Iskanje po katalogu digitalne knjižnice

Opis: Optimal planting speed of vacuum maize planters is usually suggested by planter’s manufacturers, while increased planting speed may influence plant spacing and finally yield. Our hypothesis was that by increasing planting speed over the suggested level plant spacing variability will also increase which will result in decrease of silage and grain yield and saving of seed and energy. The field trial consisted of three planting speeds of 7, 9 and 11 km/h in the form of random blocks. The following measurements were taken as follows: plant spacing, silage and grain yield, fuel and energy use at planting. Results in this study show that planting speed did not have significant influence on silage and grain yield of maize, while up to 10% less seed was needed per hectare and fuel and energy use was lower for 15%. By the increase of planting speed the distance between the plants in a row, and in most cases also the plant spacing variability increased. It was noticed that by increasing planting speed plant density decreased. This research established that at higher planting speeds significant increase of the silage yield per individual plant and of the grain yield per individual plant was achieved. The ear parameters also show that the kernel mass per individual ear, the ear mass, and the cob mass, as well as the individual kernel mass, are larger at the planting speed of 11 km/h than at the planting speed of 7 km/h. At the latter planting speed, significantly higher fuel consumption per hectare and higher energy use was achieved than at the other two planting speeds. Overall the main benefits of planting speed of 11 km/h is saving seed and energy at planting while maintaning the same level of silage and grain yield compared to lower planting speeds used in the trial.
Ključne besede: energy use, grain yield, maize, planting speed, plant spacing, seed savings, silage yield, vacuum planter
Objavljeno v DKUM: 11.03.2025; Ogledov: 0; Prenosov: 4
Celotno besedilo (386,40 KB)
Gradivo ima več datotek! Več...

Ključne besede: renewable energy, anaerobic digestion, biogas plant, mathematical models, optimization algorithms, products utilization
Objavljeno v DKUM: 31.01.2025; Ogledov: 0; Prenosov: 13
Celotno besedilo (19,46 MB)

Opis: In a typical pressurized water reactor, neutron detectors located outside the reactor core monitor reactor power. In addition, they are also used to measure the reactivity of the control rods. A novel approach to calculate the ex-core neutron detector response in a typical pressurized water reactor using the Monte Carlo technique is presented. A detailed ex-core model of the Krško nuclear power plant was developed using the Monte Carlo neutron transport code MCNP. Due to the location of the ex-core neutron detectors, the hybrid code ADVANTG is used to generate variance reduction parameters to accelerte the convergence of the results outside the reactor core. To use ADVANTG, the fixed neutron source had to be reconstructed from the criticality core calculation. This paper presents the sensitivity analysis of the response of the ex-core detectors to the neutron data libraries used, the description of the fixed neutron source and the ADVANTG parameters. It was found that a pin-wise description of the neutron source for at least two rows of fuel assemblies at the core periphery is necessary for accurate results. Our results show the importance of a correct description of the prompt neutron spectra in the high energy region and the impact this has on the response of the ex-core detectors. The method in which the prompt neutron fission spectra for important fission nuclides are weighted by the calculated reaction rates has been shown to be the best approximation, with deviations from the reference calculation within statistical uncertainty. The effect of nuclear data libraries on the response of the ex-core detector was investigated, and the difference between the ENDF/B-VII.0 and the ENDF/B-VIII.0 nuclear data libraries was ∼11%. When the deficient evaluation of the 56Fe isotope included in the ENDF/B-VIII.0 nuclear data library was replaced by the improved evaluation from the IAEA INDEN project, the differences decreased to ∼3.7%. In addition, neutron flux redistributions due to control rod movement were investigated and flux redistribution factors were updated using Monte Carlo particle transport methods. The reaction rate redistribution factors obtained with methods presented in this paper are within 1% agreement with the currently used factors.
Ključne besede: MCNP, ADVANTG, pressurized water reactor, Monte Carlo neutron transport, control rod, neutron flux redistribution factor, rod insertion, krško nuclear power plant
Objavljeno v DKUM: 29.11.2024; Ogledov: 0; Prenosov: 7
Celotno besedilo (63,82 MB)
Gradivo ima več datotek! Več...

Opis: In view of growing requirements of the food industry regarding elderberries (genusSambucus), a need to increase their productivity and improve their chemical composition has emerged.With this purpose in mind, numerous elderberry interspecific hybrids have been created. In thepresent work, the content of minerals in their crucial plant parts was studied. It was also investigatedwhether superior genotypes regarding the mineral composition of berries and inflorescences could bepredicted at early stages of plant development. The results showed that elderberry leaves containedthe highest amounts of Ca, Mg, Mn, Zn, and Sr, while K and P were predominant in fruit stalks.Fe and Al prevailed in roots and Cu in bark. Although berries showed lower mineral contentcompared to other plant parts, their mineral content is not negligible and could be comparable toother commonly consumed berries. Genotypes with a favorable mineral content of inflorescencesand berries could be predicted on the basis of known mineral composition of their shoots and leaves.The study also indicates thatS. nigragenotypes and the majority of interspecific hybrids analyzedare suitable for further genetic breeding or cultivation.
Ključne besede: interspecific hybrids, minerals, plant parts, elderberry, Sambucus
Objavljeno v DKUM: 20.08.2024; Ogledov: 70; Prenosov: 9
Povezava na celotno besedilo
Gradivo ima več datotek! Več...

Opis: Changes in soil chemistry after invasion by bracken (Pteridium aquilinum) have been studied in heathlands, but comparable studies in meadows are lacking. We investigated if bracken invasion into P-deficient meadows alters the soil nutrient-resource pool, as well as the mechanisms behind it linked to soil processes and bracken nutrition. Furthermore, we investigated how community composition responds to differences in soil chemistry before and after the invasion. Soil and plant material sampling, along with vegetation survey, were performed during bracken peak biomass. Data analyses included analysis of variance and canonical correspondence analysis (CCA). Bracken invasion increased soil P availability, soil organic C concentration, as well as C:N, C:S and N:S ratios, while decreasing Fe and Co concentrations. Bracken pinnae were rich in P, and its rhizomes were rich in K, whereas N:P of pinnae and rhizomes was low. CCA showed contrasting abundance patterns of frequent meadow species related to P and K availability. Holcus lanatus exhibited competitive advantage under extremely low P availability. Increase in P availability under bracken may have occurred through promoting the leaching of Fe and Al. By increasing P availability for its growth and increasing N limitation for other species, bracken can gain a competitive advantage from the soil resource-niche perspective. Its ability to increase soil P availability, along with the physiological mechanisms behind its high P acquisition efficiency, seem to differentiate bracken from other species of competitive ecological strategy, which are mainly confined to nutrient-rich environments. This enabled bracken to invade P-deficient meadows.
Ključne besede: vegetation succession, invasive species, biogeochemical processes, soil ecology, plant invasion
Objavljeno v DKUM: 17.06.2024; Ogledov: 152; Prenosov: 18
Celotno besedilo (515,49 KB)
Gradivo ima več datotek! Več...