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João Andrade de Carvalho

Bio: João Andrade de Carvalho is an academic researcher from Sao Paulo State University. The author has contributed to research in topics: Combustion & Diesel fuel. The author has an hindex of 32, co-authored 116 publications receiving 3573 citations. Previous affiliations of João Andrade de Carvalho include National Institute for Space Research.


Papers
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Journal ArticleDOI
TL;DR: In this paper, an attempt has been made to review the different approaches and techniques used to produce glycerol (hydrolysis, transesterification, refining crude glycerols).
Abstract: The demand for petroleum has been rising rapidly due to increasing industrialization and modernization. This economic development has led to a huge demand for energy, most of which is derived from fossil fuel. However, the limited reserve of fossil fuel has led many researchers to look for alternative fuels which can be produced from renewable feedstock. Increasing fossil fuel prices have prompted the global oil industry to look at biodiesel, which is from renewable energy sources. Biodiesel is produced from animal fats and vegetable oils and has become more attractive because it is more environmentally friendly and is obtained from renewable sources. Glycerol is the main by-product of biodiesel production; about 10% of the weight of biodiesel is generated in glycerol. The large amount of glycerol generated may become an environmental problem, since it cannot be disposed of in the environment. In this paper, an attempt has been made to review the different approaches and techniques used to produce glycerol (hydrolysis, transesterification, refining crude glycerol). The world biodiesel/glycerol production and consumption market, the current world glycerin and glycerol prices as well as the news trends for the use of glycerol mainly in Brazil market are analyzed. The technological production and physicochemical properties of glycerol are described, as is the characterization of crude glycerol obtained from different seed oil feedstock. Finally, a simple way to use glycerol in large amounts is combustion, which is an advantageous method as it does not require any purification. However, the combustion process of crude glycerol is not easy and there are technological difficulties. The news and mainly research about the combustion of glycerol was also addressed in this review.

770 citations

Journal ArticleDOI
TL;DR: In this article, the authors describe and evaluate a parameterization to include the vertical transport of hot gases and particles emitted from biomass burning in low-resolution atmospheric-chemistry transport models, which is simulated by embedding a 1D cloud-resolving model with appropriate lower boundary conditions in each column of the 3D host model.
Abstract: We describe and begin to evaluate a parameterization to include the vertical transport of hot gases and particles emitted from biomass burning in low resolution atmospheric-chemistry transport models. This sub-grid transport mechanism is simulated by embedding a 1-D cloud-resolving model with appropriate lower boundary conditions in each column of the 3-D host model. Through assimilation of remote sensing fire products, we recognize which columns have fires. Using a land use dataset appropriate fire properties are selected. The host model provides the environmental conditions, allowing the plume rise to be simulated explicitly. The derived height of the plume is then used in the source emission field of the host model to determine the effective injection height, releasing the material emitted during the flaming phase at this height. Model results are compared with CO aircraft profiles from an Amazon basin field campaign and with satellite data, showing the huge impact that this mechanism has on model performance. We also show the relative role of each main vertical transport mechanisms, shallow and deep moist convection and the pyro-convection (dry or moist) induced by vegetation fires, on the distribution of biomass burning CO emissions in the troposphere.

285 citations

Journal ArticleDOI
TL;DR: The effects of the acid concentration, temperature and residue/acid solution ratio on the hemicellulose removal and consequently on the production of sugars, as well as on the formation of by-products (furfural, 5-hydroxymethylfurfural and acetic acid) are investigated.

148 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present an overview of instruments available on the market for measurement of particulate matter, and compare the main instruments and methods of measuring concentration (gravimetric, optical, and microbalance) and size distribution.
Abstract: This review article presents an overview of instruments available on the market for measurement of particulate matter. The main instruments and methods of measuring concentration (gravimetric, optical, and microbalance) and size distribution Scanning Mobility Particle Sizer (SMPS), Electrical Low Pressure Impactor (ELPI), and others were described and compared. The aim of this work was to help researchers choose the most suitable equipment to measure particulate matter. When choosing a measuring instrument, a researcher must clearly define the purpose of the study and determine whether it meets the main specifications of the equipment. ELPI and SMPS are the suitable devices for measuring fine particles; the ELPI works in real time. In health-related studies, a Diffusion Charger is the instrument that best characterizes the surface of ultrafine particles. Several methods and different particle measuring instruments should be used to confirm the values obtained during sampling.

