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Journal articles on the topic "Land equivalent ratio. eng"
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Otto, S., T. Trautmann, and M. Wendisch. "On realistic size equivalence and shape of spheroidal Saharan mineral dust particles applied in solar and thermal radiative transfer calculations." Atmospheric Chemistry and Physics 11, no. 9 (May 12, 2011): 4469–90. http://dx.doi.org/10.5194/acp-11-4469-2011.
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Abstract. Realistic size equivalence and shape of Saharan mineral dust particles are derived from in-situ particle, lidar and sun photometer measurements during SAMUM-1 in Morocco (19 May 2006), dealing with measured size- and altitude-resolved axis ratio distributions of assumed spheroidal model particles. The data were applied in optical property, radiative effect, forcing and heating effect simulations to quantify the realistic impact of particle non-sphericity. It turned out that volume-to-surface equivalent spheroids with prolate shape are most realistic: particle non-sphericity only slightly affects single scattering albedo and asymmetry parameter but may enhance extinction coefficient by up to 10 %. At the bottom of the atmosphere (BOA) the Saharan mineral dust always leads to a loss of solar radiation, while the sign of the forcing at the top of the atmosphere (TOA) depends on surface albedo: solar cooling/warming over a mean ocean/land surface. In the thermal spectral range the dust inhibits the emission of radiation to space and warms the BOA. The most realistic case of particle non-sphericity causes changes of total (solar plus thermal) forcing by 55/5 % at the TOA over ocean/land and 15 % at the BOA over both land and ocean and enhances total radiative heating within the dust plume by up to 20 %. Large dust particles significantly contribute to all the radiative effects reported. They strongly enhance the absorbing properties and forward scattering in the solar and increase predominantly, e.g., the total TOA forcing of the dust over land.
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Tang, Xiumei, Yu Liu, and Yuchun Pan. "An Evaluation and Region Division Method for Ecosystem Service Supply and Demand Based on Land Use and POI Data." Sustainability 12, no. 6 (March 23, 2020): 2524. http://dx.doi.org/10.3390/su12062524.
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Mastering the regional spatial differences of ecosystem service supply and ecosystem service demand is of great significance to scientifically planning the development and utilization of national land and maintaining healthy development of ecosystems. Based on the relationship analysis of ecosystem service supply and ecosystem service demand, this study explored the regional ecosystem service supply by ecosystem service value based on grid data and constructed an ecosystem service demand evaluation model that integrated the construction land ecosystem service demand equivalent for static aspects and the point of interest (POI) kernel density estimation for dynamic aspects on the basis of land use and POI data. In the end, it put forward a region division method for ecosystem service supply and ecosystem service demand and conducted an empirical analysis of Haidian District, Beijing. The following results were concluded: (1) the ecosystem service value of different grids in Haidian District was between RMB (Chinese monetary unit, Yuan) 0 and RMB 2.4787 million. In terms of spatial distribution, the ecosystem service supply took on an obvious trend of gradual decrease from the northwest to the southeast, with major ecosystem service supply coming from the northwest. (2) The construction land ecosystem service demand equivalent of Haidian District was characterized by a multicenter cluster: the high equivalent area was in the southeast, while the equivalent of the northwest was relatively low. POI kernel density estimation demonstrated cluster distribution, with a high kernel density estimation in the southeast, a lower kernel density estimation in the central part, and the lowest kernel density estimation in the northwest. The ecosystem service demand index also showed cluster distribution: high index in the southeast, low index in the northwest, and prominent sudden changes from the central part to the south. (3) The bivariate local spatial autocorrelation cluster diagram method was used to divide five types of ecosystem service supply and ecosystem service demand, namely non-significant correlation region, high ecosystem service supply and high ecosystem service demand region, high ecosystem service supply and low ecosystem service demand region, low ecosystem service supply and high ecosystem service demand region, low ecosystem service supply and low ecosystem service demand region. Grids with the highest ratio belonged to the non-significant correlation region; the distribution of low ecosystem service supply and high ecosystem service demand region had the greatest concentration, mainly in the southeast; the grids of high ecosystem service supply and low ecosystem service demand region were mainly present in the northwest and in a continuous way; the grids of low ecosystem service supply and low ecosystem service demand region, and high ecosystem service supply and high ecosystem service demand region were extremely few, with sporadic distribution in the central part. The research results could provide a basis for the adjustment and fine management of regional land use structure.
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Çopur Doğrusöz, Medine, Hanife Mut, Uğur Başaran, and Erdem Gülümser. "Performance of Legumes-Turnip Mixtures with Different Seed Rates." Turkish Journal of Agriculture - Food Science and Technology 7, no. 1 (January 15, 2019): 81. http://dx.doi.org/10.24925/turjaf.v7i1.81-86.2125.
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This study aimed to investigate appropriate seed rates for legume-turnip intercrops under different harvest stages. Turnip (Brassica rapa L. var. rapa) was sown with common vetch (Vicia sativa L.), Hungarian vetch (Vicia pannonica Crantz) and pea (Pisum sativum ssp. arvense L. Poir) in 2014 with four different combinations (100% legume, 75% legume + 25% turnip, 50% legume + 50% turnip, 100% turnip) and catted in two different times when the beginning and end of the flowering of turnip. The study was conducted in Yozgat-Turkey with three replicates. Hay yield, protein yield, ADF, NDF, Ca, Mg, P, K, Land Equivalent Ratio, Competitive Ratio and Aggressivity characteristics were determined in view of the combinations. The results of this study, 50%HV + 50%T and sole pea harvested turnip was at the beginning of flowering stage were the best treatments. On the other hand, when harvest was done at end of the flowering of turnip 50%P + 50%T, 75%P + 25%T and 50%HV + 50%T intercropping were the high yielding treatment.
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Dupraz, Christian, Kevin Wolz, Isabelle Lecomte, Grégoire Talbot, Grégoire Vincent, Rachmat Mulia, François Bussière, et al. "Hi-sAFe: A 3D Agroforestry Model for Integrating Dynamic Tree–Crop Interactions." Sustainability 11, no. 8 (April 16, 2019): 2293. http://dx.doi.org/10.3390/su11082293.
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Agroforestry, the intentional integration of trees with crops and/or livestock, can lead to multiple economic and ecological benefits compared to trees and crops/livestock grown separately. Field experimentation has been the primary approach to understanding the tree–crop interactions inherent in agroforestry. However, the number of field experiments has been limited by slow tree maturation and difficulty in obtaining consistent funding. Models have the potential to overcome these hurdles and rapidly advance understanding of agroforestry systems. Hi-sAFe is a mechanistic, biophysical model designed to explore the interactions within agroforestry systems that mix trees with crops. The model couples the pre-existing STICS crop model to a new tree model that includes several plasticity mechanisms responsive to tree–tree and tree–crop competition for light, water, and nitrogen. Monoculture crop and tree systems can also be simulated, enabling calculation of the land equivalent ratio. The model’s 3D and spatially explicit form is key for accurately representing many competition and facilitation processes. Hi-sAFe is a novel tool for exploring agroforestry designs (e.g., tree spacing, crop type, tree row orientation), management strategies (e.g., thinning, branch pruning, root pruning, fertilization, irrigation), and responses to environmental variation (e.g., latitude, climate change, soil depth, soil structure and fertility, fluctuating water table). By improving our understanding of the complex interactions within agroforestry systems, Hi-sAFe can ultimately facilitate adoption of agroforestry as a sustainable land-use practice.
