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Sindt, Justin J. "Factors influencing the utilization of steam-flaked corn /." Search for this dissertation online, 2004. http://wwwlib.umi.com/cr/ksu/main.
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Moulton, Anne L. "Lowton's lithics, making sense of the Vickers flaked stone collection." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ32198.pdf.
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Phelps, Steven Kirk. "Nutrient characterization of color modified and unaltered flaked turkey thigh meat." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/46058.
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Flaked, skinless and boneless turkey thighs were successively washed in 0.03M sodium phosphate buffers at pH 5.8, 7.4 and 8.0. Proximate, mineral and riboflavin composition, as well as protein efficiency ratio (PER) and apparent digestibility (AD) using the rat bioassay technique were determined for three replications. The color modified tissue (CMT) had a higher (P=0.0429) moisture content and less (P=0.0527, 0.1240 and 0.0047, respectively) crude protein, fat and ash than flaked thigh (THI). Percentage of iron, magnesium, phosphorous, potassium and manganese decreased (P=0.0187) after color modification, whereas calcium, zinc and copper concentrations did not change (P=0.1184) and sodium increased (P=0.0058). Riboflavin was reduced by 30%.
The PER of CMT evaluated was lower (P=0.0318) than THI, but higher (P=0.0001) than either casein or egg albumin diets. AD of CMT was 90.7% which is comparable to other meat products. The overall nutritional evaluation of CMT determined that it has potential as a raw material in further processed foods.
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Khreisheh, Nada Nazem. "The acquisition of skill in early flaked stone technologies : an experimental study." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/14986.
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This thesis describes the experimental work carried out as part of the Learning to be Human Project, investigating skill and learning in early flaked stone technologies. A group of 16 volunteers were studied as they learnt skills in Oldowan style flaking, Acheulean handaxe technology and Levallois preferential flake technologies. Aptitude, practice hours and hours spent in taught sessions were recorded and skill in each of these technologies was assessed at regular intervals. This information was used to answer questions concerning the acquisition of high level skill in these technologies, the role of practice, teaching and aptitude in determining skill in terms of connaissance and savoir-faire and the archaeological visibility of skill. At a more in depth level the significance of these findings for cognitive capacities of early hominins and the evolution of modern human brains and intelligence was assessed. The results of these experiments allowed the identification of the greater impact of teaching on Acheulean handaxe and Levallois technology compared to Oldowan style flaking. Technologically focussed teaching was shown to be essential for achieving high level skill in handaxe technology while all knapping contributed to the skill achieved in Oldowan style flaking and Levallois technology. In terms of aptitude, previous craft experience and contact with flaked stone assemblages most affected skill achieved in handaxe and Oldowan technologies while spatial ability best determined skill in Levallois. The findings of the connaissance and savoir-faire analysis have indicated that the differences seen between Oldowan and Acheulean technology are predominantly physical in nature, while the differences between Levallois and the earlier technologies are cognitive. This suggests a greater cognitive capacity for the Neanderthal Levallois manufacturers in contrast with the earlier hominin species. The results have, however, highlighted problems with a strict dichotomy between physical and cognitive skills. A number of material markers that could be related to skill were identified. Future work has been identified that could provide a fuller understanding of these findings.
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Alio, Abdoulaye 1953. "Splanchnic nitrogen metabolism by growing beef steers fed sorghum grain flaked at various densities." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/289222.
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Growing beef steers were used in completely randomized block designs to evaluate effect of processing method, dry-rolled (DR) versus steam-flaked (SF) sorghum, and degree of processing (flaking density) of corn and sorghum grain on nitrogen (N) digestion and post-absorptive N metabolism. In experiments (Exp.) 1 and 2, seven duodenally and ileally cannulated steers were used to investigate N digestibilities. Experimental diets contained 77% grain: Exp. 1, DR or SF sorghum at densities of 437, 360 and 283 g/L (SF34, SF28, SF22); Exp. 2, corn at two flake densities (SF34 and SF22). Nitrogen intakes by steers fed sorghum (142 g/d) and corn (149 g/d) diets were similar among treatments. Steers fed SF compared to DR, increased ruminal (P =.04) DM digestibility. Microbial protein flow to the duodenum averaged 10% greater for SF vs DR. Reducing flaking density of sorghum grain linearly increased (P .05) ruminal DM and tended to increase linearly ruminal feed N (P =.11), total tract DM and N digestibilities and microbial efficiency (P .08). Unexpectedly, flake density did not affect DM or N digestibilities of SF corn diets by steers. In Exp. 3, eight steers implanted with indwelling catheters were used to measure blood flow, net absorption and uptake of ammonia-N, urea-N (UN) and alpha-amino N (AAN) across portal-drained viscera (PDV), hepatic and total splanchnic tissues. Experimental diets were the same as those in Exp. 1. Six arterial, portal and hepatic blood samples were collected per day at 2 h intervals for each diet and steer. Daily DM and N intakes averaged 7.0 kg and 142 g, respectively. Decreasing flake density of SF sorghum linearly increased net absorption of AAN (P =.04) and UN recycling to the gut (P =.02). Net UN recycling to the gut averaged 38% of N intake across treatments. Steers fed SF compared to DR decreased (P =.03) net splanchnic UN output (33 vs 50 g/d). The improved N retention and lower splanchnic UN output, contingent with greater ruminal microbial protein synthesis and flow to intestines may explain in part the observed higher performance of cattle fed SF compared to DR sorghum. Based on improved total tract N digestibilities and greater net absorption of AAN and UN recycling to the gut, optimum flake density for SF sorghum grain was 283 g/L (SF22).
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Iversen, David Richard. "Testing the coastal decline model with flaked stone artifacts from the San Diego region of California." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Thesis/Spring2007/d_iversen_041607.pdf.
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Meadows, Richard Keith. "Crafting K'awil : a comparative analysis of Maya symbolic flaked stone assemblages from three sites in northern Belize /." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3034984.
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Harvatine, Dana Irene. "Effectiveness of Whole Linted Cottonseed as a Forage Substitute When Fed with Ground or Steam-Flaked Corn." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406811280.
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Sitta, Cristiane. "Aditivos (ionóforo e não ionóforo), processamento de grãos de milho e concentrações de fibra insolúvel em detergente neutro (FDN) de silagem de milho em dietas para bovinos em terminação." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11139/tde-22062016-161009/.
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Foram conduzidos dois experimentos com o intuito de se avaliar o desempenho, características de carcaça e parâmetros ruminais de bovinos Nelore recebendo dietas contendo grãos de milho flint processados de diferentes formas em associação a diferentes aditivos e níveis de FDN de silagem de milho (FDNf). No Experimento 1, 239 tourinhos (PCI=350±26,79kg) foram alojados em 40 baias de acordo com o peso corporal inicial e receberam dietas contendo dois tipos de processamento dos grãos de milho (moagem fina e floculação) e diferentes aditivos (monensina sódica; 25 ppm e formulação A062 a base de virginiamicina; produto teste, não comercial, fornecido pela Ourofino Saúde Animal; nas dosagens de 17 e 25 ppm), totalizando 8 tratamentos. Os dados foram analisados pelo PROC MIXED do SAS. A floculação aumentou o peso final, o ganho de peso diário, a eficiência alimentar, o peso da carcaça quente e tendeu a aumentar o rendimento de carcaça em comparação a moagem fina. Houve tendência de interação entre processamento e fornecimento de aditivos para a ingestão de matéria seca e ganho de peso diário. A floculação reduziu o teor de amido fecal, aumentou a digestibilidade do amido no trato total, aumentou os valores de energia liquida para manutenção e ganho da dieta e o numero médio de papilas ruminais. Os aditivos aumentaram a altura, largura e área das papilas e reduziram a espessura de faixa de queratina em relação ao tratamento controle. Houve tendência das formulações a base de virginiamicina aumentarem o peso da carcaça quente dos animais em comparação com a monensina sódica, mas não em relação ao tratamento controle sem aditivo. A floculação foi mais efetiva para aumentar a digestiblidade do amido no trato total, o valor energético do milho e o desempenho dos bovinos enquanto que os aditivos não foram efetivos para aumentar o valor energético das dietas e a eficiência alimentar dos animais. No Experimento 2, 237 tourinhos (PCI=350±28,49kg) foram alojados em 32 baias de acordo com o peso corporal inicial e receberam dietas contendo dois tipos de processamento (moagem grosseira e floculação) e diferentes níveis de FDNf (4; 7; 10 e 13% MS), totalizando 8 tratamentos. Os dados foram analisados pelo PROC MIXED do SAS. A floculação tendeu a aumentar a eficiência alimentar, o peso da carcaça quente e a espessura de gordura subcutânea, reduziu o teor de amido fecal, aumentou a digestibilidade do amido no trato total como também aumentou os valores de energia liquida para manutenção e para ganho das dietas. Os níveis de FDNf afetaram ingestão de matéria seca e o peso da carcaça quente independente do método de processamento. Houve tendência de aumento linear no GPD e tendência de redução quadrática na eficiência alimentar com inclusão crescente de FDNf. A inclusão de silagem de milho em dietas com alto teor de milho flint reduziu a eficiência alimentar dos animais, mas aumentou o peso da carcaça quente. A floculação aumentou o valor energético do cereal para tourinhos Nelore em dietas com alto teor de energia.Two experiments were conducted to evaluate animal performace, carcass characteristics and ruminal parameters of Nellore bulls fed with diets containing flint corn processed by different methods in association with additives and FDN levels of corn silage (FDNf).In the first experiment, two hundred and trhirty nine Nellore bulls (IBW=350±26.79kg) were blocked based on their initial body weight and randomly divided into 40 pens. The objective was to evaluate two different corn processing methods (fine ground and steam-flaked corn) and additives (monensin; 25 ppm and A062 formulation based on virginiamycin; test product, non-commercial, provided by Ourofino Saude Animal; 17 or 25 ppm), a total of 8 treatments. Data were analyzed using PROC MIXED of SAS. Steam-flaking increased the final body weight, average daily gain, feed efficiency, hot carcass weight and tended to increase the carcass yield. There was a tendency of interaction between corn processing and feed additives for dry matter intake and daily weight gain. Steam-flaking decreased fecal starch, increased total tract starch digestibility and increased net energy for maintenance and net energy for gain values of the diet and increased average number of papillae. Additives increased papillae leight, width, and area and decreased keratin strip thickness in comparison to the control diet. There was a tendency of A062 formulations based on virginiamycin to increase hot carcass weight in comparison to monensin, but not in relation to the control treatment, without additive. Steam-flaking was more effective to increase total tract starch digestibility, corn energy values and animal performace while the feed additives were not effective to increase the net energy value of the diets and animal feed efficiency. In the second experiment, two hundred and thirty seven Nellore bulls (IBW=350±28.49kg) were blocked based on their initial body weight and randomly divided into 32 pens. The objective was to evaluate two different corn processing methods (ground and steam-flaked corn) and four FDNf levels (4; 7; 10; 13 %DM), a total of 8 treatments. Data were analyzed using PROC MIXED of SAS. Steam flaking tended to increase feed efficiency, hot carcass weight and fat thickness, decreased fecal starch, increased total tract starch digestibility and net energy for maintenance and net energy for gain diet values. Independent of corn processing, FDNf levels affected dry matter intake and hot carcass weight. There was a tendency of linear increase in daily weight gain and tendency of quadractic reduction on feed efficiency increasing FDNf levels. Corn silage in high grain diets decreased animal feed efficiency, but increased hot carcass weight. Steam-flaking increased the cereal energy value for Nellore bulls fed grain concentrate diets.
