2018, Vol. 16, No. 1

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/5372

Sirvi

Nüüd näidatakse 1 - 20 27

Harvest time and ensilage suitability of giant reed and miscanthus for bio-methane production and characterization of digestate for agronomic use
(2018) Da Borso, F.; Di Marzo, C.; Zuliani, F.; Danuso, F.; Baldini, M.
In many countries, biogas plants are mainly fed by livestock slurry and dedicated crops, including maize, which still represents one of the main energy crops utilized. Many concerns are now arising on environmental impact due to the high water consumption, chemical fertilizer and pesticide requirements and on adverse effect of maize as energy crop on the price of food and feed commodities. For these reasons two perennial crops, in particular miscanthus (Miscanthus x giganteus) and giant reed (Arundo donax L.), were cultivated at very low input and evaluated for their bio-methane yield at different harvest times and ensilage suitability, in a north-eastern area of Italy. Moreover, considering the agronomic use of the obtained digestate as fertilizer, this has been characterized by the content of heavy metals. Both multi-annual crops have proved highly productive in biomass especially with a harvest time in autumn, at which a satisfactory completion of the silage process without additives was observed. Conversely, bio-methane yield per hectare were not satisfactory with respect to the reference crops such as maize. The low BMP attained showed the main bottleneck of the methanisation of ensiled giant-reed and miscanthus, which is represented by fiber composition with high degree of lignification. The simulation use of digestate obtained as fertilizer in vulnerable areas, could lead to slightly exceed the levels allowed by the legislation of some European countries with regard of heavy metals as Cu, Zn and Cd.
Agricultural field production in an ‘Industry 4.0’ concept
(2018) Jørgensen, M.H.
Precision Agriculture is a well-established concept in agricultural field production. It has developed over the last three decades. As part of this concept, farmers are used to collect and handle data. Farmers are also used to create solutions for field operations based on their knowledge of diversity and local data. When compared to classic industrial production, agricultural field operations interact with a biologically-active system. From a production management system point of view, industrial production takes place in close, well-defined environments in which performance data can, to a great extent, be measured by deterministic matters: mass (kg), volume/dimensions (m3 /m), time (sec), etc. In agricultural operations such as work involving tillage, seeding, fertilising, and plant care, there are by nature a good many possible adjustments available in order to optimise the operation method, plus intensity and timing. The challenge here is to establish the levels of knowledge that are necessary to support the control of the individual and/or graduated, precision-based operations. Within this context, parameters such as, for example, the workability of the soil cannot be defined in terms of a few deterministic parameters. Neither can the operational impact upon the soil which is made by the tools being used. It is assumed that this challenge is part of the reason why the concept of precision agriculture still contains a great deal of unutilised potential. The hypothesis raised by this article is that analysis should be carried out in regard to whether inspiration for the concept of an ‘Industry 4.0’ can facilitate the establishment of operational solutions in the field of precision farming.
Production and profitability of low density Norway spruce (Picea abies (L.) Karst.) plantation at 50 years of age: case study from eastern Latvia
(2018) Katrevičs, J.; Džeriņa, B.; Neimane, U.; Desaine, I.; Bigača, Z.; Jansons, Ā.
Norway spruce (Picea abies (L.) Karst.) is one of the most important commercial tree species, for which wider spacing are being advocated to reduce management costs and improve radial growth. Nevertheless, little is known about tree and stand parameters at the larger age in stands of extremely low density. The aim of our study was to assess growth and economic profitability of 50 years old low density Norway spruce plantation in Latvia. Allometric parameters for all trees of Norway spruce clonal plantation planted in 1964 with two spacings (1×3 m and 5×5 m) were measured and profitability were estimated. Norway spruce plantation with wider (5×5 m) spacing ensured significantly larger tree diameter and height (35 cm and 25 m, respectively) than trees from higher density trial. However, mean net present value (3% interest rates) was non–significantly (P = 0.12) different between 5×5 m and 1×3 m spacings, 2,571.9 ± 355.6 and 3,085.8 ± 452.9 € ha-1 , respectively. Values observed in low density (5×5 m) plantation fitted well in the observation of impact of density and stand parameters drawn based on National inventory data, showing a considerable potential to use plantations with low density in practice.
