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Colour stability of thermally modified hardwood
2014
Cirule, D., Latvia Univ. of Agriculture, Jelgava (Latvia);Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Meija-Feldmane, A., Latvia Univ. of Agriculture, Jelgava (Latvia);Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Kuka, E., Latvian State Inst. of Wood Chemistry, Riga (Latvia)
Thermal wood modification has been intensively studied in the recent decades because of the possibility to produce wood with improved biodurability and dimensional stability without use of harmful chemicals. Beside altered physical characteristics, wood colour is changed to lighter or darker brown as a result of thermal treatment. Growth of interest in thermal wood treatment has stimulated numerous researches concerned with discoloration of thermally modified wood which is subjected to light exposure. The objective of this study was to evaluate the colour stability of thermally modified hardwood during storage in the dark where wood discolouration is not photoinduced but rather a result of oxidative ageing. Three thermally modified hardwood species – aspen (Populus tremula L.), alder (Alnus incana Moench), birch (Betula pendula Roth.), where investigated. Wood discoloration was monitored by spectrophotometrical measurements of reflectance spectra and chromaticity parameter calculations using CIELAB colour system where L* is the lightness, and a* and b* are the chromatic coordinates. The colour stability of thermally modified wood as well as of untreated wood of the same species was examined by means of assessment of the colour parameter changes (ΔL*, Δa*, Δb*, ΔEab). All wood specimens under study discoloured during the experiment, but the colour change did not exceed two units that are common and accepted for wood products. Untreated and thermally modified wood showed different trends of discoloration during storage in the dark. The final colour changes that were fixed at the end of the experiment were greater for the thermally treated wood.
Показать больше [+] Меньше [-]Evaluation of thermal properties of wood based composite panel walls
2014
Rozins, R., Latvia Univ. of Agriculture, Jelgava (Latvia) | Iejavs, J., Forest and Wood Products Research and Development Inst., Jelgava (Latvia)
Invention of light weight cellular wood material (CWM) with a trade mark of Dendrolight is one of the most important innovations in wood industry of the last decade. Currently CWM has been used as core material for sandwichpanels. These three layer panels are used in furniture industry and have wide non-structural applications. The aim of the research was to define the thermal properties of CWM and evaluate various wall envelopes where solid wood cellular material is used. There were 4 specimens of cellular wood material manufactured with nominal dimensions thickness 120 mm, length and with 600 mm to determine thermal conductivity and thermal transmittance according to standard EN 12667:2002. The specimens were manufactured of four layer 112 mm thick Scots pine (Pinus sylvestris L.) CWM double faced with 4 mm thick high-density fiberboard (HDF). Adhesive used in the bonding process was polivinilacetate Cascol 3353. Each direction (parallel, perpendicular) was represented by two specimens. Common procedure to evaluate the energy efficiency of building envelope is to calculate thermal transmittance in static conditions. The influence of the cellular material orientation to its thermal properties was investigated. Coefficient of thermal conductivity was determined for both material directions of CWM (l0 =0.0977 W∙m-1∙K-1 l90=0.148 W∙m-1∙K-1), combining the test method of EN 12667:2002 and calculation method of standard EN 6946:2008. To calculate thermal transmittance of various wall envelopes calculation software in JavaScript environment was created. Various compositions of external walls were assessed, thermal transmittance of these structures were calculated according to standard EN 6946:2008.
Показать больше [+] Меньше [-]Removal of heavy metals from contaminated soils by electrokinetic remediation
2014
Burlakovs, J., University of Latvia, Riga (Latvia) | Stankevica, K., University of Latvia, Riga (Latvia) | Hassan, I., Western University, London, Ontario (Canada) | Janovskis, R., University of Latvia, Riga (Latvia) | Lacis, S., University of Latvia, Riga (Latvia)
Heavy metals as well as other pollutants are widespread and create deleterious impact to the environment and human health. There are different in situ and ex situ technologies of immobilization and removal of contaminants; electrokinetic remediation is one of such technologies. It can be applied for treatment of wide areas, e.g., former industrial and military firing-grounds. Technology is applicable to water soluble contaminants at sites with homogeneous soils that are fine-grained and exhibit both, high permeability and high moisture contents. The aim of the study was to test the efficiency of electrokinetic remediation for copper contaminated clayey soil in laboratory conditions. Pilot scale experiments were applied to test the efficiency of electrokinetic removal of contaminants from soil by application of low voltage direct current (DC). Experimental results show that the use of DC power can be selected for treatment of heavy metal contaminated soils. Batch scale experiments were done by using clayey soil with known physico-mechanical properties, spiked with copper solution of known concentrations. Electric force was changed by varying its parameters. The article gives batch experimental results for diffusion of copper ions in soil under the influence of the external electric field.
