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  Subjects -> AGRICULTURE (Total: 688 journals)
    - AGRICULTURAL ECONOMICS (73 journals)
    - AGRICULTURE (462 journals)
    - CROP PRODUCTION AND SOIL (90 journals)
    - DAIRYING AND DAIRY PRODUCTS (25 journals)
    - POULTRY AND LIVESTOCK (38 journals)

AGRICULTURE (462 journals)                  1 2 3 4 5 | Last

Aceh International Journal of Science and Technology     Open Access  
Acta agriculturae Slovenica     Open Access   (Followers: 5)
Acta Agrobotanica     Open Access   (Followers: 3)
Acta Agronomica Hungarica     Full-text available via subscription   (Followers: 1)
Acta Agronomica Sinica     Full-text available via subscription   (Followers: 6)
Acta Scientiarum. Animal Sciences     Open Access   (Followers: 1)
Acta Scientiarum. Technology     Open Access   (Followers: 1)
Acta Technologica Agriculturae     Open Access   (Followers: 3)
Advances in Agriculture & Botanics     Open Access   (Followers: 10)
Advances in Agriculture, Sciences and Engineering Research     Open Access   (Followers: 12)
Advances in Agronomy     Full-text available via subscription   (Followers: 11)
Advances in Life Science and Technology     Open Access   (Followers: 5)
AFBM Journal     Open Access  
Africa Development     Open Access   (Followers: 8)
Africa Research Bulletin: Political, Social and Cultural Series     Hybrid Journal   (Followers: 8)
African Journal of Agricultural Research     Open Access   (Followers: 3)
African Journal of Food Science     Open Access   (Followers: 4)
African Journal of Food, Agriculture, Nutrition and Development     Open Access   (Followers: 6)
African Journal of Horticultural Science     Open Access   (Followers: 2)
African Journal of Range and Forage Science     Hybrid Journal   (Followers: 5)
African Journal of Sustainable Development     Full-text available via subscription   (Followers: 5)
Agribusiness : an International Journal     Hybrid Journal   (Followers: 5)
Agricultura Tecnica     Open Access   (Followers: 6)
Agricultura Tropica et Subtropica     Open Access   (Followers: 2)
Agricultural Advances     Open Access   (Followers: 4)
Agricultural and Food Science     Open Access   (Followers: 19)
Agricultural Economics     Hybrid Journal   (Followers: 46)
Agricultural History     Full-text available via subscription   (Followers: 235)
Agricultural Research     Hybrid Journal   (Followers: 5)
Agricultural Science     Full-text available via subscription   (Followers: 6)
Agricultural Science     Open Access  
Agricultural Sciences     Open Access   (Followers: 8)
Agricultural Sciences in China     Full-text available via subscription   (Followers: 4)
Agricultural Systems     Hybrid Journal   (Followers: 21)
Agricultural Water Management     Hybrid Journal   (Followers: 16)
Agriculture     Open Access   (Followers: 5)
Agriculture & Food Security     Open Access   (Followers: 12)
Agriculture (Poľnohospodárstvo)     Open Access   (Followers: 1)
Agriculture and Agricultural Science Procedia     Full-text available via subscription   (Followers: 1)
Agriculture and Human Values     Hybrid Journal   (Followers: 11)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 32)
Agriprobe     Full-text available via subscription  
Agrivita : Journal of Agricultural Science     Open Access   (Followers: 4)
Agro-Science     Full-text available via subscription  
Agroalimentaria     Open Access   (Followers: 1)
Agrociencia     Open Access   (Followers: 2)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 1)
Agronomía Colombiana     Open Access   (Followers: 1)
Agronomía Costarricense     Open Access   (Followers: 2)
Agronomía Mesoamericana     Open Access   (Followers: 1)
Agronomie Africaine     Full-text available via subscription  
Agronomy     Open Access   (Followers: 8)
Agrosearch     Open Access  
AI & Society     Hybrid Journal   (Followers: 2)
Alinteri Zirai Bilimler Dergisi : Alinteri Journal of Agricultural Sciences     Open Access  
Ambiência     Open Access  
Ambiente & Agua : An Interdisciplinary Journal of Applied Science     Open Access   (Followers: 1)
American Journal of Agricultural and Biological Sciences     Open Access   (Followers: 9)
American Journal of Botany     Full-text available via subscription   (Followers: 14)
American Journal of Economics and Sociology     Hybrid Journal   (Followers: 21)
American Journal of Potato Research     Hybrid Journal   (Followers: 2)
American Journal of Rural Development     Open Access   (Followers: 1)
Anais da Academia Brasileira de Ciências     Open Access   (Followers: 2)
Annales UMCS, Agricultura     Open Access  
Annales UMCS, Horticultura     Full-text available via subscription  
Annals of Agricultural and Environmental Medicine     Open Access   (Followers: 1)
Annals of Agricultural Sciences     Open Access   (Followers: 1)
Annual Review of Resource Economics     Full-text available via subscription   (Followers: 10)
APCBEE Procedia     Partially Free   (Followers: 2)
Applied Economics Letters     Hybrid Journal   (Followers: 22)
Applied Financial Economics Letters     Hybrid Journal   (Followers: 7)
Arboricultural Journal : The International Journal of Urban Forestry     Hybrid Journal   (Followers: 6)
Archivos de Zootecnia     Open Access   (Followers: 2)
Arquivos do Instituto Biológico     Open Access  
Arthropod-Plant Interactions     Hybrid Journal   (Followers: 1)
Asian Economic Papers     Hybrid Journal   (Followers: 3)
Asian Journal of Agricultural Research     Open Access   (Followers: 4)
Asian Journal of Plant Sciences     Open Access   (Followers: 2)
Australian Cottongrower, The     Full-text available via subscription   (Followers: 1)
Australian Economic Papers     Hybrid Journal   (Followers: 5)
Australian Forest Grower     Full-text available via subscription   (Followers: 2)
Australian Forestry     Full-text available via subscription   (Followers: 4)
Australian Grain     Full-text available via subscription   (Followers: 4)
Australian Holstein Journal     Full-text available via subscription  
Australian Journal of Agricultural and Resource Economics     Hybrid Journal   (Followers: 5)
Australian Journal of Agricultural Engineering     Open Access  
Australian Sugarcane     Full-text available via subscription  
Avances en Investigacion Agropecuaria     Open Access   (Followers: 1)
Bangladesh Journal of Agricultural Research     Open Access   (Followers: 2)
Bangladesh Journal of Scientific Research     Open Access   (Followers: 1)
Berkala Ilmiah Pertanian     Open Access   (Followers: 1)
Bioagro     Open Access   (Followers: 1)
Biocatalysis and Agricultural Biotechnology     Hybrid Journal   (Followers: 5)
Biocontrol Science and Technology     Hybrid Journal   (Followers: 5)
Biodiversity     Hybrid Journal   (Followers: 21)
Biodiversity : Research and Conservation     Open Access   (Followers: 20)
Biological Agriculture & Horticulture : An International Journal for Sustainable Production Systems     Partially Free   (Followers: 13)
Biosystems Engineering     Hybrid Journal   (Followers: 1)
Biotemas     Open Access  
Bragantia     Open Access   (Followers: 2)

        1 2 3 4 5 | Last

Journal Cover Biosystems Engineering
   [3 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1537-5110 - ISSN (Online) 1537-5129
     Published by Elsevier Homepage  [2575 journals]   [SJR: 0.757]   [H-I: 58]
  • An evaluation of a vision-based sensor performance in Huanglongbing
           disease identification
    • Abstract: Publication date: February 2015
      Source:Biosystems Engineering, Volume 130
      Author(s): Alireza Pourreza , Won Suk Lee , Ed Etxeberria , Arunava Banerjee
      Huanglongbing (HLB) disease is a critical infection which has dangerously affected the citrus production in Florida and has also been observed in California and Texas. No active treatment for this infection has been reported yet and the HLB infected tree will eventually die. However, early identification and removal of the HLB affected trees will secure the healthy trees in the grove. Accumulation of starch on infected leaves is an early symptom of HLB. Starch can rotate the polarisation plane of light in a certain waveband. A customised vision sensor was developed based on this characteristic to identify the HLB symptom. The vision sensor images were compared with the images captured by a colour camera to demonstrate the improvement achieved in this method. Also, the starch accumulation identification was studied for citrus leaves before and after being ground. The results showed an enhanced HLB identification performance using the developed vision sensor.


      PubDate: 2014-12-18T08:22:14Z
       
  • An evaluation of insect expulsion from wheat samples by microwave
           treatment for disinfestation
    • Abstract: Publication date: February 2015
      Source:Biosystems Engineering, Volume 130
      Author(s): Fuji Jian , Digvir S. Jayas , Noel D.G. White , Paul G. Fields , Nelson Howe
      The non-uniform temperature distribution created in the processed materials limits the wide application of microwave treatment. The non-uniform temperature also increases the chance of insects surviving or moving out from the treated materials. Wheat (14, 16 and 18% moisture contents, wet basis) with or without insects (Cryptolestes ferrugineus (Stephens)) was continuously or intermittently treated inside a microwave oven for 30, 60 and 90 s. Three dimensional distributions were determined by measuring temperatures and moisture contents at 27 locations inside a 10 × 9 × 9 cm3 plastic container. The adults and larvae of C. ferrugineus, which did not escape from the treated wheat, were sieved out or forced out using the Berlese funnel method. Temperatures and moisture contents had different mean, maximum and minimum values in different replicates when treatment time was 30 s. Long treatment time (90 s) generated a dry and hot spot at the same position even though the hot and dry spots were not at the same position in different replicates. Intermittent treatment did not generate more even distributions of temperatures and moisture contents in dry grain, while wet grain (>16% MC) did. Most of the introduced adults were extracted and there was no significant difference between intermittent or continuous treatment methods. Microwave treatment did not kill all insects, however the number of offspring decreased by >75%. Driving insects out of wheat could be an alternative method for insect disinfestation and detection.