Assessment of dairy cow herd indices associated with different milking systems
(2018) Gaworski, M.; Leola, Arvo; Kiiman, Heli; Sada, Oliver; Kic, P.; Priekulis, J.; Estonian University of Life Sciences. Institute of Technology
The objective of the research was to find whether any differences exist between cattle herds operated by certain milking installations. The cattle herds were studied not only by herd size but also by certain data, like annual milk yield, age and number of lactations. Data collected on dairy farms that operate pipeline milking systems, milking parlours and automatic milking systems were analysed. These farms are situated in three Baltic States. The investigated Estonian dairy farms indicated a decreased tendency in the prevalence of disease cases for udder diseases with an increase in cow herd size. An index of cow production potential was proposed to compare different (including number of lactations) group of cows in dairy farms.
Strawberry leaf surface temperature dynamics measured by thermal camera in night frost conditions
(2018) Kokin, Eugen; Pennar, Madis; Palge, Veli; Jürjenson, Kuno; Estonian University of Life Sciences. Institute of Technology. Department of Energy Application
The aim of the study was to define the strawberry leaf surface and ambient air temperature differences in night frost conditions. The study was carried out at the commercial strawberry field in late autumn at a specific natural climatic situation, corresponding to night frost conditions. Thermal camera FLIR P660 was used for obtaining thermal images and corresponding visual colour images of the strawberry leaves. The images were taken at ten-minute interval. The ambient air temperature, relative humidity, dew point, solar radiation and wind speed data were obtained by Davis Vantage Pro2 weather station. It was estimated that the surface temperature of the specific leaf is comparatively similar at different parts of the specimen and changes noticeably with the variation of solar radiation intensity. The speed of temperature changes was also analysed. During all the measurement period, the considerable difference between the temperature of the leaf and the ambient air temperature was established, especially in absence of solar radiation. The difference of the leaf surface and ambient air temperature reached 8 °C. The study showed that in night frost conditions the plants might be endangered by low temperatures even at the air temperatures above 0 °C due to intensive energy loss by long wave radiation to the sky. It is suggested that the thermal imaging or infrared radiation measurement should be used simultaneously with air temperature measurements for more exact timing of night frost prevention measures at strawberry cultivation.
The effect of ethyl 5′-(4-methoxybenzoyl)-5′,7′- dihydrospiro[cyclopentane-1,6′-[1,2,3]triazolo[5,1- b][1,3,4]thiadiazin]-3′-carboxylate on Pinus sylvestris L. seed germination
(2018) Kalinina, Т.А.; Vysokova, О.А.; Khamidullina, L.А.; Kochubei, А.А.; Cherepanova, О.Е.; Glukhareva, Т.V.
Plant growth stimulators are capable of enhancing both agricultural output and the rate of plant maturation, consequently improving the total crop yield and increasing their resistance to disease and adverse environmental conditions. This is why such compounds are used in the cultivation of both agricultural and ornamental plants. The aim of this work was to study the effect of ethyl 5′-(4-methoxybenzoyl)-5′,7′-dihydrospiro[cyclopentane-1,6′-[1,2,3]triazolo[5,1- b][1,3,4]thiadiazin]-3′-carboxylate on Pinus sylvestris L. seed germination. The article describes the synthesis of ethyl 5′-(4-methoxybenzoyl)-5′,7′-dihydrospiro[cyclopentane-1,6′- [1,2,3]triazolo[5,1-b][1,3,4]thiadiazin]-3′-carboxylate and the data from spectral and X-ray crystal analysis. The results of the experimental stimulation of Pinus sylvestris L. seed germination using spiro-1,2,3-triazolo[5,1-b]1,3,4-thiadiazine are given compared to the commercially available phytohormones thidiazuron and 6-benzylaminopurine. The estimation of germination, vitality, healthy seed ratio and cotyledon length indicated that the tested compound at a concentration of 0.5 mg L -1 had an effect similar to 6-benzylaminopurine: indeed, the speed of germination and fungal invasion rate exceeded the effect of 6-benzylaminopurine.
