Abstract This study compared the total solid content and compound properties of Hevea rubber latex produced from material collected during different periods. Samples were collected from five trees, with the collection replicated three times with tapping task as replication. Observed parameters included total solid content, vulcanization characteristics, technical and physical properties. The results exhibited that the longer latex flowed, the more total solid content tended to decrease. Results indicate that compound of latex collected 20 minutes (C20), 60 minutes (C60), and 300 minutes (C300) after tapping qualified for SIR 20. Other parameters did not show a significant difference among the three tested compounds. Considering the products requiring high dry rubber content, it is suggested not to blend the late collection with main collected latex.

Abstract One of the important parameters of the tractor’s performance - tractive efficiency - should be improved during agricultural operation; this paper observes this parameter using the Arvid 354 tractor with a chisel plough. Parameters taken into account included the tillage parameters, such as tillage depth, travel velocity, rake angle, tine width and tractor weight, as well as soil engineering properties, including cohesion and soil bulk density. Experimental results indicated that the tractor tractive efficiency increased with increasing of the tillage depth and rake angle, whereas travel velocity did not show any specific impact on it. Theoretical equations were extracted for drawbar pull, tyre slip and gross traction using dimensional analysis and experimental data. Finally, by combining these equations, the tractive efficiency was estimated. Obtained model was evaluated by means of obtained experimental data. Results showed that the proposed model is capable of predicting tractive efficiency as a function of soil parameters, tractor weight and tillage parameters of the chisel plough.

Abstract This article presents the results from the theoretical research of tension loading in a channel of fixing conveyor of the apparatus for flax beating and scutching. The analyses of literature have shown that the quality of flax fibre greatly depends on the conditions of retted straw processing by means of breaking-scutching machines, namely on machine parameters, operating regimes and design characteristics. There are considerable high fibre losses due to inappropriate fixing of straw in the conveyor canal; percentage of these losses is much higher than losses caused by any other reasons. The paper presents equations for calculation of pressure inside the conveyor canal of apparatus for flax breaking and scutching. It investigates the regularities of pressure loading in the sectors which fix the straw according to the aforementioned equation. Research shows that the highest pressure occurs in the area opposite the press-rolls axis; it decreases when distancing from it. Research also shows that pressure in the axis zone is lower when the belt tension and spring compression are low. This pressure loading causes pulling of the strands from the conveyor canal and fibre losses. These theoretical regularities can be utilized for calculation of the fixation force to secure the retted straw between belts in order to reduce the losses.

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Abstract computer simulation of a curved profile formation on a helical spiral was carried out. A feasibility study was conducted in order to choose the method suitable for manufacturing of L-shaped helical spirals using specially developed software for calculating of the costs of helical spiral formation processes. The tables presenting technological characteristics of the design parameters of screw coiling working bodies manufactured by different methods are provided. The production costs for 1 meter of helical spiral with a curved profile manufactured by different methods are calculated. Theoretical and experimental investigations proved that the most cost-effective method of L-shaped helical spiral manufacturing is to coil it along the inner face from rectangular pieces with simultaneous or subsequent shelve formation.

This paper presents the results of wort dynamic viscosity and activation energy during fermentation. The effect of temperature and storing time on both parameters was investigated. Measurements were performed on two wort samples. The first sample was taken at the beginning of fermentation, and the second sample after three hours of fermentation. Both samples were also measured after three weeks of storing. Dynamic viscosity measurements were performed with a digital rotational viscometer Anton Paar DV-3P, the principle of which is based on the dependency of sample resistance to probe rotation. Results of measurements are shown as graphical dependencies of both analysed parameters on temperature. The temperature dependence of dynamic viscosity can be characterised by a decreasing exponential function, while in case of activation energy linear increasing characters were obtained. Longer fermentation and storing period caused a decrease in both analysed parameters, due to the structural changes in wort samples during fermentation and storing.

Abstract Vacuum fluctuation was measured using three different vacuum control methods. Firstly, the use was made of a control valve delivered by the manufacturer; then, an additionally installed frequency converter was used. Lastly, a frequency converter fitted with the stabilisation device prototype was used. First, control sensitivity according to ISO was measured in all the three alternatives. Then, vacuum fluctuation during milking was measured. To conduct the measurements under objectively identified conditions, another measurement was conducted with air feed during milking being replaced with a precisely defined variable flow rate. The conducted measurement confirmed the fact that when the frequency converter is used, vacuum fluctuation in stabilised condition is at the same level as when the control valve is used. If there are sudden changes in flow rate and the frequency converter is used, vacuum fluctuation increases. The proposed stabilisation device prototype can reduce the fluctuation in small milking plant but it is not suitable in large milking parlours.

Abstract Controlled traffic farming is a technology used to avoid soil compaction introduced by field machinery load and traffic. The benefits in improved soil conditions and yield increase were shown in Australia, the US and some parts of Europe. The use of permanent tramlines for every field operation was considered as a barrier to implementation in some parts of Europe. This was mainly due to fear from tillage quality in terms of crop residues distribution. The paper reports the results of the two-year assessment of the technology compared to traditional random traffic treatments in field scale experiments. The spring barley and oilseed rape crops were grown. Measurements were taken after the stubble breaking tillage operation with the Lemken disc harrows. Image analysis was used to calculate the distribution of crop residues. Results showed that the use of permanent tramlines has no negative influence on crop residues distribution.

Abstract The research is taken on the vibroarc welding apparatus ENTON-60 equipped with an axial non-inertial vibrator in argon shield. The criteria used for assessing the flow of the electric arc process and the formation of weld overlay clad surfaces are: short circuit voltage, voltage at the start of arc combustion, short circuit amperage, and amperage at the end of arc combustion. Wire electrode‘s vibrating frequency is considered as an input variable of the cybernetic model. It has been found that amplitude of vibrations has a significant impact on the vibroarc process - voltage parameters and welding current ratio, as the minimum amperage of short circuit and the lowest voltage at the start of arc combustion is realized at 2 mm amplitude of vibrations.

Abstract One of the new methods of food drying using infrared heating under vacuum is to increase the drying rate and maintain the quality of dried product. In this study, potato slices were dried using vacuum-infrared drying. Experiments were performed with the infrared lamp power levels 100, 150 and 200 W, absolute pressure levels 20, 80, 140 and 760 mmHg, and with three thicknesses of slices 1, 2 and 3 mm, in three repetitions. The results showed that the infrared lamp power, absolute pressure and slice thickness have important effects on the drying of potato. With increasing the radiation power, reducing the absolute pressure (acts of vacuum) in the dryer chamber and also reducing the thickness of potato slices, drying time and the amount of energy consumed is reduced. In relation to thermal utilization efficiency, results indicated that with increasing the infrared radiation power and decreasing the absolute pressure, thermal efficiency increased.