      PubDate: 2014-12-13T08:06:35Z
       
  • Suitability of Spanish ‘Manzanilla’ table olive orchards for
           trunk shaker harvesting
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Sergio Castro-Garcia , Francisco J. Castillo-Ruiz , Francisco Jimenez-Jimenez , Jesus A. Gil-Ribes , Gregorio L. Blanco-Roldan
      Low harvesting efficiency and fruit damage are the main limitations for trunk shakers in the harvesting of table olives. Different cultivations of olive orchards, variations in the fruit properties over the harvesting season, and a wide range of machines both characterise and hamper the harvesting process in several traditional olive producing countries, such as Spain. The aim of the work reported was to develop the mechanical harvesting of existing orchards using commercial trunk shakers maximising the quantity of harvested fruit while maintaining its quality. Results showed that the mean value of harvesting efficiency with trunk shakers was 74%, when additional rod beating or abscission agents were not applied. In orchards where the trees were trained into shapes that facilitated the transmission of vibration, fruit properties had a limited effect on harvesting efficiency. In order to achieve harvesting efficiency >85%, tree trunk vibration parameters were set above an acceleration value of 183.4 m s−2, and at a frequency of 28.1 Hz. Although increasing the trunk acceleration improved harvesting efficiency, it led to an increase in damage to the harvested fruit. Damage caused to the fruit through mechanical harvesting was 3.5 times greater than the damage caused by manual harvesting. Adjusting the vibration parameters, limiting the power of the machine, training the canopy to reduce volume and facilitating the vibration transmission to the fruit, together with effective post-harvest field treatments that maintain the fruit quality, are all required to ensure the success of vibration harvesting systems for green olives.


      PubDate: 2014-12-06T07:50:36Z
       
  • Effective utilisation of trickling liquid discharged from a bio-trickling
           filter as a moisture conditioning agent for composting
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Chuanfu Wu , Qunhui Wang , Shanshan Shi , Niantao Xue , Dexun Zou , Siliang Pan , Shu Liu
      Primary fermentation experiments were carried out investigating the disposal and reuse of trickling liquid discharged from a bio-trickling filter as a moisture conditioning agent. The liquid was mixed with food waste and mushroom bran. Compared to the addition tap water (TW), the addition of trickling liquid (TL) was found to accelerate the decomposition/fermentation rate of organic waste, which is defined in terms of enhancement in heat generation and waste mass reduction. The acceleration effect may be due to the activity promotion of heterotrophic bacteria induced by the addition of TL containing high level of ammonium. The addition of TL also promoted compost maturity based on the evaluation indices. The carbon–nitrogen ratio, Q 2/6, and Q 4/6 of the TL treatment were 15.3, 10.7, and 7.6, respectively. These values were 8.9, 4.3, and 3.6 lower than those in the TW treatment after 15 d of primary fermentation. The germination index of the TW treatment was 22.3% lower than that of the TL treatment (79.4%), which met the criteria (80%) for maturated composting product. Furthermore, a nitrogen mass calculation indicated that mass reduction of nitrogen of the TL and the TW treatments were −9.6% and 12.2%, respectively. Therefore, reusing TL as a moisture conditioning agent for organic waste composting could enable zero discharge of TL, promote maturity, and increase the nitrogen content of compost.


      PubDate: 2014-12-06T07:50:36Z
       
  • Effect of short rotation coppice plantation on the performance and chips
           quality of a self-propelled harvester
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Vincenzo Civitarese , Salvatore Faugno , Stefania Pindozzi , Alberto Assirelli , Luigi Pari
      The performance of coppice harvesting machines is influenced by parameters such as field yield, the shape and size of the plantation and the space for turning at the headland. The quality of chips and the effect of the dendrometric characteristic of nine different species (Fraxinus angustifolia, Robinia pseudoacacia, Salix alba, Eucalyptus occidentalis, Populus nigra L. and four genotypes of Populus x euroamericana (Grimminge, Hoogvorst, Muur, Vesten) grown in the same flat plot of about 4.5 ha on the performance rate and quality of the work, was evaluated. Field yields ranged from 33 t ha−1 to ∼95 t ha−1, for the S. alba and E. occidentalis, respectively. The harvester worked with an average speed of 0.91 m s−1 (±0.22) and average productivities of 0.98 ha h−1 (±0.24) and 45.25 t h−1 (±5.56). There was a satisfactory linear correlation between the working speed of the machine and field yield. The quality of the chips showed some variability with values of moisture content ranging between 42.7% and 57.3% (for R. pseudoacacia and S. Alba respectively) and values of bulk density from 273 kg m−3 to 313 kg m−3 (for Populus euroamericana Vesten and E. occidentalis respectively).


      PubDate: 2014-12-06T07:50:36Z
       
  • Potential biogas and methane yield of maize stover fractions and
           evaluation of some possible stover harvest chains
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Simona Menardo , Gianfranco Airoldi , Vincenzo Cacciatore , Paolo Balsari
      With a yearly global production of about 75 million tonnes of dry matter (DM), maize stover remains a major untapped agricultural resource. While its use as a feedstock for biogas production has been well studied, the methane potential of separate single stover fraction begs further analysis. This study evaluated the composition of maize cobs, husks, leaves, and stalks and the potential of those components to produce biogas and methane. These analyses allowed an estimate of the preferred maize stover harvest chain conditions for quantity and quality. Methane yields from the fractions ranged between 206.6 and 307.0 lN kg−1 VS, with husks being the most productive. In total, our estimates suggest that these fractions produce about 3000 m3 ha−1 of methane from the biogas conveniently collected by different harvest chains.


      PubDate: 2014-12-06T07:50:36Z
       
  • Spatial variability of mixing ratios of ammonia and tracer gases in a
           naturally ventilated dairy cow barn
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Luciano B. Mendes , Nadège Edouard , Nico W.M. Ogink , Hendrik Jan C. van Dooren , Ilda de Fátima F. Tinôco , Julio Mosquera
      The use of the tracer gas ratio method to estimate emissions from naturally ventilated (NV) livestock barns excludes the need of monitoring ventilation rates. However, it requires accurate measurement of tracer release rate (QT) and a representative estimate of the mixing ratio between pollutant (P) and tracer (T) gases ( [ P ] / [ T ] ¯ ) . While the quality of QT simply depends on using an accurate commercial mass flow controller, determination of a representative mixing ratio [ P ] / [ T ] ¯ is not trivial, since the NV livestock barn airspace presents complex movements that might be dependent on spatial vertical and cross horizontal dimensions. The goal was to assess the spatial variability of concentrations of the artificial tracer gas sulphur hexafluoride (SF6), the metabolic carbon dioxide (CO2) and the pollutant ammonia (NH3), along with their mixing ratios ([NH3]/[CO2], [NH3]/[SF6], [CO2]/[SF6]), inside a NV dairy cow barn. The results indicated that the vertical variability of the calculated mixing ratios became more stable with increase in height, reaching approximately constant values above the animal occupied zone. Using both the metabolic CO2 and the artificially injected SF6 as tracer gases led to a homogeneous spread in behaviour of mixing ratios along V and HC directions. Finally, the possibility of finding a zone within the barn airspace where mixing ratios are considered to be representative for the whole barn, and the implications of applying artificial or metabolic tracers are discussed.


      PubDate: 2014-12-06T07:50:36Z
       
  • Monitoring of crop biomass using true colour aerial photographs taken from
           a remote controlled hexacopter
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Ramia Jannoura , Katja Brinkmann , Daniel Uteau , Christian Bruns , Rainer Georg Joergensen
      The use of unmanned aerial vehicles has been recently increasing in precision agriculture as an alternative to very costly and not readily available satellites or airborne sensors. Vegetation indices based solely on visible reflectance, which can be derived from true colour images may be a simple and cheap alternative compared to near infrared indices. A remote-controlled hexacopter with an RGB digital camera was tested for evaluating crop biomass. The hexacopter was flown over a field in which peas and oats were grown as sole crops and intercrops, fertilised with horse manure and yard–waste compost (10 t C ha−1). The images were taken at flowering stage. Based on the aerial photographs, the Normalised Green–Red Difference Index (NGRDI) was calculated, and related to aboveground biomass and leaf area index (LAI). The mean of NGRDI values ranged from 0.09 to 0.13 without any effect of cropping system, while the fertiliser significantly affected the yield and the corresponding NGRDI values. NGRDI values were positively and significantly correlated with the aboveground biomass (r = 0.58–0.78). A high autocorrelation of NGRDI, and thus biomass, was found within the treatment plots and used for block kriging to show the spatial variability in the field. No relationship was found between NGRDI and LAI in peas (P = 0.68) or oats (P = 0.15). Nevertheless, true colour images from a hexacopter and the derived NGRDI values are a cost-effective tool for biomass estimation and the establishment of yield variation maps for site-specific agricultural decision making.


