خيارات البحث
النتائج 351 - 360 من 2,189
Scots pine (Pinus sylvestris L.) stem wood and bark moisture and density influencing factors النص الكامل
2012
Millers, M., Latvia Univ. of Agriculture, Jelgava (Latvia) | Magaznieks, J., Latvia Univ. of Agriculture, Jelgava (Latvia)
Latvia uses average moisture content and density indexes obtained in Russia and European countries; though, these indexes are different, and there is no information about the most suitable one for conditions in Latvia. Research complex on Latvia’s industrially important tree species - Scots pine (Pinus sylvestris L.) stemwood and bark moisture and density changes, depending on influencing factors, is being conducted at Forestry Faculty of Latvian University of Agriculture. The research results on Scots pine, obtained during the year 2011 in the whole territory of Latvia, are outlined in this article. Wood and bark moisture and density were analyzed in 21 sampling plots, arranged in middle aged and cutting-aged reached forest stands, depending on tree age, cutting time and location place in the tree stem. The average moisture content of pine wood mostly depends on heartwood specific weight and age of the tree. With an increase of tree age, average wood moisture content value decreases from 111% (40-year-old trees) to 77% (145-year-old trees). Scots pine heartwood moisture content changes a little during the year: 30– 34% for 71 to 146-year-old trees; and 34-41% for 37–70-year-old trees. Sapwood moisture content is changes from 113% (in the summer) to 130% (in the winter), without any reference to the age of the tree. The average density of oven dry timber obtained from 71–146-year-old trees in the research is 0.501 g cmE-3, whereas in freshly cut condition – 0.848 g cmE-3.
اظهر المزيد [+] اقل [-]Assessment of bioindication methods in air pollution monitoring النص الكامل
2012
Kalnins, V., Latvia Univ. of Agriculture, Jelgava (Latvia)
The aim of air pollution monitoring is a regular and continuous collection of information on air pollution to prevent hazards influencing ecosystem and its components, including humans. Nowadays, the main technology used for this purpose is electronic sensors. As they are designed for specific measurements, a lot of important factors cannot be evaluated – various pollutants diffusion or cumulative effect, exposure, dose, and bioaccumulation. As an alternative solution – bioindication – pollution level determination from its effect on certain indicator species can be used. So far potential usage of bioindication as current air pollution monitoring network’s equivalent solution has not been studied. Therefore, the aim of the research was to assess a variety of bioindication methods for air pollution determination and their applications in air pollution monitoring. During the research, commonly used bioindication methods based on their popularity in scientific literature in 2012 were selected, as well as they were assessed using theoretical analysis method in order to determine their strong and weak points in air pollution monitoring. Research results demonstrate that current bioindication methods are not suitable for monitoring purposes. Therefore, bioindication can be combined with citizen science approach. To incorporate citizen science approach in bioindication based air pollution monitoring, development of special, for this purpose designed bioindication methodology is needed.
اظهر المزيد [+] اقل [-]Research of nutrients migration of sandy sediment aeration zone of the river bank buffer area النص الكامل
2012
Litvinaitis, A., Vilnius Gediminas Technical Univ. (Lithuania) | Bagdziunaite-Litvinaitiene, L., Vilnius Gediminas Technical Univ. (Lithuania)
The negative impact of agricultural pollution with biogenic materials on surface water bodies is a relevant problem. This problem is addressed by limiting or prohibiting certain activities in the so called buffer areas. The biogenic materials are carried by surface or groundwater runoff. Water infiltration is influenced by the lithological composition of sediments. River basins of sandy lithological structure were selected throughout the territory of Lithuania. An installed system of lysimeters in the boreholes allowed monitoring the change of water quality of sediments over time. The migration patterns of nutrients where identified during the investigation in the spring, summer and autumn seasons.
اظهر المزيد [+] اقل [-]Motivation tools for employees in regional municipal administrations of Lithuania النص الكامل
2012
Zukovskis, J., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania) | Marcinkeviciute, L., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania)
This article analyses the advantages of applicable measures of motivation, taking into consideration the internal environment of an organization as a whole and focuses on the impact of internal environmental factors upon the results of the organization. The paper is based on the survey results obtained by inquiring, municipal administration employees in Lithuanian districts in February-June 2010. The goal of the research was to propose and justify theoretical components for the motivation model of municipal administration employees. The major integrated groups of motivation measures that are the most influential to the factors of internal environment as the main results of research were identified. The authors focus on the positional adjustment of the combinations of motivation measures, in order to improve the motivation of municipal administration employees.
