Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 8
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

The article is an extension of the suggestion published earlier on determination of the relative position of a point. Introduction of formulas to convert ortho-Cartesian coordinates of points to nondimensional numerical coefficients alongside reverse converting formulas is the main part of the thesis. The said formulas have been completed with demonstrative examples that verify the correctness thereof.
Go to article

Authors and Affiliations

Lech Pitoń
Download PDF Download RIS Download Bibtex

Abstract

Condition monitoring in a centrifugal pump is a significant field of study in industry. The acoustic method offers a robust approach to detect cavitations in different pumps. As a result, an acoustic-based technique is used in this experiment to predict cavitation. By using an acoustic technique, detailed information on outcomes can be obtained for cavitation detection under a variety of conditions. In addition, various features are used in this work to analyze signals in the time domain using the acoustic technique. A signal in the frequency domain is also investigated using the fast Fourier method. This method has shown to be an effective tool for predicting future events. In addition, this experimental investigation attempts to establish a good correlation between noise characteristics and cavitation detection in a pump by using an acoustic approach. Likewise, it aims to find a good method for estimating cavitation levels in a pump based on comparing and evaluating different systems.
Go to article

Authors and Affiliations

Ahmed Ramadhan Al-Obaidi
1
ORCID: ORCID

  1. Faculty of Engineering, Department of Mechanical Engineering, Mustansiriyah University, Baghdad, Iraq
Download PDF Download RIS Download Bibtex

Abstract

The implementation of micro scale combined heat and power systems is one of the ways to improve the energy security of consumers. In fact, there are many available large and medium scale cogeneration units, which operate according to the Rankine Cycle. Due to European Union demands in the field of using renewable energy sources and increasing energy efficiency result in the importance of additionally developing systems dedicated for use in residential buildings, farms, schools and other facilities. This paper shows the concept of introducing thermoelectric generators into typical wood stoves: steel plate wood stoves and accumulative wood stoves. Electricity generated in thermoelectric generators (there were studies on both three market available units and a prototypical unit developed by the authors) may be firstly consumed by the system (to power controller, actuators, fans, pumps, etc.). Additional power (if available) may be stored in batteries and then used to power home appliances (light, small electronics and others). It should be noted that commercially available thermoelectric generators are not matched for domestic heating devices – the main problems are connected with an insufficient heat flux transmitted from the stove to the hot side of the generator (caused e.g. by the non -homogeneous temperature distribution of the surface and bad contact between the stove and the generator) and inefficient cooling. To ensure the high efficiency of micro cogeneration systems, developing a dedicated construction both of the generator and the heat source is necessary.

Go to article

Authors and Affiliations

Krzysztof Sornek
Mariusz Filipowicz
Download PDF Download RIS Download Bibtex

Abstract

With reference to the situation experienced in several Polish collieries where the risk of occurrence of gas-geodynamic phenomena is increasing and decisions to start the mining activities need to take numerous constraints associated with previous mining into account, this paper addresses certain geo-mechanical aspects of longwall mining in the zones of excavation edge interactions giving rise to major changes in the conditions of the deposit and rock strata, as a consequence of previous mining operations in adjacent coalbeds. Starting from the analytical description of displacements and stresses in the proximity of longwall mining systems, the paper summarizes the results of model tests and investiga-tions of the influence that the excavation edge has on the behavior and structural continuity of a portion of the coal body in the coalbed beneath or above an old excavation. Based on selected nonlinear functions emulating the presence of edges in the rock strata, a comparative study is carried out by investigating two opposite directions of workface advance, from the gob area towards the coal body and from the coal body towards the gobs. The discussion of the results relies on the analysis of roof deformation and the concentration factor of the vertical stress component at the workface front.

Go to article

Authors and Affiliations

Dariusz Chlebowski
Zbigniew Burtan
Jerzy Cieślik
Andrzej Zorychta
Download PDF Download RIS Download Bibtex

Abstract

The paper reports on the photoelectrical performance of the long wavelength infrared (LWIR) HgCdTe high operating temperature (HOT) detector. The detector structure was simulated with commercially available software APSYS by Crosslight Inc. taking into account SRH, Auger and tunnelling currents. A detailed analysis of the detector performance such as dark current, detectivity, time response as a function of device architecture and applied bias is performed, pointing out optimal working conditions.

Go to article

Authors and Affiliations

W. Gawron
P. Martyniuk
P. Madejczyk
A. Rogalski
J. Piotrowski
Download PDF Download RIS Download Bibtex

Abstract

This article is a proposal of a new edition of the text of Agnus Dei contained in the manuscript kept in the Kórnik Library (manuscript No. BK 101), consisting of comprehensive transliteration, scientific transcription with linguistic commentary and - which is a significant novelty compared to the previous editions of historical texts - philological translation. The combined analysis of language and versification allowed for a fuller reading of the meaning of the text and - in consequence - the drafting of a new transliteration and transcription, in many places different from the one published by M. Muszyński in 1968. The article contains a description of the codex in which the presented text is written, a short history of the European and Polish cult of wax medallions consecrated by the Pope, as well as the Latin text of a poem about Agnus Dei, which may be the source (although not necessarily a direct one) of the Polish text.

Go to article

Authors and Affiliations

Karolina Borowiec
Katarzyna Dobicka
Olga Dwornik
Maciej Gajzlerowicz
Natalia Hemmerling
Mariusz Leńczuk
Barbara Łukaszewska
Dorota Masłej
Tomasz Mika
Urszula Modrzyk
Dorota Rojszczak-Robińska
Marta Siwińska
Alicja Tempłowicz
Olga Ziółkowska

This page uses 'cookies'. Learn more