Refine search
Results 1021-1030 of 2,189
THE RESEARCH WAYS TO INCREASE THE ENERGY EFFICIENCY OF GROUND HEAT EXCHANGERS BY MEANS OF MATHEMATICAL SIMULATION Full text
2024
Mikhailutsa, Olena | Koviazin, Oleksiy | Pozhuyev, Andriy | Poliakova, Nataliia | Melikhova, Tatiana
The scientific and methodological basis for increasing the efficiency of geothermal ventilation, making it possible to use thermal energy of the Earth’s surface layers for cooling (heating) an incoming air stream are created. Mathematical modeling is performed based on the equations of hydrodynamics, heat transfer and thermal conductivity, along with a computational experiment carried out using the finite volume method. A mathematical model of the process of heat exchange between the flow of air in a heat exchanger and a soil mass is developed. This model describes a relationship between efficiency indicators of the horizontal ground heat exchanger and its performance parameters, and also natural climatic conditions. The determination of thermal fields in incoming cooled air and a soil mass at various depth locations of the horizontal ground heat exchanger is performed. The relationship between thermal efficiency and operation time of the horizontal heat exchanger, located at different depths, is proved. The energy comparison of a horizontal ground heat exchanger, located at different depths, with a vertical one, is made. he depth of the horizontal heat exchanger has been established, for which the loss of thermal energy in comparison with the vertical is insignificant (less than 7.5%). The operating time was determined, starting from which there are practically no differences in the level of thermal energy for all the studied models (> 107 s). The developed mathematical model allows to predict the energy efficiency indicators of a horizontal ground heat exchanger on the basis of its performance parameters and natural climatic conditions, that makes possible determining the economically optimal depth of the heat exchanger location under specific conditions.
Show more [+] Less [-]THE EFFECT OF SPICE EXTRACTS ON STRAWBERRY PATHOGEN BOTRYTIS CINEREA Full text
2024
Šernaitė, Lina | Valiuškaitė, Alma | Raisukevičiūtė, Neringa | Dambrauskienė, Edita | Viškelis, Pranas
Botrytis cinerea, the causal agent of strawberry grey mold, has become a severe problem of horticultural farms due to its genetic variability and growing resistance to frequently used fungicides. Plant disease could induce significant losses of yields and plants thus it is necessary to discover and apply novel approaches to control strawberry pathogens. In addition, chemical plant protection products can leave undesirable residues in fruits and the environment. Plant protection should be more friendly to the environment and human than already used chemical measures. One of the alternatives could be plant-based extracts, produced from aromatic and medicinal herbs, spices, fruits. Therefore, the aim of this study was to determine the in vitro effect of cinnamon bark (Cinnamomum cassia L.) and clove bud (Syzygium aromaticum L.) extracts on B. cinerea colony growth. Experiments were carried out at LAMMC Institute of Horticulture, Lithuania. Both extracts were obtained from dried material by extraction with CO2. For in vitro assay, extracts were separately mixed with potato dextrose agar in concentrations from 200 to 1000 μl/l, poured into Petri dishes, then each dish was inoculated with 6 mm diameter B. cinerea disc and incubated at 22±2 oC in the dark for 7 days. The diameter of the pathogen colony was measured 2, 4 and 7 days after inoculation. Concentrations of the extracts, which demonstrated reduced growth of the pathogen, were considered to have an antifungal effect. The results showed that extracts of cinnamon bark and clove bud had a similar antifungal effect on B. cinerea and suppressed the growth of 100% from 600 μl/l concentrations 4 days after inoculation. At 600-1000 μl/l, no growth of the pathogen was detected for both extracts 7 days after inoculation. However, clove bud extract considered to be more effective, as the diameter of B. cinerea colonies was smaller compared to cinnamon bark extract at 200-400 μl/l concentrations. To conclude, spice extracts of cinnamon bark and clove bud demonstrated antifungal effect on B. cinerea in vitro and could possibly be applied for control of strawberry grey mold.
