Análise da estabilidade dimensional e resistência mecânica em bambu Guadua angustifolia pós-processos de tratamentos químicos e térmico

Nowadays, bamboo is being studied because of their strength properties according with their specific mass and speed of growth, which makes it an important alternative as a new resource that will help reduce pressure on forests and helpping them favoring the minimization of uncontrolled deforestation in many regions of Brazil. This study aimed, in general, to analyze physical and mechanical properties of the material with the divulgation of its potential for industrial application. To do so, in this research were determined in relation to the physical properties, moisture content, dimensional stability and the apparent densities and the mechanics and basic, just a tension parallel to grain, in order to observe the interference of various kinds of treatments (chemical, thermal and natural) on the strength and modulus of elasticity in this request. The species used was the Guadua angustifolia, a species native of Brazil. All tests were performed at Universidade Estadual Paulista - Campus Experimental Itapeva in the laboratory of Materials Properties. The methodology used for testing of moisture, density and tension parallel to grain were based on NBR 7190/1997 for the wood, and dimensional stability tests were based on much the same as in COPANT 462/1972 (South American) . The preservative treatments conducted followed the recommendation of each manufacturer. The values obtained in tests of physical properties were satisfactory especially with respect to density and dimensional stability analyzed by the coefficient of anisotropy, showed that, compared to wood, excellent quality for the shrinkage test, obtaining a coefficient of 1.2. With respect to parallel tensile tests to fibre results showed, in most cases, that test specimens with the presence of us have lower values of resistance and modulus of elasticity when compared with those without us. In the treatment of thermal-treatment there was an apparent treatment there was an apparent increase in...

Análise teórica e simulação computacional de um sistema de resfriamento líquido de processadores de computadores pessoais

This paper aims to study the thermal aspects involved in a liquid cooling system for processors, analyzing their competitiveness and efficiency across the fins and fan system usually used by personal computers, because electronic components become more potent and consequently current methods of cooling are becoming ineffective. The liquid cooling system and air cooling system have different heat transfer mechanisms that involve mainly convection and conduction heat transfer modes, and, furthermore, requires an analysis of fluid dynamics, which can evaluate the losses involved in the closed system, consisting in an exchanger heat pipe and water blocks in liquid cooling system or heat sink and turbo-axial fan in the air cooling system

Confecção e caracterização de filmes finos de boro para a medida da taxa de reação 10B(N, a)7LI na terapia por captura de nêutrons pelo boro

The Boron Neutron Capture Therapy (BNCT), based on the 10B(n,α)7Li reaction, represents a promising modality for the treatment of cancers that are resistents to conventional treatments. So, it is necessary to find drugs (boron compounds) with high selectivity for each type of cancer, the neutrons source should be well characterized and the rate of 10B(n,α)7Li reaction should be measured with great accuracy as possible. This study aimed to develop a method for manufacturing thin films of boron, for measure the 10B(n,α)7Li reaction, and analyze the uniformity of the films. Five thin films of boron were manufactured with three different concentrations of boric acid, heated to transform the acid in boron, irradiated with thermic neutrons coupled to CR-39 detectors, in BNCT line at the reactor IEA-R1 IPEN/CNEN, São Paulo. After the irradiation, the detectors were chemically attacked with NaOH to reveal the tracks. The methodology presented is effective because it resulted in deposition of boron as thin film enabling the quantitative analysis of 10B(n,α)7Li reaction. The analysis of the uniformity of density of the induced tracks in CR-39 shows that, in most of the films, there is no uniformity in surface distribution of boron, but when the film is divided, we obtain some uniform sectors

Avaliação da influência da taxa de resfriamento posterior ao tratamento térmico nas propriedades mecânicas do aço API 5L X70

