During the spring of 1998 sympagic algae and meiofauna were studied in Ross Bay on the western coast of the Kane Basin between Ellesmere Island and Pim Island (Canada). Ice samples were collected by ice coring and the lowermost 2 cm sections were analysed. The sea-ice flora was composed of 59 taxa and was dominated by Nitzschia frigida, Navicula pelagica, Fragilariopsis oceanica and unidentified flagellates (over 60% of total number). Abundance of algae ranged from 1×109 to 3×109 cells per square meter. Sea-ice meiofauna was composed of Nematoda and Harpacticoida and was strongly dominated by nematodes (99.76%). Total sympagic meiofauna abundance ranged from 37.5×103 to 146.1×103 ind. and biomass from 2.88 to 8.83 mg C per m2. There was no clearly marked patchiness in the horizontal distribution of sympagic algae and meiofauna.
Thermoregulation is fully developed in 5 day old Wilson's storm petrels Oceanites oceanicus (Kuhl). Resting metabolic rate (RMR) and body temperature (Tb) of unattended 1- and 3-day old chicks continuously decrease at ambient temperature (Ta) of 5°C. After being heated the chicks return to normothermia. Ability to survive temporal deep hypothermia seems to be an adaptation to absence of parents and low temperatures in the nest during first days of life. After snow storm, during two days of starvation, chick RMR decreases by 40% at Ta of 0°C, but chick Tb is stable. This suggest decrease of thermal conductance (Ct). Fall of Ct may suggest beginning of hypohermia.
The article presents the phenomenon of increasing sharing in-formations for free on the Internet and the contemporary development of gift economy in the form of a movement most often called cybercommunism. The article points out two basic attitudes in treating information. According to the first one, information should be treated as a commodity to which property rights can be attributed and which is subject to market play. This involves such issues as copyright, fees, licenses and other ways of protecting the interests of market players. The second attitude is to treat valuable information as a common good, often with a moral imperative to share it (to varying degrees Open Source and Open Acces, the idea of copyleft, DIY, P2P network, YouTube, The Pirate Bay domain etc.). Since every concept or movement proclaiming a community of goods is called communism (in a broader sense of the word, in a narrower sense it is a specific political system, e.g. the Soviet Union), today we are dealing with digital communism on the Internet. Some researchers (Firer-Blaess, Fuchs) point to Wikipedia as an example. The Internet encyclopedia operates on the basis of principles that go beyond the capitalist way of production and represent an informational-communist way of production: in the subjective dimension, it is a cooperative work and in the objective dimension, a shared ownership of the means of production. The text also presents the division of ethics into an abstract and concrete one, applied to the behaviour of network users. If someone within the framework of an abstract ethics preaches the principle of “You will not pirate.” (copying and distributing illegally) is a corresponding principle of specific ethics that says “You will not pirate unless O1 or O2...or he.” In practice, concrete ethics push many Internet users to treat Internet resources as a common good, from which everyone can draw according to their own needs. Digital communism can be treated, on the one hand, as a partially implemented idea and, on the other, as a postulate. From an axiological point of view, this postulate would be connected with the Internet implementation of equality (access to resources for everyone) and freedom (access to all information).
The article presents the procedure for how to establish a mathematical model of nitrogen oxides formation based on the theory of dimensional analysis. The model is based on selected physical quantities (parameters) measurable during regular operation of a heat generation plant. The objective of using dimensional analysis to describe nitrogen oxides formation is to show that between operating parameters of the combustion equipment and the NOx formation there is a significant correlation.
The obtained results, which are further described in this article, have proved this fact. The obtained formula expressing nitrogen oxides formation, based on dimensional analysis, applies universally to any boiler fuelled by coal, gas or biomass. However, it is necessary to find C, m, n constants for the formula by experiment, individually for each type of boiler and used fuel. The experiment is based on on-line measurements of selected operational parameters for a given boiler, combusting a certain type of fuel with its actual moisture content and calorific value. The methodology, described in this article, helps to find relationships between the operational parameters and the formation of NOx emissions for a particular furnace. The developed mathematical model has been validated with boilers fuelled by black coal and biomass. Both the results obtained from direct measurements of NOx in both types of boilers, and the results obtained by calculation using equation based on the dimensional analysis, are in a very good accord. When burning coal, the variation between NOx expression from the model and the on-line measurements ranges between -12.23 % and + 9.92 %, and for burning biomass between -0.54 % and 0.48 %.
The intention of the authors is to inform the professional community about the suitability of the dimensional analysis to describe any phenomena for which there is currently no exact mathematical formulation based on differential equations or empirical formulas. Many other examples of dimensional analysis applications in practice may be found in the work of Čarnogurská and Příhoda (2011).
For solving a partial different equation by a numerical method, a possible alternative may be either to use a mesh method or a meshless method. A flexible computational procedure for solving 1D linear elastic beam problems is presented that currently uses two forms of approximation function (moving least squares and kernel approximation functions) and two types of formulations, namely the weak form and collocation technique, respectively, to reproduce Element Free Galerkin (EFG) and Smooth Particle Hydrodynamics (SPH) meshless methods. The numerical implementation for beam problems of these two formulations is discussed and numerical tests are presented to illustrate the difference between the formulations.
Today, a cascaded system of position loop, velocity loop and current loop is standard in industrial motion controllers. The exact knowledge of significant parameters in the loops is the basis for the tuning of the servo controllers. A new method to support the commissioning has been developed. It enables the user to identify the moment of inertia as well as the time constant of the closed current loop simultaneously. The method is based on the auto relay feedback experiment by Aström and Hägglund. The model parameters are automatically adjusted according to the time behaviour of the controlled system. For this purpose, the auto relay feedback experiment is combined with the technique of gradual pole compensation. In comparison to other existing methods, this approach has the advantage that a parametric model for the open velocity loop is derived directly.
en
pl
