Research in Agricultural Engineering, 2014 (vol. 60), issue 3

Improving performance parameters of combustion engine for racing purposesOriginal Paper

T. Polonec, I. Janoško

Res. Agr. Eng., 2014, 60(3):83-91 | DOI: 10.17221/26/2012-RAE  

Mechanical parts of stock engine have a performance reserve which could be utilized when the engine is used under the race conditions. Especially normal turbocharged engines have their performance parameters designed to drive in traffic, where a good flexibility, reliability, fuel consumption and a long service life is required. It is possible to utilize the whole power of the engine, when changing or modifying some of its external parts and achieve better performance parameters without modifying or changing internal engine components. Performed changes must be realized thoughtfully and on the admittable level, so the engine and other drive train components...

Dehydration kinetics of onion slices in osmotic and air convective drying processOriginal Paper

V.A. Revaskar, P.S. Pisalkar, P.B. Pathare, G.P. Sharma

Res. Agr. Eng., 2014, 60(3):92-99 | DOI: 10.17221/22/2012-RAE  

The effect of different pre-treatments (i.e. osmotic dehydration in 10, 15 and 20°Brix NaCl solution and drying air temperature of 50, 60 and 70°C) on drying behaviour of onion slices were investigated. The onion slices were dried in a laboratory model tray dryer. Drying of onion slices occurred in falling rate period. Five thin-layer drying models (Exponential, Page, Henderson and Pabis, Logarithmic and Power law) were fitted to the moisture ratio data. Among the drying models investigated, the Page model satisfactorily described the drying behaviour of onion slices. The effective moisture diffusivity of pre-treated samples was higher than...

Goose eggshell geometryOriginal Paper

Š. Nedomová, J. Buchar

Res. Agr. Eng., 2014, 60(3):100-106 | DOI: 10.17221/80/2012-RAE  

The paper presents a new approach of the eggshell geometry determination using and analysing the egg digital image and edge detection techniques. The detected points on the eggshell contour were fitted by the Fourier series. The obtained equations describing an egg profile were used to calculate the egg volume, surface area, and radius of curvature with much higher degree of precision in comparison with previously published approaches. The paper shows and quantifies the limitations of the common and frequent procedures.

Development and evaluation of full-vehicle vibration model of MF 285 tractorOriginal Paper

I. Ahmadi

Res. Agr. Eng., 2014, 60(3):107-114 | DOI: 10.17221/5/2013-RAE  

The vibration transmitted to the tractor driver not only leads to the driver health problems, but also reduces the driver working efficiency. One of the methods utilized to reduce driver vibration is the seat suspension system. Development of the tractor vibration model is the first step toward the implementation of the tractor seat suspension. In this research development and evaluation of full-vehicle vibration model of MF 285 tractor was considered. At validation phase, the developed model simulated the predictable outputs correctly. The modified parameters of the model reduced the simulation error by 30% compared to the model with primary parameters....

Effect of microstructure factors on abrasion resistance of high-strength steelsOriginal Paper

E. Zdravecká, J. Tkáčová, M. Ondáč

Res. Agr. Eng., 2014, 60(3):115-120 | DOI: 10.17221/20/2013-RAE  

Current development of high strength abrasion resistant steels is mostly oriented on high hardness, martensitic concept following the hypothesis that the abrasion resistance holds a proportional tendency with hardness. The various experimental observations have suggested that the high hardness of martenzite does not guarantee a high abrasion resistance because the brittle nature of martensite can lead to decrease their abrasive wear. The aim of this work was to analyse the influence of microstructure on abrasion resistance of selected high-strength low-alloyed steels used in the industry. The abrasive wear resistance of selected steels was obtained...

Analyses of the thermal characteristics of construction details at the biogas station plantOriginal Paper

P. Junga, P. Trávníček

Res. Agr. Eng., 2014, 60(3):121-126 | DOI: 10.17221/29/2012-RAE  

This paper presents analyses of the thermal characteristics of construction details at the biogas station plant, in order to investigate the impact of the thermal bridges on the energy consumption. Thermal bridges in the building's envelope remain a weak spot in the constructions. Heat losses of biogas plant constructions are a negative phenomenon and cause wasting of energy. If we eliminate thermal bridges in constructions we can achieve a reduction of general heat losses and save a certain amount of heat energy for utilization. Correct structural design of construction details has impact on general environmental and economic characteristics of biogas...