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Mupangwa, W., M. Mutenje, C. Thierfelder, M. Mwila, H. Malumo, A. Mujeyi, and P. Setimela. "Productivity and profitability of manual and mechanized conservation agriculture (CA) systems in Eastern Zambia." Renewable Agriculture and Food Systems 34, no. 5 (November 29, 2017): 380–94. http://dx.doi.org/10.1017/s1742170517000606.
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AbstractClimate variability and declining soil fertility pose a major threat to sustainable agronomic and economic growth in Zambia. The objective of this study was to assess crop yield, land and labor productivity of conservation agriculture (CA) technologies in Eastern Zambia. On-farm trials were run from 2012–2015 and farmers were replicates of a randomized complete block design. The trials compared three CA systems against a conventional practice. Yield and net return ha−1 were determined for maize and legume yield (kg ha−1) produced by ridge and furrow tillage, CA dibble stick planting, CA animal traction ripping and direct seeding. The dibble stick, ripline and direct seeding CA systems had 6–18, 12–28 and 8–9% greater maize yield relative to the conventional tillage system, respectively. Rotation of maize with cowpea and soybean significantly increased maize yields in all CA systems. Intercropping maize with cowpea increased land productivity (e.g., the land equivalent ratio for four seasons was 2.01) compared with full rotations under CA. Maize/cowpea intercropping in dibble stick CA produced the greatest net returns (US$312-767 ha−1) compared with dibble stick maize-cowpea rotation (US$204-657), dibble stick maize monoculture (US$108-584) and the conventional practice (US$64-516). The net-return for the animal traction CA systems showed that maize-soybean rotations using the ripper were more profitable than the direct seeder or conventional ridge and furrow systems. Agronomic and economic benefits of CA-based cropping systems highlight the good potential for improved food security and agricultural productivity for smallholder farmers.
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Widodo, Yudi, Sri Wahyuningsih, Made Jana Mejaya, and Yuliantoro Baliadi. "Intercropping Twice of Corn with Cassava to Supply the Feed of Biomass in Eastern Mount Kawi of Malang Indonesia." Rural Sustainability Research 42, no. 337 (December 1, 2019): 26–31. http://dx.doi.org/10.2478/plua-2019-0008.
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Abstract Three treatments were tested with four replications at RCBD, namely cassava monoculture, corn twice under cassava intercropping, and corn with corn monoculture where the second corn was planted 5 days after harvested. Planting distance of cassava in monoculture was 100x100 cm, and in intercropping was 200x50 cm, by which corn was planted in 50x30 cm, 1 seed per hole. All plots received dairy cattle manure 5 t ha-1. Fertilizer applied for cassava was Urea 100 kg ha−1, Ponska 200 kg ha−1 and KCl 100 kg ha−1 split into two applications two weeks after cassava planting, then when first of corn was harvested. Corn fertilization was Ponska 150 kg ha−1 + Urea 100 kg ha−1 every 3 months and split into two applications: 1 week and 4 weeks after corn was planted. Cassava and twice corn fertilization was Urea 300 kg ha−1 + Phonska 400 kg ha−1 + KCl 100 kg ha−1. Results showed that cassava monoculture can be improved by inserting of twice corn in between rows. Under sole cropping cassava, the B/C ratio was the highest 1.61, however with incorporating twice of corn the B/C ratio was 1.58. Intercropping cassava and twice of corn resulted in the Land Equivalent Ratio 2.146. By intercropping cassava with corn twice at the end of dry season, there was an opportunity to find corn biomass for dairy cattle. Under intercropping, cassava was able to produce 21.5 t ha−1 of fresh roots, while first and second of corn produced fresh biomass of 34 t ha−1 and 28 t ha−1 respectively.
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Oleson, K. W., G. B. Bonan, J. Feddema, and M. Vertenstein. "An Urban Parameterization for a Global Climate Model. Part II: Sensitivity to Input Parameters and the Simulated Urban Heat Island in Offline Simulations." Journal of Applied Meteorology and Climatology 47, no. 4 (April 1, 2008): 1061–76. http://dx.doi.org/10.1175/2007jamc1598.1.
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Abstract In a companion paper, the authors presented a formulation and evaluation of an urban parameterization designed to represent the urban energy balance in the Community Land Model. Here the robustness of the model is tested through sensitivity studies and the model’s ability to simulate urban heat islands in different environments is evaluated. Findings show that heat storage and sensible heat flux are most sensitive to uncertainties in the input parameters within the atmospheric and surface conditions considered here. The sensitivity studies suggest that attention should be paid not only to characterizing accurately the structure of the urban area (e.g., height-to-width ratio) but also to ensuring that the input data reflect the thermal admittance properties of each of the city surfaces. Simulations of the urban heat island show that the urban model is able to capture typical observed characteristics of urban climates qualitatively. In particular, the model produces a significant heat island that increases with height-to-width ratio. In urban areas, daily minimum temperatures increase more than daily maximum temperatures, resulting in a reduced diurnal temperature range relative to equivalent rural environments. The magnitude and timing of the heat island vary tremendously depending on the prevailing meteorological conditions and the characteristics of surrounding rural environments. The model also correctly increases the Bowen ratio and canopy air temperatures of urban systems as impervious fraction increases. In general, these findings are in agreement with those observed for real urban ecosystems. Thus, the model appears to be a useful tool for examining the nature of the urban climate within the framework of global climate models.
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WOOD, CHRIS M., R. G. BOUTILIER, and D. J. RANDALL. "The Physiology of Dehydration Stress in the Land Crab, Cardisoma Carnifex: Respiration, Ionoregulation, Acid-Base Balance and Nitrogenous Waste Excretion." Journal of Experimental Biology 126, no. 1 (November 1, 1986): 271–96. http://dx.doi.org/10.1242/jeb.126.1.271.
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Air-breathing Cardisoma carnifex, collected in Moorea, French Polynesia, were held in fresh water similar in chemical composition to that in their burrows. Under control conditions, which allowed branchial chamber flushing but not ventilation of the medium, crabs demonstrated net Na+ and Cl− uptake, and ammonia, urea and base excretion (= acidic equivalent uptake). Throughout 192 h of water deprivation, crabs dehydrated slowly at a rate of 0.55 g H2O kg−1 h−1, eventually reaching a near lethal 18% loss of total body water. Increases in haemolymph osmolytes were quite variable (0–29%); electrolyte excretion was negligible. MOO2 and MCOCO2 both decreased by approximately 55%, maintaining an unusually low gas exchange ratio (R = 0.53), and suggesting general metabolic depression. There was no evidence of internal hypoxia as haemolymph lactate remained at hydrated levels and PaOO2 actually increased. The dominant acid-base response was a progressive metabolic alkalosis accompanied by a partially compensating rise in PaCOCO2. Alkalosis was probably caused by blockage of the normal aquatic excretion of base produced by the metabolism of this herbivore. Other possible causes were eliminated: i.e. alkalaemia due to contraction of the ECFV; entrainment via strong ion shifts; CaCO3 mobilization; and ammonia accumulation in the haemolymph. In the absence of water, net ammonia production and excretion both appeared to cease, and alternate end products (urea, uric acid) did not generally accumulate. Within 2h of rehydration, crabs regained more than half the lost water, MOO2 and MCOCO2 increased above control levels, and ammonia excretion and haemolymph concentration both exhibited a prolonged (56 h) 4- to 6-fold rise. At the same time, metabolic alkalosis was reversed in association with elevated net base excretion into the water; the latter was correlated with an increase in the strong ion difference (SID) flux ([Na+ + K+ + Ca2+ + Mg2+ - Cl−]). Note:
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Kristiono, Afandi, Siti Muzaiyanah, Dian Adi Anggraeni Elisabeth, and Arief Harsono. "Produktivitas Tumpangsari Kedelai dengan Jagung pada Akhir Musim Hujan di Lahan Kering Beriklim Kering (Productivity of Soybean Intercropping with Maize at the End of Rainy Season in Dry Land with Dry Climate )." JURNAL PANGAN 29, no. 3 (May 17, 2021): 197–210. http://dx.doi.org/10.33964/jp.v29i3.495.