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Lozano-Ascencio, Oscar German 1956. "Post-absorptive metabolism of energy-yielding nutrients and starch digestibility by steers fed sorghum grain flaked at different densities." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282356.
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Objectives were to determine the effects of feeding dry-rolled (DR) vs steam-flaked (SF) sorghum grain and degree of processing (flake density, FD) of corn and sorghum grain on site and extent of starch digestion and post-absorptive metabolism of energy-yielding nutrients in steers fed 77% grain. The design for each trial was a randomized block. Seven steers (400 kg) with duodenal and ileal cannulas were used to determine corn and sorghum starch digestibilities (Cr ratio, 3-d collection). Steers fed SF versus DR sorghum increased starch digestibility in the rumen (23%; P < .01), total tract (2.3%; P < .01), and in the small intestine (6%; P < .01, as percentage of starch entering duodenum). Decreasing flake density of SF sorghum grain increased linearly (P < .05) starch digestion (percentage of intake) in the rumen and total tract, and diminished linearly (P < .05) starch digestibilities post-ruminally and in the small intestine. Similar responses in starch digestibilities occurred by lowering FD of SF corn. Percent dietary corn or sorghum starch digestibility in the large intestine was less than 2% of intake. Feeding SF compared to DR sorghum did not alter net absorption and uptake or release of energy-yielding nutrient across SPL tissues. As expected, net absorption of glucose across portal-drained viscera (PDV) was negative (-.60 mol/d). Incrementally decreasing FD of SF sorghum linearly increased net PDV absorption of lactate (P =.04), glucose synthesis by the liver (P =.03), and SPL output of glucose (P < .01) and L-lactate (P =.03). Net propionate PDV absorption (P =.18), hepatic uptake (P =.21), and SPL output (P =.15) tended to be increased with lower FD. Increasing degree of grain processing, by incrementally decreasing FD, linearly increased ruminal and total tract starch digestibilities and net absorption of glucose precursors (propionate and L-lactate), resulting in increased hepatic synthesis and greater output of glucose from the gut and liver to the rest of the body. Based on these changes, the optimum FD for SF sorghum grain was 283 g/L (SF22).
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Poore, Matthew H. (Matthew Henry) 1959. "RUMEN PASSAGE RATES AND FIBER DIGESTIBILITIES FOR WHEAT STRAW, ALFALFA HAY AND FLAKED SORGHUM GRAIN IN MIXED DIETS FOR STEERS." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276423.
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Simmons, Stephanie Catherine. "Exploring Colonization and Ethnogenesis through an Analysis of the Flaked Glass Tools of the Lower Columbia Chinookans and Fur Traders." Thesis, Portland State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1560956.
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This thesis is an historical archaeological study of how Chinookan peoples at three villages and employees of the later multicultural Village at Fort Vancouver negotiated the processes of contact and colonization. Placed in the theoretical framework of practice theory, everyday ordinary activities are studied to understand how cultural identities are created, reinforced, and changed (Lightfoot et al. 1998; Martindale 2009; Voss 2008). Additionally uneven power relationships are examined, in this case between the colonizer and the colonized, which could lead to subjugation but also resistance (Silliman 2001). In order to investigate these issues, this thesis studies how the new foreign material of vessel glass was and was not used during the everyday practice of tool production.
Archaeological studies have found that vessel glass, which has physical properties similar to obsidian, was used to create a variety of tool forms by cultures worldwide (Conte and Romero 2008). Modified glass studies (Harrison 2003; Martindale and Jurakic 2006) have demonstrated that they can contribute important new insights into how cultures negotiated colonization. In this study, modified glass tools from three contact period Chinookan sites: Cathlapotle, Meier, and Middle Village, and the later multiethnic Employee Village of Fort Vancouver were examined. Glass tool and debitage analysis based on lithic macroscopic analytical techniques was used to determine manufacturing techniques, tool types, and functions. Additionally, these data were compared to previous analyses of lithics and trade goods at the study sites.
This thesis demonstrates that Chinookans modified glass into tools, though there was variation in the degree to which glass was modified and the types of tools that were produced between sites. Some of these differences are probably related to availability, how glass was conceptualized by Native Peoples, or other unidentified causes. This study suggests that in some ways glass was just another raw material, similar to stone, that was used to create tools that mirrored the existing lithic technology. However at Cathlapotle at least, glass appears to have been relatively scarce and perhaps valued even as a status item. While at Middle Village, glass (as opposed to stone) was being used about a third of the time to produce tools.
Glass tool technology at Cathlapotle, Meier, and Middle Village was very similar to the existing stone tool technology dominated by expedient/low energy tools; however, novel new bottle abraders do appear at Middle Village. This multifaceted response reflects how some traditional lifeways continued, while at the same time new materials and technology was recontextualized in ways that made sense to Chinookan peoples.
Glass tools increase at the Fort Vancouver Employee Village rather than decrease through time. This response appears to be a type of resistance to the HBC's economic hegemony and rigid social structure. Though it is impossible to know if such resistance was consciously acted on or was just part of everyday activities that made sense in the economic climate of the time.
Overall, this thesis demonstrates how a mundane object such as vessel glass, can provide a wealth of information about how groups like the Chinookans dealt with a changing world, and how the multiethnic community at Fort Vancouver dealt with the hegemony of the HBC. Chinookan peoples and the later inhabitants of the Fort Vancouver Employee Village responded to colonization in ways that made sense to their larger cultural system. These responses led to both continuity and change across time. (Abstract shortened by UMI.)
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Melo, Antonio Humberto Fleury de. "Processamento de grãos de milho e concentrações de fibra insolúvel em detergente neutro (FDN) do bagaço de cana in natura em dietas para bovinos em terminação." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11139/tde-29092015-113312/.
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A finalidade deste estudo foi avaliar o uso de rações contendo grão de milho flint processado através da moagem ou floculação combinados com dietas contendo 4; 7; 10 ou 13% de FDN do bagaço de cana in natura (BIN) (% da MS) e suas interações. Foram conduzidos 2 experimentos. No experimento 1: Os 240 tourinhos Nelore (PC=350±37,36 kg) foram alocados aleatoriamente em 32 baias em um arranjo fatorial 2 × 4. Os animais foram blocados com base no PC inicial. Os dados foram analisados pelo PROC MIXED do SAS. Não houve interação entre as concentrações de FDN de volumoso (FDNv) e métodos de processamento sobre o desempenho, características de carcaça, medidas morfométricas de papilas, energia das dietas, amido e comportamento ingestivo. A moagem do milho proporcionou maior ingestão de matéria seca (IMS), amido fecal, número de papilas, área de superfície absortiva do rúmen e representatividade das papilas na superfície absortiva e menor ingestão de energia, peso final, ganho de peso diário, pior eficiência alimentar, menor peso de carcaça, tempo de ruminação, energia nas dietas, digestibilidade do amido no trato total, energia do milho que a floculação. O aumento na concentração de FDNv nas dietas causaram efeito quadrático para IMS, redução linear no rendimento de carcaça, na energia das dietas e aumento linear no tempo de ruminação e mastigação. Houve interação entre as concentrações de FDNv e métodos de processamento para a medida de largura de papilas. Os resultados indicam que a floculação foi superior à moagem do milho para otimizar o desempenho dos tourinhos Nelore. No experimento 2: Foram utilizados 16 touros da raça Nelore (PC 443,52±24,80kg) canulados no rúmen, alocados aleatoriamente em 16 baias por dois períodos, em arranjo fatorial 2 x 4. Os dados foram analisados pelo PROC MIXED do SAS. Não houve interações entre processamento e concentrações dietéticas de FDNv. A floculação aumentou na digestibilidade da MS, dos carboidratos totais (CHOT), dos carboidratos não fibrosos (CNF), do amido, no %NDT nas dietas, na concentração de propionato no rúmen e na eficiência microbiana e gerou maior volume final da degradação de CNF, taxa de degradação de CNF e redução no N-NH3 no rúmen, na ingestão de N, N ureico no plasma, N urina, na excreção de N total e no lag time. O aumento do teor de volumoso nas dietas causou resposta quadrática para IMS e na ingestão e absorção de N e redução linear na digestibilidade da MS, dos CHOT, na proporção de propionato e concentração de AGV total e aumentos lineares no tempo de ruminação e mastigação. Em conclusão a floculação foi superior à moagem em melhorar a digestibilidade da MS, em aumentar a energia do milho e das dietas e em melhorar o metabolismo de N. Aumentos nos teores de FDNv estimulam a ruminação, mas diminui a eficiência da produção de energia no rúmen.The purpose of this study was to evaluate the use of feed containing flint corn grain processed by ground or steam-flaked combined with diets containing 4; 7; 10 or 13% roughage NDF (DM basis) using sugarcane bagasse as source of fiber and their interactions. Two experiments were conducted. In experiment 1: 240 Nellore bulls (BW=350±37,36 kg) were randomly divided into 32 pens in a factorial 2 × 4 arrangement of. The animals were blocked based on their initial BW. The data were analyzed using PROC MIXED of SAS. There was no interaction between the concentrations of sugarcane bagasse NDF and processing methods on performance, carcass characteristics, morphometric measures of papillae, energy diets, starch and feeding behavior. Ground corn provided higher dry matter intake (DMI), fecal starch, number of papillae, rumen absorptive surface area of the papillae and representativeness of the absorptive surface and lower energy intake, body weight, daily weight gain, worse feed efficiency, lower carcass weight, rumination time, energy in the diet, total-tract starch digestibility energy corn than steam-flaked. The increase in the concentration of NDF of BIN in the diets caused a quadratic effect for IMS, linear reduction in carcass yield, energy diets and linear increase in rumination and chewing. There was interaction between NDF concentrations and processing methods for papillae width measurements. The results indicate that the steam-flaked was higher than ground corn to optimize the performance of Nellore bulls. In experiment 2: sixteen Nellore bulls (BW=443,52±24,80 kg) fitted with rumen cannula, randomly allocated to 16 pens for two periods in a 2 x 4 factorial arrangement. The data were analyzed using PROC MIXED of SAS. There were no interactions between corn processing and dietary concentrations of sugarcane bagasse NDF. Steam-flaking increased in DM digestibility, total carbohydrates (TCHO), non-fiber carbohydrates (NFC), of starch, dietary TDN concentration, of rumen propionate concentration and microbial efficiency and provided higher final volume of degradation CNF, CNF degradation rate and decreased rumen N-NH3 concentration, N intake, N urea in plasma (PUN), N urine, total N excretion and lag time. Increasing dietary sugarcane bagasse NDF caused a quadratic response for DMI, N intake and N absorption and linear decrease in total tract apparent digestibility of DM and of TCHO, concentration of propionate and total VFA and linear increases in rumination and chewing. In conclusion, steam-flaking was greater than the ground corn to improve the digestibility of DM, to increase energy value of flint corn and feeding and improve N metabolism. Increasing dietary sugarcane bagasse NDF stimulate rumination, but decreases the efficiency of production energy in the rumen.
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Batalha, Camila Delveaux Araujo. "Processamento de grãos de milho para vacas leiteiras em pastagem tropical." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11139/tde-16042015-154024/.
