Research in Agricultural Engineering, 2017 (vol. 63), issue 3
Risk analysis of the business profitability in agricultural companies using combine harvestersOriginal Paper
Miroslav Mimra, Miroslav Kavka, František Kumhála
Res. Agr. Eng., 2017, 63(3):99-105 | DOI: 10.17221/63/2016-RAE 
This article presents the results of entrepreneurial risk analysis in a company providing agricultural services where a group of combine harvesters is used. An economic model was created in order to emulate the operational costs of the combine harvesters using MS Excel. Based on the results of the sensitivity analysis, the key factors were determined. For these factors, the risk of achieving the desired economic results was created subsequently. For the simulated situation, the key factors were activated within the range of ± 10% using a triangular distribution of these values. The result of this analysis showed that the most frequent value...
Research on wear resistance of poly-component composite materialsOriginal Paper
Miroslav Müller, Jiří Kejval
Res. Agr. Eng., 2017, 63(3):106-114 | DOI: 10.17221/79/2015-RAE
The paper deals with the testing of composite materials based on corundum, silicon carbide and glass. The object of the experiments was a particle polymeric composite, whose continuous phase was in the form of a two-component epoxy resin and a discontinuous phase (reinforcing particles) of corundum, silicon carbide and glass of a specific particle size from 4.5 to 260 µm. The research was focused on the evaluation of abrasive wear resistance and hardness of the tested materials. A considerable improvement of the values obtained at measuring the abrasive wear resistance was reached at hybrid composite materials filled with three different components,...
Evaluation of properties of elastomer seal for fuel systems exposed to effects of rapeseed methyl esterOriginal Paper
Vladimír Šleger, Miroslav Müller, Martin Pexa
Res. Agr. Eng., 2017, 63(3):115-120 | DOI: 10.17221/55/2016-RAE
Elastomer seals in fuel systems have to evince required mechanical properties also at exposure to fuels. The aim of the research was to determine an influence of various concentrations of rapeseed methyl ester (RME) on a change of mechanical properties of sealing O-rings made from polyacrylate elastomer (an indication ACM). A permanent deformation - compression set (CS), a tensile strength and an elongation after the exposure to the tested environment for the time 20 months were evaluated within the experiment. A fall of the tensile strength, the elongation and the permanent deformation - compression set CS was proved depending on the type of the fuel....
Kinetics on anaerobic co-digestion of bagasse and digested cow manure with short hydraulic retention timeOriginal Paper
Darwin, Afrizal Fazil, Muhammad Ilham, Sarbaini, Satria Purwanto
Res. Agr. Eng., 2017, 63(3):121-127 | DOI: 10.17221/18/2016-RAE
The anaerobic co-digestion of bagasse with digested cow manure was operated in 3 l semi-continuous reactor under mesophlic temperature at 34 ± 1°C. Short hydraulic retention time and high organic loading rate applied were 10 days and 3.465 kg volatile solids (VS)/m3.day, respectively. Anaerobic co-digestion of bagasse with digested cow manure obtained higher biogas yield (69 ml/g VS) compared with the anaerobic digestion of digested cow manure alone (20.42 ml/g.VS). Kinetic assessment revealed that the maximum specific growth rate, the maximum rate of substrate consumption, half-velocity constant, endogenous decay constant and microbial...
A novel method for the quantification of interfacial tomato stresses during transportationOriginal Paper
Wynand Jacobus van der Merwe Steyn
Res. Agr. Eng., 2017, 63(3):128-135 | DOI: 10.17221/64/2015-RAE
Transportation of tomatoes on farm and market roads causes interfacial stresses of tomatoes due to truck dynamics as affected by road and transportation conditions. These stresses may affect the shelf-life of tomatoes if they are high enough to cause damage to the fruit. This paper describes a novel method for the in situ measurement of the stresses during actual transportation of tomatoes, providing the producer information that can assist in taking decisions regarding the use of alternative routes, maintenance of existing routes or changes in packing to prevent excessive stresses onto tomatoes. The process involves measurement of the stresses using...
Non-stationary processing centre for small and mediumsized blueberry farms. A ReviewReview
Kaarel Soots, Jüri Olt
Res. Agr. Eng., 2017, 63(3):136-144 | DOI: 10.17221/42/2015-RAE
Growing blueberries on exhausted milled peat fields could be a possible solution to decrease carbon dioxide emission from these areas. To operate such crop-giving plantation manually, a lot of manpower is needed. To decrease the manpower, suitable and helpful technical solutions should be introduced. The aim of this article is to investigate different technological aspects of post-harvest processing of blueberries and to study already existing technical solutions. As a result, non-stationary processing centre for small or medium-sized blueberry farms is proposed. The proposed solution allows reducing manpower, lowering production costs and increasing...