Performing biofuel use studies, a large number of parameters that characterize engine operation under different conditions and with different fuel mixtures have to be identified. The real driving conditions are usually simulated by driving cycles on a laboratory chassis dynamometer. There are two major categories of driving cycles: legislative and non-legislative. From the viewpoint of cycle formation there are also two ways. One is composed of various driving modes of constant acceleration, deceleration and speed, and is referred to as modal or polygonal. The other type is derived from actual driving data and is called as 'real world' cycle. There is a strong agreement among researchers that driving characteristics of each city are unique because of different vehicle fleet composition, driving behaviour and road network topography. It is therefore better to develop own driving cycles than using driving cycles developed elsewhere. The aim of this investigation is to develop driving cycles or models for dynamometer control software corresponding to peculiarities of Latvia. The procedure for cycle development and fuel consumption and exhaust emissions measurement was worked out. Using real driving data on the Jelgava streets, models simulating driving in different urban areas were constructed. The model quality was determined using vehicle driving parameters and fuel consumption measurement results from both the road and laboratory tests. Since the obtained data coincidence of all the parameters exceeded 98%, the elaborated cycles can be used for the biofuel use efficiency determination.

Implementation of special support measures and resolving its main problems with effective methods in medium-run may allow to maintain the dairy sector as a significant traditional element of the Latvian economy. It is important to know the gross economic effect of the Latvian dairy sector in order to take informed and rational support decisions. Authors have developed and approbated methods and by applying these have obtained new, unpublished data that characterize economic effect of the sector. The data have been analysed in Latvian and the Baltic States context. It is concluded that the dairy sector is significant to the Latvian economy mainly due to gross value added and especially because of its role in providing work opportunity. Authors call attention to reserves in gross value added growth per full time equivalent unit in the secondary production in all Baltic States. The data of the primary dairy sector level in turn indicate lower potential of growth that is evidenced by even a slight decrease in indicators of the comparatively more effective Estonian producer structure. Therefore, it can be expected that the weight of dairy sector secondary level in the dairy sector gross value added will increase. Authors point out certain possible solutions of the Latvian dairy sector's problems such as promotion of joint ownership structure. Main analysed indicators are gross value added at factor cost, use of labour in full time equivalent units and labour use effectiveness.

The traditional way of dealing with manure - storage, transportation, spreading in the fields - is currently applied very successfully, but is economically very expensive. People complain about very unpleasant smells, which are caused by gasses (indole, merkaptanas, hydrogen sulphide, ammonia) being released from the manure. Scientists are searching for other ways of handling manure which try to convert it to less harmful substances, reduce its odour and at the same time make it thicker by extracting its water content. The aim of our work was to evaluate the composition of slurry after processing it mechanically, and to test the effectiveness of the application of new coagulants and flocculants on its clarification. Fresh liquid manure from 'Sajas' pig complex(Kelme district) and the liquid manure treated in biogas reactors from Lekėčiai pig complex (Šakiai district) was used for research (2006-2008). Anionic coagulants such as aluminium chloride (Al2Cl), ferrous chloride (Fe2Cl) and pollycrilamide cationic flocculant 'Magnofloc 1011' were applied to clarify manure. 40-44% of organic pollutants can be removed from the aerated sewage under constant processing by coagulants and flocculants. The best result in pollutant removal from sewage is achieved when it is processed with 1.5 kg mE-3 norm of aluminium saline (AlCl) and 3.0 g mE-3 norm of flocculant 'Magnofloc 1011'.

This article gives a review of modern networking technologies and standards used in the development of distributed control systems. Study of related scientific and professional literature has been performed, and basing on it a multi-level model of digital network structure in the field of small-scale autonomous combined power systems has been proposed. Necessity of integration of autonomous powering into SmartHouse systems and related distributed computing and networking issues are reflected as well. As there is a wide variety of industrial networking standards used, this review covers and groups more frequently used protocols and stacks from the view of OSI (Open Systems Interconnection) reference model and layers of industrial automation. The aim of this article is to give a reference-point in the development of distributed control systems in the field of small-scale autonomous power supply and integration of them in SmartHouse systems.

The study was accomplished in 2010. The applied research methods are based on the analysis of the studies by other authors, industry experts, statistic data and the (unpublished) information provided by the Latvian district heating merchant “xxx”. Spearman’s rank correlation coefficient was used for evaluating data regularity. In 2020 the energy produced from renewable sources (Directive 2009/28/EC) in total energy consumption in Latvia has to reach 40%. Such an objective can be achieved by promoting the use of biomass at cogeneration (CHP) plants, the potential of which is the district heat supply system. Wood as an energy resource in its structure accounts for only 25-30%; therefore, the primary condition is the introduction of modern technology which would provide the possibility to diversify energy resources. The calculations confirm that the realised amount of thermal energy indirectly affects profit; directly it is affected by the rate of thermal energy, so the structure of use of energy in heat supply enterprises is associated with lowering the cost of (restrictive) factors - the energy cost, specific production technologies, energy efficiency. Currently, the primary condition of heating companies is to find such energy resource(s) to ensure the approved schedule of temperature and thermal load. The next determining factor is the energy price. In assessing the factors that will affect energy usage in the future, the main strategic principle of energy consumption will be linked to limiting the growth or even reducing heat tariff, by realising optimal efficiency and minimal environmental pollution during energy transmission.

