ANALYTICAL ASPECTS OF GRAVITY MIXING DRUM DEVICES

The research objective is improving the mixing quality of the material and determination of structurally-kinematic parameters drum paddle mixer by means of numerical methods. The basis of modern society is the use of variety mixtures and composite materials on their basis. The preparation of the initial mixtures is carried out as directly by mixers, and in some cases by various devices, including extruders and screw presses. Among such devices drum mixers, dryers, mixers, etc are widely distributed. Their feature is the low intensity of mixing, as well as the ability for a relatively short period of time possible to achieve the uniformity of the mixture. Then the quality of the mixture practically does not change. Attempted use of commercially available cement- mixers of periodic action in order to prepare such a mixture as a feed, showed that their existing structures are subject to further improvement because of the impossibility of achieving zootechnical requirements for the preparation of feed on the basis of the purchase and BPD of their own forage. This requires additional theoretical research. The process of the blade drum interaction with the material operating with periodic mixing is shown. The obtained analytical expressions allow to determine the conditions of mixing of the material by major constructive and kinematic parameters of the lobed mixer drum on the basis of numerical methods.

Potential of Cowpea Variety Mixtures to Increase Yield Stability in Subsistence Agriculture: Preliminary Results

CowpeaVigna unguiculata(L.) Walp. is an important leafy vegetable and grain legume in Uganda. Unlike in commercial agriculture, where variety mixtures are known to give higher and more stable yields, the performance of cowpea variety mixtures in subsistence agriculture is little known. Mixtures containing up to four cowpea varieties were subjected to all possible 2-way, 3-way, and 4-way combinations. These cowpea varieties and mixtures were grown at three locations in Soroti and Kumi districts in order to assess the relative mixture effect, defined as: Mixture effect (%) = (mixture yield − pure line component average)/pure line component average × 100. Yield data was subjected to one-way ANOVA using the GLM procedure of SYSTAT. PLABSTAT was used to generate ecovalence (Wi) values as a measure of stability with low ecovalence values indicating higher stability. The total cowpea dry matter (DM) yield was in the range of 3.7–6.7 g/m2(leaf) and 12.1–36.7 g/m2(grain), respectively. Mixture effects were between −9.3–14.0% (leaf) and −30.3–21.9% (grain). Yield stability spanned Wi= 0.06–5.30 (leaf) andWi= 4.45–894.84 (grain). The results suggested that yields of cowpea variety mixtures grown in marginal environments were more stable than of single varieties but not all mixtures yielded more than single varieties.