Análise de desempenho de um fogão solar construído a partir de sucatas de antena de tv

Given the growing environmental crisis caused by degradation, mainly due to the use of polluting energy sources, increasing the growing use of renewable energies worldwide, with emphasis on solar energy, an abundant supply and available to everyone, which can be harnessed in several ways: electricity generation; dehydration of food; heating, disinfection and distillation and cooking. The latter has as its primary feature the viability of clean, renewable energy for society, combating ecological damage caused by large-scale use of firewood for cooking foods, use in tropical countries with high solar radiation, and has funding NGOs throughout the world with the goal of achieving low-income population. The proposed project consists of a solar cooker for concentration, working from the reflection of sunlight by a hub that they converge to a focal point at the bottom of the pot, getting lots of heat. The solar cooker under study consists of two elliptical reflecting parabolas made from the recycling of scrap TV antenna, having 0.29 m² of surface area for each antenna, which were covered by multiple mirrors of 2 mm thick and mounted on a metal structure, with correction for the mobility of the apparent movement of the sun. This structure was built with the recycling of scrap metal, possessing a relatively low cost compared with other solar cookers, around US$ 50.00. This cost becomes negligible, since that will involve a great benefit to not have fuel costs for each meal, unlike the use of gas or firewood for cooking food. The tests show that the cooker has reached the maximum temperature of 740 ° C, for boiling water in an average time of 28 minutes, cooking various types of foods such as potatoes, rice and pasta in an average time of 45 minutes and still going as a solar oven, making pizza baking and meat. These cooking times do not differ much from the cooking times on a gas stove, it becomes the solar cooker as a good consumer acceptance, and furthermore not to deliver the same gases that can poison the food as with the wood stove. Proves the viability of using the stove to cook or bake in two daily meals for a family, still presenting a position to improve his performance with the addition of new materials, equipment and techniques

Viabilidade térmica de um forno solar fabricado com sucatas de pneus

The proposed design provides a solar furnace alternative, box-like, low-cost operation to be used in cooking, comprising three scrap tires to make the recycling thereof. The tires were coupled to each other, forming an enclosure, which stood on its bottom covered by a parable multiple mirrors made from a urupema (sieve indigenous) and the inner sides of the oven aluminum sheet painted black, obtained from beer cans, thus being made to obtain the increase in the concentration of solar radiation incident on the inside of the prototype studied. Two tires were attached, leaving an air layer between them, with the function of thermal insulation. The third tire aimed to support the other two and thermally insulate the bottom of the oven. Externally was placed a metal frame with flat mirrors to reflect the incident rays into the oven, having a mobility to correct the apparent motion of the sun. Its primary feature is the viability of clean, renewable energy to society by tackling the ecological damage caused by the large-scale use of wood for cooking food. The tests show that the furnace reached the maximum temperature of 123.8 °C and baking various foods such as pizza, bun, and other lasagne in an average time 50 minutes. Proves the feasibility of using the oven. Presenting still able to improve their performance with the addition of new materials, equipment and techniques

O ser elástico, mola, agulha, trepidação: expressões do homoerotismo em Fernando Pessoa

This Masters thesis investigates and analyzes the homoerotic expressions in Fernando Pessoa s poetry and in his heteronyms : Álvaro de Campos, Alberto Caeiro and Ricardo Reis. Through the elaboration of deceptive strategies as a way to escape from the insults and the constraints, the poet by means of creative runaway lines builds up a homoerotic poetry that differ from the established patterns and representational models of the literature. We can find, bearing in mind a problematic sexuality which overflows in the various I s, of the sinuous identities and the movable boundaries, and intense mask games. They become real in poems, especially by means of sensations, yielding the possibility of a queer discourse and generating a homoerotic poetry. Pessoa s homoerotism is, thus, presented amid friendly relationships, smooth spaces, of heterotrophy of the city, or others space and the closet s aesthetics. Based on this, it is noted the articulations of a performance gender as body scripture and inscription, thus establishing a physical-writing which reveals a transgressive sexuality, with multiple entrances and exits, affirmations and denials that originate paradoxes. In this matter, we develop links between Foucault conceptions (2010a, 2010b, 2011) towards the history of sexuality, friendship and the power-knowledge relations with traces of significance and subjectivity, in processes of faciality and BwO (Body-without-Organs) in Deleuze and Guattari (1996). We still consider the ontological questionings towards the Gay dimension in Eribon (2008) and we raise aspects concerning the construction of the idea of masculinity in Bourdieu (2010). Finally, we base ourselves on Sedgwick s 1993 closet epistemological approach, as well as on Butler s 2012 gender and performance theory, also going through a few Bataille 1987 passages about erotism, that redimension the homoaffective images of the Portuguese poet

