UMIDADE DE EQUILÍBRIO DE PAINÉIS OSB EM FUNÇÃO DA UMIDADE RELATIVA E DA TEMPERATURA AMBIENTE

http://dx.doi.org/10.5902/1980509820661The study aimed to obtain statistical models to estimate the equilibrium moisture content of OSB panels as a function of temperature and relative humidity of air, as well as evaluate the effect of some production variables on the equilibrium moisture content of the panels. The experimental design consisted of six processing conditions, three air temperature and six relative humidity of air. In the processing conditions, were evaluated three different thicknesses of the strand particles (0.4, 0.7 and 1.0 mm), two apparent densities of panels (0.65 and 0.90 g/cm³) and three levels of pressure in the pressing of the panels (40, 60 and 80 kgf/cm²). For each treatment four panels were produced with the wood of Pinus taeda and 6% of phenol formaldehyde adhesive. In the evaluation of the experiment was considered a completely randomized design arranged in a factorial triple 6 x 6 x 3, in order words, six production variables (processing conditions), three air temperatures (30, 40 and 50°C) and 6 relative humidity (40, 50, 60, 70, 80, 90%). The means were compared statistically by Scott-Knott test at the 5% level of significance. The modeling the equilibrium moisture content of OSB panels was performed with fit the multiple polynomial models for each treatment. Based on measurements of accuracy and the results can be concluded that: 1) it is recommended to use the model UEQ = β0 + β1UR + β2UR² + β3UR³ + β4Temp + ε for indirect estimation of equilibrium moisture content of OSB panels 2) The temperature shows linear influence on the equilibrium moisture content of the panels, while the relative humidity of air shows behaving of third order polynomial, and the relative humidity of air affects more pronouncedly the equilibrium moisture content of OSB panels than the ambient temperature; 3) In respect of the effect of production variables, the pressing of pressure of 80 kgf/cm² and the increased the thickness of the strand particles to 1.0mm thick promoted trend of reductions in average of the equilibrium moisture content of OSB panels. But the increased density of the panel promoted the trend of increasing of equilibrium moisture content of OSB panels; and 4) The use of multiple polynomial models allows that are produced contours to obtain the values of equilibrium moisture content of OSB as a function of relative humidity and temperature of the place where the panel is exposed, standing out for its convenience of use. http://dx.doi.org/10.5902/1980509820661O trabalho teve como objetivo obter modelos estatísticos para a estimativa da umidade de equilíbrio de painéis OSB em função da temperatura e da umidade relativa do ar, assim como também avaliar o efeito de algumas variáveis de produção sobre a umidade de equilíbrio dos painéis. O delineamento experimental se constituiu de seis condições de processamento, três temperaturas do ar e seis umidades relativas do ar. Nas condições de processamento, foram avaliadas três diferentes espessuras das partículas strand (0,4; 0,7 e 1,0 mm), duas densidades aparentes do painel (0,65 e 0,90 g/cm³) e também três níveis de pressão na prensagem dos painéis (40, 60 e 80 kgf/cm²). Para cada tratamento foram produzidos quatro painéis com a madeira de Pinus taeda e 6% de adesivo fenol-formaldeído. Na avaliação do experimento foi considerado um delineamento inteiramente casualizado disposto em esquema fatorial triplo 6 x 3 x 6, ou seja, 6 variáveis de produção (condições de processamento), 3 temperaturas do ar (30, 40 e 50°C) e 6 umidades relativas (40, 50, 60, 70, 80, 90%). As médias foram comparadas estatisticamente pelo Teste Scott-Knott em nível de 5% de significância. A modelagem da umidade de equilíbrio dos painéis OSB foi realizada mediante o ajuste de modelos polinomiais múltiplos para cada tratamento. Com base nas medidas de precisão e nos resultados obtidos pode-se concluir que: 1) recomenda-se a utilização do modelo  UEQ = β0 + β1UR + β2UR² + β3UR³ + β4Temp + ε  para a estimativa indireta da umidade de equilíbrio dos painéis OSB; 2) A temperatura apresenta influência linear na umidade de equilíbrio dos painéis, enquanto que a umidade relativa do ar apresenta comportamento polinomial de terceira ordem, sendo que a umidade relativa do ar influência de forma mais pronunciada a umidade de equilíbrio dos painéis OSB do que a temperatura ambiente; 3) Quanto ao efeito das variáveis de produção, a pressão de prensagem de 80 kgf/ cm² e o aumento da espessura das partículas strand para 1,0 mm de espessura promoveu tendência de reduções nos valores médios de umidade de equilíbrio dos painéis OSB. Já o aumento da densidade do painel promoveu uma tendência de aumento da umidade de equilíbrio dos painéis OSB; e 4) O uso de modelos polinomiais múltiplos permite que sejam produzidas curvas de nível para a obtenção dos valores de umidade de equilíbrio dos painéis OSB em função da umidade relativa e da temperatura do local onde o painel esta exposto, se destacando pela sua praticidade de utilização

