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1
Gurusingam, Pogganeswaran, Firas Basim Ismail, and Taneshwaren Sundaram. "Operating Parameter Optimization using DOE Method to Reduce Unburned Carbon of Fly Ash for Tangential Fired Subcritical Coal Fired Power Plant." MATEC Web of Conferences 225 (2018): 05008. http://dx.doi.org/10.1051/matecconf/201822505008.
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As electric demand increasing due to rapid economic growth, most developing country are sourcing for cheap fuel and low maintenance power plant which coal fired power plant become the more preferable plant. The cheap and abundant coal resources have played a major factor for coal power plant selection compare to other type of power plant. Although this plant type has low maintenance and operating cost but its emission of by product has a great effect on daily plant operation and environment. The one of the major emission was unburned carbon which by product of incomplete combustion where remaining of coal that unburned exits the furnaces with ash. Presence of higher percentage of unburned carbon indicates the low efficiency of furnace combustion and this directly affects financial status of the power plant operators. This condition causes severe damages on the boiler tube by formation of slagging and clinkering which reduces heat transfer and efficiency of the furnace. Current method proved to be more time consuming and plant operator facing difficulty to reduce unburned carbon in real time. As a solution for this problem, a best parameter was predicted to achieve low percentage of unburned carbon.
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Wu, Yu Shiang, Tzuo Shing Yeh, and Yuan Haun Lee. "Improving the Rate Capability of Unburned Carbon from Oil-Fired Fly Ash as an Anode Material in High-Power Lithium Ion Batteries." Advanced Materials Research 287-290 (July 2011): 1304–7. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.1304.
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Unburned carbon is an industrial waste product of oil-fired fly ash. Recycled ground unburned carbon with an average particle size of 5 μm after heat treatment at 2500°C displayed an first coulombic efficiency of approximately 89.8% at a charge and discharge rate of 0.1 C. The discharging capacity of this type of carbon was 293.7 mAhg-1, and its capacity retention was approximately 94.7% after 50 cycles. However, the first coulombic efficiency of ground unburned carbon receiving nitric acid treatment after heat treatment increased to 91.1%, its discharging capacity increased to 318.6 mAhg-1, and its capacity retention increased to 98.5% after 50 cycles. Rate capability tests show that the unburned carbon after heat treatment exhibited a higher capacity in the lower C-rate region (0.2~3 C) at a 0.2 C rate charge and variable C-rates discharge. However, unburned carbon with nitric acid treatment is a suitable material for the higher C-rate region (5~10 C). Unburned carbon after heat treatment exhibited a higher capacity in the lower C-rate region (0.2~0.5 C) at the same C-rate charge and discharge.
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Zhang, Sheng Bing, Yi Liu, Yan Hong Zhang, and Hua Lin Wang. "Experimental Study on Classification of High Carbon Fly Ash with a Hydrocyclone." Advanced Materials Research 955-959 (June 2014): 2779–84. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.2779.
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The fly ash has a wide range of particles size and has a large amount of unburned carbon. As a raw material, the presence of the large particles and the unburned carbon will reduce the quality of the product. How to improve the utilization of fly ash has become one of focus points. In this work, hydrocyclone was adopted for classification after decarburization in a flotation column. Hydrocyclone showed a very good classification performance. In overflow, the particles were all smaller than 85μm. About 97.34% of the particles were smaller than 25 μm. Different fly ash content was selected to investigate its influence on the decarburization. The results showed that it made no obvious differences.
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McCarley, T. Ryan, Alistair M. S. Smith, Crystal A. Kolden, and Jason Kreitler. "Evaluating the Mid-Infrared Bi-spectral Index for improved assessment of low-severity fire effects in a conifer forest." International Journal of Wildland Fire 27, no. 6 (2018): 407. http://dx.doi.org/10.1071/wf17137.
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Remote sensing products provide a vital understanding of wildfire effects across a landscape, but detection and delineation of low- and mixed-severity fire remain difficult. Although data provided by the Monitoring Trends in Burn Severity (MTBS) project are frequently used to assess severity in the United States, alternative indices can offer improvement in the measurement of low-severity fire effects and would be beneficial for future product development and adoption. This research note evaluated one such alternative, the Mid-Infrared Bi-Spectral Index (MIRBI), which was developed in savannah ecosystems to isolate spectral changes caused by burning and reduce noise from other factors. MIRBI, differenced MIRBI (dMIRBI) and burn severity indices used by MTBS were assessed for spectral optimality at distinguishing severity and the ability to differentiate between unburned and burned canopy in a conifer forest. The MIRBI indices were better at isolating changes caused by burning and demonstrated higher spectral separability, particularly at low severity. These findings suggest that MIRBI indices can provide an enhanced alternative or complement to current MTBS products in high-canopy-cover forests for applications such as discernment of fire perimeters and unburned islands, as well as identification of low-severity fire effects.
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Svietkina, Olena, Hanna Tarasova, Olha Netiaha, and Svitlana Lysytska. "Ash as an alternative source of raw materials." E3S Web of Conferences 60 (2018): 00026. http://dx.doi.org/10.1051/e3sconf/20186000026.
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The objective of the work is to study the aluminosilicate fractionation from fly ash, physical and mechanical properties of fly ash derived from the Thermal Power Plants (TPP) wastes. Ash, carbon concentrate (unburned carbon), ash concentrate and products of their treatment with reagents were tested by optical methods. The particle morphology of the objects of research was studied with the scanning electron microscope REM-100. The composition of the ash phases was investigated using the X-ray diffractometer DRON-2. A dispersed analysis of the TPP fly ash suggests a conclusion that it is advisable to separate particles of a narrow grain-size class within the range from 40 to 150 μm with an ash content of about 33%. The first product may be enriched by flotation method. Such a coal product may be used as a reducing medium in metallurgical processes, agglomeration, etc. The calorific capacitance of the concentrate is about 6000 kcal/kg (25000 kJ/kg).
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Pahl, James W., Irving A. Mendelssohn, and Thomas J. Hess. "THE APPLICATION OF IN-SITU BURNING TO A LOUISIANA COASTAL MARSH FOLLOWING A HYDROCARBON PRODUCT SPILL: PRELIMINARY ASSESSMENT OF SITE RECOVERY." International Oil Spill Conference Proceedings 1997, no. 1 (April 1, 1997): 823–28. http://dx.doi.org/10.7901/2169-3358-1997-1-823.
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ABSTRACT The high degree of physical disturbance associated with conventional responses to oil spills in wetlands is driving the search for alternative cleanup methodologies. In March 1995, in southwestern Louisiana, a spill of gas condensate product into a brackish marsh at Rockefeller Wildlife Refuge was removed by in-situ burning. A monitoring program was established to examine the recovery of the marsh site. Three treatments were examined: (1) condensate-impacted and burned, (2) condensate-impacted and unburned, and (3) a reference that was neither exposed to the condensate nor burned. In March, July, and October 1995, vegetation plots were analyzed for biomass and stem density. Permanent quadrats were surveyed in July and October for total and species-specific percent cover. Although vegetation recovery was apparent 7 months after the burn, the burn treatment resulted in significantly lower biomass and stem density compared with both unburned treatments. In addition, burning led to conditions that favored initial recolonization by the sedge Scirpus robustus in a site previously dominated by the grasses Distichilis spicata and Spartina patens. However, biomass and stem density data suggest that D. spicata is regaining dominance. On the basis of these initial results, observations made in 1996 at the study site, and previous research, it is expected that in-situ burning will be successful at this site.
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Rasmusson, H., S. Sarenbo, and T. Claesson. "Ash Products and Their Economic Profitability." Open Waste Management Journal 6, no. 1 (April 5, 2013): 1–5. http://dx.doi.org/10.2174/1876400201306010001.
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Sustainable whole-tree harvesting practice requires that nutrient removal from the forest is compensated. Wood ashes contain all the nutrients, except for nitrogen, that are found in unburned fuel and can also increase soil pH, which makes ash recycling a natural way to stabilize the nutrient balance and counteract the acidification of forest soils that occurs due to intensive forest management. Several methods for processing ashes into spreadable products have been developed. The aim of this paper is to compare these methods. The study mainly focused on an economic evaluation of production, transportation and the spreading of self-hardened ash, ash pellets and ash granules. Self-hardened ash is generally considered to be the cheapest alternative to manufactured ash products, but these results imply that the most cost effective alternative is ash pellets. Around 27% of total costs could be earned from recycling the ash by producing pellets and 8% if granules are produced instead of self-hardened ash. This partly depends on the higher density of the pellets and granules and a significant reduction in the number of transportation operations. The reduction in transportation operations and diesel consumption also has major environmental benefits. Furthermore, it is more efficient to produce granules and pellets than it is to produce self-hardened ash and it is also easier to produce a reliable product of an appropriate size, shape and texture for a market that has well defined requirements.
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Barcelos, Sheyla Thays Vieira, Ismael Plácido Tomielis, Marli Da Silva Garcia, and Marney Pascoli Cereda. "Characterization of boiler ashes from sugarcane mill." Revista Ibero-Americana de Ciências Ambientais 10, no. 3 (July 17, 2019): 179–90. http://dx.doi.org/10.6008/cbpc2179-6858.2019.003.0016.