اظهر المزيد [+] اقل [-]Economic calculation of short rotation willow plantations in Latvia النص الكامل
2012
Makovskis, K., Latvia Univ. of Agriculture, Jelgava (Latvia);Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Lazdina, D., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Bite, L., Latvia Univ. of Agriculture, Jelgava (Latvia)
Short rotation forests (SRF) can be used for biomass production for energy applications in Latvia. Establishment of plantations could be one of possibilities how to reach targets of renewable energy resource (RES) consumption of 40% in 2020. In Latvia’s conditions, one of most suitable species that could be used for SRF is willow (Salix sp.). Abandoned agricultural lands are suitable for establishment of plantations. Productivity of 8 oven- dried tons (ODT) ha-1 year -1 can lead to Rate of Return (IRR) of 17.1% and Net Present Value (NPV) 1099 Latvian Lats (LVL) if the biomass price is 33 LVL ODT-1. Establishment, harvesting and transporting costs account for 88% of the total cost of production. Price of wood chip and fuel plays the most important role in economics of plantation.
اظهر المزيد [+] اقل [-]An evaluation of using fuel wood for district heating production in Latvia النص الكامل
2012
Bronka, A., Latvia Univ. of Agriculture, Jelgava (Latvia) | Zvirbule-Berzina, A., Latvia Univ. of Agriculture, Jelgava (Latvia)
One can reasonably argue that issues related to the increased use of renewable energy resources in the energy production processes in Latvia, are at the forefront and will remain there in the future. This relates to the aspect that Latvia is not rich in non-renewable energy resources (around 70% of total primary energy consumption in Latvia is ensured by import, which can lead to undesired effects in many areas), but at the same time, there are available renewable energy resources in Latvia, with an untapped potential to be recognized. In particular this applies to fuel wood, which is already (year 2012) the most important domestic fuel in Latvia. In this context it is important to emphasize that, according to the particular study results, if unexpected socio-economic developments do not take place, raw wood material resources required for different types of fuel wood production in Latvia should be available in the same amount as it is now if not more. As for increasing the amount of fuel wood use in Latvia, an enormous ‘potential’ can be seen in general use boiler houses, where there are currently no technological limitations to utilize this ‘potential’. General use cogeneration plants can be recognized as an even greater ‘potential’ for greater use of fuel wood in Latvia, but given the circumstances of energy supply in Latvia, the ‘potential’ is currently available on a very limited basis. At the same time it is important to note that both of these ‘potentials’ could be significantly reduced in the next few years.
اظهر المزيد [+] اقل [-]Estimation of potential impact of coastal erosion protection in Latvia النص الكامل
2012
Brunina, L., Latvia Univ. of Agriculture, Jelgava (Latvia) | Konstantinova, E., Information Systems Management Inst., Riga (Latvia)
The Baltic Sea problems in context of erosion always have been very topical and since ancient times have been caused by uncontrollable and unpredictable natural factors (storms). These factors combine with the impact of human economic activities of the direct effect of factors -building offshore and aquatorium, deficit of sediment and marine dredging and growth of recreational tourism growth that promote load of coastal vegetation and dune relief. The identification of costs and benefits is significant step for evaluation of the impact of the Project and usefulness of the costs. The positive impact or benefits can occur at once, after a while or long term perspective. The economic evaluation techniques particularly cost-benefit and cost-effectiveness analysis for coastal protection in this case used for ascertain the most effective alternative. The sensitivity analysis was made for verifying impact of alternatives on taken solution. The aim of research is to verify the economic methods for application to coastal management in Latvia. The world’s coastal scientists believe that the future of coastal policy will become increasingly polarized and discussed; therefore, gradual implementation of the assessment process and development of socio-economic indicators is recommended.
