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| Registros recuperados: 1.391 | |
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| Amirouche, mawhoub. |
| The search for decision-making tools is essential in order to control agricultural practices and plan for sustainable agriculture that respects the environment. To this end, FAO has developed an evaluation model called AquaCrop, which covers most technical routes, including fertilization. In this perspective, this study focuses on the AquaCrop model (v6.1) to calibrate it for the simulation of lettuce crop yields (Lactuca sativa L), under different fertilization levels for the trial periods (2015/2016) and (2016/2017). Four levels of fertilization were examined under rain conditions, namely T1 (0 kg N/ha), T2 (60 kg N/ha), T3 (120 kg N/ha) and T4 (180 kg N/ha). The model performance was evaluated using the coefficient of determination (R2), the square root... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: AquaCrop; Lettuce; Calibration; Validation; Fertility stress; Water productivity. |
| Ano: 2021 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/6195 |
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| Mehari Zewde Tekeste; Deere&Co; Desale H Habtzghi; Department of Statistics, The University of Akron, Akron, OH; Jos Koolen; Wagenigen University. |
| Modeling of soil elastic and permanent plastic volumetric strains (compaction) caused by loading from machinery vehicles using the modified Cam-clay soil constitutive model requires understanding the behaviors of compression and rebound parameters under unsaturated soil conditions. Oedometer tests were conducted on a sandy loam, a loam, and a clay loam soil, all tropical soils, at three initial soil moisture contents and five maximum stress levels (50, 100, 200, 300 and 400 kPa). The objectives were to investigate the effects of soil moisture content and maximum applied stress on the modified compression index (l*) and modified rebound index (k*) parameters of a modified Cam-clay soil model on the three soils and predict the compressibility indices using... |
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Palavras-chave: Modified compression index (l*); Modified rebound index (k*); Axial stress; Uniaxial compression cyclic test; Soil moisture; Soil types. |
| Ano: 2013 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/2214 |
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| S. Pedersen; V. Blanes-Vidal; H. Joergensen; A. Chwalibog; A. Haeussermann; M. J. W. Heetkamp; A.J.A. Aarnink. |
| This article deals with carbon dioxide production from farm animals; more specifically, it addresses the possibilities of using the measured carbon dioxide concentration in animal houses as basis for estimation of ventilation flow (as the ventilation flow is a key parameter of aerial emissions from animal houses). The investigations include measurements in respiration chambers and in animal houses, mainly for growing pigs and broilers.Over the last decade a fixed carbon dioxide production of 185 litres per hour per heat production unit, hpu (i.e. 1000 W of the total animal heat production at 20 oC) has often been used. The article shows that the carbon dioxide production per hpu increases with increasing respiration quotient. As the respiration quotient... |
| Ano: 1969 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/1205 |
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| Obayopo, Surajudeen Olanrewaju; Oluwasanmi, Alonge. |
| Fish preservation is the most important post-harvest process in commercial fishery. The traditional methods of fish preservation are inefficient and susceptible to contamination. Few existing solar fish dryers are not designed for optimal drying performance. In this study, a direct solar dryer for fish was numerically modelled, fabricated and evaluated for performance enhancement. The modeling was performed using computational fluid dynamics (CFD) code to simulate different dimensions of the designed dryer at varying fan speeds. By applying desirability function method, (70 × 60 × 40) cm3 drying chamber with a plane of 25 cm away from the base for tray location gives optimal temperature and the best uniform air flow distribution. The performance of the... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 2019 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/5051 |
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| Kic, Pavel. |
| This paper is focused on the Computational fluid dynamics (CFD) modeling of regenerative heat exchanger suitable for animal houses. Buildings used for housing of animals in farms with intensive breeding, like poultry or pig houses, are characterized by high generation of heat inside, partly produced by animals, and in the case of small young animals, supplemented also by heating. On the other side these buildings need intensive ventilation which causes big losses of energy by exhausted air. A good way how to reduce heat losses can be the use of technical systems of heat recovery. There are two principal constructions of heat exchangers for heat recovery. There are either recuperative or regenerative heat exchangers. Industrially produced heat exchangers,... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Animal houses; Ventilation; Energy; Parameters; Czech Republic. |
| Ano: 2015 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3137 |
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| Pavel Kic. |