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Sugarcane mills produce sugar and ethanol and have always used bagasse as fuel to generate energy for self-consumption. Recently some mills have been also producing surplus electricity to sell in the market a third product from sugarcane. Although any boiler can be efficient, the sale of electricity has stimulated the improvement of the burning process. However, the investment in high-pressure boilers, much more expensive than any common boiler, is essential for the exportation of electricity. Among the 22 sugarcane mills from Mato Grosso do Sul, Brazil, only 12 power plants sell electricity to the grid. The power generation efficiency depends on the pyrolysis in boilers, which results in ashes that match the unburned mineral fraction of the fuel as oxide. Both the bagasse and the straw are composed predominantly of lignin, hemicellulose and cellulose with calorific power near to the wood at the same moisture content. However the bagasse leaves the mill with about 50% of moisture while the straw reaches the industry with about 15% of humidity. This paper characterize the ashes samples from burned bagasse from seven sugarcane mills at Mato Grosso do Sul Brazilian state, to compare the methodology available for use to measure the efficiency of the pyrolysis system. Among these sugarcane mills only two are highlighted by their higher burning efficiency, both of them selling electricity, while the others showed unburned portions characterizing an inefficient system. For these industries the ash content in the ashes showed values compatible with the Superior Calorific Value as an efficiency index for the combustion degree in boilers.
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Zaichenko, Nikolai, Irina Petrik, and Liudmila Zaichenko. "Beneficiated ponded fly ash for concretes with high volume mineral additions." MATEC Web of Conferences 315 (2020): 07006. http://dx.doi.org/10.1051/matecconf/202031507006.
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The article presents the investigation results of effect of beneficiated ponded fly ash on the properties of cement pastes and concretes with high-level replacement of Portland cement. To improve the characteristics of ponded fly ash meeting technical requirements for replacing cement in concrete the triboelectrostatic beneficiation technology has been elaborated. This technology can produce low-carbon ash product (LOI = 2.52 % in this study) for the high replacing level of cement (45 %) in concretes. The beneficiated ponded fly ash has an improved granulometric and phase composition, a decreased content of unburned carbon that accelerates the hydration process of cement, increases the rheological properties of cement paste and the ability of air-entraining admixture to hold the required involved air. In a combination with the nanostructured-carbon-based plasticizing admixture the beneficiated ponded fly ash exhibits high rate of strength increase when is used in high-volume fly ash concretes.
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Roteta, E., and P. Oliva. "OPTIMIZATION OF A RANDOM FOREST CLASSIFIER FOR BURNED AREA DETECTION IN CHILE USING SENTINEL-2 DATA." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W12-2020 (November 6, 2020): 337–42. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w12-2020-337-2020.
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Abstract. Due to the high variability of biomes throughout the country, the classification of burned areas is a challenge. We calibrated a random forest classifier to account for all this variability and ensure an accurate classification of burned areas. The classifier was optimized in three steps, generating a version of the burned area product in each step. According to the visual assessment, the final version of the BA product is more accurate than the perimeters created by the Chilean National Forest Corporation, which overestimate large burned areas because it does not consider the inner unburned areas and, it omits some small burned areas. The total burned surface from January to March 2017 was 5,000 km2 in Chile, 20 % of it belonging to a single burned area in the Maule Region, and with 91 % of the total burned surface distributed in 6 adjacent regions of Central Chile.
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Jamlus, Mohd Hanafiah Mat, and Zainal Ambri Abdul Karim. "Attaining Soot Oxidation Temperature by Inductive Coils Exposed to Electromagnetic Waves." Applied Mechanics and Materials 564 (June 2014): 304–9. http://dx.doi.org/10.4028/www.scientific.net/amm.564.304.
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This paper presents the findings in attaining soot oxidation temperature by using carbon steel coils exposed to electromagnetic waves. Soot are unburned carbon product in the exhaust gases during the combustion of diesel fuel, which are subjected to stringent emission regulations due to its harmful properties. The unburned carbon can be oxidised by heating as after-treatment strategy but in order for the oxidation to occur, it would require a temperature of not less than 600°C. In the present work, eight heating elements made from various carbon steel coil sizes were exposed to electromagnetic waves in the microwave oven cavity which heats up the coils to the oxidation temperature. Electromagnetic waves heating utilises electromagnetic radiation to induce electric field in a conductive material that causes the material to be heated. The microwave oven used has a power rating of 1000 W, with a microwave range of 2450 Mhz. Measurement of coils temperature and exposure time to electromagnetic waves were recorded and analysed. The results showed that only the coils with bigger coil loop size, i.e. 20 mm and lowest number of turns, i.e. 10 turns attained the threshold temperature of 600°C, while smaller diameter coil would accelerate the rate of heating. The findings from the research work are significant facts in the future development of in-situ exhaust gas after treatment system in reducing soot emissions.
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Micheletty, P. D., A. M. Kinoshita, and T. S. Hogue. "Application of MODIS snow cover products: wildfire impacts on snow and melt in the Sierra Nevada." Hydrology and Earth System Sciences 18, no. 11 (November 24, 2014): 4601–15. http://dx.doi.org/10.5194/hess-18-4601-2014.
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Abstract. The current work evaluates the spatial and temporal variability in snow after a large forest fire in northern California using Moderate Resolution Imaging Spectroradiometer (MODIS) snow-covered area and grain size (MODSCAG). MODIS MOD10A1 fractional snow-covered area and MODSCAG fractional snow cover products are utilized to detect spatial and temporal changes in snowpack after the 2007 Moonlight Fire and an unburned basin, Grizzly Ridge, for water years (WY) 2002–2012. Estimates of canopy-adjusted and non-adjusted MODSCAG fractional snow-covered area (fSCA) are smoothed and interpolated to provide a continuous time series of average daily snow extent over the two basins. The removal of overstory canopy by wildfire exposes more snow cover; however, elemental pixel comparisons and statistical analysis show that the MOD10A1 product has a tendency to overestimate snow coverage pre-fire, muting the observed effects of wildfire. The MODSCAG algorithm better distinguishes subpixel snow coverage in forested areas and is highly correlated to soil burn severity after the fire. Annual MODSCAG fSCA estimates show statistically significant increased fSCA in the Moonlight Fire study area after the fire (P < 0.01 for WY 2008–2011) compared to pre-fire averages and the control basin. After the fire, the number of days exceeding a pre-fire high snow-cover threshold increased by 81%. Canopy reduction increases exposed viewable snow area and the amount of solar radiation that reaches the snowpack, leading to earlier basin average melt-out dates compared to the nearby unburned basin. There is also a significant increase in MODSCAG fSCA post-fire regardless of slope or burn severity. Regional snow cover change has significant implications for both short- and long-term water supply for impacted ecosystems, downstream communities, and resource managers.
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Micheletty, P. D., A. M. Kinoshita, and T. S. Hogue. "Application of MODIS snow cover products: wildfire impacts on snow and melt in the Sierra Nevada." Hydrology and Earth System Sciences Discussions 11, no. 7 (July 4, 2014): 7513–49. http://dx.doi.org/10.5194/hessd-11-7513-2014.
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Abstract. The current work evaluates the spatial and temporal variability in snow after a large forest fire in northern California with Moderate Resolution Imaging Spectroradiometer (MODIS) snow covered area and grain size (MODSCAG) algorithm. MODIS MOD10A1 fractional snow covered area and MODSCAG fractional snow cover products are utilized to detect spatial and temporal changes in snowpack after the 2007 Moonlight Fire and an unburned basin, Grizzly Ridge, for water years (WY) 2002–2012. Estimates of canopy adjusted and non-adjusted MODSCAG fractional snow covered area (fSCA) are smoothed and interpolated to provide a continuous timeseries of daily basin average snow extent over the two basins. The removal of overstory canopy by wildfire exposes more snow cover; however, elemental pixel comparisons and statistical analysis show that the MOD10A1 product has a tendency to overestimate snow coverage pre-fire, muting the effects of wildfire. The MODSCAG algorithm better distinguishes sub-pixel snow coverage in forested areas and is highly correlated to soil burn severity after the fire. Annual MODSCAG fSCA estimates show statistically significant increased fSCA in the Moonlight Fire study area after the fire (WY 2008–2011; P < 0.01) compared to pre-fire averages and the control basin. After the fire, the number of days exceeding a pre-fire high snow cover threshold increased by 81%. Canopy reduction increases exposed viewable snow area and the amount of solar radiation that reaches the snowpack leading to earlier basin average melt-out dates compared to the nearby unburned basin. There is also a significant increase in MODSCAG fSCA post-fire regardless of slope or burn severity. Alteration of regional snow cover has significant implications for both short and long-term water supplies for downstream communities and resource managers.
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Arifutzzaman, Akhama, Iskandar Yaacob, M. A. Hawlader, and Md Abdul Maleque. "Fabrication and Characterization of Graphene from Solid Carbon Dioxide." Advanced Materials Research 1115 (July 2015): 418–21. http://dx.doi.org/10.4028/www.scientific.net/amr.1115.418.