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ABSTRAK Luas panen kedelai di Indonesia pada 2017 hanya mencapai 355.799 ha dengan produksi 538.728 ton. Untuk mencapai swasembada, luas panen tersebut harus dapat ditingkatkan menjadi 1,2 juta ha dengan produktivitas 1,6 ton/ha. Peningkatan luas panen kedelai dapat dilakukan pada lahan kering dan iklim kering yang pemanfaatannya belum maksimal. Penelitian ini bertujuan untuk mengevaluasi produktivitas dan kelayakan teknis paket teknologi budidaya kedelai tumpang sari dengan jagung di lahan kering beriklim kering. Penelitian dilaksanakan pada musim hujan (MH) 2017/2018 di Kecamatan Tegaldlimo, Kabupaten Banyuwangi, Jawa Timur pada zona iklim D3 (3–4 bulan basah/tahun) dengan jenis tanah vertisol, mengikuti pola tanam padi gogo – jagung. Hasil penelitian menunjukkan bahwa cara tanam tumpang sari kedelai dengan jagung baris ganda setelah panen padi gogo, mampu memberikan hasil biji jagung kering 2,03 ton/ha dan kedelai 1,50 ton/ha. Cara tanam ini lebih menguntungkan daripada tanam jagung atau kedelai monokultur yang berturut-turut memberikan hasil 3,50 ton/ha dan 1,85 ton/ha biji kering. Hasil kedelai dan jagung pada saat penelitian tidak maksimal karena selama pertumbuhan curah hujan hanya 194 mm, sehingga tanaman terutama jagung mengalami cekaman kekeringan. Keuntungan usahatani kedelai monokultur, jagung monokultur, dan kedelai tumpang sari dengan jagung berturut-turut adalah Rp8.633.500,00; Rp5.039.400,00; dan Rp11.090.600,00 per ha. Tumpang sari kedelai dengan jagung mampu memanfaatkan lahan lebih efisien dengan Nilai Kesetaraan Lahan (NKL) 1,39. kata kunci: jagung, kedelai, lahan kering beriklim kering, tumpang sari ABSTRACT Soybean harvested area in Indonesia in 2017 only reached 356,799 ha with a total production of 538,728 tons. To achieve self-sufficiency, the harvested area must be increased to 1.2 million ha with a productivity of 1.6 tons/ha. To increase the harvested area, soybean can be developed in a dry land with dry climate that has not been utilized optimally. The study aimed to evaluate the productivity and technical feasibility of soybean intercropping with maize in a dry land with a dry climate. The study was conducted in the rainy season of 2017/2018 at Tegaldlimo Sub-district, Banyuwangi Regency, East Java Province in the D3 climate zone (3–4 wet months/year) at vertisol soil using the cropping pattern of upland rice-maize.The results indicated that soybean is intercropping with maize in a double row after upland rice harvesting was able to provide the dry seeds yield of maize 2.03 tons/ha and soybean 1.50 tons/ha. This planting method was more profitable compared to maize monoculture yielding 3.50 tons/ha or soybean monoculture yielding 1.85 tons/ha dry seeds yield. The yields of soybean and maize in the study were not optimal due to low precipitation to only 194 mm during the plant growth, so the crops, particularly the maize experienced drought stress. The benefits of soybean monoculture, maize monoculture, and soybean intercropping with maize farming were 8,633,500 IDR, 5,039,400 IDR, and 11,090,600 IDR per ha, respectively. The soybean intercropping with maize was also able to utilize land more efficiently with a Land Equivalent Ratio (LER) of 1.39. keywords: maize, soybean, dry land with dry climate, intercropping
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Ekaka-A, E. N., N. E. S. Lale, and C. C. Wokocha. "The Land Equivalent Ratio and Its Mutualistic Implications: Computational Approach." IOSR Journal of Mathematics 10, no. 4 (2014): 82–85. http://dx.doi.org/10.9790/5728-10448285.
Full textDissertations / Theses on the topic "Land equivalent ratio. eng"
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Barros, Júnior Aurélio Paes. "Adubação nitrogenada no consórcio alface e rúcula /." Jaboticabal : [s.n.], 2008. http://hdl.handle.net/11449/105218.
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Resumo: Com o objetivo avaliar a influência de doses de nitrogênio realizadas para a alface e/ou para a rúcula, em consórcio, sobre as plantas (estado nutricional e crescimento) e sobre o consórcio (produtividade, classificação e qualidade, uso eficiente da área e rentabilidade), foi realizado um experimento no período de setembro à dezembro de 2006, na Unesp, Campus de Jaboticabal-SP. O delineamento experimental foi o de blocos casualizados completos, com quatro repetições, sendo os tratamentos arranjados em esquema fatorial 4 x 4 + 2. Os tratamentos resultaram da combinação de quatro doses de N para a alface (0, 65, 130 e 195 kg/ha de N) e quatro doses de N para a rúcula (0, 65, 130 e 195 kg/ha de N), mais dois tratamentos adicionais, correspondentes às monoculturas de alface e rúcula. As cultivares utilizadas foram Verônica (alface) e Folha Larga (rúcula). Para todas as características avaliadas de plantas de alface a monocultura (testemunha) tiveram melhor desempenho que em consórcios, não ocorrendo diferenças para as características de rúcula. O aumento da dose de N para ambas as culturas, em consórcio, proporcionou incrementos nas características de plantas de alface e rúcula. A máxima produtividade de alface, 23.744,48 kg/ha, foi obtida com 100 kg/ha de N para alface e 195 kg/ha de N para rúcula. A máxima produtividade de rúcula, 14.435,78 kg/ha, foi obtida com a adubação de 195 kg/ha de alface e 180 kg/ha de N para rúcula. A maximização do índice de eficiência de uso da área (1,86) foi obtido na dose 127 kg/ha N para a alface e 195 xv kg/ha N para rúcula. O maior lucro operacional, R$ 29.026,11/ha, foi obtido na combinação de doses de 122 kg/ha N para alface e 195 kg/ha N para rúcula.Abstract: In order to evaluate the influence how nitrogen rates used for lettuce and/or rocket, under intercropping, affect the plants (nutrition and growth conditions), and the intercropping (yielding, grading, land equivalent ratio and profitability), an experiment was carried out at the campus of Unesp in Jaboticabal-SP, from September to December 2006. The experiment was conducted in a randomized complete block design, with four replications, treatments being arranged in a 4 x 4 + 2 factorial design. The treatments were the result of a combination of four N rates for lettuce (0, 65, 130 and 195 kg/ha of N), and four N rates for rocket (0, 65, 130 and 195 kg/ha of N), plus two additional treatments, which corresponded to lettuce and rocket under single cropping. Veronica (lettuce) and Folha Larga (rocket) were the cultivars used. For all the plant characteristics of lettuce that were studied, the single cropping (witness) had better performance than in intercropping, whereas no differences were observed for the rocket characteristics. An increase in the N rate for both cultures under intercropping showed gains in the plant characteristics of lettuce and rocket. Maximum lettuce yield, 23,744.48 kg/ha, was achieved with the application of 100 kg N ha for lettuce, and 195 kg N ha for rocket. Maximum rocket yield, 14,435.78 kg/ha, was achieved with the application of 195 kg N ha for lettuce, and 180 kg N ha for rocket. The land equivalent ratio was maximized (1.86) by using 127 kg N ha for lettuce and 195 kg N ha for rocket. The highest xvii operating profit, R$ 29,026.11/ha, resulted from the combination of 122 kg N ha for lettuce and 195 kg N ha for rocket.
