a semple of virus V. B. in the same manner (intra-peritoneal) two days after bringing forth two sturdy kids. The virus V. B. was obtained from guinea-pig n. 7170 whose thermic graph was as follows: Temperatura – 38,8 – 39,1 – 39,5 – 39,4 –39,8 – 40,4 – 40,2 – 40,1 - + Necropsy – Typical lesions. The spleen weighed 5 grammes. With 3c.c. of emulsion from the nervous system of this guinea-pig, we inoculated not only the goat, as also two guineapigs, number 14 and number 5. The following is the thermic graph of one: - Guinea-pig n. 14 – 38,9 – 39,1 – 39,2 – 39.2 – 40,7 – 41,0 – 40,5 – 40,4 – 40,1 - + Typical lesions. Guinea-pig n. 2 presented the following thermic graph after the infective inoculation: - 39,5 – 39,7 – 39,7 – 39,7 – 39,5 – 39,3 – 39,5 – 39,5 – 39,5 – etc. Clinically, this animal presented nothing unusual, feeding well and suckling the kids normally. The Weil Felix reaction was positive, in “group” high very similar to the reaction obtained in June 1947, with the first infective inoculation. On the third, fourth, fifth, sixth and seventh day after the infective inoculation, we took milk from the goat and inoculated male guinea-pigs via intra-celular and via intra-peritoneal, giving 5 c.c. to each animal. Guinea-pig n. 4663, inoculated with 5 c.c. of milk, via intra-muscular, taken on the third day of the infectaive inoculation, presented the following thermic graph: - 38.8 (*) – 39,1 – 39,0 – 39,1 – 40,1 – 40,1 – 40,8 (**) – 40,8 – Killed – Typical deisions (***). The virus V. B. of this goat, circulated naturally in the blood up to the third day, having passed into the milk, producing nothing in the kids, on account of the natural resistance of these animals to the disease. The Weil Felix reaction and that of Widal for the Burcellas suis, abortus and militensis were negative for the goat and the kids. It is remarkable that, even with inoculation of the living virus after a period of seven months we cannot get a real and absolute immunity of sensitive animals. We shall return to this subject later. The hart Mazama simplicicornis may be a carrier of the virus in Brasil. The experimental serum against the virus of Exanthematic neotropical typhus has not protected guinea-pigs.