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Graphene was fabricated by a well-known technique of ignition of magnesium (Mg) metal ribbon in solid carbon dioxide. Two dry ice slabs were used as carbon source for the production of graphene. A hemispherical cavity of about 3-4 cm diameter was carved on surfaces of both dry ice slabs. About 0.5g of Mg ribbon was burnt and immediately placed into the dry ice cavity. It was then covered up by another carved slab of dry ice. After complete combustion, mixture of black and white residues was formed. It was then recovered. 20 ml of 1 M HCl acid was added to the product mixture. Reaction of HCl with MgO and unburned Mg formed MgCl2 which was then washed away by deionized water. The isolated carbon material was separated as product. Characterization of the product was performed using optical microscopy (OM), where images showed the presence of sheet-like light gray objects. Field emission scanning electron microscopy (FESEM) and transmission electron microscope (TEM) analyses revealed the presences of graphene. The lateral length of the sheet was about 3-3.5 μm and the surface area was about 3-5.5 μm2 using images analysis software.
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Li, Ruixue C., Guoming G. Zhu, and Yifan Men. "A two-zone reaction-based combustion model for a spark-ignition engine." International Journal of Engine Research 22, no. 1 (April 10, 2019): 109–24. http://dx.doi.org/10.1177/1468087419841746.
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This article presents a control-oriented two-zone reaction-based zero-dimensional model to accurately describe the combustion process of a spark-ignited engine for real-time simulations, and the developed model will be used for model-based control design and validation. A two-zone modeling approach is adopted, where the combustion chamber is divided into the burned (reaction) and unburned (pre-mixed) zones. The mixture thermodynamic properties and individual chemical species in two zones are taken into account in the modeling process. Instead of using the conventional pre-determined Wiebe-based combustion model, a two-step chemical reaction model is utilized to predict the combustion process along with important thermodynamic parameters such as the mass-fraction-burned, in-cylinder pressure, temperatures, and individual species mass changes in both zones. Sensitivities of model parameters are analyzed during the model calibration process. As a result, one set of calibration parameters is used to predict combustion characteristics over all engine operating conditions studied in this article, which is the major advantage of the proposed method. Also, the proposed modeling approach is capable of modeling the combustion process under different air-to-fuel ratios, ignition timings, and exhaust-gas-recirculation rates for real-time simulations. As the by-product of the model, engine knock can also be predicted based on the Arrhenius integral in the unburned zone, which is valuable for model-based knock control. The proposed combustion model is intensively validated using the experimental data with a peak relative prediction error of 6.2% for the in-cylinder pressure.
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Chuvieco, Emilio, Joshua Lizundia-Loiola, Maria Lucrecia Pettinari, Ruben Ramo, Marc Padilla, Kevin Tansey, Florent Mouillot, et al. "Generation and analysis of a new global burned area product based on MODIS 250 m reflectance bands and thermal anomalies." Earth System Science Data 10, no. 4 (November 13, 2018): 2015–31. http://dx.doi.org/10.5194/essd-10-2015-2018.
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Abstract. This paper presents a new global burned area (BA) product, generated from the Moderate Resolution Imaging Spectroradiometer (MODIS) red (R) and near-infrared (NIR) reflectances and thermal anomaly data, thus providing the highest spatial resolution (approx. 250 m) among the existing global BA datasets. The product includes the full times series (2001–2016) of the Terra-MODIS archive. The BA detection algorithm was based on monthly composites of daily images, using temporal and spatial distance to active fires. The algorithm has two steps, the first one aiming to reduce commission errors by selecting the most clearly burned pixels (seeds), and the second one targeting to reduce omission errors by applying contextual analysis around the seed pixels. This product was developed within the European Space Agency's (ESA) Climate Change Initiative (CCI) programme, under the Fire Disturbance project (Fire_cci). The final output includes two types of BA files: monthly full-resolution continental tiles and biweekly global grid files at a degraded resolution of 0.25∘. Each set of products includes several auxiliary variables that were defined by the climate users to facilitate the ingestion of the product into global dynamic vegetation and atmospheric emission models. Average annual burned area from this product was 3.81 Mkm2, with maximum burning in 2011 (4.1 Mkm2) and minimum in 2013 (3.24 Mkm2). The validation was based on a stratified random sample of 1200 pairs of Landsat images, covering the whole globe from 2003 to 2014. The validation indicates an overall accuracy of 0.9972, with much higher errors for the burned than the unburned category (global omission error of BA was estimated as 0.7090 and global commission as 0.5123). These error values are similar to other global BA products, but slightly higher than the NASA BA product (named MCD64A1, which is produced at 500 m resolution). However, commission and omission errors are better compensated in our product, with a tendency towards BA underestimation (relative bias −0.4033), as most existing global BA products. To understand the value of this product in detecting small fire patches (<100 ha), an additional validation sample of 52 Sentinel-2 scenes was generated specifically over Africa. Analysis of these results indicates a better detection accuracy of this product for small fire patches (<100 ha) than the equivalent 500 m MCD64A1 product, although both have high errors for these small fires. Examples of potential applications of this dataset to fire modelling based on burned patches analysis are included in this paper. The datasets are freely downloadable from the Fire_cci website (https://www.esa-fire-cci.org/, last access: 10 November 2018) and their repositories (pixel at full resolution: https://doi.org/cpk7, and grid: https://doi.org/gcx9gf).
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Hoyos-Montilla, A. A., Y. P. Arias-Jaramillo, and J. I. Tobón. "Evaluation of cements obtained by alkali-activated coal ash with NaOH cured at low temperatures." Materiales de Construcción 68, no. 332 (September 4, 2018): 170. http://dx.doi.org/10.3989/mc.2018.10117.
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The temperature at which the alkaline activation process takes place is a significant factor in the evolution of the mechanical properties of coal ash cementitious base material. In this work, the influence of temperature (8 a 38 °C) and curing time (3 and 28 days) on the mechanical properties of the alkaline synthesis of two coal ashes was evaluated through the study of the mineralogical evolution of the cementitious phases by XRD and FTIR. We found that the type of zeolite, a synthesis product, depends on the study factors. For values above 28 °C and at least 7 days, alkalinely activated cements with compressive strength above 20 MPa were achieved. Other parameters, such as SiO2/Al2O3 ratio, percentage of unburned coal and particle-size distribution, should be taken into account in the variation of mechanical performance.
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Feng, Yan, Xing Li, Yanzhen Yu, Jingyao Qi, Xinqiang Jia, Juanting Wang, and Xue Li. "Production of unburned calcium silicon filter material (UCSFM) from oyster shell and its performance investigation in an A/O integrated biological aerated filter reactor (A/O-BAF)." RSC Advances 6, no. 88 (2016): 85324–32. http://dx.doi.org/10.1039/c6ra16331a.
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Pahl, James W., Irving A. Mendelssohn, and Thomas J. Hess. "Recovery of a Louisiana Coastal Marsh 3 Years After In Situ Burning of a Hydrocarbon Product Spill." International Oil Spill Conference Proceedings 1999, no. 1 (March 1, 1999): 1279–82. http://dx.doi.org/10.7901/2169-3358-1999-1-1279.
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ABSTRACT The high degree of physical disturbance associated with conventional response options to oil spills in wetlands is driving the investigation of alternative cleanup methodologies. In March 1995, a spill of gas condensate product onto a brackish marsh at Rockefeller Wildlife Refuge in southwestern Louisiana was removed through the use of in situ burning. A monitoring program was initiated to examine three treatment marshes: (1) condensate-impacted and burned, (2) condensate-impacted and unburned, and (3) a reference that was neither exposed to the condensate nor burned. The authors compared vegetation cover, stem density and biomass between the treatment marshes as parameters defining recovery of the plant community from the condensate spill and subsequent in situ burn. After three growing seasons, stem density, live biomass, and total cover values in the impacted-and-burned marsh had recovered to levels similar to non-burned treatments. In addition, community composition within the impacted-and-burned treatment returned to a co-dominant mix of the grasses Distichilis spicata (salt grass) and Spartina alterniflora (wiregrass) characteristic of the surrounding marsh. Recovery of the marsh at Rockefeller Wildlife Refuge was largely due to proper consideration of environmental factors at the time of the burn, especially marsh type, season and water level. The results of this in situ burn evaluation support the conclusion that burning can be relied upon as an effective cleanup response to hydrocarbon spills in wetlands.
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Seydi, Seyd Teymoor, Mehdi Akhoondzadeh, Meisam Amani, and Sahel Mahdavi. "Wildfire Damage Assessment over Australia Using Sentinel-2 Imagery and MODIS Land Cover Product within the Google Earth Engine Cloud Platform." Remote Sensing 13, no. 2 (January 10, 2021): 220. http://dx.doi.org/10.3390/rs13020220.
