Análise geoestatística da variabilidade espacial do acabamento com tingidor em painéis de madeira colada lateralmente

Classical statistical techniques which necessarily assume that all sampling units are random and independent were always used in the timber industry. Geostatistics considers that certain phenomena are characterized by spatial dependence: values of sampling units closer to each other tend to be more similar than values of sampling units farther away. This study aimed to characterize the spatial variability of the finishing (dyer) in the upper and lower surfaces of four edge glued panels by using geostatistical methods using geoR. Semivariograms were constructed for the analysis of spatial dependence. The spherical mathematical model was the best fit to the semivariograms generated, and was done the interpolation of the data (kriging) in samples where the distribution of dyer presents spatial dependence. In the bottom surfaces of two panels where the spatial dependence was detected geostatistical methods characterized a very large spatial variability due to the heterogeneous application of the finishing

Produção e caracterização físico-mecânica do compósito cimento-madeira com variação granulométrica dos resíduos lignocelulósicos

The need to reduce environmental damage and add value to waste causes more and more new alternatives appear to unite these two points. One of the main ways to achieve this in timber industries and the use of waste for making panels. This work was aimed at studying the influence of particle size and density in Eucalyptus mechanical compressive strength of cement composite wood. For this study was performed production and physico-mechanical characterization of specimens, using portland cement, water and waste eucalyptus. The methodology consists of a statistical study of the results obtained by calculating the density and axial compression tests and a subsequent comparison of these results with other studies. The results showed that there are significant differences in density and compressive strength when using different particle sizes the particles of eucalyptus. In general, the smaller the particle size, the lower the compression strength and the greater the density when the samples are produced with the same trait

Estudo da influência das resinas termofixas uréia formaldeído (UF) e melamina formaldeído (MF) nas características físicas e mecânicas de painéis MDF

Thermosetting resins are very important in the production of MDF panels. They act as an adhesive in the process of compacting and consolidating the fiberboard. Thermoset resins commonly used in this process are based resin urea formaldehyde (UF) and melamine formaldehyde (MF). The first has a higher demand due to its low cost and good performance in meeting the specifications and standards. The second has a high cost compared to MF resin, but adds greater value to the MDF panel, because it gives greater moisture resistance. The process of manufacture of MDF boards was briefly presented in this study to facilitate the understanding of the work. Samples of thermosetting resins (UF and MF) were subjected to physical-chemical seeking to relate these results to the technological performance presented by their respective samples of MDF boards. Two other samples of MDF panels were subjected to physical and mechanical tests. Results were analyzed and related to the award of their respective thermoset resin. Instruments like Dahmos Trend Manager ® and Grecon Dax 5000 and TG - DSC analysis were used in this study to assist in the analysis of the results. It was observed that the results of the analysis of thermosetting resins were within the specified. Such resins do not directly influence the technological tests provided by the MDF panels, but it has been found that the process variables such as humidity and fiber production rate interfere with the performance of the resin accelerating the reaction and therefore their influence on the physical-mechanical properties of the panels MDF. Samples of MDF panels with UF and MF met all the specifications required by the Brazilian standard with regard to the technological quality. The increased demand for UF resin market is justified by the service specifications...

Análise do desempenho físico-mecânico de painéis compensados de Pinus sp. produzidos com adesivos aquosos a base de poliacetato de vinila e de homopolímero vinílico

This study aimed to evaluate the physico-mechanical performance of three PVA adhesive formulations according to the Brazilian standards for plywood testing and to evaluate the results with those presented in the technical literature and specified in normative documents. The study presents the production process of the panels, the obtaining of samples and, finally, the implementation of physico-mechanical characterization tests based on plywood Brazilian standards. For the panels production it was used a gramature of 120 g / m² and applied a pressure of 15 bars and two temperature combinations and pressing time for each adhesive. The commercial adhesives used were PVA 1810, PVA 1060 and Vinyltec 239. The physical tests conducted were thickness swelling, density, moisture content and water absorption. The mechanical tests were static flexion, for the determination of elasticity modulus (MOE) and rupture modulus (MOR), and shear in the glue line. Among the three formulations studied none showed good performance in the presence of water. However, other trials in the adhesive showed better results and closer to the commercially equivalent used, in the case the urea-formaldehyde, was the PVA 1810, that can be applied in non-structural uses and in environments without the presence of moisture