EQUILIBRIUM MOISTURE CONTENT OF OSB PANELS AS A FUNCTION OF RELATIVE HUMIDITY AND AMBIENT TEMPERATURE

O trabalho teve como objetivo obter modelos estat\uedsticos para a estimativa da umidade de equil\uedbrio de pain\ue9is OSB em fun\ue7\ue3o da temperatura e da umidade relativa do ar, assim como tamb\ue9m avaliar o efeito de algumas vari\ue1veis de produ\ue7\ue3o sobre a umidade de equil\uedbrio dos pain\ue9is. O delineamento experimental se constituiu de seis condi\ue7\uf5es de processamento, tr\ueas temperaturas do ar e seis umidades relativas do ar. Nas condi\ue7\uf5es de processamento, foram avaliadas tr\ueas diferentes espessuras das part\uedculas strand (0,4; 0,7 e 1,0 mm), duas densidades aparentes do painel (0,65 e 0,90 g/cm\ub3) e tamb\ue9m tr\ueas n\uedveis de press\ue3o na prensagem dos pain\ue9is (40, 60 e 80 kgf/cm\ub2). Para cada tratamento foram produzidos quatro pain\ue9is com a madeira de Pinus taeda e 6% de adesivo fenol-formalde\ueddo. Na avalia\ue7\ue3o do experimento foi considerado um delineamento inteiramente casualizado disposto em esquema fatorial triplo 6 x 3 x 6, ou seja, 6 vari\ue1veis de produ\ue7\ue3o (condi\ue7\uf5es de processamento), 3 temperaturas do ar (30, 40 e 50\ub0C) e 6 umidades relativas (40, 50, 60, 70, 80, 90%). As m\ue9dias foram comparadas estatisticamente pelo Teste Scott-Knott em n\uedvel de 5% de signific\ue2ncia. A modelagem da umidade de equil\uedbrio dos pain\ue9is OSB foi realizada mediante o ajuste de modelos polinomiais m\ufaltiplos para cada tratamento. Com base nas medidas de precis\ue3o e nos resultados obtidos pode-se concluir que: 1) recomenda-se a utiliza\ue7\ue3o do modelo UEQ = \u3b20 + \u3b21UR + \u3b22UR\ub2 + \u3b23UR\ub3 + \u3b24Temp + \u3b5 para a estimativa indireta da umidade de equil\uedbrio dos pain\ue9is OSB; 2) A temperatura apresenta influ\ueancia linear na umidade de equil\uedbrio dos pain\ue9is, enquanto que a umidade relativa do ar apresenta comportamento polinomial de terceira ordem, sendo que a umidade relativa do ar influencia de forma mais pronunciada a umidade de equil\uedbrio dos pain\ue9is OSB do que a temperatura ambiente; 3) Quanto ao efeito das vari\ue1veis de produ\ue7\ue3o, a press\ue3o de prensagem de 80 kgf/ cm\ub2 e o aumento da espessura das part\uedculas strand para 1,0 mm de espessura promoveu tend\ueancia de redu\ue7\uf5es nos valores m\ue9dios de umidade de equil\uedbrio dos pain\ue9is OSB. J\ue1 o aumento da densidade do painel promoveu uma tend\ueancia de aumento da umidade de equil\uedbrio dos pain\ue9is OSB; e 4) O uso de modelos polinomiais m\ufaltiplos permite que sejam produzidas curvas de n\uedvel para a obten\ue7\ue3o dos valores de umidade de equil\uedbrio dos pain\ue9is OSB em fun\ue7\ue3o da umidade relativa e da temperatura do local onde o painel esta exposto, se destacando pela sua praticidade de utiliza\ue7\ue3o.The study aimed to obtain statistical models to estimate the equilibrium moisture content of OSB panels as a function of temperature and relative humidity of air, as well as evaluate the effect of some production variables on the equilibrium moisture content of the panels. The experimental design consisted of six processing conditions, three air temperature and six relative humidity of air. In the processing conditions, were evaluated three different thicknesses of the strand particles (0.4, 0.7 and 1.0 mm), two apparent densities of panels (0.65 and 0.90 g/cm\ub3) and three levels of pressure in the pressing of the panels (40, 60 and 80 kgf/cm\ub2). For each treatment four panels were produced with the wood of Pinus taeda and 6% of phenol formaldehyde adhesive. In the evaluation of the experiment was considered a completely randomized design arranged in a factorial triple 6 x 6 x 3, in order words, six production variables (processing conditions), three air temperatures (30, 40 and 50\ub0C) and 6 relative humidity (40, 50, 60, 70, 80, 90%). The means were compared statistically by Scott-Knott test at the 5% level of significance. The modeling the equilibrium moisture content of OSB panels was performed with fit the multiple polynomial models for each treatment. Based on measurements of accuracy and the results can be concluded that: 1) it is recommended to use the model UEQ = \u3b20 + \u3b21UR + \u3b22UR\ub2 + \u3b23UR\ub3 + \u3b24Temp + \u3b5 for indirect estimation of equilibrium moisture content of OSB panels 2) The temperature shows linear influence on the equilibrium moisture content of the panels, while the relative humidity of air shows behaving of third order polynomial, and the relative humidity of air affects more pronouncedly the equilibrium moisture content of OSB panels than the ambient temperature; 3) In respect of the effect of production variables, the pressing of pressure of 80 kgf/cm\ub2 and the increased the thickness of the strand particles to 1.0mm thick promoted trend of reductions in average of the equilibrium moisture content of OSB panels. But the increased density of the panel promoted the trend of increasing of equilibrium moisture content of OSB panels; and 4) The use of multiple polynomial models allows that are produced contours to obtain the values of equilibrium moisture content of OSB as a function of relative humidity and temperature of the place where the panel is exposed, standing out for its convenience of use