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Sistemas baseados apenas na utilização de pastagens não atendem a demanda de nutrientes para altas produções individuais, a suplementação energética é necessária para corrigir as deficiências específicas de nutrientes dos animais em pastejo. Objetivou-se com este trabalho avaliara o feito da suplementação energética de vacas no terço médio da lactação com milho sob diferentes formas de processamento. Foram utilizadas 20 vacas em delineamento quadrado latino 4X4, submetidas aos seguintes tratamentos: T1: Milho moído; T2: Milho moído reidratado e ensilado; T3: Milho quebrado reidratado e ensilado e T4: Milho floculado. Os tratamentos foram oferecidos durante 64 dias, duas vezes ao dia e ajustado por período de acordo com a produção de leite De cada quadrado por subperiodo. Os dados foram analisados pelo procedimento MIXED do SAS (SAS, 2002). Os graus de liberdade para efeito de tratamento foram particionados em contrastes ortogonais com 1 grau de liberdade, para avaliar os seguintes grupos de médias: 1) MM vs. (RM e RQ), 2) Floc vs. MM e 3) RM vs. RQ. O tamanho médio de partículas dos tratamentos foi: 1,35 MM; 1,41 RM; 2,95 RQ e 5,95 mm para o floculado. As silagens continham teor de umidade de 35,4% RM e 34,8% RQ, e o período de estocagem de foi de 177 dias. Os animais foram mantidos em pastagem de capim elefante (Pennisetum purpureum cv. Cameroon). O CMS não diferiu entre os tratamentos (P>0,05). A DFDN foi superior para o milho floculado em contraste com MM. A DCNF foi maior para o RM que para o RQ (95,92 vs 93,59%). Os tempos de ruminação, ócio de pastejo não diferiram entre os tratamentos. Os diferentes processamentos não alteram a produção de leite e leite corrigido para 3,5% de gordura, produção e teores de gordura, caseína e lactose. O teor de NUL foi superior no tratamento milho moído que para o milho floculado (11,26 vs 9,80 mg/dL). O peso corporal, ECC e partição energética (ELLL, ELLM, Bal EL, ELL) não foram influenciados pelo tipo de processamento. As variáveis ruminais e sanguíneas avaliadas não foram influenciadas pelos diferentes processamentos. A substituição do milho moído por formas de processamento mais intensas não resultou melhora no desempenho.Systems based solely on use of pastures do not meet the nutrient demand for high individual production systems, thus, energy supplementation is needed to correct specific nutrient deficiencies of grazing animals. The aim of this work was to assess energy supplementation for middle lactation cows with corn under different forms of processing. Twenty cows were used in 4x4 Latin square design, and were subjected to the following treatments: T1: ground corn (GC), T2: rehydrated and ensiled ground corn (REGC), T3: rehydrated and ensiled cracked corn (RECC), and T4: flocked corn (FC). The treatments were offered during 64 days, twice a day and adjusted per period according to milk production of the square. The average size of particles of the treatments were: 1.35 mm for GC, 1.41 mm for REGC, 2.95 mm for RECC, and 5.95 mm for FC. Silages contained moisture content of 35.4% for REGC and 34.8% RECC, and the storage period was 177 days. The animals were kept on pasture of elephant grass (Pennisetum purpureum cv. Cameroon). The DMI did not differ between treatments (P>0.05). The digestibility of NDF was higher for FC, contrasting to GC. The digestibility of NSC was greater for CG than for RECC (95.92% vs. 93.59%).The rumination time, idleness grazing, did not differ among treatments. The different processes do not alter milk production and 3.5% milk fat, as well as production and contents of fat, casein and lactose. The MUN content was greater in GC and in FC (11.26 vs. 9.80 mg/dL). BW, body condition score and energy partition) were not influenced by the processing type. The ruminal and blood variables evaluated were not influenced by different processing methods. The replacement of GC for more intense processing forms did not result in improved performance.
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Mazzucco, Niccolò. "The human occupation of the southern central pyrenees in the sixth-third millennia cal BC: a traceological analysis of flaked stone assemblages." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/287893.
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El estudio del proceso de antropización del Pirineo durante la Prehistoria es relativamente reciente. Durante el siglo pasado la investigación arqueológica ha tratado solo de manera marginal las áreas de montaña del Pirineo, dirigiendo su atención hacia los monumentos megalíticos y abarcando su estudio desde un punto de vista étnico-cultural. Ha sido a partir de la última década que se ha empezado a abordar la ocupación humana de los espacios de montaña desde una perspectiva más amplia, integrando el estudio de sociedades humanas con el análisis del paisaje, del clima y de las mutuas interacciones.
Este trabajo se sitúa justo en esta línea de investigación. En él se presenta el estudio de nueve niveles de ocupación humana pertenecientes a cuatro yacimientos arqueológicos del Pirineo Central Meridional fechados entre el sexto y el tercer milenio cal BC. Se trata de yacimientos localizados en distintos ámbitos geográficos, siendo uno de los objetivos del presente trabajo el proponer una visión amplia del proceso de poblamiento de los espacios montañosos, incluyendo tanto sitios localizados en zonas de piedemonte, como contextos de media y alta montaña.
Más en detalle, el objeto de esta investigación es el registro lítico tallado, cuyo análisis está enfocado hacia una aproximación socio-económica. La finalidad principal es avanzar hacia una clasificación funcional de los diferentes contextos analizados, para entender cuál fue el rol de dichas ocupaciones dentro del sistema económico y productivo de los grupos prehistóricos que les dieron lugar.
Los resultados obtenidos por el análisis llevado a cabo han evidenciado la existencia de un gradiente de especialización económico dentro del ambiente montano. Los conjuntos líticos analizados son el resultado de diferentes actividades productivas asociadas al desarrollo de ciertas fases de la actividad pastoril. Así, pasaríamos de ocupaciones relativamente estables asociadas a un amplio abanico de actividades de subsistencia y manufactureras en el fondo del valle y en el piedemonte, a sitios más especializados hacia el pastoreo y la matanza del ganado en áreas de montañas y subalpinas. En particular se ha reconocido el desarrollo gradual, ya des de fases antiguas del Neolítico, de una forma de pastoreo móvil sobre un amplio territorio que, desde los llanos del valle Ebro, llegaría hasta los pastos alpinos del Pirineo Axial y del pre-Pirineo.The study of the process of anthropization of the Pyrenees during Prehistory is a relatively recent discipline. During the course of the last century, archaeological research investigated only marginally the mountainous areas of the Pyrenees, mainly focusing on the Megalithic monuments with an ethnic-cultural perspective. However, since the last decade, archaeologists and other researchers adopted a broader approach to the study of the human occupation of the mountains, integrating the analysis of the past human societies and of their material remains with the analysis of the ancient landscape and climate and their mutual interactions. This work follows this line of research. Here is presented the study of nine occupational layers, belonging to four different archaeological sites located in the Southern Central Pyrenees and dated between the sixth and the third millennia cal BC. Those sites are located in different geographical contexts, as one of the main aims of this research is to advance a comprehensive overview of the humanization processes of the mountains space, including the piedmont areas, the mountain zones and sub-alpine and alpine stages. More specifically, this work is focused on the lithic materials, which analysis is directed toward a socio-economic interpretation of the record. The main aim of the study is to advance a functional classification of the analyzed sites, in order to understand which role such occupations had within the economic system of the prehistoric groups that generated them. Obtained results indicated the existence of a specialization gradient within the mountain environment. The analyzed lithic assemblages are the result of different productive processes associated to certain phases of the pastoral practices. So, one observes relatively stable occupations in the piedmont areas, characterized by a variety of subsistence and manufacturing processes, while mountain and subalpine zones would be characterized by more specialized occupations more strictly related to domestic animal slaughtering or pasturing practices. In conclusion, one can recognize a gradual development, since the earlier stages of the Neolithic `period, of mobile herding strategies over a large territory which from the plain areas of the Ebro valley is extended to the highest peaks of the Axial Pyrenees.
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Martins, Carolina Guerra. "Níveis de inclusão de bagaço de cana-de-açúcar in natura associados a milho grão inteiro ou floculado em dietas de terminação de bovinos Nelore." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/11/11139/tde-13112013-145253/.
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O objetivo deste trabalho foi a avaliação metabólica de dietas contendo níveis de inclusão de bagaço de cana-de-açúcar in natura (0, 3, 6, 9% da MS da dieta) associados a milho grão inteiro ou floculado (360g/L), perfazendo um total de cinco tratamentos. Foram utilizados cinco bovinos machos castrados da raça Nelore, com peso médio inicial igual a 479,2kg; contendo cânulas no rúmen, distribuídos em um delineamento Quadrado Latino 5x5. Tratamentos aplicados: MI-0: milho inteiro sem inclusão de BIN (bagaço de cana-de-açúcar in natura); MI-3: milho inteiro com 3% de BIN; MI-6: milho inteiro com 6% de BIN; MI-9: milho inteiro com 9% de BIN; MF-6: milho floculado com 6% de BIN. O método de processamento não alterou o consumo de MS e nutrientes (p>0,05) e não houve efeito de nível de inclusão de BIN (p>0,05), exceto para o consumo de FDN que aumentou linearmente (p=0,0145) com a inclusão de BIN. Os coeficientes de digestibilidade não diferiram entre os métodos de processamento e nem entre os níveis de BIN (p>0,05), apesar do efeito positivo da inclusão de BIN no pH ruminal (p=0,0001). O milho duro utilizado no presente estudo quando fornecido inteiro para bovinos Nelore em dietas com altos teores de concentrado apresentou ao redor de 96% da concentração de ELm e de ELg (2,12 e 1,44 Mcal/Kg de MS) em relação ao valor tabular do NRC (1996) para milho dentado (2,18 e 1,50 Mcal/Kg de MS). Os maiores teores de BIN na dieta ocasionaram maiores tempos gastos na atividade de ingestão (p<0,05) e mastigação (p<0,05) e, também, houve uma tendência (p=0,0702) para maior tempo de alimentação à medida que o teor de BIN foi aumentando. O método de floculação não alterou os VfCF e VfCNF, no entanto, diminuiu a KdCF e aumentou a KdCNF e o lag time.The objective of this study was to evaluate diets containing levels of fresh sugar cane bagasse (0, 3, 6, 9% DM) associated with whole or steam flaked corn grain (360g/L) in metabolic parameters of cattle. Five rumen cannulated Nellore steers, weighing 479.2 kg at the beginning of the experiment, were distributed in five treatments in a 5x5 Latin Square design. Experimental treatments were the following finishing diets: WC-0: whole corn with no addition of sugar cane bagasse (SCB); WC-3: whole corn with 3% SCB; WC-6: whole corn with 6% SCB, WC-9: whole corn with 9% SCB; SFC-6: steam flaked corn with 6% SCB. Despite the increased in vitro Kd of non-fibrous carbohidrates (NFC), steam flaked corn did not improve the nutritional value of corn grain in comparison with whole grain based on in vivo metabolic assay. The inclusion of dietary SCB did not improve DM intake and digestibility of nutrients, but resulted in positive effects on ruminal pH. The addition of whole flint corn used in the present study in the diet of Nellore steers fed high concentrate finishing diets, had approximately 96% of NEm and NEg concentrations (2.11 and 1.44 Mcal / kg DM) in comparison to tabular values from (1996) for dent corn (2.18 and 1.50 Mcal / kg DM), for DM intake restricted to 85% of potential intake.
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Schwandt, Erin F. "Grain processing considerations influencing starch digestion and performance of feedlot cattle." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/20571.
