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Vopalensky M.,College of Polytechnics Jihlava | Platil A.,Czech Technical University
IEEE Transactions on Magnetics | Year: 2013

A typical commercially available magnetoresistive sensor, and particularly an anisotropic magnetoresistive sensor, employs a full bridge of the Wheatstone type formed by two complementary magnetoresistive elements in each branch. This configuration provides linearized response and enlarged sensitivity compared to any other configuration made up of the same elements. Since in a large scale production it is practically impossible to adjust the zero-field resistances of all the four elements to an exactly identical value, there is always some zero-field offset present at the bridge output diagonal even when the sensor is placed in the zero magnetic field. The sensitivity of the sensor, i.e., the ratio of the output voltage change to the change of the measured field H , is associated with the sensitivity of the individual elements. The change of the output voltage is determined by the change of the resistance Δ R of the individual elements. Both the offset and the sensitivity of a full-bridge magnetoresistive sensor is dependent on the zero-field resistances Ri of the elements. However, as in most metallic material, the resistivity of a magnetoresistive element is influenced by temperature. Hence, both the offset and the sensitivity of a real magnetoresistive sensor is temperature dependent. It can be shown that, theoretically speaking, the offset is temperature independent when the bridge is supplied with a constant voltage (but the sensitivity in that case is temperature dependent), and the sensitivity is temperature independent when the bridge is supplied with a constant current (but the offset in that case is temperature dependent). This hypothesis has been verified on KMZ52 sensor (albeit in small temperature range-about 25 ° C-45 ° C). © 1965-2012 IEEE.

Brtnik B.,College of Polytechnics Jihlava
WSEAS Transactions on Circuits and Systems | Year: 2011

Circuits with switched capacitors are described by a capacitance matrix. As there are also graph methods of circuit analysis in addition to algebraic methods, it is clearly possible in theory to carry out an analysis of the whole switched circuit in two-phase switching exclusively by the graph method as well. The phase of switching are called even (E) and odd (O), not 1 and 2 to avoid confusion between the sign of the phases and of the nodes. For this purpose it is possible to plot a Mason graph of a circuit, use two graphs to reduce oriented graphs for all the four phases of switching, and then plot a summary MC-graph from charge and voltage graphs. Summary MC-graph is now constructed by the incomplete common skeletons of the V-graph and the Q-graph in all four phases, branches obtained for EO and OE phase are drawn between these nodes, while their resulting transfer is multiplied by 2 1 - z to express the delay between the two phases. This summary MC-graph can then be interpreted by the Mason's relation to provide transparent voltage transfers, and so it is possible to reach the final result a quite fully graphically. This method can be used for circuits containing operational amplifier with the break point frequency, too, but summa graph is rather complicated in this case, because this description is based on the modified nodal method, where the number of nodes is remains.

Hedija V.,College of Polytechnics Jihlava
Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis | Year: 2014

This study aims to estimate the gender pay gap, cleansed at least partially of the effect of intrahousehold specialization on productivity. The estimate is based on EU-SILC data for 19 member countries of the European Union. We use an estimate of the average treatment effect on the treated, supplemented by a matching procedure to estimate the unexplained part of the gender pay gap and use a subsample of employees earning more than their partners, thus minimizing the impact of childand family-care on the gender pay gap. We conclude that the unexplained gender pay gap amounts approximately 10 percent working to the disadvantage of women. If we assume that the dominant role in family- and child-care is taken up by the partner earnings a lower wage, then this difference could neither be explained by differences in the observed personal and company characteristics nor by the dominant role of women in care for the household and children and could actually be due to wage discrimination against women.

Siska L.,College of Polytechnics Jihlava
Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis | Year: 2011

The subject of this article lies in the analysis of the financial performance of 481 enterprises with more than 20 employees based in the Vysočina Region. The analysis was carried out on the basis of publicly available data for the period of 2006-2008. The comparison used adjusted average values of ROS and sales growth for the years specified above. The results indicate differences between industrial sectors, as well as between the districts of the Vysočina Region. Financially well-performing agricultural enterprises are mostly located in the Region of Pelhřimov, while successful industrial enterprises tend to be based in the Districts of Ždár nad Sázavou and Havlíčkův Brod. On the other hand, construction companies are most successful in the Districts of Pelhřimov and Jihlava.