Sensitivity of South American tropical forests to an extreme climate anomaly

NERC Knowledge Exchange Fellowship (NE/V018760/1) to E.N.H.C.The tropical forest carbon sink is known to be drought sensitive, but it is unclear which forests are the most vulnerable to extreme events. Forests with hotter and drier baseline conditions may be protected by prior adaptation, or more vulnerable because they operate closer to physiological limits. Here we report that forests in drier South American climates experienced the greatest impacts of the 2015–2016 El Niño, indicating greater vulnerability to extreme temperatures and drought. The long-term, ground-measured tree-by-tree responses of 123 forest plots across tropical South America show that the biomass carbon sink ceased during the event with carbon balance becoming indistinguishable from zero (−0.02 ± 0.37 Mg C ha−1 per year). However, intact tropical South American forests overall were no more sensitive to the extreme 2015–2016 El Niño than to previous less intense events, remaining a key defence against climate change as long as they are protected.Publisher PDFPeer reviewe

Sensitivity of South American tropical forests to an extreme climate anomaly

Abstract: The tropical forest carbon sink is known to be drought sensitive, but it is unclear which forests are the most vulnerable to extreme events. Forests with hotter and drier baseline conditions may be protected by prior adaptation, or more vulnerable because they operate closer to physiological limits. Here we report that forests in drier South American climates experienced the greatest impacts of the 2015–2016 El Niño, indicating greater vulnerability to extreme temperatures and drought. The long-term, ground-measured tree-by-tree responses of 123 forest plots across tropical South America show that the biomass carbon sink ceased during the event with carbon balance becoming indistinguishable from zero (−0.02 ± 0.37 Mg C ha−1 per year). However, intact tropical South American forests overall were no more sensitive to the extreme 2015–2016 El Niño than to previous less intense events, remaining a key defence against climate change as long as they are protected