Orientador: Arthur Bernardes Cecílio Filho
Coorientador: Renato de Mello Prado
Coorientador: José Carlos Barbosa
Banca: Francisco Bezerra Neto
Banca: Leilson Costa Grangeiro
Banca: Domingos Fornasieri Filho
Banca: José Ricardo Mantovani
Doutor
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Bedoussac, Laurent. "Analyse du fonctionnement des performances des associations blé dur-pois d'hiver et blé dur-féverole d'hiver pour la conception d'itinéraires techniques adaptés à différents objectifs de production en systèmes bas-intrants." Phd thesis, Toulouse, INPT, 2009. http://oatao.univ-toulouse.fr/7855/1/bedoussac.pdf.
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Les associations d'espèces sont définies comme la culture simultanée d'au moins deux espèces sur la même parcelle pendant une période significative de leur croissance. Ce système permettrait d'améliorer l'utilisation des ressources du milieu (eau, azote, lumière…) et ainsi d'augmenter le rendement et la qualité des grains par rapport aux cultures monospécifiques. L'objectif de notre travail était d'analyser le fonctionnement et d'évaluer la performance des associations blé dur - pois d'hiver et blé dur - féverole d'hiver pour aider à la conception d'itinéraires techniques adaptés à différents objectifs de production. Pour cela nous avons testé, au cours de trois années d'expérimentations, différentes combinaisons de variétés de blé dur, disponibilités en azote, structures de couverts et densités de plantes. Nos résultats ont confirmé l'intérêt de ces systèmes pour améliorer le rendement et la teneur en protéines du blé dur comparativement aux cultures monospécifiques mais également pour la réduction des ravageurs, maladies et de l'enherbement dans certaines conditions. Ces systèmes sont ainsi particulièrement bien adaptés aux situations à faible disponibilité en azote en raison de la complémentarité entre céréale et légumineuse pour l'utilisation de l'azote (minéral du sol et fixation symbiotique) mais aussi pour la captation de l'énergie lumineuse. In fine, ce travail a permis de proposer des prototypes d'itinéraires techniques d'associations adaptés à différents objectifs de production, grâce notamment à l'analyse dynamique des compétitions et complémentarités entre espèces au sein du couvert et en particulier de l'élaboration du rendement du blé dur en association.
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Barros, Júnior Aurélio Paes [UNESP]. "Adubação nitrogenada no consórcio alface e rúcula." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/105218.
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Com o objetivo avaliar a influência de doses de nitrogênio realizadas para a alface e/ou para a rúcula, em consórcio, sobre as plantas (estado nutricional e crescimento) e sobre o consórcio (produtividade, classificação e qualidade, uso eficiente da área e rentabilidade), foi realizado um experimento no período de setembro à dezembro de 2006, na Unesp, Campus de Jaboticabal-SP. O delineamento experimental foi o de blocos casualizados completos, com quatro repetições, sendo os tratamentos arranjados em esquema fatorial 4 x 4 + 2. Os tratamentos resultaram da combinação de quatro doses de N para a alface (0, 65, 130 e 195 kg/ha de N) e quatro doses de N para a rúcula (0, 65, 130 e 195 kg/ha de N), mais dois tratamentos adicionais, correspondentes às monoculturas de alface e rúcula. As cultivares utilizadas foram Verônica (alface) e Folha Larga (rúcula). Para todas as características avaliadas de plantas de alface a monocultura (testemunha) tiveram melhor desempenho que em consórcios, não ocorrendo diferenças para as características de rúcula. O aumento da dose de N para ambas as culturas, em consórcio, proporcionou incrementos nas características de plantas de alface e rúcula. A máxima produtividade de alface, 23.744,48 kg/ha, foi obtida com 100 kg/ha de N para alface e 195 kg/ha de N para rúcula. A máxima produtividade de rúcula, 14.435,78 kg/ha, foi obtida com a adubação de 195 kg/ha de alface e 180 kg/ha de N para rúcula. A maximização do índice de eficiência de uso da área (1,86) foi obtido na dose 127 kg/ha N para a alface e 195 xv kg/ha N para rúcula. O maior lucro operacional, R$ 29.026,11/ha, foi obtido na combinação de doses de 122 kg/ha N para alface e 195 kg/ha N para rúcula.
In order to evaluate the influence how nitrogen rates used for lettuce and/or rocket, under intercropping, affect the plants (nutrition and growth conditions), and the intercropping (yielding, grading, land equivalent ratio and profitability), an experiment was carried out at the campus of Unesp in Jaboticabal-SP, from September to December 2006. The experiment was conducted in a randomized complete block design, with four replications, treatments being arranged in a 4 x 4 + 2 factorial design. The treatments were the result of a combination of four N rates for lettuce (0, 65, 130 and 195 kg/ha of N), and four N rates for rocket (0, 65, 130 and 195 kg/ha of N), plus two additional treatments, which corresponded to lettuce and rocket under single cropping. Veronica (lettuce) and Folha Larga (rocket) were the cultivars used. For all the plant characteristics of lettuce that were studied, the single cropping (witness) had better performance than in intercropping, whereas no differences were observed for the rocket characteristics. An increase in the N rate for both cultures under intercropping showed gains in the plant characteristics of lettuce and rocket. Maximum lettuce yield, 23,744.48 kg/ha, was achieved with the application of 100 kg N ha for lettuce, and 195 kg N ha for rocket. Maximum rocket yield, 14,435.78 kg/ha, was achieved with the application of 195 kg N ha for lettuce, and 180 kg N ha for rocket. The land equivalent ratio was maximized (1.86) by using 127 kg N ha for lettuce and 195 kg N ha for rocket. The highest xvii operating profit, R$ 29,026.11/ha, resulted from the combination of 122 kg N ha for lettuce and 195 kg N ha for rocket.