144 citations

Journal ArticleDOI
TL;DR: The workshop that led to this paper was sponsored by the EU FP7 COCOS project as discussed by the authors, and the authors acknowledge funding from the European FP7 MACC-II project (contract number 218793) and the EUFP7 GeoCarbon project (Contract number 283080).
Abstract: The workshop that led to this paper was sponsored by the EU FP7 COCOS project. Thijs van Leeuwen, Guido van der Werf, and Rob Detmers acknowledge funding from the EU FP7 MACC-II project (contract number 218793) and the EU FP7 GeoCarbon project (contract number 283080).

143 citations


Cited by
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Christopher M. Bishop1
01 Jan 2006
TL;DR: Probability distributions of linear models for regression and classification are given in this article, along with a discussion of combining models and combining models in the context of machine learning and classification.
Abstract: Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

10,141 citations

Journal ArticleDOI
TL;DR: A critical reassessment of the quality and the robustness of these models across tropical forest types, using a large dataset of 2,410 trees ≥ 5 cm diameter, directly harvested in 27 study sites across the tropics, is provided.
Abstract: Tropical forests hold large stores of carbon, yet uncertainty remains regarding their quantitative contri- bution to the global carbon cycle. One approach to quantifying carbon biomass stores consists in inferring changes from long-term forest inventory plots. Regres- sion models are used to convert inventory data into an estimate of aboveground biomass (AGB). We provide a critical reassessment of the quality and the robustness of these models across tropical forest types, using a large dataset of 2,410 trees ‡ 5 cm diameter, directly harvested in 27 study sites across the tropics. Proportional rela- tionships between aboveground biomass and the prod- uct of wood density, trunk cross-sectional area, and total height are constructed. We also develop a regres- sion model involving wood density and stem diameter only. Our models were tested for secondary and old- growth forests, for dry, moist and wet forests, for low- land and montane forests, and for mangrove forests. The most important predictors of AGB of a tree were, in decreasing order of importance, its trunk diameter, wood specific gravity, total height, and forest type (dry, moist, or wet). Overestimates prevailed, giving a bias of 0.5-6.5% when errors were averaged across all stands. Our regression models can be used reliably to predict aboveground tree biomass across a broad range of tropical forests. Because they are based on an unprece- dented dataset, these models should improve the quality

2,786 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated fire emissions during the 8 year period from 1997 to 2004 using satellite data and the CASA biogeochemical model, and found that on average approximately 58 Pg C year −1 was fixed by plants as NPP, and approximately 95% of this was returned back to the atmosphere via R h.
Abstract: Biomass burning represents an important source of atmospheric aerosols and greenhouse gases, yet little is known about its interannual variability or the underlying mechanisms regulating this variability at continental to global scales. Here we investigated fire emissions during the 8 year period from 1997 to 2004 using satellite data and the CASA biogeochemical model. Burned area from 2001–2004 was derived using newly available active fire and 500 m. burned area datasets from MODIS following the approach described by Giglio et al. (2006). ATSR and VIRS satellite data were used to extend the burned area time series back in time through 1997. In our analysis we estimated fuel loads, including organic soil layer and peatland fuels, and the net flux from terrestrial ecosystems as the balance between net primary production (NPP), heterotrophic respiration ( R h ), and biomass burning, using time varying inputs of precipitation (PPT), temperature, solar radiation, and satellite-derived fractional absorbed photosynthetically active radiation (fAPAR). For the 1997–2004 period, we found that on average approximately 58 Pg C year −1 was fixed by plants as NPP, and approximately 95% of this was returned back to the atmosphere via R h . Another 4%, or 2.5 Pg C year −1 was emitted by biomass burning; the remainder consisted of losses from fuel wood collection and subsequent burning. At a global scale, burned area and total fire emissions were largely decoupled from year to year. Total carbon emissions tracked burning in forested areas (including deforestation fires in the tropics), whereas burned area was largely controlled by savanna fires that responded to different environmental and human factors. Biomass burning emissions showed large interannual variability with a range of more than 1 Pg C year −1 , with a maximum in 1998 (3.2 Pg C year −1 ) and a minimum in 2000 (2.0 Pg C year −1 ).