Показать больше [+] Меньше [-]Evaluation of cumulative air pollution in Riga and Liepaja with cumulative pollution index method
2014
Kalnins, V., Latvia Univ. of Agriculture, Jelgava (Latvia) | Straupe, I., Latvia Univ. of Agriculture, Jelgava (Latvia) | Sudars, R., Latvia Univ. of Agriculture, Jelgava (Latvia)
Cumulative air pollution – synergy between different pollutants and environmental factors is one of the hardest to evaluate factors in the air quality monitoring field. The evaluation of cumulative effects is hindered by a lack of verified analytical frameworks. Currently used methods are relatively simple and use statistical models with small fixed number of pollutants in association with different factors. There is almost no one solution for direct, on-site cumulative effect measurements. The alternative is the use of Cumulative Pollution Index (CPI) method – solution designed for cumulative effect calculation from bioindication and air quality measurement data. However, this method is completely new and has never been used in the air pollution evaluation activities. Therefore, the objective of this study was to evaluate the opportunity to use CPI method as a cumulative pollution evaluation tool in air quality monitoring by doing measurements of cumulative effect in several air quality measurement stations in two cities of Latvia – Liepaja and Riga. Results show that Cumulative Pollution Index method is not only usable in air quality monitoring as a tool for cumulative effect evaluation, but can reveal new facts about air pollution and ways how it affects human and ecosystem health, – such climatic and environmental factors as humidity and temperature are more important than interactions between individual pollutants and can be considered main elements in forming of cumulative pollution impact.
Показать больше [+] Меньше [-]Ecological farming in Aukštadvaris and Krekenava regional parks
2014
Ivaviciute, G., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania);Kaunas College of Forestry and Environmental Engineering (Lithuania);Klaipeda State College (Lithuania)
Ecological farming is relevant to protected areas. The aim of the study is to perform an analysis of farms applying organic farming measures as well as the analysis of the change of their areas in Aukštadvaris and Krekenava regional parks (RP). The object of the investigation - the farms of Aukštadvaris and Krekenava regional parks. The study is carried out to determine how many farms, forming the regional parks‘ territory, are managed according to the principles of organic farming. The change of the above- mentioned farming area for 2009-2011 is analyzed as well. Paluknys and Naujamiestis subdistricts, not incorporated into the territory of regional parks, were chosen for the comparison analysis. The analysis of the 2009 – 2011 period showed that the declared areas in Krekenava RP have decreased, and the area of farms applying organic measures has increased by 81.69 hectares (nearly 2.5 times). The number of organic farms increased by 1.5 times in Aukštadvaris RP over the period of 2009-2011, and the area has increased by 187.36 ha. The percentage calculations revealed that in 2011 the area of farms applying organic farming measures in Aukštadvaris RP made up 18.89 per cent of the total area declared, the number of farms - 6.61 per cent. The area of farms applying organic farming measures in Krekenava RP was only 1.71 per cent, measures were applied only by 1.89 per cent of all the declared.