      PubDate: 2014-12-01T07:48:57Z
       
  • Torque and energy characteristics for strip-tillage cultivation when
           cutting furrows using three designs of rotary blade
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): M.A. Matin , J.M. Fielke , J.M.A. Desbiolles
      Strip-tillage research in developing countries usually relies on commonly used rotary blades designed for conventional full disturbance soil tillage. With the aim of optimising the blade geometry and operational settings, this study investigated the effect of three blade geometries (conventional, half-width and straight) at four rotary speeds (125, 250, 375, and 500 rpm) on torque, power and energy characteristics. A single row rotary tiller was fitted with the blades set at a cutting width of 50 mm and depth of 50 mm and tested in a soil bin (sandy loam soil). Analyses of high speed video images and corresponding blade motion revealed that the peak torque occurred at a higher blade penetration depth as the speed increased indicating transformation of the peak torque requirement from due to initial soil failure at a low speed to final soil cutting and throwing at a high speed. The straight blade design required the least torque, average power, peak power, specific energy and effective specific energy at 375–500 rpm which targeted for a small bite length for a fine soil tilth. The straight blade saved 20–25% power when compared with the conventional and half-width blades at 500 rpm. Although, the average power, peak powerand specific energy requirements increased with the rotary speed for all the blades with a steep rise over 375 rpm, the effective specific energy requirement remained almost unchanged for the straight blade indicating its high effectiveness for strip-tillage operations.


      PubDate: 2014-12-01T07:48:57Z
       
  • Detecting crop water status in mature olive groves using vegetation
           spectral measurements
    • Abstract: Publication date: December 2014
      Source:Biosystems Engineering, Volume 128
      Author(s): Giovanni Rallo , Mario Minacapilli , Giuseppe Ciraolo , Giuseppe Provenzano
      Full spectral measurements (350–2500 nm) at tree canopy and leaf levels and the corresponding leaf water potentials (LWP) were acquired in an olive grove of Sicily, at different hours of the day, during summer season 2011. The main objective of the work was to assess, on the basis of the experimental data-set, two different approaches to detect crop water status in terms of LWP. Specifically, using existing families of Vegetation Indices (VIs) and applying Partial Least Squares Regression (PLSR) were optimised and tested. The results indicated that a satisfactory estimation of LWP at tree canopy and leaf levels can be obtained using vegetation indices based on the near infrared–shortwave infrared (NIR–SWIR) domain requiring, however, a specific optimisation of the corresponding “centre-bands”. At tree canopy level, a good prediction of LWP was obtained by using optimised indices working in the visible domain, like the Normalized Difference Greenness Vegetation Index (NDGI, RMSE = 0.37 and R 2 = 0.57), the Green Index (GI, RMSE = 0.53 and R 2 = 0.39) and the Moisture Spectral Index (MSI, RMSE = 0.41 and R 2 = 0.48). On the other hand, a satisfactory estimation of LWP at leaf level was obtained using indices combining SWIR and NIR wavelengths. The best prediction was specifically found by optimising the MSI (RMSE of 0.72 and R 2 = 0.45) and the Normalized Difference Water Index (NDWI, RMSE = 0.75 and R 2 = 0.45). Even using the PLSR technique, a remarkable prediction of LWP at both tree canopy and leaf levels was obtained. However, this technique requires the availability of full spectra with high resolution, which can only be obtained with handheld spectroradiometers or hyper-spectral remote sensors.


      PubDate: 2014-11-27T07:30:33Z
       
  • Satellite-based evapotranspiration of a super-intensive olive orchard:
           Application of METRIC algorithms
    • Abstract: Publication date: December 2014
      Source:Biosystems Engineering, Volume 128
      Author(s): Isabel Pôças , Teresa A. Paço , Mário Cunha , José A. Andrade , José Silvestre , Adélia Sousa , Francisco L. Santos , Luís S. Pereira , Richard G. Allen
      METRIC™ is a satellite-based surface energy balance model aimed at estimating and mapping crop evapotranspiration (ET). It has been applied to a large range of vegetation types, mostly annual crops. When applied to anisotropic woody canopies, such as olive orchards, extensions are required to algorithms for estimating the leaf area index (LAI), surface temperature, and momentum roughness length (Z om). The computation of the radiometric surface temperature needs to consider a three-source condition, thus differentiating the temperature of the canopy (T c ), of the shaded ground surface (T shadow), and of the sunlit ground surface (T sunlit). The estimation of the Z om for tall and incomplete cover is based upon the LAI and crop height using the Perrier equation. The LAI, Z om, and temperature derived from METRIC after these adjustments were tested against field collected data with good results. The application of METRIC to a two year set of Landsat images to estimate ET of a super-intensive olive orchard in Southern Portugal produced good ET estimates that compared well with ground-based ET. The analysis of METRIC performance showed a quantitative improvement of ET estimates when applying the three-source condition for temperature estimation, as well as the Z om computation with the Perrier equation. Results show that METRIC can be used operationally to estimate and mapping ET of super-intensive olive orchards aiming at improving irrigation water use and management.


      PubDate: 2014-11-27T07:30:33Z
       
  • Three-dimensional discrete element modelling (DEM) of tillage: Accounting
           for soil cohesion and adhesion
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Mustafa Ucgul , John M. Fielke , Chris Saunders
      Recent studies have shown that the discrete element modelling (DEM) can effectively be used to model the soil-tool interaction if both an appropriate contact model and DEM parameters are used. Ucgul, M., Fielke J.M and Saunders, C. (2014a) Biosystems Engineering. 121: 105–117 showed that hysteretic spring contact model (HSCM) can give accurate predictions of draft and vertical forces for a range of sweep tillage tool geometries operating in a cohesionless soil. In this study a linear adhesion/cohesion model was integrated with the HSCM to model the cohesive behaviour of soil and its interaction with a tillage tool. The proposed contact model was validated with the direct shear tests performed and further validation was achieved via DEM simulation of the interaction between soil and tillage tool tests. The results showed that the suggested contact model can be used to predict both tillage draft and vertical tillage forces for varying speed, operating depth, moisture content and compaction levels. The results also showed that the DEM parameters determined in our earlier paper can be directly used in the suggested model without further re-calibration. It was observed that the soil bulk density has a significant effect on the predicted tillage forces and when the measured wet bulk density was used in the simulations a good correlation with measured forces was able to be achieved. Thus, the method presented has good potential to accurately model tillage forces in a range of soil and operating conditions.


      PubDate: 2014-11-27T07:30:33Z
       
  • Wine-distillery waste compost addition to a drip-irrigated horticultural
           crop of central Spain: Risk assessment
    • Abstract: Publication date: December 2014
      Source:Biosystems Engineering, Volume 128
      Author(s): María I. Requejo , María C. Cartagena , Raquel Villena , Augusto Arce , Francisco Ribas , María J. Cabello , María T. Castellanos
      The assessment of environmental effects is important before agricultural use of organic wastes, especially in irrigated agricultural areas vulnerable to nitrate pollution. A field study with melon crop was conducted during 2011 and 2012 in central Spain, using different rates of wine-distillery waste compost to quantify nitrogen (N) leaching under two regimes of irrigation. To evaluate the groundwater pollution risk associated with these practices, some environmental indices were used to determine the variation in the quality of drinking water (Impact Index (II)) and in the nitrate concentration of the groundwater (Environmental Impact Index (EII)). To combine environmental together with yield parameters, the Management Efficiency (ME) was calculated. Considering II and EII, compost addition together with adjusted irrigation (90–100% ETc) do not represent a risk to increase groundwater contamination, and, in high doses, may contribute to remove nitrate from drainage water and improve the quality of the drinking water. In contrast, applying large amounts of compost together with an excess of water (120% ETc) increased N leaching significantly and poses a higher risk of groundwater contamination. The rate corresponding to 13 t ha−1 of compost together with an efficient irrigation is sufficient to achieve the highest yield, does not exceed the maximum allowable limits established by II and EII and has an adequate ME.


      PubDate: 2014-11-27T07:30:33Z
       
  • Mapping soil hydraulic conductivity and matric potential for water
           management of cranberry: Characterisation and spatial interpolation
           methods
    • Abstract: Publication date: December 2014
      Source:Biosystems Engineering, Volume 128
      Author(s): Silvio J. Gumiere , Jonathan A. Lafond , Dennis W. Hallema , Yann Périard , Jean Caron , Jacques Gallichand
      Spatial interpolation methods are required for analysing the effects of soil hydraulic properties on irrigation management. This study was conducted to determine which interpolation methods are best suited to map these properties. During the summer of 2012 we mapped the spatial variability of soil physical properties, soil matric potential, water table depth and yield of two cranberry fields located near Quebec City, Canada. Three spatial interpolation methods, inverse distance weighting (IDW), thin plate splines (TPS) and kriging with external drift (KED), were compared by means of cross-validation. The best interpolation method for a given property was used to produce maps and perform HYDRUS 1D simulations for the purpose of irrigation management. Results show that even in highly constructed fields, such as for cranberries, spatial patterns of soil hydraulic properties exist. The TPS method was the best interpolation method based on the cross-validation analyses and generated maps. Spatial variability of crop yield showed a strong relationship with soil hydraulic properties and simulations suggest that irrigation can be reduced by 75% when accounting for the spatial variability of soil hydraulic properties.