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Paut, Raphael. "Analyse des compromis entre diversité cultivée et complexité de gestion à travers le cas d’étude du Verger-Maraîcher : Une approche combinant modélisation et méthodes qualitatives Reducing risk through crop diversification: an application of portfolio theory to diversified horticultural systems Modelling crop diversification and association effects in agricultural systems." Thesis, Avignon, 2020. http://www.theses.fr/2020AVIG0724.
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Les vergers-maraichers sont des systèmes mixtes agroforestiers qui visent à optimiser l'utilisation des ressources spatiales et temporelles en produisant des fruits et des légumes sur la même parcelle. De ce point de vue, ces systèmes semblent en mesure de répondre au double enjeu productif et environnemental auquel l’agriculture est confrontée aujourd’hui. Néanmoins, les vergers-maraichers sont caractérisés par une grande complexité structurale et organisationnelle, car ils combinent deux ateliers très exigeants possédant des dynamiques contrastées. Dans cette optique, les conditions permettant d’obtenir un compromis entre résilience des performances et complexification de la gestion du système nécessitent d’être identifiées.L’objectif de ma thèse est donc de caractériser les compromis entre les bénéfices attendus de ces systèmes et les difficultés engendrées par leur complexité structurelle et organisationnelle. La démarche de recherche s’appuie sur le développement de plusieurs modèles qui mobilisent alternativement (i) la théorie du portefeuille ; (ii) le concept de Surface Equivalente Assolée ; (iii) la modélisation dynamique de type états-contrôles.Ces outils de modélisation sont complétés par une approche compréhensive au travers d’entretiens semi-directifs réalisés auprès de 15 agriculteurs du sud-est de la France. La combinaison de ces différentes approches met en évidence quatre résultats principaux. (i) Les effets de la diversification dans un contexte horticole peuvent permettre de réduire la variabilité de la production globale jusqu’à 77% ; (ii) l’association de cultures, en plus d’augmenter le rendement global, réduit davantage le risque ; (iii) la part relative de l’arboriculture et du maraichage dans l’assolement, couplée à l’allocation du temps de travail entre ces deux ateliers sont des éléments déterminants dans la gestion à long terme de la dynamique du système ; (iv) enfin, gérer la complexité liée à la diversité des cultures et à leur agencement agroforestier implique une reconfiguration des pratiques de gestion.L’ensemble de ces résultats met en évidence que la conduite de ces systèmes permet d’arbitrer entre les différentes dimensions étudiées : réduction des risques, synergies entre cultures, différences de dynamiques entre arboriculture et maraichage, mais également, impact de la configuration agroforestière sur les pratiques agricoles. Ces travaux de thèse permettent ainsi de mieux caractériser les compromis entre les bénéfices attendus des vergers-maraichers et la complexité de leur mise en oeuvreThe need to redesign more sustainable agricultural systems able of producing more, especially through intercropping or agroforestry, cannot be achieved without taking into account the essential aspect of production variability. Yet, although many studies have focused on the effect of intercropping on overall production, the particular issue of production variability in such systems remains relatively unstudied. The approach we propose, for a shift towards a sustainable intensification of agricultural systems, considers the dual dimensions of yield and risk in a combined framework for the assessment and the comparison of two diversification strategies: (i) a simple diversification strategy (SDS) considered as an increasing number of crops grown on separate plots within a farm and (ii) an intercropping strategy (IC) considered as a within-plot increased diversity, where more than one species is grown at the same time and place. The two perspectives examined here were Modern Portfolio Theory and Land Equivalent Ratio. The former quantifies the effect of diversification on risk, the latter measures the effect of association on production. This research merges both approaches in a combined framework in order to assess intercropping system performances. By applying our framework to cases selected from the literature, we explored and compared the potential benefits of these two strategies in terms of yield and risk. Results showed that intercropping, in addition to being interesting with regard to yield, can have an additional risk reduction effect compared to a simple diversification strategy. Conversely, some crop mixtures maintained or even increased yield variability. Our work contributes to a better understanding of the possible impacts of diversification strategies on trade-offs between yield and risk, but also underlines the importance of taking yield variability into account in further studies
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Pinto, Ciro de Miranda. "ConfiguraÃÃo e antecipaÃÃo de plantio da mamona em consÃrcio com a cultura do girassol." Universidade Federal do CearÃ, 2011. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=6541.
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CoordenaÃÃo de AperfeiÃoamento de NÃvel SuperiorA mamoneira (Ricinus communis) Ã tolerante a seca e cultivada para produÃÃo de Ãleo para uso industrial. Na regiÃo Nordeste os pequenos produtores cultivam a mamona consorciada algodÃo, feijÃo caupi, gergelim, girassol, milho, sorgo ou amendoim. Dois experimentos de campo foram conduzidos nos anos agrÃcolas 2008, 2009 e 2010, na Fazenda Experimental Lavoura Seca, QuixadÃ, CearÃ, com o objetivo de avaliar o comportamento da mamona e girasssol cultivados em dois padrÃes de consorciaÃÃo. No experimento I avaliou-se o consorcio mamona (Ma) x girassol (Gi) com 1Ma:1Gi; 1Ma:2Gi; 1Ma:3Gi; 2Ma:2Gi; 2Ma:3Gi fileiras, acrescidos da mamona e girassol em monocultivo. No experimento II, avaliou-se o consorcio mamona x girassol com antecipaÃÃo do plantio da mamona em 0, 7, 14 ou 21 dias antes do plantio do girassol. Para cada experimento adotou-se o delineamento de blocos ao acaso com 4 repetiÃÃes. Avaliou-se a produtividade de grÃos, seus componentes e o uso eficiente da terra para a mamona e girassol consorciados e em monocultivo. A produtividade da mamona e girassol no monocultivo foi significativamente superior nos dois sistemas de consÃrcio. A antecipaÃÃo do plantio da mamona 14 e 21 dias em comparaÃÃo ao girassol mostraram vantagens em relaÃÃo as demais datas de plantio. No experimentos I e II verificou-se que a mamona foi dominante sobre ao girassol. PrecipitaÃÃes pluviais inferiores a demanda hÃdrica das culturas da mamona e girassol, proporcionaram reduÃÃo no uso eficiente de terra (UET).
Castor bean (Ricinus communis L.) is an oil seed crop drought tolerant with its oil having several uses in industry. In the Northeast of Brazil it is commonly cultivated by small farmers intercropped with cotton, cowpea, sesamum, sunflower, sorghum or peanuts. Two field experiments were carried during 2008, 2009 and 2010, at â Fazenda Experiental Lavoura Secaâ, Quixada, Ceara, with the objective to evaluate the behavior of castor bean and sunflower under two intercropping arrangements. In experiment I, its was evaluated the intercropping castor bean (CB) x sunflower (SF) with 1CB:1SF; 1CB:2SF; 1CB:3SF; 2SB:2SF; 2CB:3SF rows, added of sole crop of castor bean and sunflower. In the experiment II, was evaluated with the early planting of castor bean in 0, 7, 14 or 21 days in relations to sunflower the intercropping systems. In both experiments it was used a randomized complete block design with 4 replications. In this study it was determined the yield, yield components and land equivalent ratio (LER) for castor bean and sunflower grown in intercropping and sole crop. The grain yield of castor bean and sunflower was significantly higher in sole crop than intercropping in both experiments. Between the intercropping systems the highest yields were observed when early planting of castor bean was of 14 or 21 days before sunflower. In experiments I and II, showed that the castor bean was the dominant crop in relation to sunflower. Rainfall lower the water requirements of castor bean and sunflower crops, showed a reduction in LER.