In this work a study about the mechanical properties of the API 5L X70 steel, with or without heat treating, has been made, with the intetion of assess the influence of cooling after the austenitization heat treating by air cooling (normalizing) and a rapid cooling with oil (tempering). This steel is known by high strength and ductility values and it is commonly used in the manufacture of oil pipes. The growing energy demand encouraged the study and manufacture of this material. Although this microalloyed dispense subsequent heat treatings, it was proven that its implementation is very advantageous for this type of application, improving hardness and plastic stability. It was also assessed that the faster the cooling rate is, the better will be these properties

Staphylococcus sp na produção primária de leite: aspectos de saúde pública

Staphylococcus is one of the more important causes of the called Foodborne Disease(FD), being that from the 40 species described from genus, the more important is Staphylococcus aureus. During years believed that the S. aureus was the only specie from genus able to produce enterotoxins, responsable for the clinical frame in humans, but latest studies report the isolation of other species both positive coagulase (PC) as negative with enterotoxigenic potential. The symptoms of this intoxication appear after a short period of incubation (2-6 hours) and usually characterized by nausea, vomits, abdominal ache, diarrhea, and rarely is fatal. For the toxin to be formed in food is necessary that bacteria population to be at least 105 UFC/g, being that such toxins characterized by presenting great resistance front of gastrointestinal proteases and of homemade termical treatment. Among the main foods that might carry the microorganism, the milk and its derivatives have highlights. The contamination of the product might happen as from the milk from cows with clinical and/or subclinical mastitis, as the Staphylococcus genus is one of the main agents etiologic from this disease, equipments utensils badly sanitized equipments and utensils and from the manipulators. The control of these factors configures as fundamental condition for the achievement of a safe, quality product, which doesn’t offer risk to the consumers

Evolução da tecnologia móvel até 2013

In this paper expounds on the major phases or generations of the evolutionary process of wireless mobile communication, emphasizing their characteristics and changes over time. The main benefit of this process is the rate of data transfer remembering capacity spectral and methods of harnessing and improving its efficiency. The current network today is 4G and the technologies developed over the following requirements of the ITU are: Long Term Evolution Advanced (LTE-Advanced) and WirelessMAN-Advanced as part of the WiMAX IEEE 802.16m also described in this graduate work

Caracterização da liga do sistema binário Ti-15Mo para aplicações biomedicas

As they have excellent mechanical properties, corrosion resistance and biocompatibility, much research has been conducted with respect to biomedical applications of titanium alloys. This work aims to study the experimental system binary alloy Ti-15Mo, in the raw state of fusion and heat treatment after homogenization, solubilization and calcination (simulating conditions employed for nanotube growth) targeting biomedical applications. Samples were obtained by casting the components in an electric arc furnace with inert atmosphere of argon. After obtaining the alloy, it was heat treated at three different heat treatments, namely homogenizing, calcining and simulation solubilization. The phases present were analyzed by X-ray diffraction, optical microscopy and microhardness testing

Aplicação do ciclo rankine orgânico alimentado termicamente pela queima da casca do arroz e resíduos de madeira

With the growing world energy demand mainly from developing countries like Brazil, Russia, India and China, the search for efficient sources of energy becomes a challenge for the coming years. Among the most widely used alternative sources, biomass is the one that grows in a more pronounced way. This study will assess the real possibility of having it as a heat source in an Organic Rankine Cycle, which employ heat transfer fluids as working fluids instead of water. From a regional data collection in agricultural production and their potential rice production and the resulting husk was defined as more appropriate. The availability of husks together with an amount of eucalyptus wood, provided by a company in the region on a monthly basis, were analyzed, and the low participation of the wood was discarded by the thermal contribution of little significance. Based on this, it was established the calorific value of fuel for thermodynamic calculations and the cycle to be used. It was then carried out the choice of working fluid from the literature and their availability in the library of software used for the simulations, the Engineering Equation Solver - ESS. The fluid most appropriate for the burning of biomass, Octamethyltrisiloxane (OMTS), was not included in the software and so the R227ea and R134a were selected. After the initial parameters modeling definition, as condensing temperature, efficiency and live steam conditions, the simulations were performed, and only the R227ea remained within the feasible thermodynamic and technological ranges. With this fluid the turbine power output was 265.7 [kW] for a scenario of 24 hours/day burning, 800.3 [kW] to biomass burning for 8 hours/day and 2134 [kW] for burning only 3 hours/day. The thermal efficiency of the cycle remained in the range of 6%, and for plants operating with the most... (Complete Abstract click eletronic access below)