1,639 citations

Journal ArticleDOI
TL;DR: This paper presented an up-to-date, comprehensive tabulation of EF for known pyrogenic species based on measurements made in smoke that has cooled to ambient temperature, but not yet undergone significant photochemical processing.
Abstract: . Biomass burning (BB) is the second largest source of trace gases and the largest source of primary fine carbonaceous particles in the global troposphere. Many recent BB studies have provided new emission factor (EF) measurements. This is especially true for non-methane organic compounds (NMOC), which influence secondary organic aerosol (SOA) and ozone formation. New EF should improve regional to global BB emissions estimates and therefore, the input for atmospheric models. In this work we present an up-to-date, comprehensive tabulation of EF for known pyrogenic species based on measurements made in smoke that has cooled to ambient temperature, but not yet undergone significant photochemical processing. All EFs are converted to one standard form (g compound emitted per kg dry biomass burned) using the carbon mass balance method and they are categorized into 14 fuel or vegetation types. Biomass burning terminology is defined to promote consistency. We compile a large number of measurements of biomass consumption per unit area for important fire types and summarize several recent estimates of global biomass consumption by the major types of biomass burning. Post emission processes are discussed to provide a context for the emission factor concept within overall atmospheric chemistry and also highlight the potential for rapid changes relative to the scale of some models or remote sensing products. Recent work shows that individual biomass fires emit significantly more gas-phase NMOC than previously thought and that including additional NMOC can improve photochemical model performance. A detailed global estimate suggests that BB emits at least 400 Tg yr−1 of gas-phase NMOC, which is almost 3 times larger than most previous estimates. Selected recent results (e.g. measurements of HONO and the BB tracers HCN and CH3CN) are highlighted and key areas requiring future research are briefly discussed.

1,472 citations

Journal ArticleDOI
TL;DR: The Global Fire Emissions Database (GFED) as mentioned in this paper has been used to quantify global fire emissions patterns during 1997-2016, with the largest impact on emissions in temperate North America, Central America, Europe, and temperate Asia.
Abstract: . Climate, land use, and other anthropogenic and natural drivers have the potential to influence fire dynamics in many regions. To develop a mechanistic understanding of the changing role of these drivers and their impact on atmospheric composition, long-term fire records are needed that fuse information from different satellite and in situ data streams. Here we describe the fourth version of the Global Fire Emissions Database (GFED) and quantify global fire emissions patterns during 1997–2016. The modeling system, based on the Carnegie–Ames–Stanford Approach (CASA) biogeochemical model, has several modifications from the previous version and uses higher quality input datasets. Significant upgrades include (1) new burned area estimates with contributions from small fires, (2) a revised fuel consumption parameterization optimized using field observations, (3) modifications that improve the representation of fuel consumption in frequently burning landscapes, and (4) fire severity estimates that better represent continental differences in burning processes across boreal regions of North America and Eurasia. The new version has a higher spatial resolution (0.25°) and uses a different set of emission factors that separately resolves trace gas and aerosol emissions from temperate and boreal forest ecosystems. Global mean carbon emissions using the burned area dataset with small fires (GFED4s) were 2.2 × 1015 grams of carbon per year (Pg C yr−1) during 1997–2016, with a maximum in 1997 (3.0 Pg C yr−1) and minimum in 2013 (1.8 Pg C yr−1). These estimates were 11 % higher than our previous estimates (GFED3) during 1997–2011, when the two datasets overlapped. This net increase was the result of a substantial increase in burned area (37 %), mostly due to the inclusion of small fires, and a modest decrease in mean fuel consumption (−19 %) to better match estimates from field studies, primarily in savannas and grasslands. For trace gas and aerosol emissions, differences between GFED4s and GFED3 were often larger due to the use of revised emission factors. If small fire burned area was excluded (GFED4 without the s for small fires), average emissions were 1.5 Pg C yr−1. The addition of small fires had the largest impact on emissions in temperate North America, Central America, Europe, and temperate Asia. This small fire layer carries substantial uncertainties; improving these estimates will require use of new burned area products derived from high-resolution satellite imagery. Our revised dataset provides an internally consistent set of burned area and emissions that may contribute to a better understanding of multi-decadal changes in fire dynamics and their impact on the Earth system. GFED data are available from http://www.globalfiredata.org .

1,135 citations