Annals of Warsaw University of Life Sciences - SGGW.

Methods for evaluation of breaking up of maize chaff separated... 27it enabled to determine effectivenessof maize grain breaking up by forageharvester.Geometric mean of chaff particlelength X gm and standard deviation S gmwere calculated according to ANSI/ASAE S424.1 Standard with equations:−1 Σ( m XXilog i)gm = logΣmi(2)1⎡2mi Xi − X ⎤−1Σ (log log gm)2Sgm= log ⎢⎥⎢ Σm⎣i ⎥⎦(3)where:m i – mass of chaff on i-sieve, g,X i – mean length of particle on i-sieve,mm.Length of particles on the first sieve(X l ) measured with a slide caliperaveraged to 48 mm for all varieties. Themean length of particle on the bottom(X 6 ) amounted to 0.82 mm (half ofsieve diagonal of smallest dimension).Geometric means of lengths for theremaining sieves were calculated withequations:1Xi = [ Xi ⋅X( i−1)] 2 (4)where:X i – mesh diagonal of i-sieve (i = 2÷5), m,X (i-1) – mesh diagonal of sieve abovei-sieve, mm.In order to verify the geometricmean of chaff length calculated withANSI/ASAE S424.1 method there wasdetermined the particle mean value withthe use of modified dependence of Rosin-Rammler method. Thus, the hypotheticalvalue of sieve mesh X 50 (mesh diagonal)was evaluated, which passed through ahalf of material being sifted:bX− ⎛ XQ w = − ⎝ ⎜⎞⎟1 250 ⎠(5)where:Q w – cumulated frequency of undersievemass,X – mesh diagonal, mm,b – regression coefficient.By finding the double logarithmfor equation (5) there was obtained thefollowing linear equation of regressioncoefficients b and C:( )⎛log log 1−Qw⎞⎜⎟ =⎝ log 05 . ⎠= b⋅logX −b⋅ log X50== b⋅ log X + C(6)Knowing b coefficient and freeterm C in the equation (6) one couldcalculate X 50 . Regression coefficientswere determined with statistical methodswith the use of Statgraphics Plus v.4.1program.RESULTS OF MEASUREMENTSAND CALCULATIONSThe obtained breaking up indexes k zwere close to 1. In samples of SAN andLG2244 varieties of plants harvestedwith forage harvester Class Jaguar 690SL with row-independent attachment,the single grains were found (one piece