Journal of Agricultural Engineering 2019-09-12T16:16:14+02:00 Paola Granata Open Journal Systems <p>The <strong>Journal of Agricultural Engineering (JAE)</strong> is the official journal of the <a href="" target="_blank" rel="noopener"><strong>Italian Society of Agricultural Engineering</strong></a> supported by University of Bologna, Italy. The subject matter covers a complete and interdisciplinary range of research in engineering for agriculture and biosystems.</p> Flaming to control weeds in seashore paspalum (Paspalum vaginatum Sw.) turfgrass 2019-09-10T12:42:38+02:00 Luisa Martelloni Marco Fontanelli Lisa Caturegli Monica Gaetani Nicola Grossi Simone Magni Andrea Peruzzi Michel Pirchio Michele Raffaelli Marco Volterrani Christian Frasconi <p>Weed control is crucial to ensure that turfgrass is established effectively. Although herbicides are commonly used to control weeds in turfgrasses, environmental and public health concerns have led to limiting or banning the use of synthetic herbicides in urban areas. The species seashore paspalum (Paspalum vaginatum Sw.) is susceptible to such herbicides. Flame weeding could be an alternative to the use of synthetic herbicides for selective weed control in seashore paspalum. In this study, five different liquefied petroleum gas (LPG) doses of flaming (0, 61, 91, 157 and 237 kg ha<sup>–1</sup>) were tested in order to find the optimal dose, in terms of weed control and costs. The aim was to maintain a seashore paspalum (cultivar ‘Salam’) turf free of weeds during spring greenup, and at the same time avoid damaging the turfgrass. Using a self-propelled machine designed and built at the University of Pisa, flaming was applied three times when weeds started growing and the turfgrass started green-up. Our results highlight that an LPG dose of 157 kg ha<sup>–1</sup> was the most economic dose that led to a significant reduction in initial weed cover and density, enabling the turfgrass to recover three weeks after the third application.</p> 2019-06-26T00:00:00+02:00 Copyright (c) 2019 Luisa Martelloni, Marco Fontanelli, Lisa Caturegli, Monica Gaetani, Nicola Grossi, Simone Magni, Andrea Peruzzi, Michel Pirchio, Michele Raffaelli, Marco Volterrani, Christian Frasconi Noise attenuation provided by hedges 2019-09-12T16:15:46+02:00 Marcello Biocca Pietro Gallo Giuseppina Di Loreto Giancarlo Imperi Daniele Pochi Laura Fornaciari <p>During the past few decades, urban areas have experienced increasing environmental stress. Noise is considered as one of the most important sources of urban pollution with adverse effects on human health. Urban vegetation provides many ecosystem services including the reduction of noise pollution. Hedges are widespread in cities and have the peculiarity of being often grown close to the source of noise. The study investigated the noise reduction due to hedges of <em>Prunus laurocerasus</em> and <em>Laurus nobilis</em> and the effect of the vegetation on sound spectra. Four different trials were carried out, including the use of two different noise sources and the measurement of noise at different distances both from the green barrier and from the noise source. During one trial, the influence of the type of ground surfaces between the noise source and the receiver was also evaluated. In the three trials where a significant attenuation of the noise occurred, the porosity of hedges measured less than 4.6% and an average noise reduction of about 2.7 dB(A) (max 7.0 dB(A)) was observed. This effect was particularly relevant in the range of higher frequencies (between 2 and 20 kHz). This study can contribute to plan and design hedges in the urban context.</p> 2019-09-10T11:59:49+02:00 Copyright (c) 2019 Marcello Biocca, Pietro Gallo, Giuseppina Di Loreto, Giancarlo Imperi, Daniele Pochi, Laura Fornaciari Error propagation approach for estimating root mean square error of the reference evapotranspiration when estimated with alternative data 2019-09-12T16:16:14+02:00 Homayoon Ganji Takamitsu Kajisa <p>Estimation of reference evapotranspiration (<em>ET</em><sub>0</sub>) with the Food and Agricultural Organisation (FAO) Penman-Monteith model requires temperature, relative humidity, solar radiation, and wind speed data. The lack of availability of the complete data set at some meteorological stations is a severe restriction for the application of this model. To overcome this problem, <em>ET</em><sub>0</sub> can be calculated using alternative data, which can be obtained via procedures proposed in FAO paper No.56. To confirm the validity of reference evapotranspiration