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Wildfires are major natural disasters negatively affecting human safety, natural ecosystems, and wildlife. Timely and accurate estimation of wildfire burn areas is particularly important for post-fire management and decision making. In this regard, Remote Sensing (RS) images are great resources due to their wide coverage, high spatial and temporal resolution, and low cost. In this study, Australian areas affected by wildfire were estimated using Sentinel-2 imagery and Moderate Resolution Imaging Spectroradiometer (MODIS) products within the Google Earth Engine (GEE) cloud computing platform. To this end, a framework based on change analysis was implemented in two main phases: (1) producing the binary map of burned areas (i.e., burned vs. unburned); (2) estimating burned areas of different Land Use/Land Cover (LULC) types. The first phase was implemented in five main steps: (i) preprocessing, (ii) spectral and spatial feature extraction for pre-fire and post-fire analyses; (iii) prediction of burned areas based on a change detection by differencing the pre-fire and post-fire datasets; (iv) feature selection; and (v) binary mapping of burned areas based on the selected features by the classifiers. The second phase was defining the types of LULC classes over the burned areas using the global MODIS land cover product (MCD12Q1). Based on the test datasets, the proposed framework showed high potential in detecting burned areas with an overall accuracy (OA) and kappa coefficient (KC) of 91.02% and 0.82, respectively. It was also observed that the greatest burned area among different LULC classes was related to evergreen needle leaf forests with burning rate of over 25 (%). Finally, the results of this study were in good agreement with the Landsat burned products.
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Seydi, Seyd Teymoor, Mehdi Akhoondzadeh, Meisam Amani, and Sahel Mahdavi. "Wildfire Damage Assessment over Australia Using Sentinel-2 Imagery and MODIS Land Cover Product within the Google Earth Engine Cloud Platform." Remote Sensing 13, no. 2 (January 10, 2021): 220. http://dx.doi.org/10.3390/rs13020220.
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Wildfires are major natural disasters negatively affecting human safety, natural ecosystems, and wildlife. Timely and accurate estimation of wildfire burn areas is particularly important for post-fire management and decision making. In this regard, Remote Sensing (RS) images are great resources due to their wide coverage, high spatial and temporal resolution, and low cost. In this study, Australian areas affected by wildfire were estimated using Sentinel-2 imagery and Moderate Resolution Imaging Spectroradiometer (MODIS) products within the Google Earth Engine (GEE) cloud computing platform. To this end, a framework based on change analysis was implemented in two main phases: (1) producing the binary map of burned areas (i.e., burned vs. unburned); (2) estimating burned areas of different Land Use/Land Cover (LULC) types. The first phase was implemented in five main steps: (i) preprocessing, (ii) spectral and spatial feature extraction for pre-fire and post-fire analyses; (iii) prediction of burned areas based on a change detection by differencing the pre-fire and post-fire datasets; (iv) feature selection; and (v) binary mapping of burned areas based on the selected features by the classifiers. The second phase was defining the types of LULC classes over the burned areas using the global MODIS land cover product (MCD12Q1). Based on the test datasets, the proposed framework showed high potential in detecting burned areas with an overall accuracy (OA) and kappa coefficient (KC) of 91.02% and 0.82, respectively. It was also observed that the greatest burned area among different LULC classes was related to evergreen needle leaf forests with burning rate of over 25 (%). Finally, the results of this study were in good agreement with the Landsat burned products.
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Liu, Meng, Sorin Popescu, and Lonesome Malambo. "Feasibility of Burned Area Mapping Based on ICESAT−2 Photon Counting Data." Remote Sensing 12, no. 1 (December 19, 2019): 24. http://dx.doi.org/10.3390/rs12010024.
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Accurately mapping burned areas is crucial for the analysis of carbon emissions and wildfire risk as well as understanding the effects of climate change on forest structure. Burned areas have predominantly been mapped using optical remote sensing images. However, the structural changes due to fire also offer opportunities for mapping burned areas using three-dimensional (3D) datasets such as Light detection and ranging (LiDAR). This study focuses on the feasibility of using photon counting LiDAR data from National Aeronautics and Space Administration’s (NASA) Ice, Cloud, and land Elevation Satellite-2 (ICESat−2) mission to differentiate vegetation structure in burned and unburned areas and ultimately classify burned areas along mapped ground tracks. The ICESat−2 mission (launched in September 2018) provides datasets such as geolocated photon data (ATL03), which comprises precise latitude, longitude and elevation of each point where a photon interacts with land surface, and derivative products such as the Land Water Vegetation Elevation product (ATL08), which comprises estimated terrain and canopy height information. For analysis, 24 metrics such as the average, median and standard deviation of canopy height were derived from ATL08 data over forests burned by recent fires in 2018 in northern California and western New Mexico. A reference burn map was derived from Sentinel−2 images based on the differenced Normalized Burn Ratio (dNBR) index. A landcover map based on Sentinel−2 images was employed to remove non-forest classes. Landsat 8 based dNBR image and landcover map were also used for comparison. Next, ICESat−2 data of forest samples were classified into burned and unburned ATL08 100-m segments by both Random Forest classification and logistic regression. Both Sentinel−2 derived and Landsat 8 derived ATL08 samples got high classification accuracy, 83% versus 76%. Moreover, the resulting classification accuracy by Random Forest and logistic regression reached 83% and 74%, respectively. Among the 24 ICESat−2 metrics, apparent surface reflectance and the number of canopy photons were the most important. Furthermore, burn severity of each ATL08 segment was also estimated with Random Forest regression. R2 of predicted burn severity to observed dNBR is 0.61 with significant linear relationship and moderate correlation (r = 0.78). Overall, the reasonably high accuracies achieved in this study demonstrate the feasibility of employing ICESat−2 data in burned forest classification, opening avenues for improved estimation of burned biomass and carbon emissions from a 3D perspective.
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Sparks, Aaron M., Luigi Boschetti, Alistair M. S. Smith, Wade T. Tinkham, Karen O. Lannom, and Beth A. Newingham. "An accuracy assessment of the MTBS burned area product for shrub–steppe fires in the northern Great Basin, United States." International Journal of Wildland Fire 24, no. 1 (2015): 70. http://dx.doi.org/10.1071/wf14131.
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Although fire is a common disturbance in shrub–steppe, few studies have specifically tested burned area mapping accuracy in these semiarid to arid environments. We conducted a preliminary assessment of the accuracy of the Monitoring Trends in Burn Severity (MTBS) burned area product on four shrub–steppe fires that exhibited varying degrees of within-fire patch heterogeneity. Independent burned area perimeters were derived through visual interpretation and were used to cross-compare the MTBS burned area perimeters with classifications produced using set thresholds on the Relativised differenced Normalised Burn Index (RdNBR), Mid-infrared Burn Index (MIRBI) and Char Soil Index (CSI). Overall, CSI provided the most consistent accuracies (96.3–98.6%), with only small commission errors (1.5–4.4%). MIRBI also had relatively high accuracies (92.2–97.9%) and small commission errors (2.1–10.8%). The MTBS burned area product had higher commission errors (4.3–15.5%), primarily due to inclusion of unburned islands and fingers within the fire perimeter. The RdNBR burned area maps exhibited lower accuracies (92.9–96.0%). However, the different indices when constrained by the MTBS perimeter provided variable results, with CSI providing the highest and least variable accuracies (97.4–99.1%). Studies seeking to use MTBS perimeters to analyse trends in burned area should apply spectral indices to constrain the final burned area maps. The present paper replaces a former paper of the same title (http://dx.doi.org/10.1071/WF13206), which was withdrawn owing to errors discovered in data analysis after the paper was accepted for publication.
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Sabelnikov, V. A., A. N. Lipatnikov, S. Nishiki, and T. Hasegawa. "Investigation of the influence of combustion-induced thermal expansion on two-point turbulence statistics using conditioned structure functions." Journal of Fluid Mechanics 867 (March 20, 2019): 45–76. http://dx.doi.org/10.1017/jfm.2019.128.
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The second-order structure functions (SFs) of the velocity field, which characterize the velocity difference at two points, are widely used in research into non-reacting turbulent flows. In the present paper, the approach is extended in order to study the influence of combustion-induced thermal expansion on turbulent flow within a premixed flame brush. For this purpose, SFs conditioned to various combinations of mixture states at two different points (reactant–reactant, reactant–product, product–product, etc.) are introduced in the paper and a relevant exact transport equation is derived in the appendix. Subsequently, in order to demonstrate the capabilities of the newly developed approach for advancing the understanding of turbulent reacting flows, the conditioned SFs are extracted from three-dimensional (3-D) direct numerical simulation data obtained from two statistically 1-D planar, fully developed, weakly turbulent, premixed, single-step-chemistry flames characterized by significantly different (7.53 and 2.50) density ratios, with all other things being approximately equal. Obtained results show that the conditioned SFs differ significantly from standard mean SFs and convey a large amount of important information on various local phenomena that stem from the influence of combustion-induced thermal expansion on turbulent flow. In particular, the conditioned SFs not only (i) indicate a number of already known local phenomena discussed in the paper, but also (ii) reveal a less recognized phenomenon such as substantial influence of combustion-induced thermal expansion on turbulence in constant-density unburned reactants and even (iii) allow us to detect a new phenomenon such as the appearance of strong local velocity perturbations (shear layers) within flamelets. Moreover, SFs conditioned to heat-release zones indicate a highly anisotropic influence of combustion-induced thermal expansion on the evolution of small-scale two-point velocity differences within flamelets, with the effects being opposite (an increase or a decrease) for different components of the local velocity vector.