      PubDate: 2014-11-27T07:30:33Z
       
  • Editorial Board
    • Abstract: Publication date: December 2014
      Source:Biosystems Engineering, Volume 128




      PubDate: 2014-11-27T07:30:33Z
       
  • Long term irrigation with treated wastewater (TWW) and soil sodification
    • Abstract: Publication date: December 2014
      Source:Biosystems Engineering, Volume 128
      Author(s): Guy J. Levy , Pinchas Fine , Dina Goldstein , Asher Azenkot , Avraham Zilberman , Amram Chazan , Tzfrir Grinhut
      Use of treated wastewater (TWW) for irrigation has grown noticeably in recent years, especially in arid and semi-arid regions. The sodium adsorption ratio (SAR) in TWW is considerably higher than that in its fresh water of origin. Recently, there is evidence showing that subsurface (depth >30 cm) exchangeable sodium percentage (ESP) levels in Israeli orchards may reach 6–9 which is higher than expected following long-term irrigation with TWW having SAR <5. Our objectives were to (i) determine the ESP in soil profiles of orchards exposed to irrigation with TWW, and (ii) examine the relationships between the SAR of the irrigation water, the SAR of the soil solution and the ESP of the studied soils. Soil samples were taken from different depths (up to 120 cm) in orchards grown on two different soil types that had been irrigated for >10 years with TWW. In each soil sample non-adjusted SAR and adjusted SAR (SARadj) of the saturated paste and ESP were determined. In all sampled sites except one, accumulation of adsorbed sodium in the soil subsurface was noted. The obtained ESP levels were higher than those expected based on the SAR of the TWW. A satisfactory agreement was noted between ESP data and the non-adjusted SAR and SARadj of the soil solution. These observations suggest that a chemical equilibrium exists between the soil exchange phase and the soil solution and that the properties of the latter were not always dictated by those of the irrigation water.


      PubDate: 2014-11-27T07:30:33Z
       
  • Geometrical method for interpolating S-peaks from cow ECG using a
           microcontroller
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): M. Johannes Tiusanen , Mikko I. Hautala , Emma M. Ternman , Matti E. Pastell
      This paper describes a new and computationally efficient adaptive geometrical method for improving the resolution of electrocardiogram (ECG) S-peak detection. The target device is an ECG implant for dairy cows which provides limited calculation power. The method utilises only arithmetic operations and is adaptive to individual ECG curves and electrode installation effects. The method tracks the average heights of the sample points preceding and following the S-wave peak. Comparing these heights to the long-time average values provides an estimate of the offset of the peak sample from the actual peak moment. On average, the prediction of spline interpolation on the original 512 Hz turning point is 0.043 ms more accurate than our geometrical algorithm. Both methods result in less than a 0.7 ms difference from the original data. However, the proposed method is significantly more computationally efficient than cubic spline interpolation.


      PubDate: 2014-11-27T07:30:33Z
       
  • New methodology for accelerating the four-post testing of tractors using
           wheel hub displacements
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Michele Mattetti , Giovanni Molari , Andrea Vertua
      Durability tests of tractor prototypes need substantial financial and time commitments. The duration and cost of tests could be reduced using accelerated tests able to reproduce on the structural part of the tractor, the same damage produced on the tractor during its real life but over a reduced time period. It has been recently demonstrated how it is possible to speed up the tests using automotive proving grounds. However a complete prototype with all its components is necessary to perform tests on proving grounds, but to test only the structural durability is possible the use of a 4-post bench. A 4-post bench is able to reproduce a specific vehicle response, with the possibility of applying fatigue editing techniques to remove the non-damaging portions of the load signals. These techniques are usually applied to load signals measured with strain gauges during tests on proving grounds. However, strain gauge installations and data validation of the acquired signals are time-consuming. Here a new method, able to calculate the displacements on the wheel hub starting with acceleration measurements, applying fatigue editing techniques and defining drive files to command the actuators of a 4-post bench is described. The method proposed has an acceleration factor for the test of 5.3 together with a more rapid procedure to fit the transducers and to analyse the data obtained from the accelerometers compared to those obtained from the strain gauges.


      PubDate: 2014-11-27T07:30:33Z
       
  • Air disinfection in laying hen houses: Effect on airborne microorganisms
           with focus on Mycoplasma gallisepticum
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Elisa Adell , Salvador Calvet , Adriano Pérez-Bonilla , Ana Jiménez-Belenguer , Julio García , Jorge Herrera , María Cambra-López
      The application of disinfectant thermo-nebulised into the air of laying hen houses to reduce airborne microorganisms was evaluated with emphasis on its effect on Mycoplasma gallisepticum. Two air disinfectant tests were conducted in two identical laying hen houses. One of the houses was used as the treatment, whereas the other was used as a control. Airborne microorganisms were sampled before, 1 h and 6 h after disinfection. Prior to disinfection, outdoor and indoor environmental conditions, temporal concentrations of particulate matter (PM10 and PM2.5), and the spatial distribution of airborne microorganisms were measured. The average pre-disinfection concentration for PM2.5 was 0.024 ± 0.025 mg m−3 and for PM10 was 0.546 ± 0.377 mg m−3, showing high proportions of particles from feathers and manure. The concentration of airborne mesophilic aerobic bacteria ranged from 4.1 to 5.7 log colony forming units, CFU m−3. No differences were obtained between sampling height and sampling in corridors. Under the test conditions, air disinfection using wide spectrum thermo-nebulised disinfectant was not effective in reducing the concentration of mesophilic aerobic bacteria, Enterobacteriaceae and M. gallisepticum in the air. Mycoplasma spp. was confirmed by qPCR on cage surfaces and chicken's feathers before and after disinfection. The presence of outdoor Mycoplasma spp. suggests that inlet air could be a source of entry of this pathogen. Further information on the relationship between PM and airborne microorganisms and their behaviour in the air are necessary to design adequate techniques to reduce them in livestock houses.


      PubDate: 2014-11-27T07:30:33Z
       
  • Forecasting hourly evapotranspiration for triggering irrigation in
           nurseries
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Rousseau Tawegoum , Florian Leroy , Gérard Sintes , Gérard Chassériaux
      Predicting water requirements for plants is crucial in constrained nurseries during periods of intense sunlight. The temporal variations of evapotranspiration, an irrigation indicator, are described using a time series model with a seasonal component, whose parameters are identified. The resulting hourly time-scale predictive model, which makes it possible to anticipate crop water requirements, was applied to two climatic zones in steady-state weather with good accuracy. As the proposed predictive model only requires storing previous data without a significant computational effort, it can be easily used in real time. We compared predictive and real-time irrigation triggering algorithms on two plots with different irrigation thresholds in a typical nursery, and showed that the predictive approach could avoid crop exposure to water stress. In order to validate our approach, both algorithms were implemented in real-time field experiments using a standard input–output terminal to trigger the automatic irrigation of two rose plots (Rosa sinensis). When water availability was unrestricted, irrigation took place earlier in the predictive case and thus maintained the substrate properly moistened more frequently. When a midday no-irrigation period was imposed as a constraint in order to simulate water-limited resources or hydraulic network overload, irrigation was triggered slightly earlier in the “predictive“ plot, and water deficit peaks remained below irrigation thresholds more frequently than in the static threshold approach.


      PubDate: 2014-11-23T07:14:10Z
       
  • On-line firmness sensing of dates using a non-destructive impact testing
           device
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Seyed Ahmad Mireei , Morteza Sadeghi , Alireza Heidari , Abbas Hemmat
      Based upon a non-destructive falling impact test, a rapid on-line device was developed for assessing date fruits firmness. The device consisted of a conveyor unit used for carrying and throwing fruits onto a flat plate connected to a load cell and a data acquisition unit for acquiring the impact force time history. All the tests were carried out at three speeds (1, 1.5 and 2 m s−1) of the conveyor belt. The firmness predictive models were initially developed using simple and multiple regressions with individual impact indices derived from the first half-wave. These indices were also computed for the first twenty positive half-waves of the impact signal and used for further regression analysis. Moreover, all data points of the first half-wave and the entire impact signal were used as independent variables in developing partial least squares regression models. Generally, a substantial increase in prediction power appeared when using the impact indices of the twenty positive half-waves (coefficient of determination in prediction ( R p 2 ) of 0.756 and standard deviation ratio (SDR) of 2.46) instead of the impact indices of the first half-wave ( R p 2  = 0.527, SDR = 1.74). Partial least squares models with the entire impact history led to slightly better results ( R p 2  = 0.800, SDR = 2.77) as compared to those developed from the first half-wave information ( R p 2  = 0.776, SDR = 2.61). The intermediate forward speed of 1.5 m s−1 indicated the best predictions in almost all different methods.