اظهر المزيد [+] اقل [-]Effect of different plant production methods on yield and quality of pea cultivar 'Madonna' النص الكامل
2011
Tein, B., Estonian Univ. of Life Sciences, Tartu (Estonia) | Eremeev, V., Estonian Univ. of Life Sciences, Tartu (Estonia) | Keres, I., Estonian Univ. of Life Sciences, Tartu (Estonia)
The yield and quality (1000 kernel weight, protein, nitrogen, phosphorus and potassium content) of peas was studied in cultivar 'Madonna'. The peas (Pisum Sativum L.) were part of the five-year crop rotation experiment where red clover (Trifolium pratense L.), winter wheat (Triticum aestivum L.), peas, potato (Solarium tuberosum L.) and barley (Hordeum vulgare L.), were following each other. There were two production variants which followed the crop rotation. In one variant mineral fertilizers and pesticides were used, and the other variant was conversion to organic without any synthetic agrochemicals. In mineral fertilizing variants the background in all variants was N20, P25, and K95 kg haE-1. The previous crop was winter wheat which received in fertilized variants mineral fertilizers with the background of P25 and K95 kg haE-1, the N amount varied from 0 to 150 kg haE-1. The aim of this paper was to study a mineral fertilizing after-effect on the peas which followed the winter wheat. Herbicide MCPA 750 was used. In conversion to organic, the pea grains which followed the crop rotation and mineral fertilizing Nl50 after-effect variants had higher yield, protein and nitrogen content compared to the other variants where mineral fertilizing after-effect was investigated. Phosphorus contents were higher in NO, and conversion to organic variants. Potassium content remained lower in Nl00, and Nl50 mineral fertilizing after-effect variants. The 1000 kernel weight was significantly higher in the variant of conversion to organic compared to the other variants.
اظهر المزيد [+] اقل [-]Production of bio-ethanol from winter cereals النص الكامل
2011
Jansone, I., Latvia Univ. of Agriculture, Jelgava (Latvia) | Gaile, Z., Latvia Univ. of Agriculture, Jelgava (Latvia)
Renewable energy resources play an important role in energy production both in Latvia and in the world. Bio-ethanol is used as a substitute for oil products in various countries of the world. It is produced from the plants containing starch: cereals, potatoes, beet, maize. The task of the research was to evaluate the suitability of different varieties of winter wheat, triticale and rye for extraction of bio-ethanol in Latvia. The research was carried out at the State Stende Cereals Breeding Institute in 2009, and the following varieties and lines of cereals were examined: winter wheat varieties 'Mulan', 'Skalmeje', and the line '99-115', developed at the State Stende Cereals Breeding Institute; winter triticale varieties 'SW Valentino', 'Dinaro', and the line '0002-26', developed at the State Priekuli Plant Breeding Institute; winter rye varieties 'Matador', 'Placido' Fp and 'Dankowskie Nowe'. The content of crude protein and starch of grains, the grain yield, and the bio-ethanol yield were determined. The highest bio-ethanol yield was acquired from the winter wheat and triticale varieties that had the highest starch content and the lowest crude protein content of grains. The best results were obtained from winter wheat line '99-115' and variety 'Mulan' (409.4 and 406.8 L tE-1), triticale variety 'Dinaro' (423.3 L tE-1), and winter rye variety 'Matador' (370.1 L tE-1.).
اظهر المزيد [+] اقل [-]The evaluation of oil-flax (Linum usitatissimum L.) quality parameters for biofuel production النص الكامل
2011
Poisa, L., Latvia Univ. of Agriculture, Jelgava (Latvia) | Adamovics, A., Latvia Univ. of Agriculture, Jelgava (Latvia)
Oil-flax has a wide range of utilization possibilities, inclusive of bioenergy production. In our research evaluated out two oil-flax varieties 'Scorpion' and 'Flanders' after the calorific value, oil, lignin, and ash content; and also the chemical composition in 2008 -2010. The results show that oil-flax shoves have a high calorific value and high lignin content but a low temperature for ash fusion. It was established that the growth year and some unexplored factors have influence on the ash content. The oil content in the seeds was 336-458 g kgE-1, depending on the chosen variety. The flax shoves can be used as a supplement for biofuel combustion, as they have a low fusion temperature, a high calorific value, but a comparatively low yield makes oil-flax unprofitable to grow for biofuel production.
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