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Lu, Quanyang, Yunliang Zhao, and Allen L. Robinson. "Comprehensive organic emission profiles for gasoline, diesel, and gas-turbine engines including intermediate and semi-volatile organic compound emissions." Atmospheric Chemistry and Physics 18, no. 23 (December 12, 2018): 17637–54. http://dx.doi.org/10.5194/acp-18-17637-2018.
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Abstract. Emissions from mobile sources are important contributors to both primary and secondary organic aerosols (POA and SOA) in urban environments. We compiled recently published data to create comprehensive model-ready organic emission profiles for on- and off-road gasoline, gas-turbine, and diesel engines. The profiles span the entire volatility range, including volatile organic compounds (VOCs, effective saturation concentration C*=107–1011 µg m−3), intermediate-volatile organic compounds (IVOCs, C*=103–106 µg m−3), semi-volatile organic compounds (SVOCs, C*=1–102 µg m−3), low-volatile organic compounds (LVOCs, C*≤0.1 µg m−3) and non-volatile organic compounds (NVOCs). Although our profiles are comprehensive, this paper focuses on the IVOC and SVOC fractions to improve predictions of SOA formation. Organic emissions from all three source categories feature tri-modal volatility distributions (“by-product” mode, “fuel” mode, and “lubricant oil” mode). Despite wide variations in emission factors for total organics, the mass fractions of IVOCs and SVOCs are relatively consistent across sources using the same fuel type, for example, contributing 4.5 % (2.4 %–9.6 % as 10th to 90th percentiles) and 1.1 % (0.4 %–3.6 %) for a diverse fleet of light duty gasoline vehicles tested over the cold-start unified cycle, respectively. This consistency indicates that a limited number of profiles are needed to construct emissions inventories. We define five distinct profiles: (i) cold-start and off-road gasoline, (ii) hot-operation gasoline, (iii) gas-turbine, (iv) traditional diesel and (v) diesel-particulate-filter equipped diesel. These profiles are designed to be directly implemented into chemical transport models and inventories. We compare emissions to unburned fuel; gasoline and gas-turbine emissions are enriched in IVOCs relative to unburned fuel. The new profiles predict that IVOCs and SVOC vapour will contribute significantly to SOA production. We compare our new profiles to traditional source profiles and various scaling approaches used previously to estimate IVOC emissions. These comparisons reveal large errors in these different approaches, ranging from failure to account for IVOC emissions (traditional source profiles) to assuming source-invariant scaling ratios (most IVOC scaling approaches).
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Ribeiro, André, Joana Carvalho, Joana Castro, Jorge Araújo, Cândida Vilarinho, and Fernando Castro. "Alternative Feedstocks for Biodiesel Production." Materials Science Forum 730-732 (November 2012): 623–29. http://dx.doi.org/10.4028/www.scientific.net/msf.730-732.623.
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The increasing in the world population has continuously increased the energy demand. As an effective fuel, petroleum has been serving the world to meet its energy needs. Continued use of petroleum sourced fuels is widely recognized as unsustainable because of depleting supplies and all the environmental issues around its use could be responsible for a major deficit in the future. Thus, the development of alternative energy sources, are to be welcomed. Biodiesel, as an alternative fuel, has many benefits. It is biodegradable, non-toxic and compared to petroleum-based diesel, has a more favorable combustion emission profile, such as low emissions of carbon monoxide, particulate matter and unburned hydrocarbons. In brief, these merits make biodiesel a good alternative to petroleum based fuel. The use of alternative feedstock as waste cooking oils (WCO), bovine fats and microalgae oil for biodiesel production has some advantages. It is cheaper than edible vegetable oils and it is a way to valorize a sub-product. Nevertheless, these oils has some contaminants, which can reduce the quality of biodiesel, a problem that was solved by testing different operating conditions and equipment designs for each stage of processing. The technological assessment of this process was carried out to evaluate their technical benefits, limitations and quality of final product. In this work biodiesel was produced by an alkali-catalyzed transesterification, a reaction involving the WCO feedstock and an alcohol to yield fatty acid alkyl esters (biodiesel) and glycerol. The evaluation of quality from raw materials and final biodiesel was performed according to standard EN 14214. Results show that all parameters analyzed meet the standard and legislation requirements. This evidence proves that in those operating conditions the biodiesel produced from WCO, bovine fats and microalgae can substitute petroleum-based diesel.
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Kuo, T. W. "What Causes Slower Flame Propagation in the Lean-Combustion Engine?" Journal of Engineering for Gas Turbines and Power 112, no. 3 (July 1, 1990): 348–56. http://dx.doi.org/10.1115/1.2906502.
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Previous engine data suggest that slower flame propagation in lean-burn engines could be due to slower flame expansion velocity at lean conditions than at stoichiometric combustion. Two classes of model, a quasi-dimensional engine-simulation program and a multidimensional engine-flow and combustion code, were used to study this effect in detail and to assess the capabilities of the models to resolve combustion details. The computed flame-speed data from each program differed somewhat in magnitude, but the predicted trends at various equivalence ratios were quite similar. The trends include: (1) The peak in-cylinder burned-gas temperature decreases by about 300 K as the equivalence ratio is decreased from 0.98 to 0.70. (2) Both the laminar flame speed and the flame-propagation speed, the latter computed from the time derivative of flame radius, decrease with decreasing equivalence ratio. (3) The turbulent burning speed, defined as the ratio of specific fuel-burning rate to the product of the flame frontal area and unburned-mixture density, is relatively insensitive to equivalence-ratio variations at the same flame-radius position. The previous experimental finding that the reduction in flame-propagation speed with decreasing equivalence ratio is caused mainly by the lower thermal-expansion speed, calculated by subtracting the turbulent burning speed from the flame-propagation speed, was confirmed. This is a consequence of lower burned-gas temperature for the lean case. Regarding the reliability of the models to resolve the combustion details, limitations of the models are identified and discussed in detail.
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Wu, Su Xi, Shan Shan Huang, Chuan Bo Tan, and Hui Cai. "Application of Spent Bleaching Clay for Producing Environmental Brick." Applied Mechanics and Materials 204-208 (October 2012): 3668–71. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.3668.
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Spent bleaching clay(SBC) is a kind of discarded by-products from edible vegetable oil factory, often resulting in environment pollution. This study aimed to explore a feasible approach to comprehensively utilize the SBC for replacing coal ash to produce unburned and environmental brick(UEB). Through a series of experiments, and considering the cost and acceptability of bricks, the optimal conditions for producing UEB was obtained. The defatted SBC is added 25 %, fine fine sand 25 %, small pebble 30 %, cement 12 %, lime 8 %, the molding pressure is 20 MPa, and the molding moisture was 10 %. Under this condition, the average compressive strength of the UEB with 28-day storage can reach up to 18.11 MPa, higher than the value of 15 MPa in the unburned brick produced from standard coal ash.
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Lisko, Joseph G., Stephen B. Stanfill, and Clifford H. Watson. "Quantitation of ten flavor compounds in unburned tobacco products." Anal. Methods 6, no. 13 (2014): 4698–704. http://dx.doi.org/10.1039/c4ay00271g.
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Batra, Vidya S., Anna Ria Varghese, Pooja Vashisht, and Malini Balakrishnan. "Value-added products from unburned carbon in bagasse fly ash." Asia-Pacific Journal of Chemical Engineering 6, no. 5 (December 29, 2010): 787–93. http://dx.doi.org/10.1002/apj.536.
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Zhakina, A. Kh, O. V. Arnt, Ye P. Vassilets, Т. S. Zhivotova, Z. M. Muldahmetov, А. М. Gazaliev, and S. A. Sеmеnova. "SYNTHESIS AND PROPERTIES OF A COMPOSITE MATERIAL BASED ON COAL MINING WASTE." SERIES CHEMISTRY AND TECHNOLOGY 2, no. 440 (April 15, 2020): 6–13. http://dx.doi.org/10.32014/2020.2518-1491.17.
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The article presents the results of a study of the synthesis of composite materials based on coal waste combined with coal and polymer raw materials, using ultrasonic chemistry methods and determining the possibility of their use as an active mineral additive for replacing part of cement in fine-grained concrete. By varying the composition of the matrix and the filler, a composite material is obtained whose properties are quantitatively and qualitatively different from the properties of each of its components. As a filler in the composition of the composite material, burned rock is used - the product of oxidative self-firing of waste rock, extracted together with coal to the surface. Burned rocks contain an organic part (unburned carbonaceous impurities) and a mineral part (calcined clay-sandy part). Features of the material composition of burned rocks, coal industry waste allows us to consider them as secondary mineral raw materials. The binder in the composite material used is thiourea-formaldehyde resin. The resin was obtained by the standard method of polycondensation of thiourea with formaldehyde at a molar ratio of thiocarbamide:formaldehyde = 1:2. The choice of thiourea-formaldehyde resin is due to the availability, water solubility and the presence of a sufficient number of proton acceptor centers capable of complexation with a modifier. The modifier for composite materials used a coal waste product related to promising natural polymers in nanotechnology, sodium humate, extracted by alkaline extraction from oxidized coal from the Shubarkol deposit. Sodium humate refers to polyfunctional polymers with a unique combination of hydrophobic and hydrophilic sites, a variety of oxygen-containing functional groups, aromatic, heterocyclic and other groups. All this suggests a high ability of sodium humate to intermacromolecular interactions with both the burned rock and thiourea-formaldehyde resin. Composite material based on burned rock, sodium humate with thiourea-formaldehyde resin was synthesized by impregnation using ultrasonic treatment. The decisive role of ultrasonic activation is shown and the effectiveness of its application to the process of producing composites is noted. The modern physicochemical and physicomechanical methods have characterized the composition and structure of the obtained composite materials. The mineralogical composition of composite materials was studied using x-ray phase analysis, and surface morphology based on microscopic analysis using a scanning electron microscope. Filling the composite material with burnt rock provides higher physical and mechanical properties. The strength of burnt-filled composites is higher than that of samples of a similar composition without burnt rock. The resulting composite can be used as a building material. Key words: composite material, filler, binder, burned rock, thiourea-formaldehyde resin.
