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Jelgava, Latvia

The Latvia University of Agriculture is a university in Jelgava, Latvia, specializing in agricultural science, forestry, and related areas.The university originated as the Agricultural Department at the Riga Polytechnical Institute in 1863, which in 1919 became the Faculty of Agriculture at the University of Latvia. It became an independent institution in 1939, when it was established as the Academy of Agriculture in the Jelgava Palace, which had been renovated for that purpose. It was renamed to the Latvia University of Agriculture in 1990. Wikipedia.

Sondors K.,Latvia University of Agriculture
Engineering for Rural Development

The paper describes an attempt to grow microalgae in outdoor raceway ponds. The most suitable microalgae species were determined for outdoor cultivation in Latvian climatic conditions. Indoor Scenedesmus quadricauda L. microalgae cultivation was done to provide enough microalgae for raceway pond start medium. A black plastic film was used to relay the raceway pond ground. Measurements of total dissolved solids in growth media were proceeded to determine the need for adding nutrients to the pond medium. The lowest stream speed was determined to avoid microalgae sedimentation during night time to save electricity. Every day temperature measurements in raceway pond show that microalgae cultivation during summer can be performed in Latvian climatic conditions. Source

Komasilovs V.,Latvia University of Agriculture
Engineering for Rural Development

Economic benefit of an industrial company depends on forethought deployment of an industrial production system. Configuration of the robotic system affects the whole production process, and selection of inappropriate option can lead to financial losses of the company. The author proposes a formal procedure for finding an optimal specification of a heterogeneous multi-robot system. The paper presents the concept of the optimization procedure and describes the design of software modules used for implementation of the procedure. Source

Aboltins A.,Latvia University of Agriculture
Engineering for Rural Development

The purpose of this work is theoretically based methodology to determine the drying coefficient of porous material. Using the mathematical model of thick grain layer drying process, a methodology of porous material thin layer drying coefficient determination, using the experimental data, is done. The necessary drying time with constant conditions and linear drying rate is presented. Based on the experimental data, the time dependency of the moisture content and drying rate were calculated and presented. Using the drying coefficient, the layer of apple slice drying was simulated and the obtained results compared with the experimental data. The obtained measurement results are in high correlation with the calculations. The resulting drying rate can be used for modeling the drying process in a layer containing small particles, it is to numerically solve the system of partial differential equations including the matter and environmental temperatures (⊖(x, t) and T(x, t)) and mass exchange (W(x, t), d(x, t)). Source

Stalidzans E.,Latvia University of Agriculture | Berzonis A.,SIA TIBIT
Computers and Electronics in Agriculture

Determination of the annual development periods of honey bee colonies can help in synchronising the beekeeper's activities with the developmental stage of individual bee colonies in apiaries. It is proposed to determine the development periods by measuring and analysing the ambient temperature and the temperature above the upper hive body. The temperature above the upper hive body is proportional to the energy which is released during bee colony activities. Throughout the year in 2000, measurements with interval of 15. min of the temperature in 14 honey bee colonies was done in Latvia, in the Riga region. One sensor per colony was located above the upper hive body. The annual curve of the average day and night temperature was approximated by five linear pieces that possibly correspond to particular periods. Explicit transition points to the next period were determined. Five sequential periods have been proposed in the bee colony's development: (1) winter brood rearing, (2) spring brood rearing, (3) summer brood rearing, (4) autumn brood rearing and (5) autumn broodless period. These periods collectively form a hat-like annual profile. All brood rearing periods demonstrate high thermal discipline: the hive temperature follows linear dynamics in spite of fluctuations in the ambient temperature.A simple measurement system and criteria for automatic determination of transition from one period to another for apiary has been developed and tested. Thermal measurements above the upper hive body efficiently determine the transition from one period to another in the apiary. The computational system for the determination of developmental periods should be equipped with at least one ambient temperature sensor per apiary and one temperature sensor per observed bee colony. © 2012 Elsevier B.V. Source

Maize (Zea mays L.) is a comparatively new field crop grown in Latvia (extensively grown only since 1954). Some crop failures caused by adverse meteorological conditions frequently have been more expressed when inappropriate agricultural management practices were used. The importance of sowing time has been widely investigated in many countries, and the conclusion has always been that a higher yield can be obtained if sowing is done on the date which is the possibly earliest for a specific country. The aim of the present research, carried out during 2005-2008 at the Research and Study Farm Vecauce of the Latvia University of Agriculture, was to specify maize sowing date in Southwest Latvia and to analyse maize development depending on sowing time. Field trials with four maize hybrids ('Earlystar', RM-20, 'Tango', and 'Cefran') sown on four dates (25 April, 5 May, 15 May, and 25 May) were carried out on Luvic Epigleyic Phazeozem (Calcaric), lvPH (glp:ca). Maize was harvested also on four dates starting with 1 September at ten-day intervals. Results showed that earlier sown maize needed more days till emergence and from emergence till silking. Number of days from silking till maturity stage, when 250 g kg -1 of dry matter (DM) content was achieved, depended on the hybrid, but not on the sowing date. Number of accumulated growing degree days for entering specific development stage was not dependent (p > 0.05) on the sowing date. Plants were taller and stand density was higher if maize had been sown late (25 May). The best and significantly (p < 0.05) higher average DM yield was obtained when maize had been sown on 5 May (14.34 t ha -1). Average yields were lower and similar (13.28-13.47 t ha -1) when maize had been sown both earlier and later. Sowing time had a slight, but significant (p < 0.05) effect on DM, crude protein, neutral and acid detergent fibre content, net energy for lactation (NEL) and the proportion of ears in the whole DM yield, and the results were better if maize had been sown earlier. The research allows us to conclude that the best sowing time of maize in central and western part of Latvia is around 5 May. If a decision is to grow late maturity hybrids, then sowing in the last days of April has to be considered. Source

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