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Talbot, Grégoire. "L'intégration spatiale et temporelle du partage des ressources dans un système agroforestier noyers-céréales : une clef pour en comprendre la productivité ?" Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2011. http://tel.archives-ouvertes.fr/tel-00664530.
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Des mesures sur parcelles agroforestières (mélanges d'arbres et de cultures) expérimentales mettent en évidence des productivités exceptionnelles, avec des gains de plus de 30% par rapport à l'assolement de cultures pures. Nous avons mis au point et utilisé un modèle numérique dynamique en 3-D (Hi-sAFe) pour (1) tester si l'intégration spatio-temporelle du partage des ressources (lumière, eau, azote) entre espèces suffit à expliquer cette productivité et (2) évaluer l'impact de différents choix de conception ou de gestion sur cette productivité, à partir d'une compréhension des processus impliqués. Nous avons développé une méthode originale d'analyse des données simulées pour identifier et hiérarchiser les processus déterminant le rendement. Le modèle a été paramétré et calibré sur un système noyer hybride / blé dur situé sur le domaine de Restinclières (Hérault, France). Après une analyse détaillée du fonctionnement de ce système, nous avons exploré par expérimentation virtuelle sa réponse à des choix de conception : (1) traits phénologiques des espèces associées, et (2) densité et disposition des arbres sur la parcelle. Par la richesse de son comportement, Hi-sAFe permet un regard nouveau sur le fonctionnement des systèmes agroforestiers. Il éclaire la complexité du système réel. Nos résultats permettent de proposer une interprétation déterministe du rendement de chaque espèce et de la productivité totale de l'association (Land Equivalent Ratio). L'analyse des expérimentations virtuelles permet de proposer des pistes concrètes pour l'optimisation des systèmes agroforestiers.
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Maimela, Katlego Alocia. "Performance of five cowpea (Vigna uguiculata L.) varieties in cowpea/maize strip intercropping in Limpopo." Thesis, 2019. http://hdl.handle.net/10386/2972.
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Thesis (MSc. Agriculture (Agronomy)) -- University of Limpopo, 2019The traditional practice of farmers in Limpopo Province is to mixed and broadcast crops at planting without definite row arrangement. This practice hinders farm input application and results in low crop yields. Strip intercropping, where crops are planted with definite row arrangement, has the advantage of reducing inter-species competition, optimise plant population and increasing crop yield. This study aimed at improving cowpea-maize cropping systems using strip intercropping. The experiment was conducted at University of Limpopo farm and Ga-Thaba village. Five cowpea varieties (Glenda (check)), IT86K-499-35, IT82E-16, IT86D -1010, TVu-13464 and maize (PAN 6479) were evaluated using randomised complete block design with three replications. Data collected were days to flowering, days to maturity, plant height, canopy width, peduncle length, pod length, number of pods/plant, 100 seed weight, grain yield, fodder weight and land equivalent ratio was also determined. Data were analysed using the Statistix 9.0. The results revealed that in both locations TVu 13464 flowered early (50 days) respectively. At University of Limpopo farm TVu 13464, IT82E-16 and IT86D-1010 matured early (89, 88 and 91 days). At University of Limpopo farm, IT82E-16 had high cowpea grain yield (2230 kg/ha) under monocropping and also produced high grain yield of 1373 kg/ha during 2016/17 season. At Ga-Thaba, IT86D-1010 produced high cowpea grain yield of 1085 kg/ha under monocropping and during 2015/16 (660 kg/ha) while IT86K-499-35 also produced high grain yield of 915 kg/ha during 2016/17. The varieties showed yield stability depending on different locations. At University of Limpopo farm, strip intercropping achieved high maize grain yield of 3961 kg/ha during 2016/17. At Ga-Thaba, strip intercropping produced high maize grain yield 747 and 1024 kg/ha during 2015/16 and 2016/17, respectively. Monocropping produced low maize grain yield during 2015/16 with a mean of 425 kg/ha and mixed intercropping had mean of 499 kg/ha during 2016/17. The calculated LER for two crops over two seasons under strip intercropping ranged from 1.25 and 2.14, whereas under mixed intercropping, it ranged between 0.73 and 1.05 over two seasons at University of Limpopo farm. TVu 13464, IT82E-16 and IT86D-1010 are promising varieties for strip intercropping in low rainfall areas because of their early maturity and high grain yield. The calculated LER for two crops over two seasons xx under strip intercropping ranged from 1.62 and 2.98, whereas under mixed intercropping, it ranged between 0.76 and 1.67 in both seasons at Ga-Thaba.
National Research Foundation (NRF) and Water Research Commission (WRC)
Conference papers on the topic "Land equivalent ratio. eng"
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Dris, Antonis, and Mark W. Johnson. "Transition on Concave Surfaces." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53352.
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Boundary layer measurements have been made on the concave surfaces of two constant curvature blades using hot wire anemometry. All the current experiments were performed with negligible streamwise pressure gradient. Grids were used to produce a range of freestream turbulence levels between 1% and 4%. The freestream velocity increases with distance from a concave wall according to the free vortex condition making the determination of the boundary layer edge difficult. A flat plate equivalent boundary layer procedure was adopted therefore to overcome this problem. The Taylor-Goertler (T-G) vortices resulting from the concave curvature were found to make the laminar and turbulent boundary layer profiles fuller and to increase the skin friction coefficent by up to 40% compared with flat plate values. This leads to a more rapid growth in boundary layer thickness. The evolution in the intermittency through transition is very similar to that for a flat plate, however the shape factors are depressed slightly throughout the flow due to the fuller velocity profiles. For all the current experiments, curvature promoted transition. This was very marked at low freestream turbulence level but remained significant even at the highest levels. It appears that the velocity fluctuations associated with the T-G vortices enhance the freestream turbulence resulting in a higher effective turbulence level. A new empirical correlation for start of transition based on this premise is presented. The ratio of end to start of transition momentum thickness Reynolds numbers was found to be approximately constant.
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D’Ercole, Michele, Giovanni Biffaroni, Francesco Grifoni, Francesco Zanobini, and Paolo Pecchi. "Results and Experience From GE Energy’s MS5002E Gas Turbine Testing and Evaluation." In ASME Turbo Expo 2005: Power for Land, Sea, and Air. ASMEDC, 2005. http://dx.doi.org/10.1115/gt2005-68053.