Mariana , Pai contra mãe e O caso da vara : escravidão e chão histórico em Machado de Assis

Machado de Assis understood his time and brought his perception of Brazilian society in the 19th century, with its multiple aspects economy, politics, culture, amongst others - to the texts he wrote. Through the tensions lived in his novels and short stories, Machado displays Brazilian social reality and the changes it had been undergoing. Mariana and Pai contra mãe show the crisis of the slavery system, the relation of dependency, the treatment given to the captives and the lack of coherence of a country that intended to adopt Liberalism as an ideology, but which kept on living under the shadow of slavery and its consequences. A country where the priorities were given to the landlords, owners of slaves, in protection of their interests. O caso da vara tells about how the crias da casa little black girls who lived in the household and learned how to make spool embroidery were treated. What were the punishments for desobedience and how they were levelled out, how should be the behaviour of a child who lived as a social outcast. Thus, this paper aims at playing a game of mirrors between History and fiction. Not only to play it, but to analyze how Machado deals with the reflections of 19th century Brazil on his short stories

Occlusal caries prevention in high and low risk schoolchildren. A clinical trial

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Characterization of multiple reflections and phase space properties for a periodically corrugated waveguide

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Structural variations among monocot emergent and amphibious species from lakes of the semi-arid region of Bahia, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A criança abrigada: considerações acerca do sentido da filiação

O presente artigo discute os sentidos da filiação para crianças abrigadas, vítimas de violência doméstica. O desejo dessas crianças de recuperar a filiação familiar é analisado como busca de um lugar psicossocial. As crianças abrigadas, que sofreram uma ruptura na filiação primeva e história de vida, flutuam entre vinculações efêmeras, sem referências de seu passado e sem pontos fixos e sólidos para seu assentamento no presente que lhes possam servir de guia ou de novas filiações. Tal condição de desfiliação é focalizada como tendência da sociedade contemporânea em afrouxar vinculações, movimentar os ancoradouros psicossociais e produzir desterritorializações, favorecendo uma subjetividade móvel, não identitária, desenlaçada de encaixes e conexões duradouros. Como conclusão, é apontada a continuidade histórica da vitimização da infância realizada pela condição de trânsito e passagem na qual vive, impeditiva de constituições de vínculos duradouros e sólidos que permitam uma suficiente estabilidade e segurança para a prospecção do mundo.

PCM thermal insulation in buildings

This paper presents the results of a numerical and experimental study of phase change material (PCM) filled walls and roofs under real operational conditions to achieve passive thermal comfort. The numerical part of the study was based on a one-dimensional model for the phase change problem controlled by pure conduction. Real radiation data was used to determine the external face temperature. The numerical treatment was based upon using finite difference approximations and the ADI scheme. The results obtained were compared with field measurements. The experimental set-up consisted of a small room with movable roof and side wall. The roof was constructed in the traditional way but with the phase change material enclosed. Thermocouples were distributed across the cross section of the roof. Another roof, identical but without the PCM, was also used during comparative tests. The movable wall was also constructed as is done traditionally but with the PCM enclosed. Again, thermocouples were distributed across the wall thickness to enable measurement of the local temperatures. Another wall, identical but without the PCM, was also used during comparative tests. The PCM used in the numerical and experimental tests was composed of a mixture of two commercial grades of glycol in order to obtain the required fusion temperature range. Comparison between the simulation results and the experiments indicated good agreement. Field tests also indicated that the PCM used was adequate and that the concept was effective in maintaining the indoor temperature very close to the established comfort limits. Further economical analysis indicated that the concept could effectively help in reducing the electric energy consumption and improving the energy demand pattern. © 1997 by John Wiley & Sons, Ltd.