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Doctor of PhilosophyDepartment of Animal Sciences and Industry
Christopher D. Reinhardt
Two studies evaluated dry-rolled corn (DRC) manufacturing considerations in feedlot finishing diets. In study 1, feedlots (n = 35) participated in a survey to evaluate dry-rolled corn (DRC) processing practices, processed corn particle size distribution, and fecal starch content in finishing cattle. Average particle size of dry-processed corn, including DRC and hammermill-ground corn across all operations (n = 35) was 4,223 ± 1,265 µm with a range of 1,165 to 6,823 µm. Fecal starch content averaged 19.0 ± 6.5% with a range of 7.0 to 36.6%. Diet composition was evaluated for co-product [27.8 ± 13.4%] roughage concentration [8.9 ± 2.0%] and NDF concentration [19.3 ± 4.3%]. In study 2, cross-bred yearling steers (n = 360; initial BW = 395 ± 33.1 kg) were used to evaluate the effects of dry-rolled corn (DRC) particle size in diets containing 20% (DMB) wet distiller’s grains plus solubles (WDGS) on feedlot performance, carcass characteristics, and starch digestibility. Treatments were Coarse DRC (4,882 µm; COARSE), Medium DRC (3,760 µm; MEDIUM), Fine DRC (2,359 µm; FINE), and Steam-flaked corn (SFC, 0.35 kg/L). Final BW and ADG were not affected by treatment (P > 0.05). Dry matter intake was greater and G:F was lower (P < 0.05) for steers fed DRC vs. SFC. There was a linear decrease (P < 0.05) in DMI in the final 5 weeks on feed with decreasing DRC particle size. Fecal starch decreased (linear, P < 0.01) as DRC particle size decreased. In situ starch disappearance was lower for DRC vs SFC (P < 0.05) and increased linearly (P < 0.05) with decreasing particle size at 8 and 24-h. The final study evaluated steam-flaked corn (SFC) manufacturing practices implemented, equipment utilized, and methods used and parameters targeted to measure flake quality from commercial feedlots (n = 17). Significant variables contributing to the final multiple linear regression model using enzymatic starch availability (Enzymatic) as the dependent variable were: SFC Moisture, cooled flake density (CoolFD), throughput, roll diameter, steam cabinet temperature (Temperature), and temper time (Enzymatic = 19.4476 - (0.6927*SFCMoisture) - (2.1664*CoolFD) - (0.5060*Throughput) + (0.6281*Roll Diameter) + (0.4312*Temperature) – (0.1963*Temper Time; P < 0.15).
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Nishiaki, Yoshihiro. "Lithic technology of Neolithic Syria : a series of analyses of flaked stone assemblages from Douara Cave II, Tell Damishilyya, Tell Nebi Mend, and Tell Kashkashok II." Thesis, University College London (University of London), 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319659.
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Black, Patricia Lynne. "Characterizing quality and composition of beef derived from cattle fed steam-flaked corn diets with combinations of dry-rolled corn and dried distiller's grains with solubles." Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1459.
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Black, Patricia Lynne. "Characterizing quality and composition of beef derived from cattle fed steam-flaked corn diets with combinations of dry-rolled corn and dried distiller’s grains with solubles." Thesis, Kansas State University, 2009. http://hdl.handle.net/2097/1459.
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Master of ScienceDepartment of Animal Sciences and Industry
James S. Drouillard
A trial was conducted replacing portions of steam-flaked corn with either dry-rolled corn or dried distiller’s grains with solubles to evaluate effects on performance, carcass characteristics, carcass composition, meat color stability, and meat sensory attributes. Seven hundred crossbred yearling heifers (302 ± 65 kg initial BW) were used in a randomized complete block experiment with a 2 x 2 factorial arrangement of treatments. All diets contained steam-flaked corn (SFC), and factors consisted of the levels of dry-rolled corn (DRC; 0 or 25%) and dried corn distiller’s grains with solubles (DDGS; 0 or 25%). Results revealed no interactions between DRC and DDGS in terms of effects on feedlot performance, and only minor interactive effects were observed for carcass characteristics and meat quality attributes. Feedlot performance and carcass characteristics were not affected by the addition of DRC or DDGS (P > 0.05). Carcass composition and meat quality attributes were measured to determine if fat content of carcasses was altered by feeding DDGS. Diet had no significant effects, as carcasses from the four treatments contained similar amounts of separable portions of muscle, adipose, and bone; and similar percentages of protein, moisture, and ether extract. Compositions of both adipose and muscle tissue were evaluated to assess differences in fatty acid profile. Minimal effects were noted on the fatty acid profiles of the muscle and adipose tissue from cattle fed DDGS or DRC. Feeding cattle DDGS decreased alpha tocopherol (vitamin E) content of meat (P < 0.05). Meat quality attributes were largely unaffected by addition of DRC or DDGS to the diet, as retail color display life, lipid oxidation, sensory attributes, and heterocyclic amine concentrations were not different among treatments. Overall, DRC or DDGS can replace portions of SFC without negatively altering feedlot performance, carcass characteristics, meat composition, or meat quality attributes.
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West, Virginia Anne. "Stability of Selected B Vitamins in Thermally-Treated Pinto Beans." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5769.
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Beans are a commonly consumed food and a staple in many regions worldwide. Pinto beans (Phaseolus vulgaris), categorized as legumes, are dried seeds from plants and are high in protein, carbohydrate and fiber, and low in fat. They are also a good source of various minerals and well as thiamin, riboflavin, niacin, vitamin B6, and folate Beans are typically soaked and thermally processed before consumption. Different processing methods can impact the composition of beans. The purpose of this study was to examine the effect of thermal treatments on vitamin concentration in pinto beans. Beans were simmered, canned, dried-flaked, or dried-extruded, and measured for thiamin, riboflavin, folate, and vitamin B6. Beans were then reheated and measured again for vitamin concentration. Vitamin loss was comparable between the most commonly consumed stages of processing: Simmered, canned reheated, dried-flaked reheated and dried-extruded reheated. The only statistically significant differences were that simmering caused the least amount of degradation of thiamin and dried-flaked product had the least amount of vitamin B6 degradation. Though dried-flaked and dried-extruded beans generally decreased in vitamin concentration, these two products were comparable to the simmered and canned reheated products. This suggests that drying is a nutritionally acceptable means of processing pinto beans, resulting in products that are more economical to transport and more convenient to prepare.
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URIAS, ALEJANDRO RUBEN. "EFFECT OF DIETARY CONCENTRATE LEVELS ON IN SITU DRY MATTER DISAPPEARANCE, NEUTRAL DETERGENT FIBER DISAPPEARANCE AND DIGESTION KINETICS OF ALFALFA HAY, WHEAT STRAW AND STEAM PROCESSED AND FLAKED MILO GRAIN." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183830.
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A replicated 3 x 3 latin square design (3 periods and 6 rumen fistulated steers) was utilized to investigate the effect of dietary concentrate levels (30, 60 and 90%) on the in situ disappearance of dry matter (ISDMD) and neutral detergent fiber (NDF) and kinetics of fiber digestion of alfalfa hay, wheat straw and steam processed and flaked milo (SPFM). Concentrate levels of 30 and 60% did not affect (P > .05) ISDMD or NDF disappearance from any of the substrates. However, ISDMD and NDF disappearance of all substrates were depressed (P < .05) by the 90% concentrate diet. The degradation of the potentially digestible fiber in these substrates followed first order kinetics at all concentrate levels. Fiber digestion kinetics were not affected (P > .05) by dietary concentrate levels of 30 or 60%. Incubation of substrates in animals receiving the 90% concentrate diet resulted in lower potential extent of digestion (P > .05) and decreased rate of degradation (P > .05) for all substrates. However, digestion was not complete even after incubations of 168-h, and thus, it is possible that the potential extent of digestion was underestimated. For all substrates lag time of digestion appeared to increase in the 90% concentrate diet. However, influx of NDF-like material into the bag during incubation makes the validity of the lag times obtained in situ questionable. Ruminal pH was depressed in animals consuming the 90% concentrate diet and could be at least one of the factors responsible for the decreased (P > .05) fiber digestibility in this diet. Mean ruminal pH of 6.5 (30 and 60% concentrate diets) did not depress (P > .05) fiber digestibility while a mean pH of 6.2 resulted in a lower (P > .05) fiber digestibility in the rumen.
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Nanduri, Jagannath Ramchandra. "A COMPUTATIONAL STUDY OF THE STRUCTURE, STABILITY, DYNAMICS, AND RESPONSE OF LOW STRETCH DIFFUSION FLAME." Case Western Reserve University School of Graduate Studies / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=case1132237973.
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Takasao, Shinsuke. "Fundamental Magnetohydrodynamic Processes of Solar Flares: Formation of Flare-productive Regions and Evolution of Flare Loops." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215316.
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Lawal, Mohammed Shariff. "Numerical modelling of jet flames in a cross-flow : application to flares." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539693.
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Zeltner, Darrel Patrick. "NO, Burnout, Flame Temperature, Emissivity, and Radiation Intensity from Oxycombustion Flames." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3221.
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This work produced the retrofit of an air-fired, 150 kW reactor for oxy-combustion which was then used in three oxy-combustion studies: strategic oxy-combustion design, oxy-combustion of petroleum coke, and air versus oxy-combustion radiative heat flux measurements. The oxy-combustion retrofit was accomplished using a system of mass flow controllers and automated pressure switches which allowed safe and convenient operation. The system was used successfully in the three studies reported here and was also used in an unrelated study. A study was completed where a novel high oxygen participation burner was investigated for performance while burning coal related to flame stability, NO, and burnout using a burner supplied by Air Liquide. Parameters investigated included oxygen (O2) injection location, burner swirl number and secondary carbon dioxide (CO2) flow rate. The data showed swirl can be used to stabilize the flame while reducing NO and improving burnout. Center O2 injection helped to stabilize the flame but increased NO formation and decreased burnout by reducing particle residence time. Additional CO2 flow lifted the flame and increased NO but was beneficial for burnout. High O2 concentrations up to 100% in the secondary were accomplished without damage to the burner. Petroleum coke was successfully burned using the Air Liquide burner. Swirl of the secondary air and O2 injection into the center tube of the burner were needed to stabilize the flame. Trends in the data similar to those reported for the coal study are apparent. Axial total radiant intensity profiles were obtained for air combustion and three oxy-combustion operating conditions that used hot recycled flue gas in the secondary stream. The oxygen concentration of the oxidizer stream was increased from 25 to 35% O2 by decreasing the flow rate of recycled flue gas. The decrease in secondary flow rate decreased the secondary velocity, overall swirl, and mixing which elongated the flame. Changing from air to neat CO2 as the coal carrier gas also decreased premixing which elongated the flame. Flame elongation caused increased total heat transfer from the flame. The air flame was short and had a higher intensity near the burner, while high O2 concentration conditions produced lower intensities near the burner but higher intensities and temperatures farther downstream. It was shown that oxycombustion can change flame shape, temperature and soot concentration all influencing heat transfer. Differences in gas emission appear negligible in comparison to changes in particle emission.
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Piffaretti, Stefano Giuseppe. "Flame age model : a transient laminar flamelet approach for turbulent diffusion flames /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16961.
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Yamashita, Hiroshi, Naoki Hayashi, Yusuke Isobe, Shinya Kato, and Kazuhiro Yamamoto. "Lifted flame structure of coannular jet flames in a triple port burner." Elsevier, 2011. http://hdl.handle.net/2237/20041.
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Capil, Tyler George. "Flame Surface Density Measurements and Curvature Statistics for Turbulent Premixed Bunsen Flames." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/75121.