Show more [+] Less [-]EXPLORATION OF THE POSSIBILITIES FOR THE PRODUCTION OF TABLEWARE FROM THE BRAN OF VARIOUS CEREALS Full text
2024
Olt, Jüri | Soots, Kaarel | Olt, Andres | Rooni, Vahur
Biodegradable and compostable tableware is significantly more environment and nature friendly than disposable tableware and drinkware made of plastic. Tableware made of wheat bran, but also corn and rice bran is already commercially available. It is reasonable to use the by-products of the milling of also other cereals, like rye bran, barley bran and oat bran, for the production of tableware. The aim of this research was to explore the possibilities for the production of tableware and drinkware from the by-products of the milling of wheat and also other cereals like rye and oat bran. In order to achieve the aim, compacts were moulded from rye bran and oat bran and mixtures of bran (wheat bran and rye bran) using various work modes. The moulding of the compacts included different temperatures of the mould, moulding durations and compressive forces. The mechanical properties like density and flexural strength of the compacts were determined and the compostability of the compacts was studied. The test bodies were placed inside a compost bin to check their compostability and to determine the duration of composting.Biodegradable and compostable tableware is significantly more environment and nature friendly than disposable tableware and drinkware made of plastic. Tableware made of wheat bran, but also corn and rice bran is already commercially available. It is reasonable to use the by-products of the milling of also other cereals, like rye bran, barley bran and oat bran, for the production of tableware. The aim of this research was to explore the possibilities for the production of tableware and drinkware from the by-products of the milling of wheat and also other cereals like rye and oat bran. In order to achieve the aim, compacts were moulded from rye bran and oat bran and mixtures of bran (wheat bran and rye bran) using various work modes. The moulding of the compacts included different temperatures of the mould, moulding durations and compressive forces. The mechanical properties like density and flexural strength of the compacts were determined and the compostability of the compacts was studied. The test bodies were placed inside a compost bin to check their compostability and to determine the duration of composting.
Show more [+] Less [-]TECHNOLOGICAL, TECHNICAL AND QUALITY ASSESSMENT OF MAIZE SILAGE MAKING AND UNLOADING FROM TRENCH Full text
2024
Jasinskas, Algirdas | Pašvenskas, Gytis | Palšauskas, Mečys | Souček, Jiří
Silage for animal feeding can be made from different plants. One of the most important feed crops from which silage is made is maize. Special choppers can be used for cutting and chopping these coarse-stem plants. The most widespread silage preparation is done in trenches, where good quality silage can last for several years, making it one of the best feeds in winter. Incorrect picking and unloading of silage from trenches may result in secondary fermentation and may cause forage losses. Various types of equipment are used for silo unloading from storage. This work researches maize plants, the quality of maize silage and the process of silage making and unloading. The research was carried out in the laboratories of Agriculture Academy of Vytautas Magnus University and in a farmer’s farm. Tests have been performed with three different silo unloaders and a mobile feed mixer. The established average corn plant yield in 2018 was 31.8 t ha-1; for silage making, the plants were chopped with the drum chopper. After evaluation of the fractional composition of chopped mass, the chopped maize slices were found to meet the silage production requirements, as even 82.6% of the chopped particles were 3.15-16 mm long. Maize slice moisture was also found to be suitable for silage – 66.12±7.3%. The density of prepared silage was high enough and reached 699.89±19.04 kg m-3 or 230.55±6.27 kg m-3 DM (dry matter). Silage unloaders test results showed that one sample of silage could be unloaded in 31–43 s. The bucket type device could take the maximum weight sample – 567.8±77.0 kg, but the maximum density of the silage sample (30.41±1.95 kg m-3) could be taken by a block-cutting unit. Also, this unloader left the smallest unevenness on the feed surface. Distribution of feed in the farm for the animal was fairly even and this indicated that the silage-unloading device had no significant impact on the quality of feed distribution.