Genotypes performance in relation to drought tolerance in barley using multi-environment trials
(2018) Arshadi, A.; Karami, E.; Sartip, A.; Zare, M.; Rezabakhsh, P.
The selection of stable and superior genotypes, with the aim of improving grain yield in breeding programs, requires the evaluation of genotypes under different environments. In this study, the yields of 10 barley genotypes were evaluated in eight different environments using a graphical method (GGE biplot). These experiments were conducted from 2011 to 2015. There were irrigated and rain-fed conditions, as a randomized complete block design (RCBD) with three replications. Results indicated that the two components of PC1 and PC2 explained 62.9% and 14.9% of the total variation observed in the yield, respectively. Genotypes with a positive value for PC1 (i.e., PC1 > 0) had the adaptable and the highest performance, whereas genotypes with a negative value for the first component (i.e., PC1 < 0) were non-adaptable and had the lowest performance. Likewise, among the genotypes, some had their second component scores near zero, and they exhibited the greatest stability compared to other genotypes. Specifically, genotype 3 had the highest grain yield and stability, while genotypes 2 and 8 showed relatively high yields.
Fatty acid composition of oilseed rapeseed genotypes as affected by vermicompost application and different thermal regimes
(2018) Samadzadeh Ghale Joughi, E.; Majidi Hervan, E.; Shirani Rad, A.H.; Noormohamadi, Gh.
Vegetable oils with a high relative amount of unsaturated fatty acids are of great significance for human health. Hence, in a 2-year factorial split plot experiment, the effects of different sowing date (optimum (October 17) and late (October 27)), vermicompost (0 and 20 ton ha-1 ) and genotypes (BAL104, DIE710.08, BAL102, FJL330, FJL290 and Okapi) on the fatty acid composition of rapeseed were evaluated. Rapeseed genotypes and the combination of sowing date and vermicompost application were randomized to sub and main-plots, respectively. The present results revealed that yield, oil percentage and fatty acids composition is affected by sowing dates along with genotypes. However, the unsaturated fatty acid, eicosanoic acid was not affected by interaction sowing date and genotype. Vermicomposting increased the yield, oil percentage, oleic, linoleic and linolenic acids and decrease erucic unsaturated fatty acid. The FJL290 and BAL102 genotypes produced the highest values of grain yield (5,853 and 5,763 kg ha−1, respectively), oil percentage (43.98% and 43.85%, respectively), linoleic % acid (20.51 and 20.37% respectively), oleic % acid (65.23 and 64.93% respectively) and linolenic % acid (7.20 and 7.09% respectively) in comparison to the other genotypes, when they were sown at the optimum sowing date. The FJL290 and BAL102 also accelerated their growth period at the late sowing date. Consequently, oleic, linoleic and linolenic acids had the highest direct and indirect effect influence on grain oil percentage indicating their importance as selection criteria to improve yield and oil quality of rapeseed. Concluding the combination of sowing date, vermicompost and FJL290 and BAL102 lines may be the most favourable cropping strategy for rapeseed production in Iran.
