Research in Agricultural Engineering, 2009 (vol. 55), issue 4
Index of Volume 55Index
editors
Res. Agr. Eng., 2009, 55(4):I-III | DOI: 10.17221/1631-RAE 
Impact of semitrailer tyre pressure upon passive resistance and tractor unit operation economy
P. Novák, T. Šmerda, J. Čupera
Res. Agr. Eng., 2009, 55(4):129-135 | DOI: 10.17221/13/2009-RAE
The aim of the measurement was to establish and prove the effect of the semitrailer tyre pressure on the magnitude of power losses and energy intensity in a tractor unit operation. The measured and calculated values were interlaid with the corresponding functions by means of regression analysis considering the magnitude of the determination coefficient (determination index). The values of the determination index ranged from 0.95 to 0.99 for regression functions; all the regression function were highly reliable at 0.01 relevance level. The difference of the lost power was recorded at the speed of 35 km/h, 1.82 kN between 170 kPa and 300 kPa pressures....
Relationship between the looseness of soil and the electric conductivity
P. Rácz, Z. Szüle
Res. Agr. Eng., 2009, 55(4):136-140 | DOI: 10.17221/18/2008-RAE
The present article reports on an experiment as part of the research in the frame of which I search after the relationship between the looseness L of soil characterising the operating quality of the chisel-type subsoilers of a medium working depth, and the change in the electric conductivity in the soil caused by the loosening cultivation. The investigation was carried out with the help of the mobile electric-conductivity measuring device - accounted as a novelty in field-land tests - type Veris 3100 with disc electrodes, operating in field-land conditions. As the results of the investigation, the relation between the electric conductivity and...
A new method of cleaning solid surfaces contaminated with oils
V. Řezníček, V. Dvořák, K. Kykalová, J. Severa, J. Mareček, J. Fryč
Res. Agr. Eng., 2009, 55(4):141-148 | DOI: 10.17221/4/2009-RAE
The aim of the work was to find an alternative way of cleaning roads and other kinds of solid surfaces contaminated as a result of accidents. The method is designed to dissolve oil leaks coming from motor vehicles, but it is also suitable for removing other liquids with similar physical and chemical characteristics, for example plant and paraffinic oils. The principle of this method is to emulsify the contaminant with the reagent foam. The foam is applied on the contaminated surface and it reacts with the contaminant, given rise to an emulsion. The process is supported by the mechanical movement of brushes, which mix the foam with the contaminant....
Effect of carbide size in hardfacing on abrasive wear
R. Chotěborský, P. Hrabě, M. Müller, R. Válek, J. Savková, M. Jirka
Res. Agr. Eng., 2009, 55(4):149-158 | DOI: 10.17221/1/2009-RAE
Abrasive wear of high alloyed overlay materials with high contents of carbide phases of M7C3 depends on the sizes of the carbide particles and on their distribution in an overlay. This work is focused on the study of the carbide particles size effect on abrasive wear. The size of carbide particles of M7C3 type, their distribution (part) in the matrix and their effect on abrasive wear were measured. Hardness in single layers, as well as microhardness of the matrix and of carbide particles, were also measured. The abrasive wear resistance was measured using the pin-on-disk machine with bonded abrasive particles....
Hydro-sorting of apricots based on some physical characteristics
Mirzaee E., Rafiee S., Keyhani A., Emam-Djomeh Z., Kheiralipour K.
Res. Agr. Eng., 2009, 55(4):159-164 | DOI: 10.17221/11/2009-RAE
In this study, the dropping time of apricot fruits was followed experimentally using a water column. Some effective characteristics of apricots related to the dropping time were determined using standard methods. The best models for the dropping time of Nasiry, Rajabali, and Ghavami apricot varieties as a function of water and fruit densities, shape factor, and fruit volumes were executed with the determination coefficients of 0.95, 0.92, and 0.85, respectively. It was found that the differences between the fruits density minus the density of water had a major effect on their dropping time.
Determination of selected physical properties of Brachystegia eurycoma seeds
M.C. Ndukwu
Res. Agr. Eng., 2009, 55(4):165-169 | DOI: 10.17221/14/2009-RAE
The research looked at some selected physical properties of Brachystegia eurycoma, such as axial dimension, roundness, sphericity, surface area, bulk density, solid density, porosity, and volume which are essential in the design and construction of the processing and handling equipments of Brachystegia eurycoma. All the above physical properties measured showed some deviations from the average values which is typical of agricultural biomaterials. Solid density showed the highest deviation of 4.04 g/mm3 while the volume showed the least deviation of 0.01 mm3 when compared to those of other physical properties. The...