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  • Author: Daniel Mayer x
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Abstract

A significant number of deserted medieval rural settlements have been identified in Europe. These sites are at risk of disappearance as a consequence of current urban development and cropping intensification implying that relevant features of the cultural landscape informing about past rural traditions in the European countryside may be lost. The objective of this article is to illustrate this fact by means of a case study consisting of a deserted medieval rural upland settlement in Wales. A field walk carried out in this site revealed that old rural traditions and past ways of living can be identified from its own bodily engagement with the surrounding landscape. This evidence is used to argue that strategies that involve personal experience of deserted medieval rural settlements such as agroturism may be implemented to protect these sites and the cultural information contained in them.

Abstract

The magnetic field acting on the ferrofluids causes microstructural conversions that result in a change of their permeability. For this physical phenomenon is referred to as field induced magnetism (FIMA). An experimental method is described for ferrofluids in this state to examine their permeability tensor. Also an analogous phenomenon is described also when there is a change of the ferrofluids permittivity. We call it field induced dielectric anisotropy (FIDA). The contribution describes the method of measuring of the permittivity tensor. It can be expected that the FIMA and FIDA of ferrofluids will find interesting applications in designing of various sensors, in measurement technology, in mechatronic and in other areas of practice.

Identifying Determinants of Residential Property Values in South London

This paper advances the academic work conducted on identifying some of the determinants of residential property values in different countries. Such determinants might include positive factors such as access to amenities, or negative factors such as high voltage overhead transmission lines (HVOTL). The objective explored here is to extend this research in the UK by considering the particular case of residential property values in South London. A number of determinants is considered, grouped and a model which explains the effect of the determinants on value is produced. The elasticities between property values and the distances from different determinants were also analysed to help highlight relationships between the determinants and residential property values. The results showed a relationship between residential property values and the determinants, and a relationship between the determinants themselves.

Abstract

The p-class tower F p (k) of a number field k is its maximal unramified pro-p extension. It is considered to be known when the p-tower group, that is the Galois group G := Gal(F p (k)|k), can be identified by an explicit presentation. The main intention of this article is to characterize assigned finite 3-groups uniquely by abelian quotient invariants of subgroups of finite index, and to provide evidence of actual realizations of these groups by 3-tower groups G of real quadratic fields K = ℚ( √d) with 3-capitulation type (0122) or (2034).

Abstract

The Czech Republic has been developing its motorway network since the 1970s, while efforts to upgrade its railway system from the 1990s have been limited to improvements of existing major lines. Only recently has the government decided to construct new “speed connection” rail lines. This article investigates the possible territorial benefits from the future development of planned motorways and of various speed connection railway options. The modelling is based on Huff’s gravity model that calculates the benefits from improved accessibility, to job and service centres for residents of each municipality. The modelling outcomes are used to compare planned motorway development and rail development options with respect to their efficiency, related to the investment and potential numbers of users.

Abstract

This paper deals with the capacitor using magnetic fluid as a magnetic field controlled dielectrics. It is shown, that dielectrics of this capacitor exhibits magnetic field induced anisotropy.

Abstract

The article is devoted to the physical nature of geomagnetism, magnetic storms and methods of predicting their origin and deals with geomagnetic induced currents called GIC (Geomagnetically Induced Currents) and their effect on power transformers. A simplified, single-phase transmission system is described mathematically and its analysis was performed. Also the phenomenon of periodic semi-saturation of the magnetic circuit of the transformers resulting in current overload of the transformer windings, which can lead to thermal damage of the windings is explained. In addition, there is a significant deformation of the currents in the electrical system. The numerical solution of the system was verified by measurement on an electrical model.

Disturbing magnetic field (so-called magnetic smog) can be in certain areas suppressed by shielding jacket. Disturbing field is possible to be “lead away” from the shielded area with the use of jacket made of materials with high magnetic permeability (so-called passive shielding, or flux-entrapment shielding). If the disturbing field is time-variable, eddy currents are induced into electrically conductive jacket. Magnetic field generated by these eddy currents suppress the disturbing field (this is called active shielding, or lossy magnetic shielding). Both of these principles can be applied altogether (this is called combined shielding). Presented paper states numerical approach to shielding jacket design and is an introduction to following solution of a real problem of magnetic shielding when the disturbing magnetic field is space-time complicated. Effective design of the magnetic shielding should then be formulated as an optimization task.

Abstract

The process of power transmission lines, from source to load is a well-known, if the voltages and currents vary harmonically. With the lines is transmitted active power that is dissipated in load (this power exits from the system) and reactive power (this power oscillates between the source and the load). Note that it would be more appropriate designation the external power and the internal power. Such systems are known as cyclo-dissipative. The active power is dissipated in the load and the reactive power oscillates between the source and the load. Physically, reactive power is delivered to reactive elements of load. Transmitting reactive power increases Joule’s losses and voltage drops on lines. Reactive power can be compensated in a known manner. Compensation reduces the effective value of the current in the line. To the case of periodic but non-sinusoidal voltages and currents has been devoted many publications, conferences, etc. during the past 100 years. But despite much e ort, this problem has not yet been fully solved. In the present article, we show that in a system with a harmonic source of voltage even in the case of a linear pure resistive load a reactive power can be generated and can be compensated. A necessary, but not sufficient, condition is that the resistive load is time-varying. The presented study deals with a periodically sampled resistive load.

Abstract

Background: Finding accurate health-related information on the Internet may be a real challenge for users lacking the critical skills necessary to assess the validity of online content, even if they browse websites that are compliant with credibility criteria. The aim of the study was to check whether an overall high website credibility or compliance to any of the individual criteria for credibility are correlated/associated with a higher quality of health-related information on a sample of Romanian and Hungarian stroke-related websites.

Methods: The cross-sectional study included a sample of 50 websites presenting stroke for the general population in Romanian and Hungarian language. The websites’ compliance with 12 widely recognized credibility criteria, and the completeness and accuracy of the stroke-related articles found on the respective sites were systematically assessed by two independent evaluators applying a common evaluation procedure.

Results: The mean value of the credibility score was 4.3 points (95% CI: 3.9–4.8), the mean value of the completeness score was 4.8 points (95% CI: 4.2–5.5), and the mean value of the accuracy score was 6.6 points (95% CI: 6.3–6.8). Correlation coefficients between the credibility score and completeness/accuracy score did not reach statistical significance (Spearman rho = 0.038, p = 0.793 and Spearman rho = 0.156, p = 0.278, respectively). With a few exceptions, the t-tests for independent sample comparison have shown no significant differences between websites that complied and those that did not comply with each individual credibility criterion.

Conclusions: The mean credibility score of the Romanian and Hungarian stroke-related websites was poor and it was not correlated with neither completeness nor accuracy of the information displayed on the respective pages. With a few, practically irrelevant exceptions, compliance with individual credibility criteria was not associated with higher content quality on the investigated sample.