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In this work, turbulent premixed combustion was analyzed through CH (methylidyne) planar laser induced fluorescence (PLIF). Flame topography measurements in terms of flame surface density and curvature were calculated based on the flame front detected by the CH PLIF signal. The goal of this work was to investigate turbulent flames with extremely high turbulence intensity using a recently developed HiPilot burner (a Bunsen-type burner). The studies were first conducted on a series of piloted jet flames to validate the methodology, and then conducted on the highly turbulent flames generated by the HiPilot burner. All flames were controlled by combusting methane and air under a fuel to air equivalence ratio of Φ=1.05, and the Reynolds number varied from 7,385 to 28,360. Flame surface density fields and profiles for the HiPilot burner are presented. These flame surface density measurements showed an overall decrease with height above the burner. In addition, curvature statistics for the HiPilot flames were calculated and probability density functions of the curvature samples were determined. The probability density functions of curvature for the flames showed Gaussian-shaped distributions centered near zero curvature. To conclude, flame topography measurements were verified on jet flames and were demonstrated on the new HiPilot flames.Master of Science
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Hartl, Sandra. "Flamelet/progress variable modelling and flame structure analysis of partially premixed flames." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2017. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-227684.
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This dissertation addresses the analysis of partially premixed flame configurations and the detection and characterization of their local flame regimes.
First, the identification of flame regimes in experimental data is intensively discussed. Current methods for combustion regime characterization, such as the flame index, rely on 3D gradient information that is not accessible with available experimental techniques. Here, a method is proposed for reaction zone detection and characterization, which can be applied to instantaneous 1D Raman/Rayleigh line measurements of major species and temperature as well as to the results of laminar and turbulent flame simulations, without the need for 3D gradient information. Several derived flame markers, namely the mixture fraction, the heat release rate and the chemical explosive mode, are combined to detect and characterize premixed versus non-premixed reaction zones. The methodology is developed and evaluated using fully resolved simulation data from laminar flames. The fully resolved 1D simulation data are spatially filtered to account for the difference in spatial resolution between the experiment and the simulation, and experimental uncertainty is superimposed onto the filtered numerical results to produce Raman/Rayleigh equivalent data. Then, starting from just the temperature and major species, a constrained homogeneous batch reactor calculation gives an approximation of the full thermochemical state at each sample location. Finally, the chemical explosive mode and the heat release rate are calculated from this approximated state and compared to those calculated directly from the simulation data. After successful validation, the approach is applied to Raman/Rayleigh line measurements from laminar counterflow flames, a mildly turbulent lifted flame and turbulent benchmark cases. The results confirm that the reaction zones can be reliably detected and characterized using experimental data. In contrast to other approaches, the presented methodology circumvents uncertainties arising from the use of limited gradient information and offers an alternative to known reaction zone identification methods.
Second, this work focuses on the flame structure of partially premixed dimethyl ether (DME) flames. DME flames form significant intermediate hydrocarbons in the reaction zone and are classified as the next more complex fuel candidate in research after methane. To simulate DME combustion processes, accurate predictions by computational combustion models are required. To evaluate such models and to identify appropriate flame regimes, numerical simulations are necessary. Therefore, fully resolved simulations of laminar dimethyl ether flames, defined by different levels of premixing, are performed. Further, the qualitative two-dimensional structures of the partially premixed DME flames are discussed and analyses are carried out at selected slices and compared to each other as well as to experimental data. Further, the flamelet/progress variable (FPV) approach is investigated to predict the partially premixed flame structures of the DME flames. In the context of the FPV approach, a rigorous analysis of the underlying manifold is carried out based on the newly developed regime identification approach and an a priori analysis. The most promising flamelet look-up table is chosen for the fully coupled tabulated chemistry simulations and the results are further compared to the fully resolved simulation data.
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Kypraiou, Anna-Maria. "Experimental investigation of the response of flames with different degrees of premixedness to acoustic oscillations." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/275743.
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This thesis describes an experimental investigation of the response of lean turbulent swirling flames with different degrees of premixedness (i.e. different mixture patterns) to acoustic forcing using the same burner configuration and varying only the fuel injection strategy. Special emphasis was placed on the amplitude dependence of their response. Also, the behaviour of self-excited fully premixed flames was examined. kHz OH* chemiluminescence was used to study qualitatively the heat release response of the flames, while kHz OH Planar Laser Induced Fluorescence (PLIF) was employed to understand the response of the flame structure and the behaviour of the various parts of the flame. The Proper Orthogonal Decomposition (POD) method was used to extract the dominant structures of the flame and their periodicity. In the first part of the thesis, self-excited oscillations were induced by extending the length of the duct downstream of the bluff body. It was found that the longer the duct length and the higher the equivalence ratio, the stronger the self-excited oscillations were, with the effect of duct length being much stronger. The dominant frequencies of the system were found to increase with equivalence ratio and bulk velocity and decrease with duct length. For some conditions, three simultaneous periodic motions were observed, where the third motion oscillated at a frequency equal to the difference of the other two frequencies. A novel application of the POD method was proposed to estimate the convection velocity from the most dominant reaction zone structures detected by OH* chemiluminescence imaging. For a range of conditions, the convection velocity was found to be in the range of 1.4-1.7 bulk flow velocities at the inlet of the combustor. In the second part, the response of fully premixed, non-premixed with radial fuel injection (NPR) and axial fuel injection (NPA) flames was investigated and compared. All systems exhibited a nonlinear response to acoustic forcing. The highest response was observed by the NPR flame, followed by the fully premixed and the non-premixed with axial fuel injection flame. The proximity of forced flames to blow-off was found to be critical in their heat release response, as close to blow-off the flame response was significantly lower than that farther from blow-off. In the NPR and NPA systems, it was shown that the acoustic forcing reduced the stability of the flame and the stability decreased with the increase in forcing amplitude. In the fully premixed system, the flame area modulations constituted an important mechanism of the system, while in the NPR system both flame area and equivalence ratio modulations were important mechanisms of the heat release modulations. The quantification of the local response of the various parts of the flame at the forcing frequency showed that the ratio RL (OH fluctuation at 160 Hz to the total variance of OH) was greater in the inner shear layer region than in the other parts in the case of NPR and NPA flames. In fully premixed flames, greater RL values were observed in large regions on the downstream side of the flame than those in the ISL region close to the bluff body. The ratio of the convection velocity to the bulk velocity was estimated to be 0.54 for the NPR flame, while it was found to be unity for the respective fully premixed flame. In the last part of the thesis, the response of ethanol spray flames to acoustic oscillations was investigated. The nonlinear response was very low, which was reduced closer to blow-off. The ratio RL was the highest in the spray outer cone region, downstream of the annular air passage, while RL values were very low in the inner cone region, downstream of the bluff body. Unlike NPR and fully premixed flames, in case of spray and NPA systems, it was found that forcing did not affect greatly the flame structure. The understanding of the nonlinear response of flames with different degrees of premixedness in a configuration relevant to industrial systems contributes to the development of reliable flame response models and lean-burn devices, because the degree of premixedness affects greatly the flame response. Also, the understanding of the behaviour of forced spray flames is of great interest for industrial applications, contributing to the development of thermoacoustic models for liquid fuelled combustors. Finally, the estimation of the convection velocity is of importance in the modelling of self-excited flames and flame response models, since the convection velocity affects the flame response significantly.
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Usowicz, James E. "An Experimental Study of Flame Lengths and Emissions of fully-Modulated Diffusion Flames." Digital WPI, 2001. https://digitalcommons.wpi.edu/etd-theses/640.
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A pulsed fuel injector system was used to study flame structure, flame length, and emissions of ethylene jet diffusion flames over a range of injection times and duty-cycles with a variable air co-flow. In all cases the jet was completely shut off between pulses (fully-modulated) for varying intervals, giving both widely-spaced, non-interacting puffs and interacting puffs. Imaging of the luminosity from the flame revealed distinct types of flame structure and length, depending on the duration of the fuel injection interval. Flame lengths for isolated puffs (small injection times) were up to 83% less than steady state flames with the same injection velocities. With the addition of co-flow flame lengths grew to a maximum of 30% longer than flames without any co-flow. A scaling argument is also developed to predict the amount of co-flow that gives a 15% increase in mean flame length. Interacting flames with a small co-flow and small injection times (injection time = 5.475 ms) experienced flame length increases of up to 212% for a change in injection duty-cycle from 0.1 to 0.5. For interacting flames with long injection times (on time = 119 ms), essentially no change in flame length was noticeable over the same range of duty-cycles. Emission measurements suggest partial quenching of the reaction in isolated puffs with low duty-cycles and injection times (injection times less than 5.475 ms) resulting in high CO and UHC concentrations and low NO and NOx concentrations. With an increase in duty-cycle, the puffs began to interact and CO and UHC concentrations decreased while NO and NOx concentrations increased. For flames with injection times greater than 5.475 ms emission concentrations seem to be reasonably constant, with a slight increase in NO and NOx concentrations as the duty-cycle increased. Also the duty-cycle experienced in the vicinity of the probe is estimated and used as a scaling factor for the emission measurements.
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Diao, Zhaojin. "CHARACTERIZATION OF METHANE-AIR DIFFUSION FLAMES FOR FLAME SYNTHESIS APPLICATION THROUGH OPTICAL DIAGNOSTICS." UKnowledge, 2018. https://uknowledge.uky.edu/me_etds/121.
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Flame synthesis is a growing field of research aiming at forming new materials and coatings through injection of seed materials into a flame. Accurate prediction of the thermal structure of these flames requires detailed information on the radiative properties and a thorough understanding of the governing combustion processes. The objective of this work is to establish a basic optical diagnostic characterization of different methane-air diffusion flames of different complexity. The basic principles are developed and demonstrated at a rotational symmetric co-flow burner and finally applied to a burner consisting of six clustered microflames which is designed for future flame synthesis work. This work focuses on the demonstration of the optical techniques for characterizing the optical emissions from diffusion flames and of the proposed method for the determination of radiating species properties from these optical measurements.
In the co-flow diffusion flame setup, the fuel of methane diluted with nitrogen is provided through an inner tube while the air is applied through an outer duct surrounding the fuel nozzle. Filtered imaging and spectrally resolved measurements of the chemiluminescence of CH* and C2* and of water emission were conducted. A procedure for using the HITRAN database to support the spectroscopic analysis of the water emission was developed.
In the six clustered microflames burner setup, the burner consisted of six micro-nozzles arranged in a circle surrounding a central nozzle through which air and TaN seed particles with sizes between 0.3 and 3 μm were injected. Spectrally resolved measurements of the chemiluminescence of CH* and C2* were conducted for temperature measurements. Imaging results obtained from a spectral integration of the molecular emission were compared to results from Japanese collaborators who applied a tomographic analysis method to filtered emission measurements of CH* emission which can yield spatially resolved three dimensional mapping of the flame front. The analysis of the spatial distribution of the integrated band emission of CH* and C2* showed that the emission of both species is generated at the same locations in the flame which are the thin flame sheets shown in the tomography results of CH*. The ratio of the C2* and the CH* emission from the emission spectroscopy measurements was used to determine a local equivalence ratio through empirically derived correlations for premixed flames reported in literature. Rotational and vibrational temperature distributions of CH* and C2* radicals throughout the entire flame were determined from the spectrally resolved emission from CH* and C2*. The temperatures of TaN seed particles were characterized using VIS-NIR emission spectra while varying fuel-air flow rates. The temperature profiles of the particles at various heights above the base of the central nozzle, obtained by their VIS-NIR continuum emission, showed a well-defined constant temperature region that extended well beyond the actual flame front and changed as fuel and oxidizer flow rates were varied. The results demonstrate the ability to control the duration to which seed particles are subjected to high temperature reactions by adjusting fuel and oxidizer flow rates in the clustered microflames burner.