Sensitivity of South American tropical forests to an extreme climate anomaly

Funder: A Moore Foundation grant, Royal Society Global Challenges grant (Sensitivity of Tropical Forest Ecosystem Services to Climate Changes), CNPq grants (441282/2016-4, 403764/2012-2 and 558244/2009-2), FAPEAM grants 1600/2006, 465/2010 and PPFOR 147/2015, CNPq grants 473308/2009-6 and 558320/2009-0. European Research Council (ERC Advanced Grant 291585 - 'T-FORCES'), the Gordon and Betty Moore Foundation (#1656 'RAINFOR', and 'MonANPeru'), the European Union's Fifth, Sixth and Seventh Framework Programme (EVK2-CT-1999-00023 - 'CARBONSINK-LBA', 283080 - 'GEOCARBON', 282664 - 'AMAZALERT), the Natural Environment Research Council (NE/ D005590/1 - 'TROBIT', NE/F005806/1 - 'AMAZONICA', E/M0022021/1 - 'PPFOR'), several NERC Urgency and New Investigators Grants, the NERC/State of Sao Paulo Research Foundation (FAPESP) consortium grants 'BIO-RED' (NE/N012542/1), 'ECOFOR' (NE/K016431/1, 2012/51872-5, 2012/51509-8), 'ARBOLES' (NE/S011811/1, FAPESP 2018/15001-6), 'SEOSAW' (NE/P008755/1), 'SECO' (NE/T01279X/1), Brazilian National Research Council (PELD/CNPq 403710/2012-0), the Royal Society (University Research Fellowships and Global challenges Awards) (ICA/R1/180100 - 'FORAMA'), the National Geographic Society, US National Science Foundation (DEB 1754647) and Colombia's Colciencias. We thank the National Council for Science and Technology Development of Brazil (CNPq) for support to the Cerrado/Amazonia Transition Long-Term Ecology Project (PELD/441244/2016-5), the PPBio Phytogeography of Amazonia/Cerrado Transition Project (CNPq/PPBio/457602/2012-0), PELD-RAS (CNPq, Process 441659/2016-0), RESFLORA (Process 420254/2018-8), Synergize (Process 442354/2019-3), the Empresa Brasileira de Pesquisa Agropecuaria - Embrapa (SEG: 02.08.06.005.00), the Fundacao de Amparo a Pesquisa do Estado de Sao Paulo - FAPESP (2012/51509-8 and 2012/51872-5), the Goias Research Foundation (FAPEG/PELD: 2017/10267000329) the EcoSpace Project (CNPq 459941/2014-3) and several PVE and Productivity Grants. We also thank the "Investissement d'Avenir" program (CEBA, ref. ANR-10LABX-25-01), the Sao Paulo Research Foundation (FAPESP 03/12595-7) and the Sustainable Landscapes Brazil Project (through Brazilian Agricultural Research Corporation (EMBRAPA), the US Forest Service, USAID, and the US Department of State) for supporting plot inventories in the Atlantic Forest sites in Sao Paulo, Brazil. L.E.O.C.A. was supported by CNPq (processes 305054/2016-3 and 442371/2019-5). We thank to the National Council for Technological and Scientific Development (CNPq) for the financial support of the PELD project (441244/2016-5, 441572/2020-0) and FAPEMAT (0346321/2021). NE/B503384/1, NE/N012542/1 - 'BIO-RED', ERC Advanced Grant 291585 - 'T-FORCES', NE/F005806/1 - 'AMAZONICA', NE/N004655/1 - 'TREMOR', NERC New Investigators Awards, the Gordon and Betty Moore Foundation ('RAINFOR', 'MonANPeru'), ERC Starter Grant 758873 -'TreeMort', EU Framework 6, a Royal Society University Research Fellowship, and a Leverhulme Trust Research Fellowship.AbstractThe tropical forest carbon sink is known to be drought sensitive, but it is unclear which forests are the most vulnerable to extreme events. Forests with hotter and drier baseline conditions may be protected by prior adaptation, or more vulnerable because they operate closer to physiological limits. Here we report that forests in drier South American climates experienced the greatest impacts of the 2015–2016 El Niño, indicating greater vulnerability to extreme temperatures and drought. The long-term, ground-measured tree-by-tree responses of 123 forest plots across tropical South America show that the biomass carbon sink ceased during the event with carbon balance becoming indistinguishable from zero (−0.02 ± 0.37 Mg C ha−1 per year). However, intact tropical South American forests overall were no more sensitive to the extreme 2015–2016 El Niño than to previous less intense events, remaining a key defence against climate change as long as they are protected.</jats:p