The paper deals with the evaluation of resource price preferences and resource utilization efficiency in Latvian dairy sector that shows Latvian relative competitive position both in terms of producing competitive products for the market, as well as ensuring competitive salaries and a general rise in living standard for the employees. The evaluation is carried out through analyzing price levels of the main production resources and the utilization efficiency of these resources, based on the comparison with other EU countries. The efficiency indicators in Latvian primary milk production sector are considerably lower and despite resource price preferences the cost level per production value in Latvia is higher than in other countries. The analyzed resource utilization efficiency is low in Latvia also at the processing industry level, though the current price level of the main production resources helps to ensure competitive positions of Latvian dairy products. But considering large differences in compensation levels for labour force between Latvia and other EU countries, without increase in productivity, the situation is not sustainable in long-term.

The possibilities to use other media instead of the sand in the filters of vertical flow are analysed in the article. The media used has to be inexpensive and its possibilities to clean the wastewater have to surpass that of the sand. The modelling of the wastewater treatment in the vertical flow filters was carried out in 2008 at the Water Research Institute of the Faculty of Water and Land Management of Lithuanian University of Agriculture. Dolomite powder was chosen for the investigation. Two models of 0.2 square m filters were made: one was filled with the sand, but the other was filled with the dolomite powder. It was found that the dolomite filter was less reactive to the primary contamination of the wastewater with the organic pollutants: when their amount rose from 320 to 460 mg O2 LE-1 according to the BOD7 index, the amount of the pollutants in the wastewater cleaned with the dolomite powder filter rose from 1.4 to 3.1 and amount in the wastewater which passed the sand filter rose from 0.5 to 13.9 mg O2 LE-1. General phosphorus was removed with the efficiency of 99.9% in the dolomite powder filter (and only with the efficiency of 87.0% in the sand filter). Therefore the dolomite powder filter will be removing phosphorus from the wastewater to the allowable contamination level for a much longer period. General nitrogen was cleaned with the effectiveness of 13.0% in the dolomite powder filter. Therefore, it is necessary to use additional means for its removal from the wastewater in the vertical filters with the output higher than 5 m**3 dE-1.

The aim of the research is to determine the criteria of internal factors influencing the effectiveness of outdoor advertising. The eye-tracking experiment was conducted in Lithuania in 2016. Consumers’ visual attention toward specific criteria of internal factors influencing the effectiveness of outdoor advertising was measured. The chosen criteria were headline font size, the number of elements in the advertisement, and dominating elements in the advertisement (visual or textual). The main results of the research reveal that when the surface size of visual and textual outdoor advertising elements is the same, textual elements attract more visual attention than visual ones and that advertisements containing a large number of elements attract more visual attention than the ones containing a small number of elements. Moreover, when the font sizes of two headlines are both larger than the body text, but those headlines differ in font size one from another, there is no significant difference in consumers’ visual attention toward those headlines. Consequently, it is recommended to create outdoor advertisements with a large number of elements, where most of them are textual, in order to attract the consumers’ attention.

The most efficient way to dewater sewage sludge is the thermal drying, which simultaneously with the granulation allows obtaining the product in the form of granules, being a non-putrescible fertilizer that is also easy for transportation, storage and bringing into soil. When large volumes of sewage sludge are formed, which are unfit for use in agriculture, application of other utilization methods, such as burning, would be purposeful. The aim is to determine the optimum drying modes of sewage sludge with application of pneumatic pulse method at treatment facilities in the pilot project. To do this, it is necessary to develop a proposal for the design of operating model. The design and making of working model is necessary to determine the optimal conditions for sewage sludge drying at sewage disposal works. The drying process is provided to be realized in a closed-loop cycle (without emission into atmosphere). Due to inner recirculation of dry air, the installation heat consumption is reduced. Calculations have shown that there is economic expediency of using the pneumatic pulse method in sewage sludge thermal drying technology and possibility of using sewage sludge as an alternative fuel. Optimization of sewage sludge thermal drying process with the use of pneumatic pulse method will considerably extend the perspectives for utilization and further use of sewage sludge.

The article explores the possibility of the vertical filter instead of sand used for more coarse media for recharging, which would reduce the risk of freezing and clogging and ensure the cleaning of wastewater up to the limits. For this purpose the dolomite chippings have been chosen for research. It was equipped with two 0.2 m2 filters area: one of their models was 0.4 m dolomite chippings layer, the other 0.8 m. They have been loaded by the wastewater after the primary cleaning in the septic system. Medium contamination in organic pollutants have been 358 mg O2 LE-1, Ptotal 14.6 mg LE-1, Ntotal 108.5 mg LE-1, suspended solids 161.1 mg LE-1, pH 7.8. Hydraulic load of the filters was 0.03 m3 mE-2 dE-1. Wastewater flowing through a vertical sand layer by an average of 98.2% of the organic pollutants to be detained. The average of effluent wastewater contamination of the filter was 22 mg O2 LE-1. In the filter with dolomite chippings media can be cleaned wastewater with pollution reaches 500 mg O2 LE-1. The maximum load of organic pollutants is 14 mg O2 LE-1. The filtration path length to ensure wastewater cleaning up tolerance 0.8 m. In the filter with dolomite chippings media Ptotal is cleaned even 87.0%, Ntotal only 13.0% efficiency.