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Adamczyk, Zdzisław, Joanna Komorek, Barbara Białecka, Joanna Całus-Moszko, and Agnieszka Klupa. "Possibilities of Graphitization of Unburned Carbon from Coal Fly Ash." Minerals 11, no. 9 (September 21, 2021): 1027. http://dx.doi.org/10.3390/min11091027.
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The paper presents the characteristics of products annealing at the temperatures of 2400 and 3000 °C of unburned carbon from coal fly ash in terms of its possible use as a starting material in the graphitization process. An amorphous substance (organic substance) with an admixture of some minerals has been found in samples subjected to graphitization. However, the graphite phase is dominant in products subjected to graphitization. Studies have also shown a diverse grain morphology in individual samples. The presence of plate-shaped and tube-shaped grains was found. As the graphitization temperature of the starting material increases (2400 and 3000 °C), the specific surface area in the graphitization products decreases. The total pore volume in the samples after the graphitization process was significantly lower than the pore volume of active carbons produced from other unburned carbon. Average pore diameter is similar to the pore diameter in active carbons. The reflectance value of the matrix for the sample graphitized at 3000 °C is characteristic for graphite. Unburned carbon from Polish fly ash can be used as the starting material for graphitization.
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Weekley, Carl W., and Eric S. Menges. "Burning creates contrasting demographic patterns in Polygala lewtonii (Polygalaceae): a cradle-to-grave analysis of multiple cohorts in a perennial herb." Australian Journal of Botany 60, no. 4 (2012): 347. http://dx.doi.org/10.1071/bt11271.
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Fire drives the population dynamics of many plants. By following successive cohorts of Polygala lewtonii Small (Polygalaceae), a short-lived herb endemic to fire-maintained Florida sandhills, in both burned and unburned microsites, we investigated how fire affected vital rates throughout cohort lifetimes. We followed cohorts from before to 6 years after a prescribed fire in 220 25-cm-radius quadrats, recording survival and seedling recruitment quarterly, and growth and fecundity annually. Fire effects were most pronounced in the first 2 post-burn quarterly censuses, when cohorts in burned (v. unburned) quadrats had seven-fold higher seedling recruitment, significantly higher seedling survival, and a 16.7% gain (v. 1.2% loss) in quadrat occupancy. Plants in burned (v. unburned) quadrats also flowered earlier, were more likely to survive to reproduce and had longer lifespans. The negative effects of density on survival were relaxed in burned quadrats for the first 2 censuses. Burning creates contrasting demographic trajectories for burned v. unburned cohorts. In burned microsites, higher seedling recruitment and survival, earlier flowering and longer lifespans combine to produce a greater contribution to the seedbank and, thus, to population viability. The present study documents the pyro-demographic mechanisms linking the life history of a perennial herb with a frequent fire regime.
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Zhang, Huixian, Daniel Fiifi Tawia Hagan, Ricardo Dalagnol, and Yi Liu. "Forest Canopy Changes in the Southern Amazon during the 2019 Fire Season Based on Passive Microwave and Optical Satellite Observations." Remote Sensing 13, no. 12 (June 8, 2021): 2238. http://dx.doi.org/10.3390/rs13122238.
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Canopy dynamics associated with fires in tropical forests play a critical role in the terrestrial carbon cycle and climate feedbacks. The aim of this study was to characterize forest canopy dynamics in the southern Amazon during the 2019 fire season (July–October) using passive microwave-based vegetation optical depth (VOD) and three optical-based indices. First, we found that precipitation during July–October 2019 was close to the climatic means, suggesting that there were no extreme hydrometeorological events in 2019 and that fire was the dominant factor causing forest canopy anomalies. Second, based on the active fire product (MCD14ML), the total number of active fires over each grid cell was calculated for each month. The number of active fires during the fire season in 2019 was above average, particularly in August and September. Third, we compared the anomalies of VOD and optical-based indices (the normalized difference vegetation index (NDVI), the enhanced vegetation index (EVI), and the normalized burn ratio (NBR)) against the spatiotemporal distribution of fires during July–October 2019. Spatially, the location with a concentrated distribution of significant negative VOD anomalies was matched with the grid cells with fire activities, whereas the concentrated distribution of strong negative anomalies in optical-based indices were found in both burned and unburned grid cells. When we focused on the temporal pattern over the grid cells with fire activity, the VOD and the optical-based indices behaved similarly from July to October 2019, i.e., the magnitude of negative anomalies became stronger with increased fire occurrences and reached the peak of negative anomalies in September before decreasing in October. A discrepancy was observed in the magnitude of negative anomalies of the optical-based indices and the VOD; the magnitude of optical-based indices was larger than the VOD in August–September and recovered much faster than the VOD over the grid cells with relatively low fire activity in October. The most likely reason for their different responses is that the VOD represents the dynamics of both photosynthetic (leaf) and nonphotosynthetic (branches) biomass, whereas optical-based indices are only sensitive to photosynthetic (leaf) active biomass, which recovers faster. Our results demonstrate that VOD can detect the spatiotemporal of canopy dynamics caused by fire and postfire canopy biomass recovery over high-biomass rainforest, which enables more comprehensive assessments, together with classic optical remote sensing approaches.
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Kong, Xiang Wen, Li Li Ren, Xia Ai, and Jing Zhang. "Preparation of a New Unburned Brick from Ti-Bearing Blast Furnace Slag and PVA Modified by Epikote." Advanced Materials Research 785-786 (September 2013): 328–31. http://dx.doi.org/10.4028/www.scientific.net/amr.785-786.328.
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A new unburned brick was prepared from the Ti-bearing blast furnace slag as an aggregate and PVA modified by epikote as cementitious materials. The effects of modified PVA and auxiliaries on compressive strength of unburned brick were studied by the orthogonal test method. The results show that samples have better properties and low cost when the samples have a composition of slag dosage 72 %, modified PVA dosage 6%, auxiliary 1 dosage 6%, auxiliary 2 dosage 10%, water 6% and the process conditions of preparing the brick sample were mixing time 1 h, forming time 10 min, forming pressure 40 MPa, and curing time 7 d. The study reveals that the samples properties can meet the standard requirements of excellent grade products (MU20) in GB11945-1999.
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Chakraborty, Nilanjan, and Andrei N. Lipatnikov. "Statistics of Conditional Fluid Velocity in the Corrugated Flamelets Regime of Turbulent Premixed Combustion: A Direct Numerical Simulation Study." Journal of Combustion 2011 (2011): 1–13. http://dx.doi.org/10.1155/2011/628208.
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The statistics of mean fluid velocity components conditional in unburned reactants and fully burned products in the context of Reynolds Averaged Navier Stokes (RANS) simulations have been studied using a Direct Numerical Simulation database of statistically planar turbulent premixed flame representing the corrugated flamelets regime combustion. Expressions for conditional mean velocity and conditional velocity correlations which are derived based on a presumed bimodal probability density function of reaction progress variable for unity Lewis number flames are assessed in this study with respect to the corresponding quantities extracted from DNS data. In particular, conditional surface averaged velocities(ui)¯Rsand the velocity correlations(uiu)j¯Rsin the unburned reactants are demonstrated to be effectively modelled by the unconditional velocities(ui)¯Rand velocity correlations(uiuj)¯R, respectively, for the major part of turbulent flame brush with the exception of the leading edge. By contrast, conditional surface averaged velocities(ui)¯Psand the velocity correlations(uiu)j¯Psin fully burned products are shown to be markedly different from the unconditional velocities(ui)¯Pand velocity correlations(uiuj)¯P, respectively.
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Abellán García, Joaquín, Nancy Torres Castellanos, Jaime Antonio Fernandez Gomez, and Andres Mauricio Nuñez Lopez. "Ultra-high-performance concrete with local high unburned carbon fly ash." DYNA 88, no. 216 (February 22, 2021): 38–47. http://dx.doi.org/10.15446/dyna.v88n216.89234.
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Ultra-high-performance concrete (UHPC) is a kind of high-tech cementitious material with superb mechanical and durability properties compared to other types of concrete. However, due to the high content of cement and silica fume used, the cost and environmental impact of UHPC is considerably higher than conventional concrete. For this reason, several efforts around the world have been made to develop UHPC with greener and less expensive local pozzolans. This study aimed to design and produce UHPC using local fly ash available in Colombia. A numerical optimization, based on Design of Experiments (DoE) and multi-objective criteria, was performed to obtain a mixture with the proper flow and highest compressive strength, while simultaneously having the minimum content of cement. The results showed that, despite the low quality of local fly ashes in Colombia, compressive strength values of 150 MPa without any heat treatment can be achieved.