Показать больше [+] Меньше [-]Froude number for estimation of biodiversity in small Lithuanian rivers
2014
Geguzis, R., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania) | Baublys, R., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania) | Vaikasas, S., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania)
The majority of natural Lithuanian rivers were regulated during intensive land reclamation period. Straightening of rivers caused unfavourable conditions for biodiversity. Four tributaries of the Merkys River in the South Lithuania were selected to explore changes in biodiversity patterns and determine the relationships between flow energy distribution in beds and ecological status of selected rivers. The research has shown that variation of cross sections area was usually 1.2 to 2.3 times higher in natural beds as compared to regulated ones. The range of rivers flow energy, estimated by Froude number, values were characterized as higher in natural (0.0 to 0.35) streams than in regulated (0.0 to 0.20) ones. This is the reason why the biggest number of macroinvertebrate taxa during the research period was recorded in natural riverbeds and the lowest - in the fields of the regulated segments. The assessing the abundance of fish revealed that total fish density in natural river sections was four times higher than in regulated ones. The research has approved the importance of naturalness for biodiversity and rehabilitation of regulated rivers in Lithuania.
Показать больше [+] Меньше [-]Prospects of a pneumatic pulse method of dehydration of the sewage sludge
2014
Gusarevs, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
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.
Показать больше [+] Меньше [-]Role of agriculture on regional variation of parliamentary election results in Latvia
2014
Paiders, J., University of Latvia, Riga (Latvia) | Paiders, Ju., University of Latvia, Riga (Latvia)
The main objective of this research is to find out if quantitative factors describing agriculture have a statistically significant role on the parliamentary election results in Latvia. If this statistical relationship can be proven, then it is important to interpret the causality behind it. 18 agricultural indicators from the 2001 Census of Agriculture were selected to be analyzed with the 8th Saeima political party election results by using multiple linear regression analysis. These 18 parameters are different in their character, and they describe the size of farms, level of education for farmers, land usage statistics, proportion and productivity of certain crops, livestock and the usage of farm machinery. The main hypothesis of this research was that the rural civil parishes with a high intensity of agriculture have a statistically significant difference in election results when compared to the rest of the election results in Latvia. Initial results showed a strong correlation between election results and agricultural indicators, but when the ethnic factor was taken into account in the linear regression model the role of these agricultural indicators was greatly diminished.
Показать больше [+] Меньше [-]Staff motivation in municipal administration: example of R. Hackman's and G. Oldham's work characteristic model
2014
Marcinkeviciute, L., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania) | Zukovskis, J., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania)
This article analyses the elements of R. Hackman’s and G. Oldman’s work characteristics model: the essential work characteristics, critical psychological states, as well as personal and activity results. Research aim is to offer municipal administrative staff innovative elements of the motivation system. The elements of employee motivation are linked with certain work characteristics, distinguishing specific features of the work process that would meet the needs of workers such as the use of self-expression and potential opportunities, ensuring satisfaction with the content of work, independence and recognition. Before suggesting innovative motivation system elements, the factors and motivation measures that most influence municipal administrative staff of Raseiniai, Joniškis, Pakruojis, Akmenė had been found out. Essential elements of work characteristics model (essential work characteristics, psychological states and personal and activity results) among the employees were identified. It presents the characteristics of innovative motivation system elements of municipal administrative staff. Main analysis methods were used: analysis of documents, quantitative research – survey, comparative analyses, methods of statistical and cluster analysis.
Показать больше [+] Меньше [-]Farm diversification in Hungary
2014
Hamza, E., Research Inst. of Agricultural Economics, Budapest (Hungary)
The value of farm diversification is unquestionable especially in terms of additional income generation, income stability and easing the employment difficulties of agricultural producers; its importance has recently been in the focus of agricultural and rural policies. The research purpose was to describe the situation of farm diversification in Hungary and to analyse the characteristics of diversified farms, as well as to determine which factors influence the extent and direction of diversification. The research method is based on statistical data analysing and questionnaire survey. Contrary to the above my analyses showed that the share of diversified farms is rather low in the small-scale, semi-commercial and part-time farms; its wide scale distribution is hindered by several factors. Based on the analyses I found that in private farms and in corporate farms it is characteristic that farm diversification activities are closely connected to the main activity of the farm, but they are of different type. I could state that the share of diversified farms is more significant in the labour-intensive farms and primarily in commercial farms. The share of young farmers and farmers in active age, qualified and with a full-time job is higher in the diversified and organic farms.
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