      PubDate: 2014-11-23T07:14:10Z
       
  • Measurement of semiochemical release rates with a dedicated environmental
           control system
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Heping Zhu , Harold W. Thistle , Christopher M. Ranger , Hongping Zhou , Brian L. Strom
      Insect semiochemical dispensers are commonly deployed under variable environmental conditions over a specified period. Predictions of their longevity are hampered by a lack of methods to accurately monitor and predict how primary variables affect semiochemical release rate. A system was constructed to precisely determine semiochemical release rates under environmentally-controlled conditions. Three dissimilar types of solid matrix, passive emission semiochemical dispensers (P339 Sirex, Beetleblock-MCH, W230 terpinolene) were selected to verify the system capabilities. The rate of mass loss for each semiochemical was measured inside a 0.11 m3 air sealed reservoir. Each product was tested at five ambient temperatures and three values of relative humidity. Temperatures were maintained at their set points within ±1.0 °C and relative humidity within ±0.4%. Mass losses for the relatively large P339 Sirex dispensers were linear over the test period; losses for the smaller Beetleblock-MCH and W230 terpinolene dispensers fell sharply over the first 10 h of exposure and then fell linearly with exposure time. Test results demonstrated that release rates of the three semiochemicals at the linear fall stage increased exponentially as ambient temperature increased, and those rates were not apparently affected by relative humidity. Compared to release rates measured under field conditions, determination of semiochemical release rates was more precise and consistent with this dedicated, controlled environmental system. Semiochemical release rates measured with this system should provide a baseline for predicting performance and useful lifetime of semiochemical devices deployed for pest management in agriculture and forestry.


      PubDate: 2014-11-23T07:14:10Z
       
  • Modelling the control of African Armyworm (Spodoptera exempta)
           infestations in cereal crops by deploying naturally beneficial insects
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Fina Faithpraise , Joseph Idung , Chris Chatwin , Rupert Young , Philip Birch
      A solution was sought for control of Spodoptera exempta in cereal crops. The proposed solution enhanced a previous scheme since it provided control of the pest eggs and larvae and improved the quality of crop products by replacing pesticides. The scheme consists of a surveillance and monitoring system to activate a measured response to pest invasion. In the control phase naturally beneficial insects (NBIs) were deployed via an unmanned aerial vehicle (UAV) system to control the pest population; parasite egg wasps (Trichogramma) were combined with a larval parasite Diptera (Tachinidae) to achieve greater control of the life cycle stages of the African Armyworm – Spodoptera exempta.


      PubDate: 2014-11-23T07:14:10Z
       
  • Theoretical analysis of micro-vibration between a high moisture content
           rape stalk and a non-smooth surface of a reciprocating metal cleaning
           screen matrix
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Zheng Ma , Yaoming Li , Lizhang Xu
      Because rape stalk has a high water content, rape materials easily adhere to the cleaning screens of combine harvesters leading to a high screen loss. Inspired by friction-reducing research on bionic non-smooth metal surfaces, a special rape cleaning screen with non-smooth surface was developed and compared with a standard screen in field experiment. It showed good anti-adhesion performance to rape components. To understand the mechanism, a reciprocating friction test between a rape stalk and non-smooth metal surface was carried out. The result was consistent with the findings of a field experiment. In the test, a vertical micro-vibration was discovered between rape stalk and the non-smooth metal surface. This did not exist in the case of a common smooth metal surface and was considered as an important factor in the mechanism. In this paper, a theoretical analysis was proposed to explain how the vertical micro-vibrations occurred during a horizontal reciprocating translation of non-smooth units. Firstly, according to the case of friction test, a geometry contact model and a dynamic equation were established. Then computing methods of vertical impact force and its action time were respectively deduced. Finally, a simulation was produced with a time-scale factor of two. The result from the simulation was consistent with basic trend of test data. Although the theoretical analysis requires improvement for further investigation, it could still provide the basis of a theoretical model and the foundation for further friction-reducing research for non-smooth surfaces.


      PubDate: 2014-11-23T07:14:10Z
       
  • Rill erodibility as influenced by soil and land use in a small watershed
           of the Loess Plateau, China
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Zhen-wei Li , Guang-hui Zhang , Ren Geng , Hao Wang
      Land use can significantly affect soil properties, root systems, and tillage practices, and hence probably influence rill erodibility (K r ) considerably. Nevertheless, there is little quantitative research on the effects of land use on K r . The objectives of this study were to evaluate the influence of land use on K r , quantify its potential influencing factors, and develop a regression model to estimate K r in a small Loess Plateau watershed. Undisturbed samples were collected from four different land uses on red Loess soil and seven different land uses on yellow Loess soil. Soil detachment capacity by overland flow was measured in a sand-glued hydraulic flume under six different shear stresses (5.59–18.31Pa) to determine K r . The results indicated that K r was affected by soil type significantly and the average K r of yellow Loess soil was 1.5 times greater than that of red Loess soil. K r was also significantly influenced by land use. For the red Loess soil, cropped land had the maximum K r and followed by orchards, shrub land, and grassland. For the yellow Loess soil, cropped land also had the maximum K r , which was 1.74, 9.17, 11.65, 26.34, 28.88, and 42.57 times greater than those of roads, orchards, shrub land, woodland, grassland, and wasteland, respectively. K r increased with silt content, and decreased with soil cohesion, water stable aggregate, soil organic matter, and root mass density. A nonlinear regression showed that K r could be estimated well (NSE = 0.87) by silt content, soil cohesion, water stable aggregate, and root mass density in the Loess Plateau.


      PubDate: 2014-11-23T07:14:10Z
       
  • Prediction of pelleting outcomes based on moisture versus strain
           hysteresis during the loading of individual pea seeds
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Ryszard Kulig , Grzegorz Łysiak , Stanisław Skonecki
      The pelleting of pea is related to some of the mechanical features of the seeds. Varying in moisture, intact seeds were assigned to unconfined loading–unloading with the help of a universal testing machine. Elastic and permanent strain energy and associated deformations were evaluated on the basis of load–displacement curves. In parallel, samples of pea at the same moisture levels were pelleted. The pelleting energy usage and pellet quality features, that is strength, durability, and bulk density, were tested for correlations with strain hysteresis data. Seed moisture and energy loss during the loading of a single seed showed a strong relevance to the processing and pellet properties. An observed increase in the proportion of non-recoverable strain energy, from 15.5 to 176.1 mJ, resulted in a significant decrease in all analysed pelleting features. The specific energy consumption decreased from 296.5 to 240.1 kJ kg−1. Bulk density and pellet strength SI decreased from 773.6 to 652.7 kg m−3 and 16.61 to 13.60 kN m−1, respectively. An empirical model was introduced for the estimation of pelleting effects as a function of seed plasticity. It was based on a hyperbolic formula, which proved to be accurate for the prediction of energy requirements for pelleting and the properties of pellets.


      PubDate: 2014-11-19T07:04:03Z
       
  • Evaluation and stability comparison of different vehicle configurations
           for robotic agricultural operations on side-slopes
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Renato Vidoni , Marco Bietresato , Alessandro Gasparetto , Fabrizio Mazzetto
      Progress in sensors, controllers and mechatronics devices and the development of (semi-) autonomous systems that can travel safely on uneven terrain and perform many operations has encouraged research interest in the use of robotics for agriculture and forestry in hilly and mountainous terrains. Here, the main mobile configurations that are likely to be used for robotic platforms as implement-carriers (3-wheeled, conventional/articulated 4-wheeled, tracked) were reviewed and discussed in terms of their suitability for agricultural operations and their stability. A numerical index accounting for the lateral stability of a vehicle, the roll stability index, was used to indicate the in-field working capacity of these platforms during side-slope operations. Assuming the same overall dimensions for all the configurations, the 3-wheel configuration, although very simple and agile, was seen as being the least stable, while a tracked vehicle was the most stable, although it had some important drawbacks when used in an agricultural context. This drawbacks included increased soil erosion and landslides caused by its tracks especially in the areas involving turning manoeuvres. The articulated system was found to be the most suitable for uneven and side-slope terrains because of its optimal steering capacity, agility and good stability. It was found to reach a critical stability angle close to the 4-wheel vehicle.


      PubDate: 2014-11-19T07:04:03Z
       
  • Evaluation of a dry filter and an electrostatic precipitator for exhaust
           air cleaning at commercial non-cage laying hen houses
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Albert Winkel , Julio Mosquera , André J.A. Aarnink , Peter W.G. Groot Koerkamp , Nico W.M. Ogink
      The removal performance of two exhaust air cleaning systems for abatement of particulate matter (PM) emission in poultry houses were investigated: a commercially available dry filter (DF) and a full-scale prototype electrostatic precipitator (ESP). Each system was connected to two commercial, non-cage laying hen houses: one with aviary housing, the other with floor housing. At each house, six to nine 24-h measurements were carried out, spread over the year and the laying cycle. Upstream and downstream of the systems, we measured PM10, PM2.5, and carbon dioxide concentrations, temperature, and relative humidity. Additional measurements of particle size distribution only were carried out at the DF of another poultry house. The latter showed that removal of PM by the DF increased with increasing particle diameter. Mean removal efficiency of the DF for PM10 was 40.1%, whereas PM2.5 was not significantly removed. The ESP reduced concentrations of PM10 by an average of 57.0% and concentrations of PM2.5 by an average of 45.3%. For neither of the two systems an effect of upstream PM concentration on removal performance was found. Results of this study are compared with the available literature and possibilities to improve removal performance are discussed. The mean (SD between houses) untreated emissions rate from the non-cage layer houses was 7.81 (4.12) mg PM10 h−1 bird−1 and 0.44 (0.28) mg PM2.5 h−1 bird−1. In conclusion, the evaluated systems show potential to reduce PM emissions from poultry houses.