| This paper is focused on the Computational fluid dynamics (CFD) modeling of regenerative heat exchanger suitable for animal houses. Buildings used for housing of animals in farms with intensive breeding, like poultry or pig houses, are characterized by high generation of heat inside, partly produced by animals, and in the case of small young animals, supplemented also by heating. On the other side these buildings need intensive ventilation which causes big losses of energy by exhausted air. A good way how to reduce heat losses can be the use of technical systems of heat recovery. There are two principal constructions of heat exchangers for heat recovery. There are either recuperative or regenerative heat exchangers. Industrially produced heat exchangers,... |
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Palavras-chave: Animal houses; Ventilation; Energy; Parameters; Czech Republic. |
| Ano: 2015 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3137 |
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| Kyu-Hyun Park; Ngwa Martin Ngwabie; University of Guelph; Claudia Wagner-Riddle. |
| Composting has the potential to mitigate methane (CH4) and nitrous oxide (N2O) emissions from manure. The heterogeneous nature of emitting surfaces makes it difficult to quantify these emissions. CH4 and N2O fluxes measured using eight small chambers (0.72 m2) and a mega chamber (90 m2) were compared, and the effect of aeration on the fluxes during composting was studied. Two batches of compost were placed in three channels and 2-3 small flux chambers were deployed on each channel. The channels were enclosed by a building serving as a mega chamber. Chamber location significantly affected gas fluxes, pointing to strong spatial heterogeneity. Mean CH4 fluxes from the small chambers were similar or... |
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Palavras-chave: Chamber; Compost; Greenhouse gases; Aeration; Flux. |
| Ano: 2014 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/2467 |
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| Park, Kyu-Hyun; Ngwabie, Ngwa Martin; Wagner-Riddle, Claudia. |
| Composting has the potential to mitigate methane (CH4) and nitrous oxide (N2O) emissions from manure. The heterogeneous nature of emitting surfaces makes it difficult to quantify these emissions. CH4 and N2O fluxes measured using eight small chambers (0.72 m2) and a mega chamber (90 m2) were compared, and the effect of aeration on the fluxes during composting was studied. Two batches of compost were placed in three channels and 2-3 small flux chambers were deployed on each channel. The channels were enclosed by a building serving as a mega chamber. Chamber location significantly affected gas fluxes, pointing to strong spatial heterogeneity. Mean CH4 fluxes from the small chambers were similar or 1.4 times higher compared to the mega chamber. Mean... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Chamber; Compost; Greenhouse gases; Aeration; Flux. |
| Ano: 2014 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/2467 |
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| S. Pedersen; P. Ravn. |
| In respect to improving animal welfare and to minimize the ammonia emission from animal facili-ties, it is important to have appropriate information on the impact of the flooring system in pig pens. Twelve different floors, six commercially available and six experimental floors for pig pens, were investigated in respect to four different characteristics: friction coefficients, shock absorption, am-monia emission and heat conduction. The friction coefficients were measured as dynamic friction for dry floors and floors wetted with water and rapeseed oil and as static friction for dry floors. The floor elasticity was measured as shock absorption when letting a weight fall on the test floors. The ammonia emission was measured in a wind tunnel with ammonia... |
| Ano: 1969 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/1202 |
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| Segun, Bello Raphael. |
| Abstract Performance characterization of some selected conventional cook stoves in South Eastern Nigeria had been carried out. Three conventional cook stoves (3-stone stove, charcoal stove and sawdust stove) were selected and evaluated. Their performances were compared with those of improved stove. The results show that the time spent in cooking 1 Kg of rice/(yam) is significantly different in all the conventional stoves under test; (maximum 0.75 (0.44) kg/hr for 3-stone stove and minimum 0.61 (0.35) hr/kg for charcoal). Fuel utilization also differs for instance lesser quantity of charcoal would be required to cook the same quantity of food on the charcoal stove than the open fire stove. Also the specific fuel consumption value of charcoal stove is... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Wood products & Machinery Cook stove; Fuel consumption; Thermal efficiency; Burn rate. |
| Ano: 2015 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3037 |
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| HOMDOUNG, NIGRAN. |
| Torrefaction and densification are suitable techniques for upgrading solid biomass materials. They can improve the energy properties of solid fuels. The objective of this research was to evaluate changes in physico-chemical properties of agricultural residues (corn-cobs and rice husks) during torrefaction. Physical properties of the torrefied biomass pellets were analysed. The results showed that increasing the torrefaction temperature and time resulted in reduced moisture and volatile matter content of corn-cobs and rice husks. At the same time, fixed carbon, ash content and heating values were increased. The heating values of both torrefied fuels were in the range of 14.9–16.9 MJ/kg, increased by about 16 to 22% from the raw biomass. The optimum... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Agricultural residues; Torrefaction; Densification; Torrefied biomass; Solid fuels. |
| Ano: 2020 |
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/5741 |
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| Registros recuperados: 1.391 | |
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