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GE Energy’s new gas turbine, the MS5002E, is a 30 MW-class industrial gas turbine for mechanical drive and power generation applications. The MS5002E (fig.1) is the latest in the Frame5 two-shaft family and, while it retains some features from previous versions, the machine has been specifically designed for low environmental impact and high reliability, in direct response to customer demand for high efficiency and availability [1] & [2]. Main features for the MS5002E are: • 32 MW base load power at ISO inlet conditions (no losses); • 36% thermal efficiency; • 11-stage axial compressor and 17:1 pressure ratio; • reverse flow, six cans, Dry Low NOx (DLN2 technology) combustion system; • two-stages reaction type HP turbine; • two-stages PT leveraged from the LM2500+ HSPT (High Speed Power Turbine); • HP speed operating range 90% (6709rpm) / 101% (7529rpm); • PT speed operating range 50% (2857rpm) / 105% (6000rpm); • exhaust gas temperature (EGT): ∼510°C; • two-baseplates configuration (gas turbine flange-to-flange unit and auxiliary system); • integrated enclosure and baseplate, providing maximum accessibility for maintenance. The design of the MS5002E has been validated through an extensive test program which has included some key-test rigs such as the Rotordynamic Test, the CTV Test (full-scale axial compressor test) and numerous component and full-scale combustion tests in laboratory, conducted in advance of the First Engine to Test (FETT). The MS5002E First Engine to Test was initially started in January 2003 and the validation program has been completed with a full gas turbine teardown, dirty layout (visual and dimensional inspections for each major gas turbine component in as-is conditions) and NDT inspection in June 2004. During engine teardown, disassembly/assembly procedures and tools have been tested and validated. Additional endurance and operability testing is ongoing and will be completed by the end of 2005. The First Engine to Test is a complete equivalent-to-production package including gas turbine, auxiliaries and control system. For the test, a dedicated plateau has been built in Massa, Italy [3]. The gas turbine has been equipped with over 1400 direct measurement points (for a total of more than 2400 direct and indirect measurements) covering the flange-to flange, the package and auxiliaries. All critical-to-quality parameters, such as turbine gas path components temperatures and stresses, combustor temperatures and dynamics, performances and emissions, have been carefully verified by means of redundant instrumentation. This paper presents how the test program has been built on the GE Energy NPI (New Product Introduction) Development Process and how results from tests are fed back to the gas turbine design process. The paper discusses test rig and facilities layout, gas turbine operation experience and lessons learned. Results from the tests and measurements are also discussed.
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Lampert, Dieter, Robert F. Steele, Markus Rosenfelder, and Salvatore DellaVilla. "Equivalent Availability Measurement for Combined-Cycle Power Plants: A New Approach." In ASME Turbo Expo 2001: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-gt-0579.
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The Equivalent Availability Factor (EAF) is the most important RAM characteristic in statistics for benchmarks and guarantees for power plants. It represents an energy ratio of the amount available in a period and the theoretical maximum. Representing the impact of scheduled and forced outages of components along with any deratings, a large number of parameters are involved from design, operation to the environment. In 1993, ABB and SPS commenced a cooperation on the fields of data procurement and recording. ABB brought large experience as a power plant supplier, SPS its competence as the leading firm specialized on RAM data service for the power industry worldwide. In May 2000 ALSTOM affiliated the whole power generation division of ABB. ALSTOM and SPS agreed to complete their periodic reports on time based reliability and availability data with EAF data. As the available energy must be calculated from the attributes of its components — in contrast to the effective produced energy that can be measured — the question of accuracy arises. Starting from the definition formula set as standard by ISO 3977/9 (former ANSI/IEEE 762), different methods have been considered to find the most suitable approach. The accuracy of comparisons of plants of different designs and operation modes and the ability to interpret the results is a measure for the suitability of the model chosen. Finally, some recommendations to handle and apply the EAF in the power plant business are given.
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Schuermans, Bruno, Felix Guethe, Douglas Pennel, Daniel Guyot, and Christian Oliver Paschereit. "Thermoacoustic Modeling of a Gas Turbine Using Transfer Functions Measured at Full Engine Pressure." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59605.
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Thermoacoustic transfer functions have been measured of a full-scale gas turbine burner operating at full engine pressure. Excitation of the high-pressure test facility was done using a siren that modulated part of the combustion airflow. Pulsation probes have been used to record the acoustic response of the system to this excitation. In addition, the flame’s luminescence response was measured by multiple photomultiplier tubes and a light spectrometer. Three techniques to obtain the thermoacoustic transfer function are proposed and employed: two combined acoustical-optical technique and a purely acoustic technique. The first acoustical-optical technique uses one single optical signal capturing the chemiluminescence intensity of the flame as a measure for the heat release in the flame. It only works, if heat release fluctuations in the flame have only one contribution, e.g. equivalence ratio or mass flow fluctuations. The second acoustic-optical acoustic-optical technique makes use of the different response of the flame’s luminescence at different optical wavelengths bands to acoustic excitation. It also works, if the heat release fluctuations have two contributions, e.g. equivalence ratio and mass flow fluctuation. For the purely acoustic technique, a new method was developed in order to obtain the flame transfer function, burner transfer function and flame source term from only three pressure transducer signals. The purely acoustic method could be validated by the results obtained from the acoustic-optical techniques. The acoustic and acoustic-optical methods have been compared and a discussion on the benefits and limitations of the methods is given. The measured transfer functions have been implemented into a non-linear, three-dimensional, time domain network model of a gas turbine with an annular combustion chamber. The predicted pulsation behavior shows a good agreement with pulsation measurements on a field gas turbine.
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Drennan, Scott A., Chen-Pang Chou, Anthony F. Shelburn, Devin W. Hodgson, Cheng Wang, Chitralkumar V. Naik, Ellen Meeks, and Hasan Karim. "Flow Field Derived Equivalent Reactor Networks for Accurate Chemistry Simulation in Gas Turbine Combustors." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59861.
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A method has been developed in which the flow field predicted by Computational Fluid Dynamics (CFD) is automatically condensed into an Equivalent Reactor Network (ERN), composed of well stirred reactors, allowing rapid and accurate analysis of emissions. This paper presents the effectiveness of utilizing an ERN that is a direct abstraction of the computational flow field for combustion analysis. The CFD results are divided into reactors using various filters on flow-field variables to construct an ERN that represents the 3-D combustor flow field and flame structure. Detailed kinetics can then be used in ERN simulations to analyze effects of fuel composition and operating condition on emissions. The technique is applied to a commercial industrial gas turbine combustor fuel injector and compared against experimental emissions results. Sensitivity of emissions predictions to different parameters in the network extraction is also presented. Parameter variations in fuel flow rate are applied to the ERN to obtain relative impacts of fuel-air ratio on the emissions of NOx without requiring new CFD solutions. This automatic approach has been found to reduce the time required to construct and analyze flow field derived ERNs with detailed chemistry by 90%. A local calculation of Damko¨hler number, important for stability analysis, is also presented. This calculation also uses abstracted information from the CFD flow field and detailed-kinetics simulations for more accurate, cost-effective analysis.
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Nickolaus, Daniel A., D. Scott Crocker, David L. Black, and Clifford E. Smith. "Development of a Lean Direct Fuel Injector for Low Emission Aero Gas Turbines." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30409.
