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  • Author: Jozef Varga x
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Abstract

The aim of the study was to analyse the impact of land use and altitudinal gradient including geological conditions on selected soil physical properties with subsequent effect on earthworms as important soil organisms. The research was conducted at three study sites (Očová – OC, Tajov – TA, Liptovská Teplička – LT) situated in the different climatic and natural conditions of Slovakia each with 3 plots differing in land use (arable land - AL, permanent grasslands – PG, forest land – FL). During 2014 over two periods, we measured soil penetration resistance (PR) with total depth of the measurement (DP) and soil moisture (SM). Earthworms were hand sorted counted and weighed. We found out high variability of measured parameters conditioned by time, space (altitudinal gradient) and land use. PR values of all measurements ranged from 0.19 to 5.00 MPa, DP values from 0.02 to 0.80 m and soil moisture from 2 to 50%. Paired samples test confirmed differences between different land use types mainly between AL and FL plots. There were confirmed significant differences between three ecological gradients in all observed properties with one exception. Correlations among observed variables under different altitudinal gradients and land use types were found. The earthworm density and biomass was significantly higher in permanent grasslands compared to forest and arable land. In arable land, the earthworm density and biomass negatively correlated with the penetration resistance and positively with the depth of the total measurements. In permanent grasslands earthworm biomass positively correlated with soil moisture.

Abstract

The article deals with analysis of the charakter of the interaction of milling tools with cutting edges of the primary contact with the working materials. Based on the monitoring of wear is observed various charakter and intensity of wear of the cutting wedge, which is dependent on the position of the milling tool frame to the workpiece. Given the issue is analyzed in the state, according to the proposed method is the primary interaction of tool and workpiece milling tool, in order to increase tool life.

Abstract

Application of miniature machining is currently rapidly increasing mainly in biomedical industry and machining of hard-to-machine materials. Machinability of materials with increased level of toughness depends on factors that are important in the final state of surface integrity. Because of this, it is necessary to achieve high precision (varying in microns) in miniature machining. If we want to guarantee machining high precision, it is necessary to analyse tool wear intensity in direct interaction with given machined materials. During long-term cutting process, different cutting wedge deformations occur, leading in most cases to a rapid wear and destruction of the cutting wedge. This article deal with experimental monitoring of tool wear intensity during miniature machining.

Abstract

Technology of rotational turning is a progressive machining technology with a defined tool geometry, which has the potential to replace conventional finishing technologies using the tools with undefined geometry. This article deals with the influence of the cutting parameters on the surface roughness after machining and comparing the roughness parameters with the computed roughness. Since this is a new machining technology with new kinematic structure with atypical geometry of the cutting tool, the article is focused on the measurement methodology of the certain roughness parameters on machined surface after rotary turning with nonlinear cutting edge. Executed experimental tests and their evaluation are verified with the method of roughness parameters determination and results show, how the real process correlate with implementation of empirical relations.

Abstract

In this article, unconventional kinematics of turning is examined with the aim on influence of cutting parameters on surface layers residual stress. The auto-rotary cutting tool prototype for turning was developed, designed and constructed at the University of Zilina. The tool is made of high speed steel. Residual stress examination of material 100Cr6 was performed by non-destructive measuring method of X-ray diffraction. This method is able to determine normal and shear stress conditions without damaging the examined sample.

Abstract

Skiving is a relatively new technology that can partially replace a lead of tooth grinding. This article aims to introduce the results of skiving in a particular production. In the first parts of the article authors focused on the technology of skiving and its patterns. In the following part they introduce results of tooling. The last part of the article describes appreciation, advantages and disadvantages of the technology.

Abstract

Increased use of forging tools in mass production causes their increased wear and creates pressure to design more efficient renovation process. Renovation is complicated because of the identification of cracks expanding from the surface to the core material. Given that the production of forging tools is expensive, caused by the cost of tool steels and the thermo-chemical treatment, it is important to design forging tool with its easy renovation in mind. It is important to choose the right renovation technology, which will be able to restore the instrument to its original state while maintaining financial rentability. Choosing the right technology is difficult because of nitrided and heat-treated surface for high hardness and wear resistance. Article discusses the use of non-destructive method of detecting cracks taking into account the size of the cracks formed during working process.

Abstract

This article is focused on non-destructive detection method of residual stress and chemical properties of stainless steel. By X-ray diffractometry, there it is possible to determine accurately the values of residual stress and austenite percentage without any damage the sample without any change of its original function. Identification of residual stress and its distribution can improve the prediction of failures or damage incidences due to workload over lifetime of components. It can be also used as one of evaluation parameter of suitability of applied manufacturing technological operations.

Abstract

Despite the fact that wind erosion seriously affects the sustainable use of land in large part of the world and even though in Slovakia there is not that big percentage of agricultural land influence by wind erosion it still has an effect on the soil. Valid wind erosion model that predicts wind-blown mass transport on regional scale is lacking. The objective of this research was to compare two empiric methods to determine wind erosion. One of them is deflametric method, in which we capture soil units in one hour during wind erosion events. Second method we used was volumetric method where we calculate amount of eroded soil behind the wind barrier. With deflametric method we determined that actual wind speed needed to lift and carry soil unites is 9 - 10 m.s-1. With volumetric calculation we found out that our measurement is 1.7 times higher than in WEQ model. We can say that models can portray certain areas and soil types, but only field measurement can provide precise amount of eroded soil on particular land.

Abstract

Value tightening of acceptable soil loss by wind erosion in amendment to the Act No. 220/2004 on Protection and Use of Agricultural Land in the Slovak Republic from 1st of April 2013 is necessary to reconsider wind erosion intensity in agricultural territories. The paper presents results of wind erosion intensity calculation by using Wind Erosion Equation (WEQ) that is recommended by Act No. 220/2004. As observed we choose cadastral area Moèenok territory and had determined and compared changes in levels of soil endangerment of arable land by wind and spatial delamination of wind erosion in specific territory of Moèenok. According to WEQ calculation, we determined that soil loss from 3778.85 ha arable land is 1220.52 ha, which is highly endangerment by wind erosion. By defining levels of soil erosion endangerment (LSEE), we found out that area in 3rd class of endangerment rose from 1.48% to 43.37% after changing acceptable soil from 40 to 15 t ha-1 year-1. Results enable us to specify priority areas where to implement erosion control measures in according to sustainable use and protection of arable land in model area.