Desenvolvimento de filmes finos de Bi3NbO7 pelo método dos precursores poliméricos em diferentes eletrodos óxidos

Technology always advances and thus the device miniaturization and improved performance, besides multifunctionality, they become extremely necessary. A wave of research on the area tends to grow in number and importance in today's market, it is necessary to search for new materials, new applicability of the existing ones and new processes for increasingly cheaper costs. Dielectric materials are considered a key element in this sector being the main electrical properties its high dielectric constant and low dielectric loss. The Polymeric Precursor Method appears as a good alternative because is a low cost, simple process with controlled stoichiometry. In this method, two steps were performed. In a first step, the precursor solution was decomposed into powders and in a second step the precursor solution was converted in thin films. In this work, was used the polymeric precursor methods to get thin films where they were heat treated and characterized by XRD, SEM and AFM. We have obtained Bi3NbO7 thin films with good homogeneity and uniform distribution of grains were noted. We observed that the best condition to obtain the tetragonal phase is annealing the film at high temperatures for a longer soaking time and with excess of bismuth. Several oxides electrodes were evaluated aiming to obtain textured dielectric thin films

Estudo de falhas por fadiga em caldeiras

In recent years, increasing demand for energy has led to studies to increase the amount of electricity produced. Due to this fact, more and more boilers are becoming important sources of electricity generation. To raise the efficiency of energy generated in the boilers is necessary to raise the steam pressure and temperature to values previously unimaginable. The use of more resistant materials and maintenance practices and most appropriate operation made it possible. The objective of this study is to test the main types of failure in a chemical recovery boiler, in particular due to fatigue in the superheater, because it is a component subjected to high temperatures and thus more subject to different failures. In this manner this study aims to reduce the incidence of unscheduled maintenance shutdowns, increasing the operation time under appropriate conditions. Modeling performed in this study, the failure did not occur, because we considered only the mechanical stress. Under normal conditions, mechanical stress in combination with thermal stresses can cause cracks in the tubes due to cyclical stresses, leading to fatigue failure

Comportamento da temperatura da massa de resíduos aterrados em um aterro sanitário

In this paper we investigate the temperature variation of the mass of waste along the depth in a household waste landfill of Rio Claro - SP, São Paulo, having a climate characterized as Tropical Altitude. In this research, there were two holes in two distinct points of the landfill, with different depths and characteristics in order to fix several thermal sensors - RTDs - to record the temperature at predetermined depths. Overall, the results show the influence of temperature at depths of up to 3.0 meters (from the surface) and that it varies in a manner to stabilize at depths above 5.0 meters. The highest temperature obtained was approximately 37.5 ° C for a time of waste disposal of 7 to 10 years. The results showed the presence of organic matter (substrate) which resulted in elevated temperature resulting from biological activity

Obtenção e caracterização de compósitos nanoestruturados de poli(sulfeto de fenileno) reforçados com nanotubos de carbono

Pós-graduação em Engenharia Mecânica - FEG

Desenvolvimento de parafuso de interferência bioabsorvível para cirurgia de joelho em PLDL (poli ácido lático) e compósito PLDL + βTCP (beta trifosfato de cálcio)

Pós-graduação em Engenharia Mecânica - FEB

Efeito do tipo de adesivo e do seu mecanismo de ativação, assim como da viscosidade da resina composta, na resistência de união à dentina antes e após envelhecimento artificial

Pós-graduação em Odontologia Restauradora - ICT

Influência de três tratamentos de superfície para cerâmicas a base de zircônia na resistência adesiva e no comportamento à fadiga do material

Pós-graduação em Odontologia Restauradora - ICT