Theory of retaining potato bodies during operation of spiral separator
(2018) Bulgakov, V.; Nikolaenko, S.; Adamchuk, V.; Ruzhуlo, Z.; Olt, Jüri; Estonian University of Life Sciences. Institute of Technology
The increase of the efficiency and quality of performance of the work process of potato heap separation can be achieved by means of improving the design of the vibrational spiral separator and substantiating theoretically its rational parameters under the condition of eliminating damage to the potato tubers. An equivalent schematic model of the interaction between the potato tuber and the surface of the cantilever spiral springs has been devised. On the basis of the model, the kinematic characteristics of the tuber’s flight and its impact contact with the elastic surface of the over mounted rebounding conveyor have been investigated. A new analytical mathematical model of the potato tuber’s flight from the surface of the spiral separator and its subsequent encounter with the rebounding conveyor mounted above the spiral springs has been developed. New analytical dependences have been obtained for finding out the distance and height of the potato tuber’s flight to the point of impact contact as well as the trajectory equation fo r the travel to the said contact, which makes it possible to obtain the kinematic constraints imposed on the allowed rate of travel under the condition of not damaging the tuber. On the basis of the obtained analytical dependences, the kinematic parameters of the improved design of the spiral potato harvester separator in its interaction with a potato tuber under the condition of not damaging the latter have been investigated .
The influence of cultivar, weather conditions and nitrogen fertilizer on winter wheat grain yield
(2018) Linina, A.; Ruza, A.
Winter wheat (Triticum aestivum L.) is one of the most productive and significant cereal species in Latvia used for food grain production. The aim of the research was to e valuate winter wheat grain yield depending on nitrogen fertilizer rate, crop - year (meteorological conditions) and cultivar and determine the impact and interaction of research factors on grain yield. Field experiments with winter wheat cultivars ‘Bussard’ and ‘Zentos’ were conducted at the Latvia University of Agriculture, Study and Research farm Peterlauki during a three year period (2009/2010, 2010/2011 and 2011/2012). Nitrogen (N) was applied (N60, N90, N120, N150 kg ha - 1 ) in spring after resumption of v egetative growth. Assessment of both winter wheat cultivars showed that crop - year, cultivar, nitrogen fertilizer, crop - year × cultivar had a significant (p < 0.05) impact on grain yield. Nitrogen fertilizer did significantly (p < 0.05) affect the grain yie ld of winter wheat, treatment with N90 showed of yield increase, compared to N60, while further use of increasing amounts of N fertilizer did not increase grain yields significantly. Results suggest, that winter wheat grain yield by 34% depended on cultiva r, by 33% on crop - year (weather conditions), and by 13% on crop - year × cultivar. Influence of the nitrogen fertilizer effect was small – 3%. Medium strong positive correlation was found between HTC in the vegetation period from winter wheat heading to grai n ripening.
Theory of impact interaction between potato bodies and rebounding conveyor
(2018) Bulgakov, V.; Nikolaenko, S.; Adamchuk, V.; Ruzhуlo, Z.; Olt, Jüri; Estonian University of Life Sciences. Institute of Technology
In order to increase substantially the quality of the potato heap separation, it is necessary to carry out the theoretical substantiation of the spiral separator’s parameters with regard to the impact interaction between the product and the tools of the un it under the condition of not damaging the tubers. An equivalent schematic model of the impact interaction between a potato tuber and the surface of the rebounding conveyor has been devised. Taking into account the coefficient of restitution of the tuber’s velocity in case of an impact, new analytical expressions have been obtained for determining the magnitude and direction of the potato tuber’s velocity after the impact. They provided the basis for applying the principle of momentum at impact and obtainin g the analytical expressions that allow determining the impact impulse and impact force at the impact of the tuber on the surface of the rebounding conveyor and, eventually, the dynamic constraints on the permitted velocity of the tuber prior to the impact interaction under the condition of not damaging it. A new analytical mathematical model of the impact interaction of the potato tuber during the potato heap separation has been developed. On the basis of the obtained theoretical results, studies have been carried out on the rational kinematical parameters of the high - quality performance of the above - mentioned work process under the condition of keeping the potato tubers undamaged .
Evaluation of dried compost for energy use via co-combustion with wood
(2018) Malaťák, J.; Bradna, J.; Velebil, J.; Gendek, A.; Ivanova, T.