      PubDate: 2014-11-19T07:04:03Z
       
  • Web-based forecasting system for the airborne spread of livestock
           infectious disease using computational fluid dynamics
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Il-hwan Seo , In-bok Lee , Se-woon Hong , Hyun-seok Noh , Joo-hyun Park
      Livestock infectious diseases, such as foot-and-mouth disease (FMD), cause substantial economic damage to livestock farms and their related industries. Among various causes of disease spread, airborne dispersion has previously been considered to be an important factor that could not be controlled by preventive measures to stop the spread of disease that focus on direct and indirect contact. Forecasting and predicting airborne virus spread are important to make time for developing strategies and to minimise the damage of the disease. To predict the airborne spread of the disease a modelling approach is important since field experiments using sensors are ineffective because of the rarefied concentrations of virus in the air. The simulation of airborne spread during past outbreaks required improvement both for farmers and for policy decision makers. In this study a free license computational fluid dynamics (CFD) code was used to simulate airborne virus spread. Forecasting data from the Korea Meteorological Administration (KMA) was directly connected in the developed model for real-time forecasting for 48 h in three-hourly intervals. To reduce computation time, scalar transport for airborne virus spread was simulated based on a database for the CFD computed airflow in the investigated area using representative wind conditions. The simulation results, and the weather data were then used to make a database for a web-based forecasting system that could be accessible to users.


      PubDate: 2014-11-15T06:46:45Z
       
  • Kinetics of alfalfa drying: Simultaneous modelling of moisture content and
           temperature
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): J.A. Siles , P. González-Tello , M.A. Martín , A. Martín
      The kinetics of the dehydration of alfalfa stems, leaves and the whole alfalfa plant (Medicago sativa L) was studied experimentally at lab-scale using a fixed-bed dryer with warm air at 328, 333, 338 and 343 K. Following the evaluation of the influence of bed thickness, air mass rate and air temperature on the kinetics of drying, a kinetic model of globalised parameters is proposed. The kinetic model was designed to simulate the exchange of moisture between alfalfa and the surrounding air and the variation of temperature inside the substrates with time simultaneously. In a first step, the kinetic model was applied to stems and leaves separately. The model reproduced 94.4% and 70.1% of the moisture experimental results obtained for stems and leaves, respectively, within an error band of 15%. Moreover, 95% of the experimental results regarding the variation of temperature inside stems with time were simulated. The kinetic model was then applied to the whole alfalfa plant considering its content of stems (60% wet weight) and leaves (40% wet weight) using the same kinetic parameters and variables fixed for their single modelling. The model reproduced 82.2% of the moisture experimental results obtained for the drying of the whole alfalfa plant. This kinetic model could be a useful tool for the design of a drying device based on scientific evidence.


      PubDate: 2014-11-15T06:46:45Z
       
  • Water resources management for a sustainable environment
    • Abstract: Publication date: Available online 7 November 2014
      Source:Biosystems Engineering
      Author(s): Giuseppe Provenzano , Leonor Rodriguez-Sinobas , José Roldán-Cañas



      PubDate: 2014-11-10T06:05:07Z
       
  • Anaerobic digestion of ammonia-pretreated corn stover
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Hairong Yuan , Rongping Li , Yatian Zhang , Xiujin Li , Chunmei Liu , Ying Meng , Meina Lin , Ziyi Yang
      The effect of ammonia pretreatment on the anaerobic digestibility of corn stover was investigated. Corn stover with different moisture contents (30%, 50%, 70%, and 90%) was pretreated with three concentrations of ammonia (2%, 4%, and 6%) at 35 ± 2 °C for the following batch digestion. Results showed that the reagent of 4% ammonia and 70% moisture content could achieve the highest anaerobic digestibility. In comparison with the untreated, the time needed to produce 90% of the maximum digester gas production (T 90) shortened from 52 d to 37 d. The total biogas production and the unit volatile solids (VS) biogas yield were 20,740 ml and 427.1 ml respectively, both 26.70% higher than the untreated. It was found that the digesters with high moisture contents of 70% and 90% were more stable and had shorter acidification periods relative to the low moisture contents of 30% and 50%. The decreases in cellulose, hemicelluloses and lignin indicated that ammonia pretreatment could destroy the lignocellulose (LCH) structure and furthermore enhance the biogas production. Following anaerobic digestion, 80.6% of cellulose and 68.52% of hemicelluloses were consumed where there was 4% ammonia and 70% moisture content, indicating why these conditions produced the highest level of biogas.


      PubDate: 2014-11-07T05:58:53Z
       
  • A simulation model for a rice-harvesting chain
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Patrizia Busato
      Management of rice harvesting presents a number of unique challenges that require development of dedicated tools. Challenges include in-field trafficability constraints affecting the transport units, the increased number of combine unloading events due to low grain hopper capacity, and the transport cycle times for different fields. Furthermore, when a combine reaches the headland area, sequential decisions must be made whether to stop harvesting and proceed to the unloading location or to continue harvesting with a full or reduced operating width. The objectives were to: 1) develop a simulation model that incorporates operational features unique to rice harvesting, 2) use the model to provide performance evaluation measures, and 3) to demonstrate the capabilities of this model as a tool for operations management. Experimental field operations were carried out to identify the necessary set of input parameters and to validate the simulation model. From measurements taken for validation, it was found that the error in operational parameter prediction was considerably low, ranging from 2.59 % to 3.12 %. In addition, using the simulation model, the practice of selectively harvesting at a reduced operating width was compared with the practice of harvesting a full operating width. It was found that harvesting at a reduced operating width significantly increased capacity (up to 7%), particularly when the available transport unit capacity was a system performance limiting factor.


      PubDate: 2014-11-07T05:58:53Z
       
  • Comparative experiments to assess the performance of an innovative
           horizontal centrifuge working in a continuous olive oil plant
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Antonia Tamborrino , Alessandro Leone , Roberto Romaniello , Pasquale Catalano , Biagio Bianchi
      The performance of an innovative horizontal centrifugal decanter working in a continuous industrial olive oil extraction plant was evaluated. This decanter produces two streams a semi-solid residue (or pulp) formed from the wastewater and soft solids (i.e. without fragments of stone) and a husk rich in rigid solids from pit shells. Considering the phase separation obtained using this machine, and increasing number of restrictive laws on waste disposal, this decanter is of significant interest for use in olive oil extraction. The effects of varying the decanter centrifuge settings are documented and discussed. A correlation between the mass flow rate, water ring levels and conveyor-bowl differential speed with respect to the extracted efficiency, husk fat content and pulp water fat content was evaluated. The decanter studied was found to maintain high values of extraction efficiency between 86.5% and 90.8% for a large range of feed mass flow rates (4075–5820 kg h−1) and for a large range of conveyor-bowl differential speeds (15.5–26.0 rpm). In addition, by appropriately adjusting the ring level of the waste-water output, it was possible to obtain a greater or lesser soft solid content, with a greater or lesser amount of residual oil.


      PubDate: 2014-11-07T05:58:53Z
       
  • Testing and simulation of the three point bending anisotropic behaviour of
           hazelnut shells
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Elvio Bonisoli , Cristiana Delprete , Raffaella Sesana , Alessandra Tamburro , Stefano Tornincasa
      In order to improve the performance of shelling machines, and to enhance the numerical modelling of anisotropic behaviour of hazelnuts shells, the mechanical properties of shells are useful experimental data. A procedure to obtain an effective numerical model and to calibrate anisotropic material properties by means of experimental testing is described. The procedure was applied to a commercial variety of Italian hazelnuts and the mechanical properties were experimentally obtained for shell on specimens obtained from conform hazelnuts. The numerical finite element model investigates single and double curvature geometry simulation performance of the shell specimens.
      Graphical abstract image

      PubDate: 2014-11-02T05:38:09Z
       
  • Cost of boundary manoeuvres in sugarcane production
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Mark Spekken , José P. Molin , Thiago L. Romanelli
      Machinery has direct and indirect costs associated with their work in field, with non-productive time spent in manoeuvres when machinery reaches field borders. Much work has been carried reducing the number of manoeuvres in complex field shapes and changing the type of manoeuvre in order to speed them up. Biofuel producing crops such as sugarcane (Saccharum spp.) besides requiring economic profitability demand positive energy output in their production chain. Sugarcane uses narrow width equipment which requires time-costly manoeuvres adding significant inputs particularly on short rows. Using a method and calculations that is applicable for other crops, this study takes operational, spatial, economic, and energy factors into account to observe the impact of manoeuvres at the headland of a sugarcane crop. Energy and economic costs were retrieved from the hourly use of machines for four main field operations and their respective manoeuvring costs. Crop parameters were retrieved with their data compared with operational costs to establish the dimensions of row-length benefits. Increases in row length and width has decreasing benefits that may conflict with the logistics of servicing auxiliary units. The impacts of turning patterns were obtained, it suggests changes to minimise time and space for manoeuvring in planting and cultivating operations, and using wider roads and more steerable carriers in harvesting operations. In standard scenarios of a production system it was found that the income from row lengths less than 50 m were less than the economic costs occurred in turning at the headland.
      Graphical abstract image

      PubDate: 2014-10-26T04:40:35Z
       
  • The use of additives and fuel blending to reduce emissions from the
           combustion of agricultural fuels in small scale boilers
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): J.P. Carroll , J.M. Finnan
      The results of tests to determine the efficacy of fuel blending and additives to reduce emissions from the combustion of agricultural fuels are presented. It was shown that peat blended with miscanthus and tall fescue has the potential to significantly reduce both PM1 emissions and problems related to ash melting. However, the high nitrogen content of the peat (1.5%) compared to the two agricultural fuels tested (miscanthus – 0.33 and tall fescue- 0.69) leads to increased NOx emission with increasing proportions of peat in the blend. The results also showed that for both fuels a kaolin addition rate of 4% gave significant reductions in PM1 emissions. With increasing peat/kaolin addition ash sintering temperature increased while potassium release decreased. With further developments in the use of additives and fuel blending it is foreseen that pellets from agricultural fuels may form a viable alternative to wood pellets.


