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Number of results: 5
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Abstract

The aim of the present study was to determine changes in oxidative status in plasma of sows during periparturient period using markers of lipid and protein peroxidation intensity. Plasma from 12 pregnant gilts collected on days 14 and 1 before parturition and on days 1, 7 and 14 postpartum was used in the study. As indicators of alterations in the oxidative status, plasma concentrations of thiobarbituric acid reactive substances (TBARS) and sulphydryl groups (SH groups) were measured spectrophotometrically, as well as plasma concentrations of bityrosine and formylokinurenine were determined by the spectrofluorimetric method. Compared to the 14th day antepartum, the concentration of TBARS increased significantly on day 1 postpartum and then decreased significantly on days 7 and 14 after parturition. The concentration of SH groups increased significantly on the last day before parturition and decreased significantly on day 14 postpartum. The concentration of bityrosine increased significantly on the last day before parturition and decreased significantly on days 7 and 14 postpartum. The concentration of formylokinurenine increased significantly on the last day before parturition, remained at this level on the first day after parturition and then decreased slightly on days 7 and 14 postpartum. These results indicate that during periparturient period in sows, especially around the parturition, the oxidative/antioxidative balance is disturbed, which leads to oxidative stress. Considering that oxidative stress is potentially harmful for mothers and neonates, this may be an important factor in the increased risk of diseases occurring during this period.

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Authors and Affiliations

M. Szczubiał
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Abstract

The article introduces a new proposal of a defuzzification method, which can be implemented in fuzzy controllers. The first chapter refers to the origin of fuzzy sets. Next, a modern development based on this theory is presented in the form of ordered fuzzy numbers (OFN). The most important characteristics of ordered fuzzy numbers are also presented. In the following chapter, details about the defuzzification process are given as part of the fuzzy controller model. Then a new method of defuzzification is presented. The method is named center of circles intersection (CCI). The authors compare this method with a similar geometric solution: triangular expanding (TE) and geometric mean (GM). Also, the results are compared with other methods such as center of gravity (COG), first of maxima (FOM) and last of maxima (LOM). The analysis shows that the proposed solution works correctly and provides results for traditional fuzzy numbers as well as directed fuzzy numbers. The last chapter contains a summary, in which more detailed conclusions are provided and further directions of research are indicated.

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Authors and Affiliations

H. Zarzycki
W.T. Dobrosielski
Ł. Apiecionek
T. Vince
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Abstract

Application of active noise reduction (ANR) systems in hearing protectors requires the use of control algorithms to ensure stability of the ANR system and at the same time highly effective active noise reduction. A control algorithm based on NOTCH filters is an example of solutions that meet these criteria. Their disadvantage is operation over a narrow frequency band and a need for prior determination of frequencies to be reduced. This paper presents a solution of the ANR system for hearing protectors which is controlled with the use of modified NOTCH filters with parameters determined by a genetic algorithm. Application of a genetic algorithm allows to change the NOTCH filter reference signal frequency, and thus, adapt the filter to the reduced signal frequency.
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Authors and Affiliations

Paweł Górski
Leszek Morzyński
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Abstract

Effects of charge composition on microstructure, mechanical and fatigue properties of nodular cast irons have been studied. For experiments, five melts of nodular cast iron were used – three types of unalloyed nodular cast irons (with different ratio of steel and pig iron in a charge and different additives for regulation of the chemical composition) and two types of alloyed nodular cast irons (SiMo- and SiCu- nodular cast iron). The microstructure of the specimens was evaluated according to a norm and by automatic image analysis. The mechanical properties were investigated by the tensile test, impact bending test and Brinell hardness test. The fatigue tests were carried out at sinusoidal cyclic push-pull loading at ambient temperature. The best mechanical properties were reached in the nodular cast iron alloyed by Si and Cu, what is related to its microstructure.

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Authors and Affiliations

A. Vaško
J. Belan
E. Tillová

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