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CFD Research Corporation has developed a promising lean direct fuel injector for application to all sizes of aero gas turbine engines. The patented injector design utilizes a bifurcated flow pattern structure that produces low NOx emissions at full power conditions and low CO, UHC and smoke emissions at low power. The design consists of three swirlers and two fuel circuits, and a flow splitter that divides the airflow into two airstreams. Two concentric fuel circuits fuel the two airstreams, producing two distinct flames: a pilot flame and a main flame. This unique flame structure allows separate control of two flame regions, but still allows them to interact. A large percent of combustor airflow enters through the injector. At low power (idle and approach), only the pilot circuit is fueled. The pilot fuel flows into the pilot airstream, and a flame is anchored in the bifurcated recirculation zone. Lean blowouts at idle conditions as low as an injector equivalence ratio of 0.04 have been realized. Low CO, UHC and smoke emissions have been demonstrated at these conditions. For power settings above approach, the fuel flow through the pilot is reduced, and the main is fueled. At cruise to max power conditions, only 10% of the fuel goes through the pilot and 90% goes through the main to achieve both low NOx and good stability. At max power conditions, the injector equivalence ratio is approximately 0.60–0.65, and the flame is blue and non-luminous, resulting in reduced heat loads to the liner. NOx emission levels have been measured in single-injector tests that show this injector has the potential to reduce the Landing/Takeoff (LTO) NOx levels by 60–70% compared with 1996 ICAO standards. This paper presents an overview of how the fuel injector works and how overall performance was achieved. The most difficult aspect of injector performance, i.e. achieving low lean blowout (LBO) fuel-air ratio, is described at the end of the paper, including LBO data for a range of configurations.
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Menon, S. "CO Emission and Combustion Dynamics Near Lean-Blowout in Gas Turbine Engines." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53290.
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Lean-Blowout (LBO) is a phenomenon that occurs in both land-based premixed and propulsion liquid-fuelled gas turbine engines when the effective equivalence ratio is reduced close to the lean flammability limit. Small perturbations in the flame or flow can result in local quenching that can subsequently lead to total extinction (LBO). Prediction of pollutant emission (e.g., CO) and combustion dynamics near LBO is very complicated since physics at many interacting scales have to be resolved. Here, LES studies of both premixed and liquid-fuelled gas turbine engines are reported using a subgrid linear-eddy mixing (LEM) model. In the premixed study, comparison is made with a thin-flame model and it is shown that the flame length can be changed by adjusting the parameters in this model, whereas the flame length is actually predicted in the LEMLES approach. Results of spray combustion in a full-scale liquid-fuelled gas turbine are also discussed for startup and full power operations. It is shown that the LEMLES is able to anchor the flame at the proper location without requiring any model adjustment.
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Yoon, JeongJung, and HeonSeok Lee. "The Study on Development of Low NOx Combustor With Lean Burn Characteristics for 20 kW Class Microturbine." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53200.
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In order to reduce NOx emissions for the 20kW class microturbine under development, the low NOx characteristics were investigated as an application of the lean burn premixed combustion technology. This study was performed under the conditions of high temperature and high pressure. The compressed air of 2.5bar, 3.0bar, and 5.0bar with temperature of 560K was supplied to the combustor through the preheater. The exhaust air was sampled and measured at the immediate exit of the combustor. It is found that NOx increased while CO decreased as increasing inlet air temperature and pressure. NOx decreased, but CO increased as increasing mass flow of inlet air. Equivalent ratio was maintained between 0.10 and 0.16 in the lean region. NOx increased along equivalent ratio, while CO decreased because of the influence of flame temperature. Through numerical approach work with an appropriate combustion model, a complicated swirling flow pattern was predicted, and numerical values of NOx and CO emission were calculated and compared with experiments. As the results of this study, NOx can be reduced up to less than 42ppm at 15% of oxygen when the 20kW class microturbine is operated at design condition.
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Engdar, Ulf, Fredrik Hermann, Rolf Gabrielsson, and Jens Klingmann. "CFD Investigation of the Effects of Different Diluents on the Emissions in a Swirl Stabilized Premixed Combustion System." In ASME Turbo Expo 2005: Power for Land, Sea, and Air. ASMEDC, 2005. http://dx.doi.org/10.1115/gt2005-68683.
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Recently, new cycles for power generation, such as wet cycles and cycles for CO2 capture, have gained increasing interest. These new cycles use some sort of dilution in the air/fuel mixture, e.g. steam or CO2. Gas turbine cycles using LCV gases can also be said to fit this description. Almost all modern gas turbines use a lean premixed combustion system, since it combines low NOx emissions with high combustion efficiency. The main objective of this paper is to study the influence of different diluents on the NOx and CO emissions at different inlet temperature, equivalence ratio, pressure and mass flow. The studied combustor was a premixed swirl stabilized combustor with optical access and emission sampling equipment. The combustor uses Danish natural gas as its main fuel. Computational fluid dynamics (CFD) has been employed to perform the investigations. It is common knowledge that turbulence models based on the Buissinesq assumption are not generally capable of handling a highly swirling flow in a correct way. Therefore, a differential Reynolds stress model (DRSM) has been employed for modeling of the turbulence. The turbulent combustion has been modeled with the level-set flamelet library approach (FLA). In this approach a laminar flamelet is linked to turbulent flow field via a non-reacting scalar G and its variance. The laminar flamelet is modeled with separate code. This code solves the combustion development with a detailed reaction mechanism for a laminar, non-stretched and premixed one-dimensional flame. This is of great importance when emissions are to be predicted. All fluid dynamics computations were performed with the commercial CFD code Star-CD, version 3.20, where the FLA combustion model was implemented through Fortran based user subroutines. The computed flow field was validated against experimental data during non-reaction flow conditions. The computations showed good agreement with the experimental data. The computed CO and NOx emissions showed the same trends as the experimental data for the reacting case with an undiluted flame, when the equivalence ratio was altered. The computed emissions were used to build up an emission map for different dilutions during different operation conditions.
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Zhang, Chao. "Low Cycle Fatigue Crack Initiation of Rotating Structures Under Biaxial Stress States." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59249.
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Rotating structures can experience biaxial stress states with a wide range of biaxiality ratios on structure surfaces. Low cycle fatigue (LCF) crack initiation in such conditions demonstrates different fatigue characteristics in terms of crack orientation, fatigue life, etc. The biaxial stress states can be categorized into two types: in-phase and out-of-phase under which fatigue characteristics can be significantly different according to rig test results. This paper presents an investigation of LCF crack initiation under in-phase and out-of-phase biaxial stress states based on rig test results of a nickel alloy. The crack orientations are reviewed and discussed at different stress states. Relations of biaxial LCF life debit factor vs biaxiality ratio are derived (the debit factor is defined as a ratio of the LCF life at a biaxial stress state to the LCF life at corresponding uniaxial stress state which has same cyclic and mean stresses as the primary cyclic and mean stressees of the biaxial stress state). The rig test results showed that the crack orientation is usually normal to the primary stress vector under in-phase biaxial stress states but is inclined to the primary stress vector under out-of-phase stress states. As per the derived biaxial LCF life debit factors, the LCF life was found to be slightly reduced with increasing biaxiality ratios under in-phase biaxial stress states but significantly reduced under out-of-phase biaxial stress states compared with corresponding uniaxial primary stress states. The equivalent cyclic stress fatigue criterion is also employed to theoretically model the biaxial LCF life debit factor under in-phase biaxial stress states. The hydrostatic cyclic stress is included in the equivalent cyclic stress in order to take into account the hydrostatic cyclic pressure effects. The equivalent cyclic stress in the criterion can physically reflect the materials’ ductility reduction under in-phase multiaxial stress states.
Reports on the topic "Land equivalent ratio. eng"
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Fernandes, R., M. Maloley, and F. Canisius. Relationship between leaf area index and Landsat Operational Land Imager equivalent reduced simple ratio vegetation index for the Athabasca oil sands region, northern Alberta. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2018. http://dx.doi.org/10.4095/308333.
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