calculated using alternative data (<em>ET</em><sub>0(Alt)</sub>), the root mean square error (<em>RMSE</em>) needs to be estimated; lower values of RMSE indicate better validity. However, RMSE does not explain the mechanism of error formation in a model equation; explaining the mechanism of error formation is useful for future model improvement. Furthermore, for calculating <em>RMSE</em>, <em>ET</em><sub>0</sub> calculations based on both complete and alternative data are necessary. An error propagation approach was introduced in this study both for estimating <em>RMSE</em> and for explaining the mechanism of error formation by using data from a 30-year period from 48 different locations in Japan. From the results, <em>RMSE</em> was confirmed to be proportional to the value produced by the error propagation approach (Δ<em>ET</em><sub>0</sub>). Therefore, the error propagation approach is applicable to estimating the RMSE of <em>ET</em><sub>0(Alt)</sub> in the range of 12%. Furthermore, the error of <em>ET</em><sub>0(Alt)</sub> is not only related to the variables’ uncertainty but also to the combination of the variables in the equation.</p> 2019-09-10T11:47:15+02:00 Copyright (c) 2019 Homayoon Ganji, Takamitsu Kajisa From biogas to biomethane: Techno-economic analysis of an anaerobic digestion power plant in a cattle/buffalo farm in central Italy 2019-09-11T16:16:39+02:00 Ester Scotto di Perta Elena Cervelli Maria Pironti di Campagna Stefania Pindozzi <p>Anaerobic digestion (AD) is a mature technology commonly used for manure treatment, both for the stabilisation of waste and for the production of energy. The introduction of new incentives could represent an opportunity for biogas production, when the current feed-in-tariffs, which improved the financial feasibility of AD plants producing electricity will end. This paper examines the feasibility of reconverting an existing AD biogas production plant into a biomethane production plant. The AD plant, in this case study, is a two-stage reactor situated in the centre of Italy and mainly fed with livestock manure from both cows and buffaloes. The economic analysis of two hypotheses is provided: i) continuing the electricity production from biogas after the end of the current incentives (2025); ii) considering the new incentives program for the biomethane and reconverting the plant, using hollow-fibre membranes for the purification of the raw biogas (SEPURAN® Green modules, EnviTec). For this purpose, investment and operating costs, based on plant monitoring data (2105.3 m<sup>3</sup> d<sup>–1</sup>, Biogas production; 4432.9 kWh d<sup>–1</sup>, electricity production) as well as on market analysis for costs evaluation were considered. The mean biogas production for the considered year was about 30% less than the expected production, indicated by producer, highlighting the need for the optimisation of the management of the reactors. Moreover, based on the averaged methane production (June 2017-June 2018), results show that: i) plant conversion for the biomethane production is not suitable for small-scale plants, due to the high investment costs of upgrading technology (1.2 M€); ii) when current incentives end, the electricity production from biogas in the current plant may not be self-sufficient, due to the highly expensive operating costs. This paper provides a first analysis of the possible fate of the biogas plants under the new incentives.</p> 2019-09-10T12:07:14+02:00 Copyright (c) 2019 Ester Scotto di Perta, Elena Cervelli, Maria Pironti di Campagna, Stefania Pindozzi Development of a new washing machine in olive oil extraction plant: A first application of usability-based approach 2019-09-11T16:16:10+02:00 Alessio Cappelli Chiara Parretti Enrico Cini Paolo Citti <p>This paper suggests an approach based on usability engineering, used to assess the usability of machines and plants in the agrofood industry, aiming to enhance machines efficacy, efficiency and safety with a development focused on users’ needs. Furthermore, the article examines the validation of the suggested approach through its application in a case study regarding a washing machine for the production of extra virgin olive oil. Firstly, it was necessary to identify the target cluster. For this reason, only Tuscan high quality extra virgin olive oil manufacturers were selected. The selected producers are of between 30 and 65 years old, with working experience in the field of at least 10 years. Once the cluster was identified, through brainstorming, the critical phases of the process were