Utilizing the CORBA platform in the construction of a highly immersive virtual environment

This article presents the implementation of a distributed system of virtual reality, through the integration of services offered by the CORBA platform (Common Object Request Broker Architecture) and by the environment of development of 3D graphic applications in real time, the WorldToolkit, of Sense8. The developed application for the validation of this integration is that of a virtual city, with an emphasis on its traffic ways, vehicles (movable objects) and buildings (immovable objects). In this virtual world, several users can interact, each one controlling his/her own car. Since the modelling of the application took into consideration the criteria and principles of the Transport Engineering, the aim is to use it in the planning, project and construction of traffic ways for vehicles. The system was structured according to the approach client/server utilizing multicast communication among the participating nodes. The chosen implementation for the CORBA was the Iona's ORBIX software. The performance results obtained are presented and discussed in the end.

A simple constant-current neural stimulator with accurate pulse-amplitude control

A simple constant-current electrocutaneous stimulator for high-impedance loads using low-cost, standard high-voltage components is presented. A voltage-regulator powers an oscillator built across the primary of a transformer whose secondary delivers, after rectification, the high-voltage supply to switched current-mirrors in the driving stage. Since the compliance high-voltage is proportional to the stimulation current, overall power consumption is minimized. By adjusting the regulated voltage, control of the pulsed-current amplitude is achieved. A prototype with readily available components features stimulation currents of amplitude and pulsewidth in the range 0≤Iskin≤20mA and 50μs ≤Tpulse≤1ms, respectively. Pulse-repetition spans from 1 Hz to 10Hz. Worst-case ripple is 3.7% @Iskin=1mA. Measured pulse fall-time is shorter than 32μs. Overall consumption is 4.4W @Iskin=20mA. Subject isolation from line is 4KV.

Origo Vitae: Um diálogo intertextual entre Haroldo de Campos e Gustave Courbet

This work intends to undertake a comparative reading of two works of two different artists: The painting The Origin of the World by Gustave Courbet and the poem Origo Vitae by Haroldo de Campos and, from this reading, to verify how the border between the visible and the invisible may vanish and how, in a process of transcodifying, one mirrors the other in a dialogue that, besides surpassing different codes and times, produces new meanings and elicits a conversation about the act of reading these different codes.

Environment mapping for mobile robots navigation using hierarchical neural network and omnivision

Autonomous robots must be able to learn and maintain models of their environments. In this context, the present work considers techniques for the classification and extraction of features from images in joined with artificial neural networks in order to use them in the system of mapping and localization of the mobile robot of Laboratory of Automation and Evolutive Computer (LACE). To do this, the robot uses a sensorial system composed for ultrasound sensors and a catadioptric vision system formed by a camera and a conical mirror. The mapping system is composed by three modules. Two of them will be presented in this paper: the classifier and the characterizer module. The first module uses a hierarchical neural network to do the classification; the second uses techiniques of extraction of attributes of images and recognition of invariant patterns extracted from the places images set. The neural network of the classifier module is structured in two layers, reason and intuition, and is trained to classify each place explored for the robot amongst four predefine classes. The final result of the exploration is the construction of a topological map of the explored environment. Results gotten through the simulation of the both modules of the mapping system will be presented in this paper. © 2008 IEEE.

Experienciando Materiais Manipulativos para o Ensino e a Aprendizagem da Matemática

This paper presents some outcomes from research based on classroom experiences. The main themes are the use of mirrors, kaleidoscopes, dynamic geometry software, and manipulative material considering their possibilities for the teaching and learning of Euclidean and non-Euclidean geometries.

Development of silicon carbide substrates for aerospace applications

Payload and high-tech are important characteristics when the goals are aerospace applications. The development of the technologies associated to these applications has interests that transcend national boundaries and are of strategic importance to the nations. Ultra lightweight mirrors, supports and structures for optical systems are important part of this subject. This paper reports the development of SiC substrates, obtained by pressing, to be applied on embedded precision reflective optics. Different SiC granulometries, having YAG as sintering additive, were processed by: ball milling, drying and deagglomeration, sift, uniaxial and isostatic pressing, and, finally, argon atmosphere sintering at 1900°C. Different porosities were obtained according to the amount of organic material added. Into one side of the samples pellets of organic material were introduced to generate voids to reduce the weight of samples as a whole. The substrates were grinding and polished, looking for a SiC surface having low porosity, as porosity is directly related to light scattering that should be avoided on optical surfaces. Laser surface treatments were applied (using or not SiC barbotine) as a method to improve the surface quality. The samples were characterized by optical and laser confocal microscopy, roughness measurements and mechanical tests. The results are very promissory for future applications. © 2012 Materials Research Society.