Rehulka J.,Silesian Museum | Minarik B.,College of Polytechnics Jihlava
Aquaculture Research | Year: 2012

Physiological (reference) value intervals determined by the lower 2.5% and upper 97.5% quantiles were calculated for blood plasma cholesterol (CHOL) and triacylglycerol (TGL) in farmed rainbow trout, Oncorhynchus mykiss, in raceway culture. The fish were given dry pelleted diets that contained 37-47% crude protein and 7-14% crude fat and were kept at a stocking density of 50 kg m -3 in tanks provided with running freshwater at an ambient temperature of 3-16°C and dissolved oxygen, 8.4-11.5 mg L -1. Blood was sampled between September and November at a photoperiod of 9:00-13:00 hours: 11:00-15:00 hours (light:dark). Cholesterol levels were significantly (P = 0.0001) greater in males (4.7-12.1 mmol L -1, n = 34, mean weight 406 ± 138 g) than immature females (3.2-9.7 mmol L -1, n = 386, mean weight 416 ± 147 g). Physiological range for TGL in immature females and males was 2.4-14.4 mmol L -1 (n = 249, mean weight 418 ± 149 g). The distribution and density of the quantiles in the tested reference group were made possible by the use of histograms, which showed normal distributions for CHOL in males and in females, but not for TGL, in which a sinistral asymmetry was found. Correlation and regression analyses indicated significant (P = 0.0000) dependence between the CHOL and total protein (r 2 = 76.2%), CHOL and Fulton's condition factor (r 2 = 43.3%) and CHOL and absolute weight of liver (r 2 = 45.5%). Fluctuation in cholesterolaemia and triacylglycerolaemia, depending on nutrition and the aquaculture method is discussed below. © 2011 Blackwell Publishing Ltd.

Circuits with switched capacitors are described by a capacitance matrix and seeking voltage transfers then means calculating the ratio of algebraic supplements of this matrix. As there are also graph methods of circuit analysis in addition to algebraic methods, it is clearly possible in theory to carry out an analysis of the whole switched circuit in two-phase switching exclusively by the full graph method as well. In this case the summary graph can be constructed by the transformation graph or two graphs and can be simply evaluated by the Mason's relation.

Hojdarova M.,College of Polytechnics Jihlava
APLIMAT 2016 - 15th Conference on Applied Mathematics 2016, Proceedings | Year: 2016

This paper gives basic functions and general principles for effective application of technical diagnostics, which forms a significant part of the whole system of rules for optimal machine operability protection. Evaluation of the normative for the right time of an element renewal helps to increase economy of the whole machine operation and brings financial savings.

Krejcova J.,College of Polytechnics Jihlava
APLIMAT 2016 - 15th Conference on Applied Mathematics 2016, Proceedings | Year: 2016

The paper discusses the results of the examinations in mathematics at the College of Polytechnics Jihlava. The aim is focused on the differences between the scores of students of different secondary schools. This work is a part of a long-term monitoring, which tests the same students, and monitors their progress.

Dvorak K.,College of Polytechnics Jihlava
Proceedings of 2016 7th International Conference on Mechanical and Aerospace Engineering, ICMAE 2016 | Year: 2016

Free form surface modeling is one of the most advanced procedures of creating digital models in CAD. Use of free surface for creating solid models has become increasingly relevant in terms of technological possibilities of production in the subsequent phases of the product lifecycle. Multi-axis computer-controlled machines are standard even in small workshops and rapid prototyping is undergoing progressive development and deployment of industry. Initial geometry is a system of free curves in space. Free-form surfaces are reference geometry for shape complex solid objects. Applicability of free formed bodies for implementing subsequent manufacturing processes depends on the consistency of surfaces enveloping model. Using exact quantitative analysis of the free-form surface is difficult and inappropriate. The presented paper describes analysis methods of initial free curves and subsequent free areas in order to identify and assess the consistency and smoothness of the surface for the use the model in the subsequent phases of the product lifecycle. © 2016 IEEE.

Krejci I.,College of Polytechnics Jihlava
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2013

Recently, physical modelling of human and animal organs has become very popular. The objective of this invention was to construct a physical lung model - an apparatus comprising an artificial lung and an automatic self-controlled system working on a principle of a negative feedback loop. This contribution is focused mainly on the function of the control system with a special attention paid to the sensor network. The control system is equipped with sensors measuring various physical variables (e.g. air flow, pressure difference) necessary for a proper system operation. Sampling frequency, sensorstype and their accuracy play an important part in the quality of measurement and directly affect the accuracy of the control response. The physical lung model and the sensor system have been successfully built and fully completed from the hardware and software's point of view. In the future, this lung model is expected to be used in different testing applications, e.g. in studies comparing physiological and pathological breathing patterns or observing effects of different aerosols on the lung tissue. © IFAC.

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