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Gonzalez, S. L., L. Ghermandi, and D. V. Peláez. "Growth and reproductive post-fire responses of two shrubs in semiarid Patagonian grasslands." International Journal of Wildland Fire 24, no. 6 (2015): 809. http://dx.doi.org/10.1071/wf14134.
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Variation in fire intensity affects the post-fire survival and growth of shrubs. We examined effects of maximum fire temperature (a proxy for fire intensity) on the survival, growth and reproductive performance of the shrubs Mulinum spinosum and Senecio bracteolatus at 1 and 2 years post-fire in north-west Patagonian grasslands. We applied two fire temperature treatments to plants of each species. All M. spinosum plants survived fire treatments but high fire temperature notably decreased survival of S. bracteolatus. Bud position and plant architecture probably influenced shrub survival. During the first growing season, M. spinosum did not produce seeds whereas S. bracteolatus plants burned at low temperature produced three times more seeds and bigger seeds than unburned plants. Also, seeds from burned plants of S. bracteolatus had higher germinability than seed from unburned plants. High survival and resprouting capacity of M. spinosum even after high fire intensity indicate that this species might be less affected by changes in fire regime.
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Călătan, Gabriela, Andreea Hegyi, Elvira Grebenisan, and Anamaria Cătălina Mircea. "Possibilities of Recovery of Industrial Waste and By-Products in Adobe-Brick-Type Masonry Elements." Proceedings 63, no. 1 (December 9, 2020): 1. http://dx.doi.org/10.3390/proceedings2020063001.
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The purpose of this study is to search for possibilities to capitalize on industrial waste, which occupies huge storage spaces. This paper presents an experimental study on the possibility and efficiency of this industrial waste in the composition of clay mixtures suitable for making unburned clay bricks. Living in harmony with nature is part of sustainable development. For this purpose, six compositions based on clay and industrial waste were made. The studied industrial wastes were: ash from the Mintia thermal power plant, Romania, limestone sludge, gypsum sludge, and damped waste from the processing of imported ore.
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Zethsen, Karen Korning. "Has Globalisation Unburdened the Translator?" Meta 55, no. 3 (December 9, 2010): 545–57. http://dx.doi.org/10.7202/045076ar.
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In an age where globalisation has become an everyday word it is quite natural to assume that the task of the translator has become much less complicated. As people around the globe increasingly buy the same standardised products, are entertained by the same American films and listen to the same music, it is often taken for granted that generally they have the same frame of reference, that they share a cultura franca. If this is so, translation should indeed be more straightforward as cultural concepts will have a ready name in each language. It would be nonsensical to argue that no global culture exists, but it seems relevant to ask whether the global culture is the only culture or whether it is only a fragment of the cultural framework of a person. This article aims at discussing and defining the concept of cultura franca and whether globalisation has in fact unburdened the translator.
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Zhang, Yinzhi, Zhe Lu, M. Mercedes Maroto-Valer, John M. Andrésen, and Harold H. Schobert. "Comparison of High-Unburned-Carbon Fly Ashes from Different Combustor Types and Their Steam Activated Products." Energy & Fuels 17, no. 2 (March 2003): 369–77. http://dx.doi.org/10.1021/ef0201782.
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Dixon-Lewis, Graham. "Laminar premixed flame extinction limits. II Combined effects of stretch and radiative loss in the single flame unburnt-to-burnt and the twin-flame unburnt-to-unburnt opposed flow configurations." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 462, no. 2066 (November 29, 2005): 349–70. http://dx.doi.org/10.1098/rspa.2005.1549.
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Numerical methods have been used to examine the effects of (a) stretch alone, and (b) a combination of stretch and radiative loss, on the properties and extinction limits of methane–air flames near the lean flammability limit. Two axisymmetric opposed flow configurations were examined: (i) a single flame, unburnt-to-burnt (UTB) system in which fresh reactant is opposed by a stream of its own combustion products at the unburnt temperature, and (ii) a symmetric unburnt-to-unburnt (UTU) configuration where twin flames are supported back to back, one on each side of the stagnation plane. The maximum temperatures achieved in the UTB system are always away from the stagnation plane. For a fixed sufficiently sub-adiabatic product stream temperature, increasing flame stretch or gaseous radiative emissivity, or a combination of both, will augment downstream conductive heat loss, leading to a reduction in T max and eventually to an abrupt extinction if the loss rate is sufficiently large. The UTU system is more complex, and offers the additional possibility of purely stretch-induced extinctions where the flames are forced together back-to-back so that radiative loss is restricted to upstream of the maximum temperature. Extinction in these cases occurs by straightforward truncation of the hot sides of the reaction zones. At sufficiently low stretch, near and at the standard flammability limit, radiative loss makes a major contribution to the overall extinction mechanism in both configurations. The detailed effects of flame stretch on extinction behaviour depend on the diffusion characteristics within the near-limit mixtures, in particular the Lewis number, Le, of the deficient component. The effect of high stretch is always to attenuate the composition range of flammability. However, for Le<1 this range is extended at low to moderate stretch, particularly in the UTU situations where downstream radiative loss is not present at extinction. Lewis number effects for a global methane–air chemistry, and with assumed Le≥1, are discussed in the light of numerical results previously presented by Ju et al . ( Ju et al . 1998 Combust. Flame 113 , 603–614).
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Chakraborty, Nilanjan. "Influence of Thermal Expansion on Fluid Dynamics of Turbulent Premixed Combustion and Its Modelling Implications." Flow, Turbulence and Combustion 106, no. 3 (March 2021): 753–848. http://dx.doi.org/10.1007/s10494-020-00237-8.
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AbstractThe purpose of this paper is to demonstrate the effects of thermal expansion, as a result of heat release arising from exothermic chemical reactions, on the underlying turbulent fluid dynamics and its modelling in the case of turbulent premixed combustion. The thermal expansion due to heat release gives rise to predominantly positive values of dilatation rate within turbulent premixed flames, which has been shown to have significant implications on the flow topology distributions, and turbulent kinetic energy and enstrophy evolutions. It has been demonstrated that the magnitude of predominantly positive dilatation rate provides the measure of the strength of thermal expansion. The influence of thermal expansion on fluid turbulence has been shown to strengthen with decreasing values of Karlovitz number and characteristic Lewis number, and with increasing density ratio between unburned and burned gases. This is reflected in the weakening of the contributions of flow topologies, which are obtained only for positive values of dilatation rate, with increasing Karlovitz number. The thermal expansion within premixed turbulent flames not only induces mostly positive dilatation rate but also induces a flame-induced pressure gradient due to flame normal acceleration. The correlation between the pressure and dilatation fluctuations, and the vector product between density and pressure gradients significantly affect the evolutions of turbulent kinetic energy and enstrophy within turbulent premixed flames through pressure-dilatation and baroclinic torque terms, respectively. The relative contributions of pressure-dilatation and baroclinic torque in comparison to the magnitudes of the other terms in the turbulent kinetic energy and enstrophy transport equations, respectively strengthen with decreasing values of Karlovitz and characteristic Lewis numbers. This leads to significant augmentations of turbulent kinetic energy and enstrophy within the flame brush for small values of Karlovitz and characteristic Lewis numbers, but both turbulent kinetic energy and enstrophy decay from the unburned to the burned gas side of the flame brush for large values of Karlovitz and characteristic Lewis numbers. The heat release within premixed flames also induces significant anisotropy of sub-grid stresses and affects their alignments with resolved strain rates. This anisotropy plays a key role in the modelling of sub-grid stresses and the explicit closure of the isotropic part of the sub-grid stress has been demonstrated to improve the performance of sub-grid stress and turbulent kinetic energy closures. Moreover, the usual dynamic modelling techniques, which are used for non-reacting turbulent flows, have been shown to not be suitable for turbulent premixed flames. Furthermore, the velocity increase across the flame due to flame normal acceleration may induce counter-gradient transport for turbulent kinetic energy, reactive scalars, scalar gradients and scalar variances in premixed turbulent flames under some conditions. The propensity of counter-gradient transport increases with decreasing values of root-mean-square turbulent velocity and characteristic Lewis number. It has been found that vorticity aligns predominantly with the intermediate principal strain rate eigendirection but the relative extents of alignment of vorticity with the most extensive and the most compressive principal strain rate eigendirections change in response to the strength of thermal expansion. It has been found that dilatation rate almost equates to the most extensive strain rate for small sub-unity Lewis numbers and for the combination of large Damköhler and small Karlovitz numbers, and under these conditions vorticity shows no alignment with the most extensive principal strain rate eigendirection but an increased collinear alignment with the most compressive principal strain rate eigendirection is obtained. By contrast, for the combination of high Karlovitz number and low Damköhler number in the flames with Lewis number close to unity, vorticity shows an increased collinear alignment with the most extensive principal direction in the reaction zone where the effects of heat release are strong. The strengthening of flame normal acceleration in comparison to turbulent straining with increasing values of density ratio, Damköhler number and decreasing Lewis number makes the reactive scalar gradient align preferentially with the most extensive principal strain rate eigendirection, which is in contrast to preferential collinear alignment of the passive scalar gradient with the most compressive principal strain rate eigendirection. For high Karlovitz number, the reactive scalar gradient alignment starts to resemble the behaviour observed in the case of passive scalar mixing. The influence of thermal expansion on the alignment characteristics of vorticity and reactive scalar gradient with local principal strain rate eigendirections dictates the statistics of vortex-stretching term in the enstrophy transport equation and normal strain rate contributions in the scalar dissipation rate and flame surface density transport equations, respectively. Based on the aforementioned fundamental physical information regarding the thermal expansion effects on fluid turbulence in premixed combustion, it has been argued that turbulence and combustion modelling are closely interlinked in turbulent premixed combustion. Therefore, it might be necessary to alter and adapt both turbulence and combustion modelling strategies while moving from one combustion regime to the other.