There is still a question of utilization of compost of unsatisfactory quality. This article deals with energy utilization of untreated compost. The energy utilization of raw compost as a fuel is not directly possible without further processing. Separation might be necessary due to large amount of mineral content (soils and other inert substances). This article is focused on the analysis of the basic fuel characteristics of compost. Proximate and elemental analyses were performed and stoichiometric combusti on was calculated. Finally, the sample was co - burned with wood biomass in a fixed grate combustion device and the gaseous emissions were determined in dependence on the amount of combustion air supplied. The emissions were expressed in graphs against exces s air coefficient and flue gas temperature. Elemental analysis of the compost sample shows high percentage of ash up to 61.70% wt. on dry basis causing low average calorific value of 8.51 MJ kg - 1 on dry basis. For combustion tests, the heating value was in creased by addition of wood chips to reach an average calorific value of the mixture to 13.4 MJ kg - 1 . The determined stoichiometric parameters can help in optimization of diffusion controlled combustion of composts or similar materials. In combustion of th e mixture of compost and wood biomass an optimum of emission parameters was found not exceeding the emission limits. Measured emission concentrations show the possibility of optimizing the combustion processes and temperatures while lowering CO emissions v ia the regulation of combustion air.
Effects of fertilization on Picea abies stands situated on drained peat soils
(2018) Cekstere, G.; Osvalde, A.; Nollendorfs, V.; Karlsons, A.; Pormale, J.; Zalitis, P.; Snepsts, G.; Minova, S.; Jankevica, L.; Laivins, M.
Norway spruce used for afforestation of drained peat soils frequently has low productivity and decay in a long - term, which could be related to soil chemical composition and nutrient status. The research aim was to elucidate the effect of PSM on new Norway spruce plantings (1st experiment) and 20 - year - old spruce stands (2nd experiment) on drained peat soils by evaluating: (1) nutrient accumulation in soil - plant system, (2) soil microbiological activity, (3) health status of spruce individuals, (4) growth int ensity and productivity of spruce, (5) changes in composition of vascular plant and moss species. The study was conducted at two forest ( Myrtillosa turf.mel .) sites in Latvia, each consisting of two plots: control and treated with PMS (100 g m - 2 in Septemb er 2007, 50 g m - 2 in April 2008). During 2008 – 2016, regular analysis of soil, spruce needles, soil microbiology, assessment of tree crown vitality, stand productivity, inventory of vascular plant and moss species were done. The results showed that the fert ilization with PMS resulted in a significantly improved K, Ca, Zn, and N status of trees, crown vitality and up to three times increased tree growth parameters at both experiments during the study period. The average count of bacteria and fungi in soil of fertilized plots, accompanied by a remarkable variability in the study years, was significantly higher only for the 1 st experiment. Fungi : bacteria ratio for the fertilized and control plots differed significantly only for the 1 st experiment. Significant i ncrease of cover with nitrophilic plant ( Urtica dioica, Antriscus sylvestris, Rubus idaeus ) and moss ( Plagiomnium cuspidatum , P. ellipticum ) species at both fertilized sites were stated.
Germination and growth of primary roots of inoculated bean (Vicia faba) seeds under different temperatures
(2018) Senberga, A.; Dubova, L.; Alsina, I.
Temperature stress strongly affects legumes, rhizobia, and the efficiency of legume - rhizobia interaction. An experiment in 2016 was developed to test the seed germination in Petri dishes using different microorganism inoculation under several temperature treatments (4, 8, 12 and 20 °C) . The goal of t his study was to test the effect of rhizobium inoculation under low root zone temperature, and to examine whether the addition of mycorrhiza fungi could enhance rhizobia resistance to abiotic stress and improve faba bean ( Vicia faba ) germination. Four faba bean cultivars were selected for the experiment (‘Lielplatone’, ‘Fuego’, ‘Bartek’ and ‘Karmazyn’). Four different seed inoculation variants were included in this experiment – 1) with rhizobium inoculation; 2) with a commercial preparation containing mycor rhiza fungi; 3) inoculation with both rhizobium and the mycorrhiza fungi preparation; 4) control variant. The number of germinated seeds, the length of the primary root and the primary root weight ratio were determined. The effect of inoculation was found out to be dependent not only on the temperature treatment, but it also significantly varied between the bean cultivars. Variants where seeds were inoculated with both mycorrhiza and rhizobia resulted in the highest results (length and weight ratio of prima ry roots), comparing with other inoculation variants, regardless of temperature. Variants where seeds were treated only with rhizobia mostly showed the lowest results – both length and weight ratio of primary roots, especially under treatment of 4 °C . Faba bean inoculation with only rhizobia might not be efficient, when sowing seeds under a low temperature stress. Inoculation with both rhizobia and mycorrhiza fungi could be a potential solution, when the root zone temperature is still below the optimal temp erature.