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Ma, Terence Kwai Kin. "Flame surface density modelling for the large eddy simulation of turbulent premixed flames." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/14645.
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Large Eddy Simulation (LES) has become an increasingly useful tool for the prediction of turbulent reactive flows with the increasing availability of cheaper and faster computing power. In the context of premixed combustion, LES encounters the challenge of resolving the flame thickness, which is normally smaller than the filter width used in typical engineering applications. This thesis considers the Flame Surface Density (FSD) approach to provide closure to the filtered LES reaction rate. The FSD can either be modelled algebraically (FSDA) or determined through a transport equation (FSDT) and both approaches are investigated in the LES of three different test cases. The first case explores the response of different FSDA models towards changes in turbulence levels, and compares the instantaneous flame structures and reaction rates predicted by FSDA and FSDT methods. The remaining cases examine the LES of two turbulent premixed burners. A relatively large range of FSDA models are tested under the same operating conditions for the first time, and the LES-FSDT equation is applied to premixed flames that involve a higher level of geometric complexity than earlier work. Generally, the results show that the performance of some FSDA models are inconsistent between the two premixed burners, suggesting that the models may operate optimally under different turbulent conditions. By contrast, the consistently good agreement of the FSDT results with experiments suggests that the method has much potential in the LES modelling of turbulent premixed flames. However, the improved FSDT predictions were dependent on the value of the model constant within the sub-grid curvature model, and the value yielded an additional dependency on filter width. For these reasons as well as for the higher computational expense, the effective use of FSDT requires further development, while the application of the FSDA models remains a viable alternative to the FSDT approach.
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Glaser, Michael. "Snow Flakes." Bowling Green State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1174418689.
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Khanna, Vivek K. "A Study of the Dynamics of Laminar and Turbulent Fully and Partially Premixed Flames." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/28527.
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This present research effort was directed towards developing reduced order models for the dynamics of laminar flat flames, swirl stabilized turbulent flames, and in evaluating the effects of the variation in fuel composition on flame dynamics. The laminar flat flame study was conducted on instrument grade methane, propane, and ethane flames for four total flow rates from 145 cc/sec to 200 cc/sec, and five equivalence ratios from 0.5 to 0.75. The analysis was done by measuring the frequency resolved velocity perturbations, u', and the OH* chemiluminescence, as a measure of unsteady heat release rate, q'. The experimental data showed the corresponding flame dynamics to be fourth order in nature with a pure time delay. One of the resonance was shown to represent the pulsation of the flame location caused by fluctuation in the flame speed and fluctuating heat losses to the flame stabilizer. The other resonance was correlated to the dynamics of the chemical kinetics involved in the combustion process. The time delay was correlated to the chemical time delay. Upon comparing the results of the experiments with the three fuels, it was concluded that for all equivalence ratios studied, propane flame had a higher dynamic gain than methane flames. Ethane flames exhibited a higher dynamic gain than methane flame in the frequency range of 20-100 Hz. Thus, burning of propane instead of methane increased the likelihood of the occurrence of thermo-acoustic instabilities. The experimental techniques developed during the dynamic studies conducted on laminar flat flames were applied to swirl stabilized turbulent flames. Experiments were performed for QAir = 15 scfm and 20 scfm, F = 0.55, 0.6, 0.65, and S = 0.79 and 1.19. The results of fully premixed experiments showed that the flame behaved as a 8th order low pass filter. The results of the partially premixed experiment exhibited a rich spectra, which maintained its bandwidth over the entire range of frequency studied. Comparison of fully and partially premixed flames in the frequency range of 200-400 Hz, indicated that at overall lean conditions the dynamic gain of the totally premixed flames was almost an order of magnitude lower than that of the partially premixed conditions. Thus, it was concluded that combustors with fully premixed flames have a higher probability of being thermo-acoustically stable than those with partially premixed flames.Ph. D.
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Marques, Rodrigo da Silva. "Efeitos da variação dos níveis de forragem em dietas contendo grãos de milho inteiro e os benefícios da floculação na terminação de tourinhos Nelore." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/11/11139/tde-13092011-104435/.
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Foram utilizados 116 tourinhos da raça Nelore (373 Kg) distribuídos aleatoriamente em 20 baias, com o objetivo de comparar dietas com níveis crescentes de bagaço de cana de açúcar (0, 3, 6% da MS) com grãos de milho inteiro do tipo duro ou flint (69,5% de vitreosidade). Também foi incluso um tratamento com maior teor de proteína bruta por meio da adição de nitrogênio de liberação lenta (Optigen ®) e um quinto tratamento com milho floculado, ambos com 6% de bagaço. Os dados foram analisados em delineamento em blocos completos ao acaso, análises de regressão foram realizadas para os tratamentos que continham níveis crescentes de forragem e aplicação de contrastes ortogonais entre os tratamentos com milho inteiro com 6% de forragem Nas dietas com milho inteiro a inclusão de bagaço na dieta, aumentou a IMS (ingestão de matéria seca) de forma quadrática (P<0,05), aumentou o GPD (ganho de peso diário), o PF (peso corporal final) e o PCQ (peso de carcaça quente) de forma linear (P<0,05), mas não teve efeito (P>0,05) na eficiência alimentar (GPD/IMS). O aumento do teor de proteína da dieta com a adição de fonte de nitrogênio de liberação lenta não melhorou (P>0,05) o desempenho dos animais alimentados com grãos inteiro de milho. A floculação do milho melhorou (P<0,05) de forma significativa o desempenho dos animais em comparação ao uso de grãos de milho inteiro. Em comparação com a dieta contendo grãos de milho inteiro sem bagaço, a floculação não alterou a IMS, mas aumentou o GPD, o PF, o PCQ e a eficiência alimentar dos animais. Em comparação com a dieta contendo grãos de milho inteiro e 6% de bagaço, a floculação reduziu (P<0,05) a IMS, não alterou (P>0,05) o GPD, o PF, e as características de carcaça, mas aumentou (P<0,05) a eficiência alimentar dos animais. A inclusão de bagaço com milho inteiro, assim como a inclusão de fonte de nitrogênio de liberação lenta, não afetaram (P>0,05) os teores observados de energia das dietas. No entanto, a floculação aumentou (P<0,05) de forma expressiva o teor de energia da dieta em comparação com o milho inteiro com ou sem bagaço na dieta. A inclusão de bagaço resultou em redução linear (P<0,10) no teor de amido fecal e conseqüente aumento na DTA (digestibilidade total do amido) e na estimativa de energia líquida dos grãos de milho inteiro. A floculação reduziu (P<0,05) os teores de amido fecal e por conseqüência, aumentou (P<0,05) a digestibilidade do amido no trato digestivo total e a estimativa de energia líquida dos grãos de milho. As características de carcaça não foram afetadas (P>0.05) pelos tratamentos e a incidência de abscessos hepáticos foi insignificante. Com base nos resultados conclui-se que a inclusão de forragem em dietas com milho inteiro melhora o desempenho dos animais e a digestibilidade do amido. A floculação do milho do tipo flint propicia maior energia nas dietas e maior eficiência alimentar dos animais. Tourinhos Nelore não respondem ao aumento no teor de proteína bruta da dieta com a inclusão de nitrogênio de liberação lenta.One hundred sixteen yearling Nellore bulls (373 kg IBW) were allotted randomly to 20 pens in order to compare diets with increasing sugarcane bagasse levels (0, 3, 6% DM) and whole flint corn grains (69,5% vitreousness). A treatment with higher crude protein level containing a slow release urea source (Optigen ®) and another containing steam flaked corn, both with 6% bagasse, were also included. The data were analyzed in randomized block design, regression analysis was performed for the treatments that contained various levels of forage and application of orthogonal contrasts between treatments with 6% of forage and whole corn against treatments with 6% of forage with addition of slow-release nitrogen source and against steam flaked corn with 6% of forage. Bagasse inclusion to diets containing whole corn quadraticaly (P<0,05) increased dry matter intake (DMI) and linearly (P<0,05) increased average daily gain (ADG), final body weight (FBW) and hot carcass weight (HCW) but didn´t affect (P>0,05) feed efficiency (ADG/DMI). Increasing diet protein level with inclusion of slow release urea didn´t improve (P>0,05) the performance of animals fed whole corn. Steam flaking corn significantly improved (P<0,05) performance compared to whole corn. Compared to the whole corn and no bagasse diet, steam flaked corn didn´t affect DMI but increased ADG, FBW, HCW and feed efficiency. In relation to the whole corn and 6% bagasse diet steam flaking corn decreased DMI, didn´t affect ADG, FBW and carcass parameters and increased feed efficiency. Bagasse inclusion to whole corn diets as well as slow release urea source didn´t affect diets´ observed energy concentration. However, steam flaking corn expressively increased diet energy content compared to whole corn, with or without bagasse. Bagasse inclusion resulted in linear decrease (P<0,10) on fecal starch concentration with increase on total starch digestibility (TSD) and increase on whole corn grains estimated net energy levels. Corn flaking decreased fecal starch concentration and as a consequence increased total tract starch digestibility and estimated corn grains net energy levels. Liver abscess incidence was negligible. Trial results lead to the conclusion that roughage inclusion to whole corn grain diets improve animal performance and starch digestibility. Steam flaking of flint corn allows higher energy levels e better feed efficiency. Nellore Bulls not respond to the increase in crude protein diet with the inclusion of slow-release nitrogen.
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Allred, Joel C. "Observations and radiative hydrodynamic simulations of solar and stellar flares /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/9631.
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Pederson, Steven Patrick. "Flawed nature cosmology." University of Southern Queensland, Faculty of Sciences, 2008. http://eprints.usq.edu.au/archive/00004433/.
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[Abstract]: This thesis presents a new cosmological model based on a blank-slate reconsideration of the issue of the first cause in cosmology. It is proposed that a pre-Big Bang evolution of nature occurred that removes the need for postulating the existence of matter, energy and time. This new approach leads to an underlyingconceptualisation of nature consistent with quantum mechanics.The problems of first cause and initial conditions in cosmology are reconsidered. It is proposed that the initial conditions were flawed and evolved toproduce the Big Bang as a natural response to these flaws. This contrasts with the traditional approach of postulating a homogeneous initial state requiring perturbation by an additional first cause.In flawed nature cosmology the origin of time occurs as a natural response to the flawed set of initial conditions, and removes the need to postulate time. The development of causality remains an ongoing process rather than being fully determined by the first cause. Ongoing development of causality provides a conceptual understanding of the probabilistic nature of quantum mechanics and itsrelationship with classical physics.Flawed nature cosmology is used to examine pre-Big Bang evolution, in order to justify rather than postulate a set of conditions leading to the Big Bang. Thisexamination of pre-Big Bang evolution also introduces a structured method to start addressing the question of the origin of matter and the forces of nature.Flawed nature cosmology reconsiders the issues that introduced the manyuniverses concept into physics such as spontaneous first causes, the many-worlds interpretation of quantum mechanics, brane cosmology’s use of the extra dimensions in string theory, and parallel universes to solve the fine tuning problem. The manyuniversesconcept has found favour, as much of the puzzling behaviour of the universe can be avoided by simply stating that if there are many universes, one couldmatch our experience. In contrast, flawed nature cosmology demonstrates that the universe we experience is the unique product of its evolutionary history.
