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1

Influence of moisture on external friction coefficient and basic physical properties of Astoria variety wheat grain

Markowska A., Warechowska M., Warechowski J.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2016

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nr 19(1)

17--26

EN

This paper analyzed the effect of moisture content on selected physical properties of Astoria variety wheat grain using six levels of grain moisture content (14%, 16%, 18%, 20%, 22% and 24%). The following were determined for each level of moisture content: angle of repose, static angle of repose (SAR), bulk density and thousand kernel weight. The friction coefficients for four different construction materials (CEF) were also determined: acid-resistant steel, wear-resistant steel, plastic (PPLD) and rubber. It was found that an increasing moisture content in grains was accompanied by an increase in the thousand kernel weight, angle of repose, SAR, as well as the CEF against each of the surfaces used in the study. The highest value of the CEF was recorded for a rubber surface (0.782) and the smallest was for a polypropylene surface (0.443). The highest values of the angle of repose and the SAR were recorded for the grain with the highest moisture content: 37.15o and 39.44o, respectively. An increase in the moisture content in kernels reduced their bulk density from 79.870 kg · hl–1 (moisture content: 14%) to 68.783 kg · hl–1 (moisture content 24%).

2

Frictional properties of selected seeds

Kaliniewicz Z., Markowski P., Anders A., Jadwisieńczak K.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2015

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nr 18(2)

85--101

EN

The thickness, width, length and weight of five seed species (buckwheat, vetch, pea, lupine and faba bean) and their external friction angle were determined on two types of surfaces - steel and rubber. The experiment was performed with the use of a an inclined plane with an adjustable angle of inclination that measures the angle of external friction and the time taken by seeds to travel a given distance, which supports the determination of the coefficient of kinetic friction. The measured parameters were used to calculate arithmetic and geometric mean diameter, aspect ratio and sphericity index. The dimensions, weight and the calculated indicators of the examined seeds did not significantly affect their coefficients of static and kinetic friction or their coefficients of rolling resistance and rolling friction. The studied parameters were largely influenced by the type of friction surface, and significantly lower average values were reported for steel than rubber. In the studied seed species, the static friction coefficient was determined in the range of 0.187 to 0.582, kinetic friction coefficient - 0.134 to 0.479, rolling resistance coefficient - 0.148 to 0.529 and rolling friction coefficient - 0.29 to 1.80 mm.

3

The stand for laboratory tests of loose materials

Polański K.

AGH Drilling, Oil, Gas

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2013

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Vol. 30, no. 3

405--411

EN

The paper describes a laboratory stand for tests of properties of bulk materials. It can be helpful for select proppants and materials for bedding layer. Tests were carried out according to Eurocode‑1 norm, which required the construction of laboratory to allow the appointment of the angle of internal friction and external friction of granular materials in accordance with the Jenike procedure. The results obtained during the experiments allowed us to compare properties of various materials and a summary of the results obtained with the values quoted in the literature

4

Badania współczynnika tarcia zewnętrznego ziarna zbóż w funkcji wilgotności

Kram B. B.

Inżynieria Rolnicza

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2006

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R. 10, nr 3(78)

175-182

PL

Współczynniki tarcia zewnętrznego ziaren zbóż (pszenica ozima Almari i Rosa, pszenica jara Omega i Eta, żyto Dańkowskie Złote i Motto, pszenżyto ozime Presto i Malno, pszenżyto jare Jago i Maja) wyznaczono na podstawowych materiałach konstrukcyjnych: stali, drewnie i gumie. Badane ziarno było nawilżane od wilgotności W = 9% do W = 33%. Zmienność współczynników tarcia zewnętrznego w funkcji wilgotności na badanych podłożach opisują proste rosnące. Najniższy współczynnik tarcia wynosił µ= 0,2991 (dla pszenżyta Maja, na podłożu stalowym), a najwyższy µ= 0,9999 (dla pszenicy Rosa na podłożu gumowym).

EN

The coefficient of external friction of cereals grain (winter wheat Almari and Rosa, spring wheat Omega and Eta, rye Dańkowskie Złote and Motto, winter triticale Presto and Malno, winter triticale Presto and Malno, spring triticale Jago and Maja) was determined for three major materials: steel, wood and rubber. The grain was wetted in special containers in order to attain the moisture levels within 10%-32%. The values of external friction coefficient have the from of linear regression and show the relationship between the coefficient of external friction and moisture levels. The smallest coefficient of external friction (µ= 0,2991) was for triticale Maja for steel base, and the highest (µ= 0,9999) was for wheat Rosa for the rubber base.