Intra–annual height growth of hybrid poplars in Latvia. Results from the year of establishment
(2018) Šēnhofa, S.; Zeps, M.; Ķēniņa, L.; Neimane, U.; Kāpostiņš, R.; Kārkliņa, A.; Jansons, Ā.
Fast growing hybrid poplars (Populus spp.) could be successfully used for bioenergy as well as wood production. Productivity of clones had been studied in Baltic States recently, however, little is known about the impact of weather conditions on poplar height growth, thus the potential effect of climate change. Therefore, the aim of this study was to characterize the intra– annual height growth of hybrid poplar clones in Latvia. Height increment of 12 hybrid poplar clones was measured on average with an 11–day interval in the first vegetation season in 2016. Annual shoot height was on average 81.0 ± 6.8 cm, significantly (p < 0.001) depending on the poplar clone. Use of long (0.5 m) instead of short (0.3 m) cuttings leaded to larger annual height increment during the year of establishment of the plantation. From June to September the mean growth intensity was 10 to 15 mm day-1 . The trend of height growth intensity, described by Gompertz model, indicated that the poplar clones with largest height had relatively fast increase of the growth intensity from June to July. Changes of growth intensity was linked both with the temperature and sum of precipitation. This tendency was not so pronounced for clones with largest height increment, emphasizing the importance of the phenotypic plasticity in selection of clones for plantations.
Energy consumption of milking pump controlled by frequency convertor during milking cycle
(2018) Vaculik, P.; Prikry, M.; Bradna, J.; Libich, L.
The article deals with selected parameters affecting the energy consumption of a vacuum pump in a milking system during the whole milking cycle in variants with and without regulation by a frequency convertor. When put into practice, the latest research of creation, control and stabilization of vacuum in milking devices allows dairy farmers to obtain a vacuum system that ensures maximum stability of milking pressure, which is a basic requirement affecting the health of dairy cows. The choice of vacuum system prioritizes in particular high performance, maximum operational reliability, minimum maintenance, long service life, environmental friendliness and economy. The vacuum pump was a Roots vacuum pump with a rotary piston which is typical for this use. Use of a frequency convertor significantly affected the efficiency of this pump for control of vacuum pressure level and pump performance by varying the rotation frequency according to the actual airflow requirement. Using this control system, only as much vacuum pressure is produced as necessary. By measurement of an experimental setup, it was found that the average power requirement of a setup with a control valve was 3.8 kW compared to 1.7 kW in the case of the variant with frequency convertor. Measurements and calculations have shown that this system is capable of saving more than 50% of electric energy.
Investigation of the sugar content in wood hydrolysates with iodometric titration and UPLC-ELSD
(2018) Meile, K.; Zhurinsh, A.; Briede, L.; Viksna, A.
Autohydrolysis of birch wood is a mild pretreatment process, which gives a notable yield of sugars – monosaccharides and oligosaccharides – in the aqueous hydrolysate, while a solid lignocellulose fraction can be further processed into other valuable products within a biorefinery concept. In this work two analytical methods – iodometric titration and ultra-high performance liquid chromatography with evaporative light scattering detection (UPLC-ELSD) – have been optimized and compared for the determination of the sugar content in series of birch wood hydrolysates. The results of both methods were consistent and showed that the highest yield of sugars, mostly xylose, was obtained by hydrolysis at 180 °C after 75 min.