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Haynes, Joel M. "Aerodynamic design of no NOx oil diffusion flames using the radially stratified flame core burner." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/11224.
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Preetham, Preetham. "Modeling the Response of Premixed Flames to Flow Disturbances." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19817.
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Modeling the Response of Premixed Flames to Flow Disturbances
Preetham
178 pages
Directed by Dr. Tim Lieuwen
Low emissions combustion systems for land based gas turbines rely on a premixed or partially premixed combustion process. These systems are exceptionally prone to combustion instabilities which are destructive to hardware and adversely affect performance and emissions. The success of dynamics prediction codes is critically dependent on the heat release model which couples the flame dynamics to the system acoustics. So the principal objective of the current research work is to predict the heat release response of premixed flames and to isolate the key non-dimensional parameters which characterize its linear and nonlinear dynamics.
Explicit analytical solutions of the G- equation are derived in the linear and weakly nonlinear regime using the Small Perturbation Method (SPM). For the fully nonlinear case, the flame-flow interaction effects are captured by developing an unsteady, compressible, coupled Euler-G-equation solver with a Ghost Fluid Method (GFM) module for applying the jump conditions across the flame.
The flame s nonlinear response is shown to exhibit two qualitatively different behaviors. Depending on the operating conditions and the disturbance field characteristics, it is shown that a combustor may exhibit supercritical bifurcations leading to a single stable limit cycle amplitude or exhibit sub-critical bifurcations wherein multiple stable solutions for the instability amplitude are possible. In addition, this study presents the first analytical model which captures the effects of unsteady flame stretch on the heat release response and thus extends the applicability of current models to high frequency instabilities, such as occurring during screech. It is shown that unsteady stretch effects, negligible at low frequencies (100 s of Hz) become significant at screeching frequencies (1000 s of Hz). Furthermore, the analysis also yields insight into the significant spatial dependence of the mean and perturbation velocity field induced by the coupling between the flame and the flow field. In order to meaningfully compare the heat release response across different flame configurations, this study has identified that the reference velocity (for defining the transfer function) should be based on the effective normal velocity perturbing the flame and the Strouhal number should be based on the effective residence time of the flame wrinkles.
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Fecteau, Andre. "The Effects of Compressibility on the Propagation of Premixed Deflagration." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39402.
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The thesis addresses the influence of compressible effects on the stability of deflagration waves. Due to the quasi-isobaric nature of slow flames, compressible effects in laminar flames are usually neglected. Nevertheless, turbulent deflagrations may propagate at substantially higher speeds, suggesting that compressible effects may play a role in their dynamics. In the present thesis, the stability of diffusion-dominated high-speed deflagrations is addressed. The deflagration is studied in the thickened regime, hence addressing the long wavelength limit of these deflagrations. The deflagrations are modelled by the compressible reactive Navier-Stokes equations with a single-step Arrhenius reaction model. The 2D stability of the steady traveling-wave solution is studied by direct simulation. It is found that, as the flame compressibility becomes significant, not only does the growth rates of the cellular profile of the deflagration waves increase, but the traditional correlation of the burning velocity and the flame surface area become far less strong. Significant compression regions form in front of the nonlinear flames. These compression regions have been found to increase the growth rates by increasing the temperature of the unburned gas in front of the flames, as well as convecting the flame forward. The results show that the flame propagation velocity in references to the unburned gas was significantly faster than the burning velocity. The vorticity was given consideration, as the compressibility of flame increase one can expect the baroclinic source to be of greater significance. The vorticity was show to, in effect, increase as compressibility increases while unexpectedly having a stabilizing direction of rotation on the cellular structure of the flames.
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Park, Doyoub. "EFFECTS OF TRANSPORT PROPERTIES AND FLAME UNSTEADINESS ON NITROGEN OXIDES EMISSIONS FROM LAMINAR HYDROGEN JET DIFFUSION FLAMES." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2968.
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Experimental studies on the coupled effects of transport properties and unsteady fluid dynamics have been conducted on laminar, acoustically forced, hydrogen jet diffusion flames diluted by argon and helium. The primary purpose of this research is to determine how the fuel Lewis number and the flow unsteadiness play a combined role in maximum flame temperature and affect NOx emission from jet diffusion flame. The fuel Lewis number is varied by increasing/decreasing the mole fraction of diluents in the fuel stream. Therefore, maximum flame temperatures and then NOx emission levels were expected to differ for Ar- and He-diluted flames. In an investigation of unsteady flames, two different frequencies (10 and 100 Hz) were applied to observe a behavior of NOx emission levels and flame lengths by changes of unsteady fluid dynamics and transport properties.M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
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Amato, Alberto. "Leading points concepts in turbulent premixed combustion modeling." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52247.
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The propagation of premixed flames in turbulent flows is a problem of wide physical and technological interest, with a significant literature on their propagation speed and front topology. While certain scalings and parametric dependencies are well understood, a variety of problems remain. One major challenge, and focus of this thesis, is to model the influence of fuel/oxidizer composition on turbulent burning rates.
Classical explanations for augmentation of turbulent burning rates by turbulent velocity fluctuations rely on global arguments - i.e., the turbulent burning velocity increase is directly proportional to the increase in flame surface area and mean local burning rate along the flame. However, the development of such global approaches is complicated by the abundance of phenomena influencing the propagation of turbulent premixed flames. Emphasizing key governing processes and cutting-off interesting but marginal phenomena appears to be necessary to make further progress in understanding the subject.
An alternative approach to understand turbulent augmentation of burning rates is based upon so-called "leading points", which are intrinsically local properties of the turbulent flame. Leading points concepts suggest that the key physical mechanism controlling turbulent burning velocities of premixed flames is the velocity of the points on the flame that propagate farthest out into the reactants. It is postulated that modifications in the overall turbulent combustion speed depend solely on modifications of the burning rate at the leading points since an increase (decrease) in the average propagation speed of these points causes more (less) flame area to be produced behind them. In this framework, modeling of turbulent burning rates can be thought as consisting of two sub-problems: the modeling of (1) burning rates at the leading points and of (2) the dynamics/statistics of the leading points in the turbulent flame. The main objective of this thesis is to critically address both aspects, providing validation and development of the physical description put forward by leading point concepts.
To address the first sub-problem, a comparison between numerical simulations of one-dimensional laminar flames in different geometrical configurations and statistics from a database of direct numerical simulations (DNS) is detailed. In this thesis, it is shown that the leading portions of the turbulent flame front display a structure that on average can be reproduced reasonably well by results obtained from model geometries with the same curvature. However, the comparison between model laminar flame computations and highly curved flamelets is complicated by the presence of negative (i.e., compressive) strain rates, due to gas expansion. For the highest turbulent intensity investigated, local consumption speeds, curvatures, strain rates and flame thicknesses approach the maximum values obtained by the laminar model geometries, while other cases display substantially lower values.
To address the second sub-problem, the dynamics of flame propagation in simplified flow geometries is studied theoretically. Utilizing results for Hamilton-Jacobi equations from the Aubry-Mather theory, it is shown how the overall flame front progation under certain conditions is controlled only by discrete points on the flame. Based on these results, definitions of leading points are proposed and their dynamics is studied. These results validate some basic ideas from leading points arguments, but also modify them appreciably. For the simple case of a front propagating in a one-dimensional shear flow, these results clearly show that the front displacement speed is controlled by velocity field characteristics at discrete points on the flame only when the amplitude of the shear flow is sufficiently large and does not vary too rapidly in time. However, these points do not generally lie on the farthest forward point of the front. On the contrary, for sufficiently weak or unsteady flow perturbations, the front displacement speed is not controlled by discrete points, but rather by the entire spatial distribution of the velocity field. For these conditions, the leading points do not have any dynamical significance in controlling the front displacement speed. Finally, these results clearly show that the effects of flame curvature sensitivity in modifying the front displacement speed can be successfully interpreted in term of leading point concepts.
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Nivarti, Girish Venkata. "The bending effect in turbulent flame propagation." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/270335.
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In the present thesis, the sensitivity of flame propagation to the turbulent motion of burning gases is investigated. The long-standing issue of the 'bending effect' is focused upon, which refers to the experimentally-observed inhibition of flame propagation velocity at high intensities of turbulence. Plausible mechanisms for the bending effect are investigated by isolating systematically the effects of turbulence intensity. By providing a novel perspective on this topic, the thesis addresses the fundamental limits of turbulent burning. The investigation employs Direct Numerical Simulation (DNS), which enables the basic conditions of burning to be controlled directly. A parametric DNS dataset is designed and generated by increasing turbulence intensity over five separate simulations. Effects of turbulent motion are isolated in this manner, such that the bending effect is reproduced in the variation of flame propagation velocity recorded. Subsequently, the validity of Damköhler's hypotheses is investigated to ascertain the mechanism of bending. Analysis of the DNS dataset highlights the significance of kinematic flame response in determining turbulent flame propagation. Damköhler's first hypothesis is found to be valid throughout the dataset, suggesting that the bending effect may be a consequence of self-regulation of the flame surface. This contradicts the dominant belief that bending occurs as a result of flame surface disruption by the action of turbulence. Damköhler's second hypothesis is found to be valid in a relatively limited regime within the dataset, its validity governed by flame-induced effects on the prescribed turbulent flow field. Therefore, this thesis presents turbulent flame propagation and the bending effect as emergent from the dynamics of a flame surface that retains its internal thermo-chemical structure. Finally, experimental validation is sought for the proposed mechanisms of bending. Comparisons have been initiated with measurements in the Leeds explosion vessel, based on which the widely accepted mechanism of bending was hypothesized twenty-five years ago. Modifications to the DNS framework warranted by this comparison have aided the development of novel computationally-efficient algorithms. The ongoing work may yield insights into the key mechanism of the bending effect in turbulent flame propagation.
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Thumuluru, Sai Kumar. "Effect of harmonic forcing on turbulent flame properties." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37099.
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Lean premixed combustors are highly susceptible to combustion instabilities, caused by the coupling between heat release fluctuations and combustor acoustics. In order to predict the conditions under which these instabilities occur and their limit cycle amplitudes, understanding of the amplitude dependent response of the flame to acoustic excitation is required. Extensive maps of the flame response were obtained as a function of perturbation amplitude, frequency, and flow velocity. These maps illustrated substantial nonlinearity in the perturbation velocity - heat release relationship, with complex topological dependencies that illustrate folds and kinks when plotted in frequency-amplitude-heat release space. A detailed analysis of phase locked OH PLIF images of acoustically excited swirl flames was used to identify the key controlling physical processes and qualitatively discuss their characteristics. The results illustrate that the flame response is not controlled by any single physical process but rather by several simultaneously occurring processes which are potentially competing, and whose relative significance depends upon forcing frequency, amplitude of excitation, and flame stabilization dynamics. An in-depth study on the effect of acoustic forcing on the turbulent flame properties was conducted in a turbulent Bunsen flame using PIV measurements. The results showed that the flame brush thickness and the local consumption speed were modulated in the presence of acoustic forcing. These results will not only be a useful input to help improve combustion dynamics predictions but will also help serve as validation data for models.
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Anderson, Anne Lee. "Assessment of thermal radiation arithmetic's for jet flames : A study involving generic calculation methods concerning radiation from jet flames with the purpose to determine the safety distance for flame effects." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-67173.
