119 research outputs found
Regularity of pressure in the neighbourhood of regular points of weak solutions of the Navier-Stokes equations
summary:In the context of the weak solutions of the Navier-Stokes equations we study the regularity of the pressure and its derivatives in the space-time neighbourhood of regular points. We present some global and local conditions under which the regularity is further improved
Data Mailboxes in the Czech Republic – Useful or Useless?
This article evaluates the impact of data mailboxes – a new legal and technical initiative introduced to the Czech Republic with effect from 1 st July 2009. In this article we emphasize both the theoretical context of data mailboxes and their practical aspect for private entities. We also evaluate the process of implementation of data mailboxes into the Czech environment, as well as raising the issue whether data mailboxes provide the basis for complete digitalization of public delivery of data
Approaches to identification and interpretation of mining heritage: the case of the Jáchymovsko area, Ore Mountains, Czechia
Mining heritage refers to a complex of both tangible and intangible features and values whose formation was associated with the development of mining activities in the given region. After mining activities are completed, original industrial and related subsidiary structures either fall into dereliction or are subject to conversion. One of frequent modes of transformation of objects is their presentation as heritage and utilization for the needs of tourism. The way of its interpretation and presentation to the public plays a very important role in mining heritage preservation, since it may be attributed not only historical and architectural values, but may also reflect political or ideological background of the period in which it was formed. The paper discusses the definition of mining heritage and the questions concerning its origin, recognition, protection, management and interpretation in the case of the Jáchymovsko area, part of the cross-border mountainous region in Czech-German borderland which is being proposed to be included into the UNESCO heritage list. The Jáchymovsko area is distinguished by the fact that it combines a 500-year-old history of mineral extraction and therefore local mining heritage is very diverse. Thus, different types of local mining heritage and its conversion for other purposes (e.g. tourism) are analysed, ways of local mining heritage identification, management and interpretation are discussed
POSSIBILITY OF HYDRAULIC FLUIDS WITH A LOW ENVIRONMENTAL IMPACT APPLICATION IN AGRICULTURE AND TRANSPORT MACHINERY
Agricultural and transport equipment is ideally suited to use hydraulic oils. After engine oils, hydraulic fluids are the second most important group of lubricants. More than 85 % of these materials are currently mineral oil-based. In view of their high ecotoxicity and low biodegradability, mineral oil-based lubricants constitute a considerable threat to the environment. In contrast, most hydraulic fluids based on plant oils have a low environmental impact and are completely biodegradable. Moreover, lubricants based on plant oils display excellent tribological properties and generally have very high viscosity indices and flash points. For this reason, therefore, particularly soybean, sunflower and rapeseed seem to possess the relevant properties as a potential hydraulic fluid. There are several tribotechnical methods how to assess the current technical state of used lubricants (viscosity, water content, flash point, acidity). One of the modern methods how to detect wear particles is LaserNet Fines, which is a suitable technique for machine condition monitoring. The ageing of test oils is analysed by the Fourier transform infrared spectroscopy (FT-IR); for determining anti-wear properties of hydraulic oils, the standard STN EN ISO 20623:2004 indicates 1 hour under an applied load of 150 N. The objective of the paper is to show the description and examples of modern tribotechnical methods used for determination of the technical state of used biolubricants utilized in agriculture and transport machinery
Growth Response of Sessile Oak and European Hornbeam to Traditional Coppice-with-Standards Management
Research Highlights: The influence of litter raking and livestock grazing on the development of juvenile sessile oak and European hornbeam sprouts as well as on sessile oak standards were studied. Such experiments are very rare, especially in central Europe where these activities have been prohibited for several decades. Little is known on how these ancient management activities affect tree growth. Background and Objectives: Traditional management practices in coppice forests such as grazing and litter raking have been abandoned, but have recently been studied as to whether these practices can substantially contribute to an increase in the species diversity of coppices. The important question is, however, how these practices influence the growth of coppice-with-standards. Therefore, this study focused on the effect of grazing, litter raking, and their combination on both sprouts and adult trees in a coppice-with-standards system one year after harvest. Materials and Methods: The experiment was carried out in the area of the Training Forest Enterprise Masaryk Forest Křtiny, Czech Republic, in a forest stand dominated by sessile oak and European hornbeam. We analyzed 132 oak polycormons, 132 hornbeam polycormons, and 163 oak standards. Results: The number of sprouts per stump was affected by the stump size and management practice: (A) coppice-with-standards, litter raking, and sheep grazing; (B) coppice-with-standards and sheep grazing; (C) coppice-with-standards and litter raking; and (D) coppice-with-standards), but not by tree species. The number of the sprouts as well as their height increased with the stump size. In contrast, grazing resulted in a smaller height of the sprouts while thinner sprouts were found under a combination of grazing and raking. When comparing the species, the oak sprouts were higher and thicker when compared to the hornbeam sprouts. The increment of standards increased after stand harvest. This, however, was not the result of grazing or raking, but the response to the reduction of tree number and thus of competition between neighboring trees. Conclusions: The results showed that there were rather negative impacts from the implemented traditional management practices on the growth of sprouts. This may lead to the question of whether ecological diversity resulting from the traditional practices may prevail their negative effect on the growth of the coppices.O
Obraz jako zdroj rozmanitých informací =A Picture as a Source of a Variety of Information
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Krajina v české geografii a otázka relevance přístupů anglo-americké humánní geografie =Landscape in Czech geography and the problem of relevance of Anglo-American human geography approaches
The article is a response to the discussion on the concept of landscape in Czech geography initiated in No. 1 of Geografie-Sborník ČGS in 2008. This discussion has drawn attention on some possibilities for the future development of human geographic research on landscape in Czechia inspired by Anglo-American human geography. The aim of this article is to contribute to this discussion by presenting own place, time, culture and subject specific views of the conception of landscape in Anglo-American human geography and its past development as well as to suggest possible sources of inspiration for landscape research in Czech geography14515
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