This article concerns the issues of modeling and the optimizational approach for the performance of ore comminution circuits. A typical, multi-stage comminution circuit was analyzed with the high-pressure grinding rolls unit operating at a fine crushing stage. The final product of the circuit under investigation was, at the same time, a flotation feed in which particle size distribution initially determined the effectiveness of flotation operations. In order to determine the HPGR-based comminution circuit performance, a suitable mathematical model was built wherein the target function was linked directly with the effectiveness of the flotation processes. The target function in the presented model considers the issue in terms of the flotation operation’s effectiveness. The particle size distribution of individual comminution products and resulting from the weight recoveries of individual size fractions were criteria determining the quality of the comminution product. Weight recoveries of individual size fractions, in turn, were tied with the technical operating parameters of individual comminution devices. In the first model, profit maximization was the target function, while the second variant of the model took into account maximization of the useful mineral weight recovery in the concentrate. The HPGR application into ore processing circuits also results in energy saving benefits which were presented in a comparative analysis of the energy consumption of two comminution circuits – the first based on conventional crushing devices, and the second on the HPGR unit application which replaced the rod mills. The main benefit of such a modernization was almost two times lower energy consumption by the fine crushing stage and a decrease in the ball mills’ grinding operations load through bypassing a part of the material directly for the rough flotation operations.
CFD modelling of momentum and heat transfer using the Large Eddy Simulation (LES) approach has been presented for a Kenics static mixer. The simulations were performed with the commercial code ANSYS Fluent 15 for turbulent flow of three values of Reynolds number, Re = 5 000, 10 000 and 18 000. The numerical modelling began in the RANS model, where standard k−ε turbulence model and wall functions were used. Then the LES iterations started from the initial velocity and temperature fields obtained in RANS. In LES, the Smagorinsky–Lilly model was used for the sub-grid scale fluctuations along with wall functions for prediction of flow and heat transfer in the near-wall region. The performed numerical study in a Kenics static mixer resulted in highly fluctuating fields of both velocity and temperature. Simulation results were presented and analysed in the form of velocity and temperature contours. In addition, the surface-averaged heat transfer coefficient values for the whole insert length were computed and compared with the literature experimental data. Good compliance of the LES simulation results with the experimental correlation was obtained.
This paper outlines a method of determining the deformation and strength parameters for a hypothetical, homogeneous, substitute material which approximates the properties of heterogeneous materials in reinforced concrete elements. The model of the substitute material creates a concrete reference model, in which the static - strength - deformation parameters were modified on the basis of the homogenizing function with the homogenization coefficient assumed as the effective reinforcement ratio of the reinforced concrete structural elements. The results of the comparative analysis of the numerical models using the hypothetical substitute material with experimental results for statically loaded beams and deep beams taken from the literature are presented.
Construction planning always requires labour productivity estimation. Often, in the case of monolithic construction works, the available catalogues of productivity rates do not provide a reliable assessment. The paper deals with the problem of labour estimation for reinforcement works. An appropriate model of labour prediction problem is being introduced. It includes, between others, staff experience and reinforcement buildability. In the paper it is proposed, that labour requirements can be estimated with aggregated classifiers. The work is a continuation of earlier studies, in which the possibility of using classifier ensembles to predict productivity in monolithic works was investigated.
The purpose of the paper is to examine the discursive strategies of persuasion exploring the rhetorical
argument from community combined with linguistic politeness. Based on eighty reviews of two French
comedies, the author shows how the persuasive strategies reflect some methods used in advertising
discourse, especially with regard to the rhetoric principle of movere and delectare and indirect means
of interpretation, activated in discourse by the use of quantity and quality.
The topic of this paper is the universal call to holiness with reference to the notion of „ordinary holiness”. The contemporary teaching of the Catholic Church, particularly since Vatican II, has underlined that holiness is both a gift and a task for all Christians. It is illustrated with several papal pronouncements by Paul VI, John Paul II and Benedict XVI. Finally the paper points out to some examples which confrm that any activity in life is appropriate for fulflling the call to holiness. It is also noticed that ordinary holiness is a positive reaction and response of Christ’s disciples to the signs of the time they face. Some of those signs of the time are nowadays: man’s changing attitude to the truth, to human life as a fundamental value, to conjugal love which is in its essence faithful and exclusive, as well as to service as a form of daily love.
The growing popularity of so-called cognitive enhancement technologies raises questions about their impact on the sphere of individual legal responsibility. This article examines the issue of whether, in a situation where a surgeon, prone to making a fatigue-related medical error, refuses to undergo a safe cognitive enhancement before surgery, the surgeon can be attributed liability for damages. The answer to this question is negative, however, as indicated in the article, the impossibility of attributing damages is a result of (1) the lack of professional guidelines requiring doctors to undergo cognitive enhancement; (2) the lack of scientific evidence that the use of such measures results in the elimination of fatigue and reduces the risk of error. As a result, the negative answer to the analyzed question is not determined by the solution of the model of liability for damages adopted in Polish law, but rather by the current state of research on cognitive improvement. This gives the analysis a universal character and makes it possible to relate the method adopted in it to new results of research on means of cognitive enhancement if any.