Research in Agricultural Engineering, 2010 (vol. 56), issue 4
Index of Volume 56Index
editors
Res. Agr. Eng., 2010, 56(4):I-II | DOI: 10.17221/1630-RAE 
Frequency of occurrence of a certain air temperature at various sites in the Czech Republic
V. Šleger, P. Neuberger
Res. Agr. Eng., 2010, 56(4):127-137 | DOI: 10.17221/4/2010-RAE
The present paper analyses the problem of calculation of the average number of hours in a year during which air temperature is lower than a preselected limiting level. A method for estimating the number of hours in situations where only the minimum, average, and maximum daily temperature data are available has been suggested and tested. The work encompassed 30 sites in the Czech Republic at different altitudes and with different average temperatures, using weather data from the 1961-2000 period. The results are presented in the tabular form. It is shown that interdependence exists between the number of hours with temperatures lower than a preselected...
The usage of CAN-Bus messages for engine power determination
J. Čupera, T. Šmerda
Res. Agr. Eng., 2010, 56(4):138-146 | DOI: 10.17221/45/2009-RAE
Determination of the actual power of tractor's engine in the operation can be done by calculation which requires the use of a range of parameters such as coefficient of rolling resistance, mechanical efficiency, the moments of inertia, etc. Their values are usually tabulated and therefore the engine power cannot be determine without simplifying. Another solution is to use the actual engine torque message from the CAN-Bus, which brings a specific value of the actual torque. The aim is to use the current torque to calculate the engine power in the deployment of tractor's set in transport operation. The results show that at a uniform movement of the flat...
Microbial contamination of the sand from the wastewater treatment plants
M. Szostková, T. Vítěz
Res. Agr. Eng., 2010, 56(4):147-153 | DOI: 10.17221/21/2009-RAE
Primary treatment of domestic wastewater represents an extensive range of physical and chemical activities which directly or indirectly affect functionality of the treatment plant as a whole. The aforementioned effect might be rather significant in many respects. However, an incorrectly designed or operated primary treatment might result in an unnecessary increase of operating costs and, principally, a negative impact on the biological level or sludge treatment and disposal. The subject matter of this contribution comprises contemplations related to functionality of this level, both with respect to its relation to functionality of wastewater treatment...
Particle size distribution of sawdust and wood shavings mixtures
T. Vítěz, P. Trávníček
Res. Agr. Eng., 2010, 56(4):154-158 | DOI: 10.17221/8/2010-RAE
Particle size distribution of the sample of waste sawdust and wood shavings mixtures were made with two commonly used methods of mathematical models by Rosin-Rammler (RR model) and by Gates-Gaudin-Schuhmann (GGS model).On the basis of network analysis distribution function F (d) (mass fraction) and density function f (d) (number of particles captured between two screens) were obtained. Experimental data were evaluated using the RR model and GGS model, both models were compared. Better results were achieved with GGS model, which leads to a more accurate separation of the different particle sizes in order to obtain...
Determination of loading capacity depending on bevel angle of the wooden bonded scarf joint
O. Dajbych, D. Herák, A. Sedláček, G. Gűrdil
Res. Agr. Eng., 2010, 56(4):159-165 | DOI: 10.17221/1/2010-RAE
The paper is focused on comparison of experimental and simple theoretical method of determination of loading capacity depending on bevel angle of wooden bonded scarf joint. The Mohr's circle principle, thus shear stress dependence on normal stress, is used for loading capacity formula derivation. It has been established that for random bevel angle under approximately 70 degrees the future loading capacity can be calculated from knowledge of ultimate force for bevel angle 0 and 90 degrees.