      PubDate: 2014-10-26T04:40:35Z
       
  • Cooling systems in screenhouses: Effect on microclimate, productivity and
           plant response in a tomato crop
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): R. Leyva , C. Constán-Aguilar , E. Sánchez-Rodríguez , M. Romero-Gámez , T. Soriano
      Mediterranean climates are characterised by summer temperatures that exceed 35 °C, high solar radiation ∼ 30 MJ m−2, relative humidity < 20% at around midday, and limited water resources generating yield loss in crops. For this reason, new climate strategy for greenhouses used in Mediterranean climates has been developed to avoid plant injury. Cherry tomato plants were assessed during 2010 and 2011 under different environmental conditions, namely in a screenhouse (S), in a screenhouse equipped with a fogging system (SF) and in a screenhouse with a plastic sheeting to maintain the microclimate created by the fogging system (SFS). SFS improved microclimatic conditions during the 2010 and 2011 growing seasons by, reducing incident radiation 37% and 30%, respectively while increasing relative humidity by 20% and 16%, respectively and respect to S lowering the vapour pressure deficit. These adjustments in microclimate could moderate the extremes of microclimate during the summer, avoiding episodes of physiological stress that affect yield and final quality. The dry mass vegetables plants parts grown under SFS increased while the marketable mass per plant was not significantly different. This was due to 45% increased in mean tomato fruit mass in 2010 and by 20% in 2011. Although tomato leaves grown under SFS registered the lowest values in foliar temperature, they showed the highest values for LAI, SLA, and LAR. It was concluded that a fogging could improve the climatic conditions under screenhouse and extend the growing season during adverse environmental conditions.


      PubDate: 2014-10-21T04:05:04Z
       
  • Parametric evaluation using mechanistic model for release rate of
           phosphate ions from chitosan-coated phosphorus fertiliser pellets
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): N.N.R. Ahmad , W.J.N. Fernando , M.H. Uzir
      Evaluation of nutrient release from a controlled-release fertiliser (CRF) using mechanistic model is important in order to increase the understanding towards the mechanism that might involve in a release process. In this study, a mechanistic model was used to evaluate the parameters that govern the phosphate release rate through chitosan-coated phosphorus fertiliser. The model considers the phenomena of boundary layer formation on the external surface of the coat and the coating thickness changes due to erosion. Static release experiments were conducted in order to study the effect of the number of coatings and pH conditions to the release rate of phosphate ions. The respective parameters of the phosphate release such as diffusion coefficient were evaluated using the model in both cases. The diffusivity of the phosphate was found to increase as the number of coatings and pH values of the medium decreased. Regeneration of the released data for the phosphate ions using the model indicated a very satisfactory fit with the experimental data.


      PubDate: 2014-10-21T04:05:04Z
       
  • Mechanical analysis of the bending behaviour of plant stems
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Tom Leblicq , Simon Vanmaercke , Herman Ramon , Wouter Saeys
      In order to optimise the processing of stem crops, insight into the deformation behaviour of the crop and the interaction between crop and machine is essential. Most research in the area of mechanical and physical properties of crop stems is focused on characterising the agricultural products to the point of failure using mechanical parameters and empirical relations. No studies have been conducted on the processes which lead to failure of stems and on the processes that take place after failure. In this paper it is shown that the bending behaviour of wheat and barley stalks is very similar to that of steel tubes. Two consecutive phases can be distinguished: ovalisation and buckling. During ovalisation the forces on the wall tend to flatten the cross-section. When this process continues the flexural stiffness is reduced until the structure becomes unstable and buckles. The cross-section locally completely flattens. This deformed cross-section offers virtually no resistance to bending. Mechanical models described in literature have successfully been adapted to describe the bending behaviour of crop stalks during both phases ( R 2 > 0.98 for ovalisation and R 2 > 0.97 for buckling). The crop species, growing conditions, stem diameter and wall thickness were found to influence the bending process significantly. The presence of a core-rind structure increases the bending resistance of the stems.


      PubDate: 2014-10-21T04:05:04Z
       
  • Determining total solids and fat content of liquid whole egg products via
           measurement of electrical parameters based on the transformer properties
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Yamei Jin , Na Yang , Xiang Duan , Fengfeng Wu , Qunyi Tong , Xueming Xu
      A method for determining the total solids and fat content of liquid whole egg products based on the principle of transformer was developed. The electrical parameters (terminal voltage and λ value) in the secondary circuit, where the sample acted as the coil, were investigated under the action of alternating magnetic flux in the frequency range from 60 to 400 Hz. Findings indicated that subtle changes of quality indices could be detected by electrical parameters based on the transformer properties that relate to the amount of free ions in the samples. As the inductive voltage was fixed, terminal voltage was negatively correlated with quality indices of total solids and fat content. Therefore the decrement of impedance in the secondary circuit caused the increment of inductive current according to Ohm's law. Linear prediction models for the aforementioned quality indices based on these electrical parameters were also established. Judging from coefficients of determination (R 2) and the root mean square error of prediction (RMSEP) of these models, the λ value was found to be a better predictor for quality indices of liquid whole egg products than terminal voltage. It is believed that this method has the potential to evaluate the quality of liquid food materials over a wider frequency and temperature range.


      PubDate: 2014-10-16T03:37:25Z
       
  • Design and analysis of the response of elastically supported wind-break
           panels of two different permeabilities under wind load
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Anastasios Giannoulis , Antonios Mistriotis , Demetrios Briassoulis
      The design and response of elastically supported short-length windbreak panels of different permeabilities under wind load is presented. The response of the panels was investigated through full-scale experiments and numerical simulation analysis. Two cladding materials were used: an impermeable film and a permeable net (62% porosity ratio). For the field experiments the elastic support of the panel was achieved by using extension springs which allowed it to pivot in response to wind loading through a hinge support at its base. The wind pressures developed on the panel for various equilibrium positions reached under different wind velocities were measured. The elastic support response resulted in a significant reduction of the wind pressures and the stress resultants on the windbreak for both cladding materials. A combined model coupling two-dimensional computational fluid dynamic simulation and non-linear structural analysis was used to analyse the behaviour of the elastically supported panel when interacting with the wind. The numerical results for the elastic support response under wind load, and the developed wind pressures, were found to agree with the full-scale experiments for both cladding cases. For the permeable cladding case, the wake flow of the elastically supported panel was shown to be free of large scale turbulent eddies when analysed by numerical simulations. The wake airflow for the impermeable panel case was found to be complex and extensive investigation is required.


      PubDate: 2014-10-12T03:10:13Z
       
  • Simulation and prediction of radio frequency heating in dry soybeans
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Zhi Huang , Hankun Zhu , Rongjun Yan , Shaojin Wang
      Radio frequency (RF) heating is considered as a potential postharvest technology for disinfesting legumes. However, the non-uniformity in RF heating is still a major problem in developing effective RF heat treatments for pest control and other applications. A computer simulation model was developed with a finite element-based commercial software, COMSOL, to analyse the temperature distributions. Dry soybeans packed in a rectangular plastic container were used to determine the heating uniformity and validate the simulation model using a 27.12 MHz, 6 kW RF system. Both simulated and experimental results showed similar heating patterns in RF treated soybeans, in which corners and edges were more heated and the temperature values were higher in the lower part of the container. The simulation results demonstrated that the RF heating uniformity could be improved using a similar dielectric material around the samples, a smaller top plate area (similar to the sample size), and placing the samples in the middle of the two plate electrodes. The simulation model developed in this study could be applied to improve the RF heating uniformity and to optimise the treatment parameters.


      PubDate: 2014-10-12T03:10:13Z
       
  • The effects of storage time and temperature on biogas production from
           dairy cow slurry
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): James D. Browne , Stephen R. Gilkinson , John P. Frost
      The effects of length of storage time and storage temperature on subsequent biogas production from dairy cow slurry by anaerobic digestion were investigated. Slurry was stored under anaerobic conditions at 9 °C and 20 °C for between 1 and 26 weeks prior to digestion. Digestion was carried out in 7 l continuously stirred tank reactors, with an average hydraulic retention time of 25 d. Storage of slurry at 9 °C had no significant effect on subsequent biogas production. However, after 8 weeks of storage at 20 °C there was an increasing negative impact on subsequent biogas production so that after 26 weeks of storage at 20 °C biogas production had decreased from 16.4 m3 t−1 to 5 m3 t−1 of fresh slurry. This reduction was strongly related to the decrease in the concentration of volatile solids in the stored slurry which was approximately 0.4 g kg−1 week−1. Storage time and temperature had no affect on the total nitrogen concentrations in the slurries, though both factors resulted in small increases in ammonia nitrogen concentrations.


