The use of renewable sources for obtainment of chemicals, biofuels, materials and energy has become each time larger due to environmental, political and economical problems of non-renewable energies utilization. Among...The use of renewable sources for obtainment of chemicals, biofuels, materials and energy has become each time larger due to environmental, political and economical problems of non-renewable energies utilization. Among several products that can be obtained from lignocellulosic biomass, which is a renewable source, there is furfural, a chemical from which many other value added chemical products can be obtained. The main route for furfural production consists of an acid hydrolysis of hemicelluloses present in lignocellulosic biomass to obtain xylose, which goes through a dehydration reaction to produce furfural. Due to the presence of an aldehyde group and a conjugated system of double bounds, furfural can go through several reactions, allowing the production of a range of value added products. In this sense, this article performs a review about mechanisms of furfural production from lignocellulosic biomass, highlighting its chemical properties which enable its utilization in different industrial applications of economic interest.展开更多
Brazil is the world largest producer of sugarcane (Saccharum officinarum) leading to a great generation of residues such as bagasse and straw, which represent two thirds of sugarcane energetic potential. Regarding the...Brazil is the world largest producer of sugarcane (Saccharum officinarum) leading to a great generation of residues such as bagasse and straw, which represent two thirds of sugarcane energetic potential. Regarding these residues energetic potential, it is interesting to study their application in biorefinery processes. Thus, this work aimed at performing a chemical characterization of sugarcane straw and bagasse from RB867515 cultivar grown in Rio Grande do Sul-Brazil aiming at their use as feedstock in biorefinery processes. The obtained results were compared to data from other states and it was possible to conclude that edaphoclimatic conditions of Rio Grande do Sul have little influence in sugarcane residues chemical composition. Sugarcane bagasse presents larger potential for energetic use because of its volatiles content (74.82%) slightly higher than straw (68.90%), besides its high lignin content (21.85%) and higher calorific value (18.70 MJ/kg). Both sugarcane residues produced in Rio Grande do Sul have potential use as substrate in the obtainment of high value-added products from their cellulosic fractions (41.30% and 37.25%, respectively). The evaluation of energetic and chemical potential of sugarcane bagasse and straw produced in Rio Grande do Sul leads to the conclusion that these materials have high potential for use as feedstock in biorefineries.展开更多
Simulation studies of three synchronous reluctance motor(SynRM)control strategies are presented:field-oriented control(FOC),direct torque control(DTC),and finite-set model-predictive control(FS-MPC).FOC uses linear co...Simulation studies of three synchronous reluctance motor(SynRM)control strategies are presented:field-oriented control(FOC),direct torque control(DTC),and finite-set model-predictive control(FS-MPC).FOC uses linear controllers and pulse-width modulation to control the fundamental components of the load voltages vectors.In contrast,DTC and FS-MPC are nonlinear strategies wherein the voltage vectors are directly generated in the absence of a modulator.Theoretical operating principles and control structures of these control strategies are presented.Moreover,a comparative analysis of the static and dynamic performance of the control strategies is conducted using Matlab/Simulink to identify their advantages and limitations.It is confirmed that each of the control strategies has merits and that all three of them satisfy the requirements of modern high-performance drives.展开更多
文摘The use of renewable sources for obtainment of chemicals, biofuels, materials and energy has become each time larger due to environmental, political and economical problems of non-renewable energies utilization. Among several products that can be obtained from lignocellulosic biomass, which is a renewable source, there is furfural, a chemical from which many other value added chemical products can be obtained. The main route for furfural production consists of an acid hydrolysis of hemicelluloses present in lignocellulosic biomass to obtain xylose, which goes through a dehydration reaction to produce furfural. Due to the presence of an aldehyde group and a conjugated system of double bounds, furfural can go through several reactions, allowing the production of a range of value added products. In this sense, this article performs a review about mechanisms of furfural production from lignocellulosic biomass, highlighting its chemical properties which enable its utilization in different industrial applications of economic interest.
文摘Brazil is the world largest producer of sugarcane (Saccharum officinarum) leading to a great generation of residues such as bagasse and straw, which represent two thirds of sugarcane energetic potential. Regarding these residues energetic potential, it is interesting to study their application in biorefinery processes. Thus, this work aimed at performing a chemical characterization of sugarcane straw and bagasse from RB867515 cultivar grown in Rio Grande do Sul-Brazil aiming at their use as feedstock in biorefinery processes. The obtained results were compared to data from other states and it was possible to conclude that edaphoclimatic conditions of Rio Grande do Sul have little influence in sugarcane residues chemical composition. Sugarcane bagasse presents larger potential for energetic use because of its volatiles content (74.82%) slightly higher than straw (68.90%), besides its high lignin content (21.85%) and higher calorific value (18.70 MJ/kg). Both sugarcane residues produced in Rio Grande do Sul have potential use as substrate in the obtainment of high value-added products from their cellulosic fractions (41.30% and 37.25%, respectively). The evaluation of energetic and chemical potential of sugarcane bagasse and straw produced in Rio Grande do Sul leads to the conclusion that these materials have high potential for use as feedstock in biorefineries.
文摘Simulation studies of three synchronous reluctance motor(SynRM)control strategies are presented:field-oriented control(FOC),direct torque control(DTC),and finite-set model-predictive control(FS-MPC).FOC uses linear controllers and pulse-width modulation to control the fundamental components of the load voltages vectors.In contrast,DTC and FS-MPC are nonlinear strategies wherein the voltage vectors are directly generated in the absence of a modulator.Theoretical operating principles and control structures of these control strategies are presented.Moreover,a comparative analysis of the static and dynamic performance of the control strategies is conducted using Matlab/Simulink to identify their advantages and limitations.It is confirmed that each of the control strategies has merits and that all three of them satisfy the requirements of modern high-performance drives.