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Jet flames are commonly used as flame effects in pyrotechnical shows, and are also a possible risk in industries that uses pressurised flammable gas. For these users it is important to make fire safety engineering calculations to minimise the risks. This project focus on jet flames that are used in pyrotechnic shows where, e.g. it is important to determine the safety distance to the audience. Up to now most studies made concerning jet flames regards jet flames in subsonic regiments, whilst there is a lack of studies concerning sonic jet flames and mathematical formulations for radiation from these cases are limited. This makes pre-determination of temperatures, safety distances, flame heights etc. a challenge. Based on information found, and assumptions when needed, calculations of the safety distance were made.
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Palacios, Rosas Adriana. "Study of Jet Fires Geometry and Radiative Features." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/6487.
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Entre els accidents greus que poden ocórrer a les instal·lacions industrials o durant el transport de substàncies perilloses, els dolls de foc presenten un especial interès. Tot i que tenen una distància relativament més curta d'afectació que altres accidents greus, es caracteritzen per originar grans fluxos de calor i, en cas de contacte de la flama amb un equip, originen sovint un efecte domino, desencadenant una subseqüent explosió, incendi o altres esdeveniments amb greus conseqüències.Diversos estudis experimentals i teòrics han estat efectuats; no obstant això, la majoria d'aquests han estat enfocats a dolls de foc a escala de laboratori, flames subsòniques o torxes, les condicions de les quals difereixen significativament d'aquelles trobades en dolls de foc accidentals reals, que normalment assoleixen majors longituds de flama i velocitats de sortida sònica. Aquesta manca d'investigació és la raó per explicar perquè els dolls de foc eren encara molt mal coneguts i la predicció dels seus efectes i conseqüències era encara un problema. Aquesta tesi ha estat elaborada per a obtenir informació nova i útil sobre els dolls de foc, millorant la comprensió de la seva geometría i de les característiques tèrmiques, mitjançant l'anàlisi, l'experimentació i el modelatge matemàtic.
Aquest estudi s'ha centrat alhora en dades existents i en noves dades experimentals, implicant Aixa dolls de foc verticals i horitzontals alliberats en absència de vent, implicant diversos combustibles (hidrogen, metà i propà). L'estudi comprèn una àmplia gamma de variables d'operació (velocitats de sortida del combustible, pressions en la canonada i diàmetres d'orifici de sortida). L'estudi experimental ha implicat dolls de foc amb flames de fins a 10.3 m de longitud i 1.5 m d'amplada. El combustible utilitzat ha estat propà, amb velocitats de sortida sònica i subsònica, utilitzant diversos diàmetres d'orifici de sortida. Els dolls de foc han estat filmats amb dues càmeres de vídeo (VHS) i una càmera termográfica d'alta velocitat (IR). Les principals característiques geomètriques de les flames (dimensions i forma) han estat analitzades en funció de la velocitat de sortida del combustible,
del flux màssic i del diàmetre d'orifici de sortida. L'anàlisi i tractament d'imatges infraroges i de les mesures obtingudes amb tres sensors de flux de calor situats a diferents distàncies de la sortida del doll de foc han permès l'obtenció de les seves principals característiques de radiació: flux de calor irradiat als voltants (persones i instal·lacions) en funció de la distancia, poder emissiu i emisivitat de les flames. Diverses expressions han estat proposades per estimar les dimensions de la flama en funció de diverses variables (flux màssic, diàmetre d'orifici de sortida i nombres de Froude i Reynolds). Els resultats i expressions obtinguts en aquest estudi contribueixen a una millor comprensió dels dolls de foc, representant un avanç en les metodologies i l'establiment de noves mesures, normes i polítiques de planificació per a la prevenció i/o el control d'aquest tipus d'accident greu amb foc, tant en establiments industrials com en el transport de materials perillosos.
Among the major accidents that can occur in processing plants or in the transportation of hazardous materials, jet fires are of particular interest. Although they have a relatively shorter distance of influence than other major accidents, they are characterized by high heat fluxes and if there is flame impingement they can originate a domino effect, leading to a subsequent explosion, large fire, or other events with severe effects. Several experimental and theoretical studies have been carried out; however, most of those works have been focused on small-scale jet fires, subsonic flames or flares, the conditions of which significantly differ from those found in real accidental jet fires, usually reaching larger flame lengths and sonic exit velocities. This lack of research is the reason to explain why the current knowledge of jet fires was still rather poor and the accurate prediction of their effects and consequences was still a problem. The present thesis has been addressed to produce a significant amount of novel and useful information on jet fires, by improving understanding of jet fire structure, reach and radiative features, through analyses, experiment and mathematical modelling. This study has been focused on both existing and also new experimental jet flame data, comprising all together, turbulent non-premixed jet flames vertically and horizontally released into still air, involving several fuels (hydrogen, methane and propane), over a wide range of operational conditions (jet exit velocities, release pressures and pipe diameters). The experimental study developed in this thesis has concerned relatively large jet fires with flames of up to 10.3 m in length and 1.5 m in width. The fuel was propane, and both sonic and subsonic jet exit velocities were obtained from different outlet diameters. The jet fires were filmed with two videocameras registering visible light (VHS) and a thermographic camera (IR). The main geometrical features of the flames were analyzed as a function of the fuel velocity, mass flow rate and jet outlet diameter: jet flame size and flame shape. The treatment of infrared images and measurements obtained from three heat flow sensors located at different distances from the jet fire outlet also led the main radiative features of jet fires to be obtained: incident thermal radiation heat over a target, surface emissive power and emissivity of the flames.
Expressions for estimating jet flame reach as a function of several variables (mass flow rate, orifice exit diameter, Froude and Reynolds numbers) have also been proposed. The results and the expressions obtained in this study contribute to a better understanding of jet fires for accurate risk assessment, allowing the obtention of important advances in risk assessment methodologies and the establishment of new measures, regulations, and risk planning policies for the prevention and/or control of this type of major fire, occurred world-wide in industrial establishments and in the transportation of hazardous materials.
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Marshall, Andrew. "Turbulent flame propagation characteristics of high hydrogen content fuels." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53859.
Full textAbstract:
Increasingly stringent pollution and emission controls have caused a rise in the use of combustors operating under lean, premixed conditions. Operating lean (excess air) lowers the level of nitrous oxides (NOx) emitted to the environment. In addition, concerns over climate change due to increased carbon dioxide (CO2) emissions and the need for energy independence in the United States have spurred interest in developing combustors capable of operating with a wide range of fuel compositions. One method to decrease the carbon footprint of modern combustors is the use of high hydrogen content (HHC) fuels. The objective of this research is to develop tools to better understand the physics of turbulent flame propagation in highly stretch sensitive premixed flames in order to predict their behavior at conditions realistic to the environment of gas turbine combustors.
This thesis presents the results of an experimental study into the flame propagation characteristics of highly stretch-sensitive, turbulent premixed flames generated in a low swirl burner (LSB). This study uses a scaling law, developed in an earlier thesis from leading point concepts for turbulent premixed flames, to collapse turbulent flame speed data over a wide range of conditions. The flow and flame structure are characterized using high speed particle image velocimetry (PIV) over a wide range of fuel compositions, mean flow velocities, and turbulence levels. The first part of this study looks at turbulent flame speeds for these mixtures and applies the previously developed leading points scaling model in order to test its validity in an alternate geometry. The model was found to collapse the turbulent flame speed data over a wide range of fuel compositions and turbulence levels, giving merit to the leading points model as a method that can produce meaningful results with different geometries and turbulent flame speed definitions. The second part of this thesis examines flame front topologies and stretch statistics of these highly stretch sensitive, turbulent premixed flames. Instantaneous flame front locations and local flow velocities are used to calculate flame curvatures and tangential strain rates. Statistics of these two quantities are calculated both over the entire flame surface and also conditioned at the leading points of the flames. Results presented do not support the arguments made in the development of the leading points model. Only minor effects of fuel composition are noted on curvature statistics, which are mostly dominated by the turbulence. There is a stronger sensitivity for tangential strain rate statistics, however, time-averaged values are still well below the values hypothesized from the leading points model. The results of this study emphasize the importance of local flame topology measurements towards the development of predictive models of the turbulent flame speed.
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Hinton, Nathan Ian David. "Measuring laminar burning velocities using constant volume combustion vessel techniques." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:5b641b04-8040-4d49-a7e8-aae0b0ffc8b5.
Full textAbstract:
The laminar burning velocity is an important fundamental property of a fuel-air mixture at given conditions of temperature and pressure. Knowledge of burning velocities is required as an input for combustion models, including engine simulations, and the validation of chemical kinetic mechanisms. It is also important to understand the effect of stretch upon laminar flames, to correct for stretch and determine true (unstretched) laminar burning velocities, but also for modelling combustion where stretch rates are high, such as turbulent combustion models. A constant volume combustion vessel has been used in this work to determine burning velocities using two methods: a) flame speed measurements during the constant pressure period, and b) analysis of the pressure rise data. Consistency between these two techniques has been demonstrated for the first time. Flame front imaging and linear extrapolation of flame speed has been used to determine unstretched flame speeds at constant pressure and burned gas Markstein lengths. Measurement of the pressure rise during constant volume combustion has been used along with a numerical multi-zone combustion model to determine burning velocities for elevated temperatures and pressures as the unburned gas ahead of the spherically expanding flame front is compressed isentropically. This burning velocity data is correlated using a 14 term correlation to account for the effects of equivalence ratio, temperature, pressure and fraction of diluents. This correlation has been modified from an existing 12 term correlation to more accurately represent the dependence of burning velocity upon temperature and pressure. A number of fuels have been tested in the combustion vessel. Biogas (mixtures of CH4 and CO2) has been tested for a range of equivalence ratios (0.7–1.4), with initial temperatures of 298, 380 and 450 K, initial pressures of 1, 2 and 4 bar and CO2 fractions of up to 40% by mole. Hydrous ethanol has been tested at the same conditions (apart from 298 K due to the need to vaporise the ethanol), and for fractions of water up to 40% by volume. Binary, ternary and quaternary blends of toluene, n-heptane, ethanol and iso-octane (THEO) have been tested for stoichiometric mixtures only, at 380 and 450 K, and 1, 2 and 4 bar, to represent surrogate gasoline blended with ethanol. For all fuels, correlation coefficients have been obtained to represent the burning velocities over wide ranging conditions. Common trends are seen, such as the reduction in burning velocity with pressure and increase with temperature. In the case of biogas, increasing CO2 results in a decrease in burning velocity, a shift in peak burning velocity towards stoichiometric, a decrease in burned gas Markstein length and a delayed onset of cellularity. For hydrous ethanol the reduction in burning velocity as H2O content is increased is more noticeably non-linear, and whilst the onset of cellularity is delayed, the effect on Markstein length is minor. Chemical kinetic simulations are performed to replicate the conditions for biogas mixtures using the GRI 3.0 mechanism and the FlameMaster package. For hydrous ethanol, simulations were performed by Carsten Olm at Eötvös Loránd University, using the OpenSMOKE 1D premixed flame solver. In both cases, good agreement with experimental results is seen. Tests have also been performed using a single cylinder optical engine to compare the results of the hydrous ethanol tests with early burn combustion, and a good comparison is seen. Results from tests on THEO fuels are compared with mixing rules developed in the literature to enable burning velocities of blends to be determined from knowledge of that of the pure components alone. A variety of rules are compared, and it is found that in most cases, the best approximation is found by using the rule in which the burning velocity of the blend is represented by weighting by the energy fraction of the individual components.