Análise comparativa entre Brasil e Alemanha sobre autoprodução de energia elétrica residencial

The energy crisis has affected many countries. With the growing warning with the emission in the atmosphere and the lack of resources, the seek for sustainable sources for energy genaration have become even bigger. Some Countries, as Germany, started first in this journey, creating an incentive program to self-generation with renewable sources (wind, photovoltaics, biomass, etc.), giving priority for smaller plants. In Germany the program called EEG started in 2004. In Brazil, since the beggining of 2012, the self-generators did not know how they could be beneficted for self-generation, and self-generation didn't become commun in the country. However, with NR 482, of April 17th, 2012, the parameters were defined, and the self-generator could have a guideline. Therewith, studyies can be redirected for a better knowlegde of the conditions the self-generator will be sujected, in addition to Germany's case as reference to compare with Brazil's case. In this paper these studies are made, focused in wind power (wind turbines) and photovoltaic panels

Efeito protetor da proteína anti-inflamatória Galectina-1 sobre o processo de uveíte induzida pelo inflamógeno lipopolissacarídeo

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

Aplicação do conceito de geração distribuída a um sistema fotovoltaico residencial

This work presents a study about distributed generation using photovoltaic systems in the context of smart grids. The characteristics of a Smart Grid and the several aspects this concept involves - distributed generation among them - are discussed. There are also examples of equipment, like smart meters, and of national and international projects. The specificities of distributed generation and the rules and standards necessary in this sort of installation are talked through with focus in the solar energy generation method. Regarding photovoltaic systems, the working principles of the panels are presented, along with its main electrical characteristics and the technologies available. Finally there is a study concerning the sizing of a distributed generation system that involves photovoltaic panels in a residential plant. An analysis of the costs and return of investment period is made about the specific case in consideration.

Chaveamento de cargas intermitentes usando sensor de corrente

Due to concerns about rational use of energy, several alternative technologies of power generation appeared, including the conversion of solar energy into electrical energy by photovoltaic panels. In low-income households, the refrigerator represents considerable impact on the electric bill, since it requires constant power given its use in food preservation. It is possible to reduce this share, with the use of an alternative energy source. This work presents a timed switching electronic system, which allows commercial equipment that is not affected by short interruptions in the power supply to use a photovoltaic panel as a source of alternative energy, which usually do not provide energy continuously. Switching is made automatically in case of low incidence of sunlight, and without any form of energy storage. Between each switching, there is a dead time without power supply, therefore preventing the use of synchronizers circuits between the photovoltaic panel and the public power grid. A circuit containing a 80C31 microcontroller is used to control the system’s switching. The photovoltaic panel’s voltage inverter is in H bridge configuration, and is also controlled by the microcontroller through Pulse Width Modulation, which makes use of preprogrammed tables to generate the control signals of the power transistors. Through the use of software simulations, the proposed system was tested, which is capable of supplying intermittent single-phase loads. The simulations indicates that the project developed in this paper can be assembled into a prototype and be tested under real operating conditions, as long as the scaling of components, the characteristics of the photovoltaic panel to be used, and the project involved load are taken into account

Análise do processo de fresamento de MDF em centro de usinagem CNC

Pós-graduação em Engenharia Mecânica - FEG

Correlação das características ultrassonográficas com perfil imunoistoquímico dos tumores mamários malignos

Pós-graduação em Ginecologia, Obstetrícia e Mastologia - FMB

Painéis de Medium Density Fiberboard fabricados com bagaço de cana-de-açúcar e madeira de reflorestamento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Considerações e avaliações das solicitações em estruturas de edificações de paredes de concreto pré-moldado utilizando o modelo de pórtico tridimensional: estudo de caso

