Advanced Materials Research Vol. 1059

Abstract: This article focuses on temperature relations of selected thermophysical parameters for three different types of wheat flour. The main objective of experiment was to determine the thermal conductivity, thermal diffusivity and volume specific heat of wheat flour produced in Slovakia. Measurements were performed in laboratory settings. Thermal parameters were measured by the thermal analyser Isomet 2104 with two types of probes – a linear probe and plane probe. Measurement by the linear probe is based on the hot wire method, and measurement by the plane probe is based on the extended dynamic plane source method. Both methods are described in the text. Two types of measurement methods were used because of the non-homogenous structure of measured material. All thermophysical parameters were measured during the temperature stabilisation in the temperature interval 5–24 °C. Obtained graphical relations had linear increasing progresses with high values of determination coefficients in all cases.

Abstract: The purpose of this paper is to monitor the amount of discharged radioactive liquid discharges from nuclear power plant and propose ways to reduce the amount given. The report consists of a literature review, objective and methodology proposed. The methodology and results consist of distribution of waste, originally liquid radioactive waste (LRW), a source of LRW, a year-round monitoring of liquid effluents of nuclear power plant and eventual adoption of protective measures. Tritium, as one of the LRW, is a radioactive substance having a negative impact on the environment. In the course of our research, we have found an increased dose of tritium over permitted annual limit. We investigated the impact of tritium on the environment and took protective measures to reduce the amount of tritium released in the environment. The report may serve as a basis for other nuclear power plants and the entire nuclear industry.

Abstract: In practice, adhesive bonded joints are loaded by different intensity and rate. In the case where bond bearing capacity is exceeded, failure occurs. One of the affecting factors is strain rate. In the laboratory tests, ČSN EN 1465 is used as a basic standard, specifying the rate of deformation in the interval of 65±20 seconds. The goal of this research is to describe the behaviour of two-part epoxy adhesives at different strain rate of bonded joints. Experiments evaluated the changes of bond strength, deformation and time to failure. Time to failure is particularly significant because of the potential consequences of fast structural joint violation.

Abstract: The application of quick-setting adhesives based on cyanoacrylates is considerably spread in technical practice. The limit of these adhesives is the 'zero layer' of the adhesive. The advantage is in the speed of hardening process. A fast creation of bond, minimalizing of fixation means, and the possibility of fast manipulation with the adhesive bond are connected with that. The goal of the research is to describe the behaviour of quick-setting adhesives based on cyanoacrylates at different speed of deformation of adhesive bonds in the interval from 1 mm.min^-1 to 48 mm.min^-1. The change of adhesive bond strength, deformation and failure time were evaluated in experiments. A 3D model was set from experiment results by means of the least-square method.

Abstract: As it is generally known, diesel engines operate with air excess, i.e. lean mixtures. Intake resistances in intake manifolds of diesel engines negatively influence their ecological parameters. Based on these facts, we may conclude that less air in the intake manifold causes increased production of exhaust fumes and fuel consumption. One of the reasons of increased intake resistance is a blocked air filter. In the experiment, we have simulated the increased intake resistance and wished to point out possible consequences of pressure drop at the end of the compression stroke. The choking effect was realized by means of a throttle and scale, which was mounted on the air filter position. By using the dynamic method and obtained results, we found that choking at the rotation angle of 90° and 45° caused the difference of 0.16 MPa of the measured quantity during the maximum revs set on 2000 min^-1. The difference in pressure at the end of the compression stroke with the rotation angle of 30° and 90° was by 0.86 MPa higher. Pressure drop in manifold showed the value 0.15 MPa. Manufacturers recommend regular replacement of air cleaners of combustion engines in service intervals; however, we must also keep in mind the environment in which the engine operates. In excessively dusty and otherwise polluted areas, it is necessary to replace cleaners a bit earlier.

Abstract: Hydraulic pumps are the most important components of hydraulic circuits in agricultural tractors. Their durability is influenced by flow characteristics and thus the flow efficiency. This paper presents the laboratory test of an ecological synthetic hydraulic fluid of UTTO type. This fluid is currently under development. In terms of a decrease in hydraulic pump flow efficiency, laboratory tests of these fluids did not show negative effects of its application. It can be stated that after completion of laboratory tests, it will be needed to continue with trials under operational conditions.

Abstract: Solid carbon (C) is produced during hydrocarbon fuels combustion by the molecules heat decomposition process in a local lack of oxygen. More reactive hydrogen consumed the part of oxygen in the zone of an oxygen-rich mixture, so carbon particles are not gaining access to oxygen. Solid carbon particles are bound to other various materials such as mechanical impurities, sulphates, condensates, and liquid fuel residues, some of them with high toxicity – such as polycyclic aromatic hydrocarbons (PAH). The cause of high solid carbon emissions is a significant inhomogeneity of the mixture up to the value λ = 0 inside the fuel droplets where oxygen absences up to λ = ∞ in the space where fuel does not even come. Therefore, solid carbon emissions highly depend on the quality of atomization of the fuel which is injected into the cylinder. The supply of oxygen required for oxidation is improved by increasing the total amount of the air in the cylinder. In Slovakia as well as in other countries (the Czech Republic, etc.), there have been recently multiple instances of removing catalysts from vehicles by services, deactivation of diesel particulate filters (DPF, SCR), or vehicle control units reprogramming (tuning), or a combination of the previous actions. From the perspective of a company and its interest, it is a large interference with vehicle design, and it also affects the relationship with the environment. From the perspective of society, it is irrelevant whether it is the individual's conduct or the conduct of certain groups. This article explores the possible solutions for checking the illegal diesel engines conversion due to deactivation of particulate matter filters in exhaust systems of diesel engines as well as the current legislation that covers this issue.

Abstract: Technical and technological aspects of variable rate nitrogen fertilization receive much attention nowadays. Current commercial technology is based on the use of spectral reflectance of crop. However, these have some limitations as variety dependence, crop health effect and limited use in more developed growth stages. New parameters overcoming these problems need to be assessed and their potential in precision agriculture should be considered. Multispectrally induced fluorescence is a progressive method. In addition to chlorophyll content, it allows to determine phenolic compounds, which is a product of metabolism of the plant under nitrogen deficit and is considered as the most exact indicator of nitrogen deficit. Comparing the spectral reflectance indices (normalized difference vegetation index – NDVI and normalized difference red edge index – NDRE) and multispectral fluorescence index (nitrogen balance index – NBI), these performed similarly in terms of determining the leaves biomass and nitrogen content in %, NDRE and NBI reflected significantly also aboveground N; however, only the correlation of NDVI reflected with N uptake and with leaf area was highly significant.