Show more [+] Less [-]THE PROBLEMS OF MICROCLIMATE IN LITHUANIAN COWSHEDS Full text
2024
Bagdonienė, Indrė | Bleizgys, Rolandas
The experimental studies were carried out in the most common cowsheds in Lithuania. The cowsheds involved in the research featured different insulation patterns and livestock keeping technologies where cows were kept tied or loose. The efficiency of ventilation system was measured in 7 cowsheds based on the variation in air temperature, air relative humidity (RH) and ammonia. The main problems of microclimate in Lithuanian cowsheds were found to be as follows: a high relative humidity resulting in water vapour condensation on the roof structures; the air temperature is regularly below the recommended minimum of -7 °C; the air temperature is regularly above the recommended maximum of 25 °C. Optimization of the microclimate in cowsheds concerned, it is recommended to adjust the ventilation intensity based on the difference of air temperatures within the barn and outdoors. During cold months of winter it is recommended to keep the air temperature in semi-insulated cowsheds by 8–11 °C higher than that outdoors, whereas in uninsulated box-type cowsheds with roof cement – higher by 5–7 °C, and in uninsulated box-type cowsheds with roof metal – higher by only 3–5 °C. During severely freezing periods of outdoor temperature, the air temperature was found not to drop below -7 °C only in insulated cowsheds. Whereas during extremely hot days when the outdoor temperature rises above 26–28 °C, the cowsheds of all types (those insulated and uninsulated) were found to be too hot for cows. Consequently, thermal insulation of a cowshed’s roof and adjustment of the ventilation intensity are not sufficient for solving the problems caused by heat stress in the cowsheds.
Show more [+] Less [-]CREATED OF AN INTEGRATED QUALITY SYSTEM FOR THE PRODUCTION OF CANNED MEAT FOR CHILD NUTRITION Full text
2024
Voloshina, Elena | Dunchenko, Nina | Odintcova, Arina | Kuptsova, Svetlana | Fedotova, Olga
The development of an integrated safety and quality system at enterprises for the production of baby food includes measures thataimed at analyzing risks and identifying critical control points throughout the process. The article presents studies on the identification and analysis of hazards and assessing the severity of the consequences of their manifestation. In order to integrate, the international standards ISO 9001 and ISO 22000 were selected, on the basis of which the quality system processes were identified, the resources and requirements for them were determined, as well as the parameters for monitoring these processes, the criteria for evaluating the effectiveness and efficiency of the developed system were established. Within the framework of the integrated system, the main and interior processes were identified. The main processes include organization management processes, planning and implementation processes for safe and quality products, and processes for monitoring, analysis and improvement. Support processes include processes for managing the organization’s personnel, its infrastructure and production environment, as well as processes for managing documentation and records of the system.
Show more [+] Less [-]FOOD QUALITY MANAGEMENT BASED ON QUALIMETRIC METHODS Full text
2024
Yankovskaya, Valentina | Dunchenko, Nina | Artykova, Dinara | Ginzburg, Marina | Mikhaylova, Kermen | Voloshina, Elena
Fusing best international and local quality management and control practices is one of the most effective ways to gain competitive advantage. Among other things, this includes implementing "customer focus" and "factual decision-making", the key principles of Universal Quality Management, through qualimetric models. The authors have identified qualimtric models with the best quality management potential across the food processing industry, at different product life cycle stages. They especially emphasize the potential of applying qualimetric forecast to food quality and safety. The authors have identified the main stages of product quality metrics forecasting to predict and achieve the desirable food quality in the most effective way possible. The proposed methods are a combination of qualifying methods and world’s best quality management tools and techniques. With the example of quality management in curd products at the development stage the authorship points out the indicators defining product quality and safety, ranks value in building product quality, gives a math formula to describe product quality and an algorithm to assess product quality based on a comprehensive quality indicator and deduce recommendations to achieve desirable and predictable product properties. The proposed stages of qualimetric forecasting, based on the integration of qualimetric models in quality management, have been tested on some curd products in production and proven to be practically effective.