identified. According to the results, the washing process was considered the most critical phase. The reached conclusions were analysed and translated into technical aspects through the Quality Function Deployment. The predominant needs to be introduced in the new washing machine were related to the reduction of processing time, the improvement of washing system, the reduction of water consumption, and the increase of worker safety. Successively, a virtual prototype was developed and tested with 8 experts. Afterwards, a usability test was performed with 15 users. Two different olive washing machines were evaluated (traditional <em>vs</em> new machine). The Wilcoxon signed-rank test was utilised for users’ scores interpretation. According to P-values (ranging from P&lt;0.001 to P=0.008) several statistically significant differences emerged between the two washing machines. In particular, remarkable differences regarding efficacy, efficiency, usability, human-machine interaction, reliability and an increase in safety were highlighted. Moreover, the results indicate that the new washing machine is overall perceived as more usable machine. In conclusion, the results are encouraging and give robustness both to the proposed methodological approach and to the improvement of the new washing machine.</p> 2019-09-10T12:16:08+02:00 Copyright (c) 2019 Alessio Cappelli, Chiara Parretti, Enrico Cini, Paolo Citti Geometric shape and tensile forces on silo bags for grain storage 2019-09-11T16:14:55+02:00 Ana Scarabino <p>This work consists in the analytical derivation and numerical solution of the equation which determines the shape of the section of a <em>silo bag</em>: a long horizontal cylindrical plastic bag filled with either a liquid or a granular material which behaves similarly, exerting normal, but not frictional forces against the wall. The bag is considered inextensible and completely flexible, capable of supporting only tensile loads. These suppositions lead to a secondorder differential equation for the membrane shape, which is normalised and solved, in a way that allows, for any bag with any amount of filling, a simple computation of its geometry, enclosed area and tensile loads. A discussion is included about the effects on the theoretical results of the silo bag tensile deformation.</p> 2019-09-10T12:23:26+02:00 Copyright (c) 2019 Ana Scarabino Optimisation of energy consumption of a solar-electric dryer during hot air drying of tomato slices 2019-09-10T12:42:39+02:00 Nnaemeka R. Nwakuba <p>High-energy demand of convective crop dryers has prompted study on optimisation of dryer energy consumption for optimal and cost effective drying operation. This paper presents response surface optimisation of energy consumption of a solar-electric dryer during hot air drying of tomato slices. Drying experiments were conducted with 1 kg batch of tomato samples using a 33 central composite design of Design Expert 7.0 Statistical Package. Three levels of air velocity (1.0, 1.5 and 2.0 ms<sup>–1</sup>), slice thickness (10, 15 and 20 mm) and air temperature (50, 60 and 70°C) were used to investigate their effects on energy consumption. A quadratic model was obtained with a high coefficient of determination (R<sup>2</sup>) of 0.9825. The model was validated using the statistical analysis of the experimental parameters and normal probability plot of the energy consumption residuals. Results obtained indicate that the process parameters had significant quadratic effects (P&lt;0.05) on the energy consumption. The energy consumption varied between 5.42 kWh and 99.78 kWh; whereas the specific energy consumption varied between 5.53 kWhkg<sup>–1</sup> and 150.61 kWhkg<sup>–1</sup>. The desirability index method was applied in predicting the ideal energy consumption and drying conditions for tomato slices in a solar-electric dryer. At optimum drying conditions of 1.94 ms<sup>–1</sup> air velocity, 10.36 mm slice thickness and 68.4°C drying air temperature, the corresponding energy consumption was 5.6 8kWh for maximum desirability index of 0.989. Thermal utilisation efficiency (TUE) of the sliced tomato samples ranged between 15 ≤TUE ≤58%. The maximum TUE value was obtained at 70°C air temperature, 1.0 ms<sup>–1</sup> air velocity and 10 mm slice thickness treatment combination, whereas the minimum TUE was obtained at 50°C air temperature, 2.0 ms<sup>–1</sup> air velocity and 20 mm slice thickness. Recommendation and prospect for further improvement of the dryer system were stated.</p> 2019-07-24T00:00:00+02:00 Copyright (c) 2019 Nnaemeka R. Nwakuba