Effect of different compositions on anaerobic co-digestion of cattle manure and agro-industrial by-products
(2018) Meiramkulova, K.; Bayanov, A.; Ivanova, T.; Havrland, B.; Kára, J.; Hanzlíková, I.
The present research is dedicated to the study of anaerobic co-digestion process of different biomass materials. Anaerobic co-digestion of digested sludge, grass silage, haylage and cattle manure was evaluated in mesophilic tank reactors in the lab-scale experiment. Twelve laboratory scale tank reactors (1.5 L) were used during the incubation period of 45 days. First triplet of reactors was fed with pure digested sludge and the other three with different mixtures having the volumetric ratios of 30/35/25/10, 40/30/20/10 and 50/25/15/10 for digested sludge/corn silage/grass haylage/cattle manure. Methane production was analyzed for all labscale reactors individually. The resulting specific methane production of above-mentioned batches was 336.34, 238.1 and 233.23 LSTP[CH4] kg-1 [TVS], respectively. Other results such as cumulative biogas and methane yield, volumetric biogas and methane yield, volumetric biogas and methane yield per day were also assessed. These results had the highest meaning when complex substrate had no more than 30% of inoculum.
Energy analysis of hydrogen as a fuel in the Czech Republic
(2018) Obergruber, M.; Hönig, V.; Procházka, P.; Zeman, P.
The concept of ‘hydrogen economy’ dates back to the 1970s. It was first introduced as s response to the first oil crisis. In the context of the hydrogen economy, it is important to calculate how much hydrogen would be needed to power all motor vehicles in the Czech Republic. This is main topics of this paper. To calculate the amount of hydrogen, we used two different methods. One is based on thermodynamic laws and the other on normal operating conditions. Both approaches yielded comparable results. It was found out that even with the use of all the electricity produced in the Czech Republic in 2016, we would not be able to cover the amount of energy that is required for production. It would cover only 75% resp. 76% depending on the calculation method used. Eventually, the Czech Republic could buy necessary amount of hydrogen and it would cost between 11 and 29 billion euros which is between 6% and 16% of GDP of the Czech Republic. In the calculations, authors found out that most fuel is burnt in the passenger cars. Therefore, we made a sensitivity analysis to find out how much our results would differ if fuel consumption changed. It turns out that with an increase in consumption of 1l per 100 km, hydrogen production coverage will decrease by about 4% (again with the use of all electricity produced in the Czech Republic).
Mathematical model for monitoring carbon dioxide concentration in industrial greenhouses
(2018) Laktionov, I.; Vovna, O.; Cherevko, О.; Kozlovskaya, T.
Processes of monitoring and control the industrial greenhouses microclimate play a decisive role in growing crops under protected cultivation. Providing optimal climatic conditions in the production process of greenhouse agricultural products requires solving the scientific and applied problem of developing and researching a mathematical model for monitoring carbon dioxide concentration in industrial greenhouses. The proposed model takes into account the processes of diffusion and absorption of carbon dioxide, the geometric parameters of greenhouses, as well as the types and vegetation periods of crops grown under protected cultivation. Time characteristics of the carbon dioxide dynamics process under greenhouse conditions are estimated. Quantitative estimates of the diffusion transfer duration and carbon dioxide absorption are made for indeterminate varieties of tomatoes during planting and fruiting periods. Recommendations are given on the development of an adaptive methodology for the functioning and structural and algorithmic organization of computerized monitoring and management system for carbon dioxide top-dressing modes for greenhouse crops. The necessity of improving the proposed mathematical model and confirming the adequacy of its implementation efficiency on yield indicators of greenhouse crops is substantiated.

Sirvi

Sirvi 2018, Vol. 16, No. 1 Kuupäev järgi

Tulemused lehekülje kohta

Sorteerimisvalikud