An environmental impact assessment of the management of cassava waste: a case study in Thailand

In Thailand, cassava waste is one of the main biomass residues and has the potential to be used as a biomass fuel. However, currently most cassava waste in Thailand is left in agricultural fields or burnt on site and is not utilised for any energy-related purposes. This research investigates the environmental impacts associated with three cassava waste management practices including (i)- ploughing the waste to the soil (ii)-burning the waste in the field (iii)- collecting and using the waste in cassava-based bioethanol plant. The environmental impact assessment and material flow analysis associated with these management practices were conducted using the Global Emissions Model for Integrated Systems (GEMIS) package [1]. The outcomes of this study reveal that the CO2 emissions associated with these waste management practices are about 0.195, 0.243 and 0.361 kg CO2-eq/kg of as received (wet) cassava waste, respectively. Compared to other cassava waste disposal methods such as ploughing and burning, cassava waste collection would result in the biggest environmental impact, emitting nearly 85% more GHGs than ploughing and 48% more than burning

An investigation of the impact of time of generation on carbon savings from PV systems in Great Britain

PV only generates electricity during daylight hours and primarily generates over summer. In the UK, the carbon intensity of grid electricity is higher during the daytime and over winter. This work investigates whether the grid electricity displaced by PV is high or low carbon compared to the annual mean carbon intensity using carbon factors at higher temporal resolutions (half-hourly and daily). UK policy for carbon reporting requires savings to be calculated using the annual mean carbon intensity of grid electricity. This work offers an insight into whether this technique is appropriate. Using half hourly data on the generating plant supplying the grid from November 2008 to May 2010, carbon factors for grid electricity at half-hourly and daily resolution have been derived using technology specific generation emission factors. Applying these factors to generation data from PV systems installed on schools, it is possible to assess the variation in the carbon savings from displacing grid electricity with PV generation using carbon factors with different time resolutions. The data has been analyzed for a period of 363 to 370 days and so cannot account for inter-year variations in the relationship between PV generation and carbon intensity of the electricity grid. This analysis suggests that PV displaces more carbon intensive electricity using half-hourly carbon factors than using daily factors but less compared with annual ones. A similar methodology could provide useful insights on other variable renewable and demand-side technologies and in other countries where PV performance and grid behavior are different

Application of Rational Second Kind Chebyshev Functions for System of Integrodifferential Equations on Semi-Infinite Intervals

Rational Chebyshev bases and Galerkin method are used to obtain the approximate solution of a system of high-order integro-differential equations on the interval [0,∞). This method is based on replacement of the unknown functions by their truncated series of rational Chebyshev expansion. Test examples are considered to show the high accuracy, simplicity, and efficiency of this method

A study on the dependence of structure of multi-walled carbon nanotubes on acid treatment

In the current research, the role of both concentrated nitric acid and ultrasound waves on oxidation of multi-walled carbon nanotubes (MWNTs) was studied. The functionalized MWCNTs were characterized by transmission electron microscopy (TEM), thermogravimetric analyzer, and Fourier transform infrared spectroscopy (FTIR) techniques. It was found that desirable modifications to MWNTs occurred after acid treatment. Carboxylic acid groups were appeared on the side surfaces of MWNTs. FTIR presented the formation of oxygen-containing groups such as C=O and COOH after modification by concentrated nitric acid. The TEM images showed that the aspect ratio of opened MWCNTs was controlled by both ultrasonic waves and acid treatment time. It was also found that the exposure of about 4 h in nitric acid led to the highest removal of the impurities with the least destructive effect

Fabrication of Iron Aluminide Coatings (Fe3Al and FeAl3) on Steel Substrate by Self-Propagating High Temperature Synthesis (SHS) Process

Iron aluminides (Fe3Al and FeAl3) coatings were fabricated on a steel substrate by self-propagating high temperature synthesis (SHS) method. Raw materials, Fe and Al powders, were mixed at two different stoichiometry ratios (3:1 and 1:3). The mixtures and the substrate were placed in a furnace at 950 °C to ignite the SHS process. Coating phases were investigated using X-ray diffraction (XRD) and Energy Dispersive Spectroscopy (EDS). The microstructure of the coatings was analyzed with optical microscopy (OM) and scanning electron microscopy (SEM). The results confirmed that it is possible to produce Fe3Al and FeAl3 coatings on steel substrate using SHS method. In addition, the results show that the coatings were composed of two different phases and their microstructures were non-porous and dense. Wear resistance of the coatings were higher than that of the substrate

Investigating the Effect of Mechanical Activation Parameters on Structural Changes and Leaching Rate of Molybdenite Concentrate

AbstractIn this research, mechanical activation (MA) was employed for leaching rate improvement of molybdenite concentrate in nitric acid media. These experiments were performed in two groups: with and without aluminum oxide (alumina). A full factorial design was used for each group of experiments. Leaching rate increment up to 5 times was observed only in 2hours activation procedure. XRD analysis demonstrated structural disordering in activated MoS2. TEM images showed that particle size has been reduced to nanoscale. The initial powder size was 80% between 2-44μm and dropped to about 10nm and 140nm in MA experiments with and without alumina, respectively. This size reduction would be the main reason of leaching rate enhancement which is more achievable in MA in presence of alumina. The results demonstrate that alumina has a motivating effect in activation procedure to achieve a nanostructure molybdenite. Analysis of variance revealed milling speed is the main parameter in MA without alumina, while, ball to powder ratio is the most important factor in MA procedure in presence of alumina on leaching rate

Application of Homotopy Analysis Method to SIR Epidemic Model

Abstract In this article, the problem of the spread of a non-fatal disease in a population which is assumed to have constant size over the period of the epidemic is considered. Mathematical modeling of the problem leads to a system of nonlinear ordinary differential equations. Homotopy analysis method is employed to solve this system of nonlinear ordinary differential equations

Experimental Study on Vibration-Assisted Magnetic Abrasive Finishing for Internal Surface of Aluminum Tubes

In this research, a new apparatus is designed and set to polish the internal surface of aluminum tube in the presence of axial vibration (AV) for the poles. Several parameters influence the quality of polished surface during magnetic abrasive finishing. The effect of such parameters has been the subject of researches to achieve the best finished surface with desired characteristics. This paper has a statistical approach to investigate the effects of four parameters, i.e., mesh size of the abrasives, the weight of the abrasive powders, the number of cycles and especially vibration frequency of the poles on surface roughness and material removal weight in finishing process. Design of experiments (DOE) methods and analysis of variance are applied to determine the significant factors. Microscopic view of the working surface is also presented for better understanding the parameters effect on the finished surface

GT2003-38 A NUMERICAL INVESTIGATION OF AEROACOUSTIC FAN BLADE FLUTTER

ABSTRACT This paper reports the results of an ongoing research effort to explain the underlying mechanisms for aeroacoustic fan blade flutter. Using a 3D integrated aeroelasticity method and a single passage blade model that included a representation of the intake duct, the pressure rise vs. mass flow characteristic of a fan assembly was obtained for the 60%-80% speed range. A novel feature was the use of a downstream variable-area nozzle, an approach that allowed the determination of the stall boundary with good accuracy. The flutter stability was predicted for the 2 nodal diameter assembly mode arising from the first blade flap mode. The flutter margin at 64% speed was predicted to drop sharply and the instability was found to be independent of stall effects. On the other hand, the flutter instability at 74% speed was found to be driven by flow separation. Further post-processing of the results at 64% speed indicated significant unsteady pressure amplitude build-up inside the intake at the flutter condition, thus highlighting the link between the acoustic properties of the intake duct and fan blade flutter