      PubDate: 2014-10-12T03:10:13Z
       
  • Climate change, effective water use for irrigation and adaptability of
           maize: A case study in southern Italy
    • Abstract: Publication date: Available online 3 October 2014
      Source:Biosystems Engineering
      Author(s): Eugenia Monaco , Antonello Bonfante , Silvia M. Alfieri , Angelo Basile , Massimo Menenti , Francesca De Lorenzi
      Climate change may lead to differences in the distribution of precipitation and to reduced water availability, with constraints on the cultivation of some crops. An analysis of vulnerability and of opportunities for adaptation is required for crops in areas where they are currently cultivated. The intra-specific biodiversity of crops is a significant resource for the adaptation of agriculture, but requires better knowledge of the responses of cultivars to environmental stressors. Simulation models of water flow in the soil-plant-atmosphere system can be coupled with future climate scenarios to describe the soil water regime, taking into account different irrigation scheduling options. The adaptive capacity of maize hybrids is evaluated in an irrigated district in Southern Italy. Two climate cases were studied: “reference” (1961–1990) and “future” (2021–2050). The model SWAP was run to determine the soil water balance for different irrigation levels. For each level the effectiveness of irrigation was evaluated by means of a performance indicator (IE). The Relative Evapotranspiration Deficit (RETD) was used as an indicator of water availability. The yield response to water availability of several maize hybrids was determined; their hydrologic requirements were thus defined and compared with the simulated values of RETD in response to climate and irrigation. Soil moisture regime and irrigation performance were also analysed. The adaptability of hybrids to the future water regime was assessed for different irrigation levels. The study indicated how, in the future climate case, the intra-specific crop biodiversity, in combination with cropping patterns better adapted to soil characteristics, may allow the current production system to be maintained.


      PubDate: 2014-10-08T02:43:52Z
       
  • A method of optimal traction control for farm tractors with feedback of
           drive torque
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Pavel V. Osinenko , Mike Geissler , Thomas Herlitzius
      Traction efficiency of farm tractors barely reaches 50% in field operations (Renius et al., 1985). On the other hand, modern trends in agriculture show growth of the global tractor markets and at the same time increased demands for greenhouse gas emission reduction as well as energy efficiency due to increasing fuel costs. Engine power of farm tractors is growing at 1.8 kW per year reaching today about 500 kW for the highest traction class machines. The problem of effective use of energy has become crucial. Existing slip control approaches for farm tractors do not fulfil this requirement due to fixed reference set-point. This paper suggests an optimal control scheme which extends a conventional slip controller with set-point optimisation based on assessment of soil conditions, namely, wheel-ground parameter estimation. The optimisation considers the traction efficiency and net traction ratio and adaptively adjusts the set-point under changing soil conditions. The proposed methodology can be mainly implemented in farm tractors equipped with hydraulic or electrical infinitely variable transmissions (IVT) with use of the drive torque feedback.


      PubDate: 2014-10-08T02:43:52Z
       
  • Effects of mechanical distribution on survival and reproduction of
           Phytoseiulus persimilis and Amblyseius swirskii
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Fabio Pezzi , Roberta Martelli , Alberto Lanzoni , Stefano Maini
      The application of beneficial organisms to protected crops requires substantial manpower and obliges operators to remain for long periods in a hot and humid environment that leads to discomfort and fatigue. Mechanisation of this operation could reduce the distribution time with subsequent benefits for the health and safety of workers. A prototype distribution system for beneficial arthropods that could increase labour productivity and distribution quality on protected crops was developed. Experiments were conducted to assess the efficiency of the mechanical distribution system and its effect on the distributed organisms. Releases of the predatory mites Phytoseiulus persimilis and Amblyseius swirskii were tested in the laboratory. The release quality was verified through evaluation of distribution patterns and the effects on the viability and fecundity of both beneficial arthropods. The prototype was shown to properly perform the release without compromising the quality and biological traits of either species.


      PubDate: 2014-10-08T02:43:52Z
       
  • Prototype emitter for use in subsurface drip irrigation: Manufacturing,
           hydraulic evaluation and experimental analyses
    • Abstract: Publication date: Available online 3 October 2014
      Source:Biosystems Engineering
      Author(s): Wanderley de Jesus Souza , Leonor Rodrigues Sinobas , Raúl Sánchez , Tarlei Arriel Botrel , Rubens Duarte Coelho
      The current research aims to analyse theoretically and evaluate a self-manufactured simple design for subsurface drip irrigation (SDI) emitter to avoid root and soil intrusion. It was composed of three concentric cylindrical elements: an elastic silicone membrane; a polyethylene tube with two holes drilled on its wall for water discharge; and a vinyl polychloride protector system to wrap the other elements. The discharge of the emitter depends on the change in the membrane diameter when it is deformed by the water pressure. The study of the operation of this emitter is a new approach that considers mechanical and hydraulic principles. Thus, the estimation on the membrane deformation was based on classical mechanical stress theories in composite cylinders. The hydraulic principles considered the solid deformation due to force based on water pressure and the general Darcy–Weisbach head-loss equation. Twenty emitter units, with the selected design, were handcrafted in a lathe and were used in this study. The measured pressure/discharge relationship for the emitters showed good agreement with that calculated by the theoretical approach. The variation coefficient of the handcrafted emitters was high compared to commercial emitters. Results from field evaluations showed variable values for the relative flow variation, water emission uniformity and relative flow rate coefficients, but no emitter was obstructed. Therefore, the current emitter design could be suitable for SDI following further studies to develop a final prototype.


      PubDate: 2014-10-08T02:43:52Z
       
  • Wind pumps for irrigating greenhouse crops: Comparison in different
           socio-economical frameworks
    • Abstract: Publication date: Available online 3 October 2014
      Source:Biosystems Engineering
      Author(s): Rodrigo Díaz-Méndez , Adnan Rasheed , Manuel Peillón , Alicia Perdigones , Raúl Sánchez , Ana M. Tarquis , José L. García-Fernández
      A simple methodology was used to compare the economic feasibility of wind pump technology, solar photovoltaic pumping, diesel generators, and connection to the electrical grid to provide energy for pumping irrigation water in commercial greenhouses in Spain, Cuba and Pakistan (countries with different developmental backgrounds). The analysis took into account wind resources, distance to the grid, water storage tank volume requirements, and planting dates. Comparisons were made in terms of the levelised cost of energy associated with each system. For all three countries, if a grid connection was already in place, installing wind pumps would be economically unwise. Where no grid connection exists, the distance to the grid and the wind resource available are key factors to be taken into consideration when deciding between options: a 10% increase in the average wind speed is equivalent to a 20% reduction in the distance to the grid in terms of costs return. Finally, the water elevation has a major influence on the economic feasibility of wind pump technology, much more than, for example, on solar photovoltaic pumping technology. The results reveal that, generally, the critical factors to consider when making energy management decisions differ depending between countries. In Spain, the proximity of the electrical grid makes the connection to it the best option. In Pakistan, scarce wind resources are a serious limiting factor. Cuba, however, has good wind resources; water elevation, distance to the grid and water storage needed are the critical factors when determining the economic feasibility of wind pumping there.


      PubDate: 2014-10-08T02:43:52Z
       
  • Diurnal pattern in canopy light interception for tree fruit orchard
           trained to an upright fruiting offshoots (UFO) architecture
    • Abstract: Publication date: January 2015
      Source:Biosystems Engineering, Volume 129
      Author(s): Jingjin Zhang , Matthew D. Whiting , Qin Zhang
      Fractional interception of photosynthetically active radiation (FIPAR) (i.e. light interception) by tree fruit canopies determines, in large part, fruit quantity and quality, and thus profitability. This study aimed to elucidate the diurnal pattern in FIPAR and determine the optimum time at which the measured FIPAR best represents mean daily FIPAR in sweet cherry trees trained to the planar UFO (Upright Fruiting Offshoots) architecture. Two experiments were conducted to assess the influence of canopy development stages and of canopy height to row spacing ratios (H/S ratio) on diurnal FIPAR pattern and optimum measurement time. For different canopy development stages, three adjacent north-to-south sample blocks were selected. For different H/S ratios, three levels of 0.75, 1.00, and 1.25 were used, and 9 north-to-south sample block for each level were selected. Daily FIPAR was determined from measurements taken within ±6 h of solar noon. Gaussian process regression with four parameters was applied to obtain the diurnal pattern with coefficients of determination (R 2) ranging from 0.97 to 1.00. The diurnal pattern was symmetric with the lowest point around solar noon. Mean daily FIPAR increased during the season, as well as with increasing H/S ratio. For both experiments, there was no substantial difference in optimum measurement time among stages and among H/S ratios, with maximum difference of 0.3 h and 0.4 h respectively. We recommend an optimal measurement time window of −2.5 h to −2.0 h with reference to solar noon for the planar UFO architecture to estimate mean daily FIPAR with ±10% tolerance interval.


      PubDate: 2014-10-08T02:43:52Z
       
 
 
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