Abstract. Lithuania medium rotation plant plantations are started to breed relatively recently, so reliable data on suitability of these crops for biofuel production cannot be found. Studies have established wild cherry chop physical properties. 8-16 mm particles make the main, chopped by a drum chopper, wood fraction; on the average, it makes 84 % of total chop mass. Experimental results show that humidity has greater impact on the wild cherry wood chop collapse angle: with decrease of the moisture content the collapse angle increased from 65 ± 1.0 to 82 ± 2.0 degrees, when humidity is lower, the influence on the natural slope angle is lower. It fell accordingly from 36 ± 1.0 to 42 ± 2.0 degrees. Chop bulk density variation with the change of wood humidity was determined; with increase of humidity of wild cherry from 35.1 ± 1.0 to 6.4 ± 0.1 % the density varied from 342.67 ± 4.81 to 236.67 ± 2.6 kg·m -3 . Wild cherry ash content is low, and it does not increase 1.87 ± 0.18 %, and the calorific value of wood reached 18.70 ± 0.36 MJ·kg -1 ; it is close to the standard accepted in Lithuania -birch caloricity. The determined elemental composition of wild cherry wood showed that carbon (C) quantity reached 49.16 ± 1.10 %, nitrogen (N) quantity does not increase 0.23 ± 0.10 %, and quantity of sulphur (S) does not exceed 0.01 %. Having determined and evaluated the main criteria for biofuel (finesse of chop, calorific value, ash content, elemental composition), it is possible to state that wild cherry wood fully complies for production of qualitative biofuel. However, from the economic point of view, it is purposeful to use only branches and tops of wild cherry trees for biofuel, and valuable part of wood may be used for production of furniture or in other industry branches.
Straipsnyje nagrinėjamas studijų kokybės sistemos kūrimas ir valdymas Lietuvos aukštųjų neuniversitetinių mokyklų - kolegijų pavyzdžiu. Patikslinta studijų kokybės samprata vadybos požiūriu. Pasitelkus lyginamąją analizę įvertinti kolegijų pasiekimai kuriant ir valdant studijų kokybės sistemą. Išanalizuota tarptautinio standarto ISO 9001 : 2000 taikymo kolegijose galimybės ir patirtis. Nubrėžtos tolesnės studijų kokybės sistemos plėtros gairės, pateikiami pagrindiniai kokybės valdymo sistemos diegimo etapai.
The article presents silage production technology using vibratory method. The objective of this research was to quantify the selected theoretical model by comparison to experimental results and to determine more reasonable calculations methods for practical issues. Based on the classical theory of mechanical oscillations a numerical analysis of silages thickening by vibrator was developed. Using the developed numerical model, the vibrator operational characteristics were obtained. Numerical and experimental investigation was performed using a direct-action vibrator to compact chopped maize. A comparison between the experimental and numerical results is presented. The results can be used to determine technical characteristics of the vibrator for silage thickening dynamics. The obtained system parameters can be used to prepare technical tasks for selection of vibratory silages thickening equipment.
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