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Norman, AB, TA Perfetti, PF Perfetti, and RG Hayworth. "The Heat of Combustion of Tobacco and Carbon Oxide Formation." Beiträge zur Tabakforschung International/Contributions to Tobacco Research 19, no. 6 (July 1, 2001): 297–307. http://dx.doi.org/10.2478/cttr-2013-0716.
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AbstractRecent studies demonstrated a relationship between mass burn rates of straight-grade cigarettes and heats of combustion of the tobacco materials. In the present work, relationships between measured heats of combustion and elemental composition of the tobacco materials were further analyzed. Heats of combustion measured in oxygen were directly correlated with the carbon and hydrogen content of the tobacco materials tested. Ash content of the materials was inversely related to the heats of combustion. The water insoluble residues from exhaustively extracted tobacco materials showed higher heats of combustion and higher carbon content than the non-extracted materials, confirming a direct relationship between carbon content and heat of combustion. A value for the heat of formation of tobacco was estimated (1175 cal/g) from the heat of combustion data and elemental analysis results. The estimated value for heat of formation of tobacco appears to be constant regardless of the material type. Heat values measured in air were uniformly lower than the combustion heats in oxygen, suggesting formation of CO and other reaction products. Gases produced during bomb calorimetry experiments with five tobacco materials were analyzed for CO and CO2 content. When the materials were burned in oxygen, no CO was found in the gases produced. Measured heats of combustion matched estimates based on CO2 found in the gas and conversion of the sample hydrogen content to water. Materials burned in air produced CO2 (56% to 77% of the sample carbon content) and appreciable amounts of CO (7% to 16% of the sample carbon content). Unburned residue containing carbon and hydrogen was found in the air combustion experiments. Estimated heat values based on amounts of CO and CO2 found in the gas and water formed from the hydrogen lost during combustion in air were higher than the measured values. These observations indicate formation of products containing hydrogen when the materials were burned in air. CO and CO2 formation during combustion in air were related to the composition of the tobacco materials. Materials with high carbon and low ash content showed evidence of higher CO2 formation. Amounts of unburned residue also varied with material composition. Thus, energy released during tobacco combustion in air is related to material-dependent formation of reaction products in addition to the carbon oxides and to the quantity of unburned material.
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Kong, Xiang Wen, and Dan Wang. "Preparation of Unburned Brick from the High Titania Blast Furnace Slag and Styrene-Acrylate Emulsion." Advanced Materials Research 512-515 (May 2012): 2982–85. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.2982.
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The unburned brick was prepared by using the high titania blast furnace slag as an aggregate, styrene-acrylate emulsion as cementing materials and two admixtures. Factors such as amounts of admixtures and styrene-acrylate emulsion, forming pressure and curing time on the properties of the products were studied. The optimal process conditions for preparing the brick sample were as follows: mass fractions of the slag, styrene-acrylate emulsion, admixture 1, admixture 2 and water were respectively 70%, 8%, 8%, 10% and 4%, forming pressure 30 MPa, curing time 7 d. The properties of the brick sample prepared under these process conditions are better than that of MU 25 in GB / T 2542 - 2003.
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Aldrich, Alyssa, Edna Gennarino-Lopez, Gabriel Odugbesi, Kaylandra Woodside, and Shokouh Haddadi. "Screening Carpet Substrate Interferences in Arson Identification by Solid Phase Microextraction and Gas Chromatography-Mass Spectrometry." Separations 7, no. 4 (November 19, 2020): 63. http://dx.doi.org/10.3390/separations7040063.
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The sample analysis and data interpretation is the most challenging step of fire debris analysis, due to the presence of combustion and pyrolysis products in the substrate material. In this study, a headspace solid phase microextraction (HS-SPME) procedure was applied to the extraction of combustion and pyrolysis products from three commonly used carpet substrate materials, made of nylon 6,6 and polyesters. Each carpet sample was burned with and without two different ignitable liquids (ILs), i.e., gasoline and kerosene, and the Total Ion Chromatograms (TICs) and Extracted Ion Profiles of characteristic class compounds of ILs were obtained and compared to those of unburned neat ILs, using gas-chromatography mass spectrometry (GC-MS), to study the possible interferences of these substrate materials in fire debris analysis.
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Subbotin, V. A. "Mixing of unburnt gas with reaction products as an explosion mechanism." Combustion, Explosion, and Shock Waves 29, no. 3 (May 1993): 400–403. http://dx.doi.org/10.1007/bf00797669.
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Kato, Akira, L. Monika Moskal, Jonathan L. Batchelor, David Thau, and Andrew T. Hudak. "Relationships between Satellite-Based Spectral Burned Ratios and Terrestrial Laser Scanning." Forests 10, no. 5 (May 23, 2019): 444. http://dx.doi.org/10.3390/f10050444.
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Three-dimensional point data acquired by Terrestrial Lidar Scanning (TLS) is used as ground observation in comparisons with fire severity indices computed from Landsat satellite multi-temporal images through Google Earth Engine (GEE). Forest fires are measured by the extent and severity of fire. Current methods of assessing fire severity are limited to on-site visual inspection or the use of satellite and aerial images to quantify severity over larger areas. On the ground, assessment of fire severity is influenced by the observers’ knowledge of the local ecosystem and ability to accurately assess several forest structure measurements. The objective of this study is to introduce TLS to validate spectral burned ratios obtained from Landsat images. The spectral change was obtained by an image compositing technique through GEE. The 32 plots were collected using TLS in Wood Buffalo National Park, Canada. TLS-generated 3D points were converted to voxels and the counted voxels were compared in four height strata. There was a negative linear relationship between spectral indices and counted voxels in the height strata between 1 to 5 m to produce R2 value of 0.45 and 0.47 for unburned plots and a non-linear relationship in the height strata between 0 to 0.5m for burned plots to produce R2 value of 0.56 and 0.59. Shrub or stand development was related with the spectral indices at unburned plots, and vegetation recovery in the ground surface was related at burned plots. As TLS systems become more cost efficient and portable, techniques used in this study will be useful to produce objective assessments of structure measurements for fire refugia and ecological response after a fire. TLS is especially useful for the quick ground assessments which are needed for forest fire applications.
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Bielowicz, Barbara. "Petrographic Characteristics of Coal Gasification and Combustion by-Products from High Volatile Bituminous Coal." Energies 13, no. 17 (August 25, 2020): 4374. http://dx.doi.org/10.3390/en13174374.
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The coal was gasified in a fluidized bed reactor with CO2 as a gasifying agent at 889–980 °C. The coal and gasification residue produced during gasification was burned at temperatures up to 900 °C. The petrographic analysis, gasification residues, and fly and bottom ash resulting from the combustion of coal and chars showed the efficiency of the gasification and combustion processes. The gasification residue primarily comprised inertoids and crassinetwork, which accounted for 60% of the sample. The analysis of the petrographic composition of fly ash revealed that the fly ash formed during the combustion of gasification residue had a higher mineral content. The fly ash from the combustion of gasification products contained significantly less unburned coal compared to that from coal. The samples of the bottom ash from coal combustion were composed of approximately 25% organic matter, most of which was chars. The bottom ash formed from the combustion of coal gasification products was composed mainly of mineral matter (95% or higher). The obtained results have significant implications in determining future waste management strategies.
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Han, Hong Jing, Yan Guang Chen, Jia Lu, Ting Ting Xu, Yong Hui Jiang, and Jia Li Bai. "Investigation of Removing Iron from Fly Ash." Advanced Materials Research 807-809 (September 2013): 1194–97. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.1194.
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Fly ash, as an environmental pollutant, is generated in the process of coal combustion for energy conversion. It has been widely used in so many applications, such as, preparation of zeolite, extracting alumina, and so on. Iron composition has some side-effect on the purity and whiteness of the products prepared form fly ash. In this paper, removal of unburned carbon and iron composition was investigated. The results show that the carbon can be removed completely from fly ash after calcination under 800°C for 2h. Acid leaching was used to remove iron from the fly ash after decarburization. The optimum processing parameter is, hydrochloric acid concentration 5mol·L-1, reaction temperature 80°C and reaction time 2h.