The present study is in reference to precast concrete (panels) walls as the main structural system. The diversification of the structural systems is a reality due to specific characteristics', as a result there is a lack of study and analysis. Some systems are already established in their applications, for instance: conventional reinforced concrete, structural masonry, metal structures, and wood structure. Apart from this precast concrete elements has had a growth in building sites in Brazil, therefore professionals should be more aware. Affordable house funding initiatives to address the housing shortage has been recurrent throughout the country, additionally precast concrete walls has been an alternative that meets the three basic concepts of engineering, which are: the technique, economy, and security. The objective of this study is to gather concepts from the literature and TOMO (2012) about precast concrete walls and make a didactic synthesis of how they are viewed. The modeling structure method of the system was performed following the concept of assigning bars, using the computer program of calculations SAP2000. Initially will be presented a theoretical part, furthermore a case study to illustrate the sizing of the walls using EXCEL tables programmed with calculation routine. The results will be presented in calculated efforts by the program for further analysis. Finally, will be highlighted important items of modeling and interpretation of the results

Production of particleboards with bamboo (Dendrocalamus giganteus) reinforcement

The focus of this research was to study the utilization of residues from bamboo (Dendrocalamus giganteus) lamination in the manufacturing of panels for structural purposes. Bamboo particleboards were produced under three conditions: pure boards, reinforced with bamboo laminas, and with treated particles. Castor oil-based polyurethane was the resin binder, in view of using lower toxicity materials. The mechanical tests were performed according to Brazilian Standard (NBR) 14810-3 (2006) and European Standard (EN) 310 (2000). The results were superior to those recommended by these and other standards for internal adhesion resistance, modulus of rupture, and elasticity in static bending, as well as to the results of other studies. Starch treatment was an unnecessary stage. According to the conditions of this process, the studied panels showed a good potential for construction use. Moreover, the bamboo particleboards are an economically viable, environmentally friendly, and sustainable alternative for the use of waste generated during the processing of Dendrocalamus giganteus bamboo species, allied with castor oil-based polyurethane resin. The reinforced particleboard and its production process are being licensed as an Innovation Patent in Brazil, (BR 1020130133919-1-2013).

Medium density particleboard reinforced with bamboo laminas

The objective of this work was to evaluate the effect of the addition of bamboo laminas of the species Dendrocalamus giganteus to three-layer medium density particleboard (MDP). These laminas were glued onto both the top and the bottom of each panel. With the manufactured panels laminated with bamboo, mechanical tests based on the Brazilian Standard ABNT NBR 14810 were carried out to determine the modulus of rupture (MOR) in static bending and the tensile strength parallel-to-surface. These mechanical tests were realized in particleboards of eucalyptus and in reinforced particleboard, both produced in the laboratory. The modulus of rupture and tensile strength parallel-to-surface of the laminated MDP had values close to those that have been reported. The reinforcements increased the values of these studied properties. Nevertheless, this fact indicated the possibility to produce a stronger MDP using bamboo lamina as surface layers. These results show the possibility of using coatedbamboo MDP for utilization in large spans, for example, in flooring for mezzanines with finish on both sides, and for robust furniture as bookshelves, beds, tables, etc.

Produção de chapas de partículas com resíduos de madeira Cordia goeldiana

The aim of this research consisted in the use of wastes from tropical wood (Cordia goeldiana) with low density and the polyurethane resin (mono and bicomponent) castor oil based in the manufacture of particleboards, generating subsidies as application in rural and civil construction, as well in the furniture industry. The particleboards were manufactured with 15% of polyurethane resin content (one part of pre-polymer and one part of polyol), compaction pressure of 4MPa, pressing temperature of 90 degrees C and press time of 7 minutes. The physical and mechanical properties investigated were density, moisture content, strength modulus in bending and internal bond, both obtained according to the recommendations of the Brazilian standard ABNT NBR 14810:2002. The mean values obtained for these properties were systematically superior to the Brazilian standard requirement. This point showed that it is possible the use of Cordia goeldiana wastes in the particleboard production. We confirmed the hypothesis of a significant linear relation between density and the internal bond of the panels, allowing the estimation of the internal bond of particleboards.