Show more [+] Less [-]PRE-SOWING SEED TREATMENT WITH PHYSICAL STRESSORS INDUCES CHANGES IN AMOUNT OF SECONDARY METABOLITES IN NEEDLES OF PICEA ABIES SEEDLINGS Full text
2024
Kačiušis, Mantas | Sirgedaitė-Šėžienė, Vaida | Žemaitis, Povilas | Mildažienė, Vida | Paužaitė, Giedrė | Koga, Kazunori | Shiratani, Masaharu | Novickij, Vitalij | Baliuckas, Virgilijus
Tree resistance to pathogens is related to the general viability of trees, their growth energy, and ability to synthesize and to mobilize secondary metabolites (SMs), usually phenolic compounds, in tissues. The total phenolic content (TPC) in Norway spruce needles was determined during two vegetation seasons in order to compare the chemical background and ability of different Norway spruce half-sib families to synthesize TPC in response to seed treatment with physical stressors: cold plasma for 1 and 2 min (CP1, CP2) and electromagnetic field for 2 min (EMF2). TPC in seedling needles significantly differed between affected and control groups, but differences were stronger exerted during the first year of vegetation. In the first vegetation season, the strongest positive effects on TPC synthesis were induced by EMF2 treatment in 463 and 577 half-sib families, by CP1 treatment − in 457 half-sib family and by CP2 treatment − in 541 half-sib family; in the second vegetation season strongest effects were detected in CP1 treated 457 half-sib family and in CP2 treated 548 and 477 half-sib families. The half-sib families of Picea abies with higher TPC induced by seed treatment with different physical stressors could be more resistant to pathogens and diseases. The variance component of family for TPC variated from 14±10 % till 17±11 %, and was significant. The interaction of genotype and environment on TPC was as high as 49 ± 20%.
Show more [+] Less [-]THEMING DISCURSE IN VILLAGE DEVELPOMENT Full text
2024
Kazlauskienė, Ingrida | Atkočiūnienė, Vilma
The issues of the development of thematic villages are mostly investigated in Poland, Austria, Lithuania. Village development theming is usually defined as a strategy or model. It acts as a vehicle for village renewal, enabling even small villages to develop successfully in the age of globalization. An experiential marketing strategy guides village development towards sustainability and helps to ensure integration between village environmental, economic and social development dimensions. Thematic villages play a heuristic role, they "push" locals and customers out of established spaces, village storytelling schemes, and encourage the search for alternative life, behavior and business models. This research aim was achieved: to determine the characteristics of the village theming development: thematic space, integrated (complex) consumption, co-creation, recreation, interests (needs), experience. Thematic analysis, collation and other methods of scientific literature were applied. Representatives of the various stakeholders must be involved in the village development theming characteristics package planning, management and control processes. There is a two-way communication between the development of various thematic objects in economic, social and environmental terms and the creation of a thematic space which must serve not only the interests of the visitors but also the inhabitants.
Show more [+] Less [-]ASSESSMENT OF THE AGRARIAN LANDSCAPE STRUCTURE IN THE DEVELOPMENT AREA OF THE MAJOR CITIES OF LITHUANIA Full text
2024
Valčiukienė, Jolanta | Juknelienė, Daiva | Atkocevičienė, Virginija
Agrarian landscape structure in Lithuania is relatively stable and changes only due to intensive economic activities such as construction of buildings, land reclamation, and afforestation. The changes due to the aforementioned activities are most evident in the development areas of the major cities, which are characterized by the increasing process of chaotic urbanization. The suburban municipalities, bordering the three major cities of Lithuania (Kaunas, Vilnius, Klaipėda), were chosen for the research. To determine areas that were influenced by the urban development among the analyzed cities, the multicriteria analysis method was chosen, which helped to assess the intensity of the suburban area development. The determined areas, which were influenced by the urban development, were divided into three categories, in which the villages of 583 agrarian territories are included. The greatest influence of the urban development on the agrarian landscape is evident in the territories that are closest to the major cities (in the areas of category I) and in which the structure of the components of the agrarian landscape changes mostly by reducing the agricultural land. To ensure a balanced influence of urban development on the agrarian landscape, the average built-up area in the development area of the major cities should not be higher than 20%–30% and the agricultural land area should not be lower than 30%–45%. To preserve the fertile land, the built-up areas should be designed in the agricultural lands with lower productivity.
Show more [+] Less [-]