Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 9
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

The exploitation and processing of lignite in the Bełchatów region is connected with the formation of various mineral waste materials: varied in origin, mineral and chemical composition and raw material properties of the accompanying minerals, ashes and slags from lignite combustion and reagipsum from wet flue gas desulphurisation installations. This paper presents the results of laboratory tests whose main purpose was to obtain data referring to the potential use of fly ashes generated in the Bełchatów Power Plant and selected accompanying minerals exploited in the Bełchatów Mine in the form of self-solidification mixtures. The beidellite clays were considered as the most predisposed for use from the accompanying minerals , due to pozzolanic and sorption properties and swelling capacity. Despite the expected beneficial effects of clay minerals from the smectite group on the self-settling process as well as the stability of such blends after solidification, the results of physical-mechanical tests (compressive strength and water repellence) were unsatisfactory. It was necessary to use Ca (OH)2, obtained from the lacustrine chalk as an activator of the self-settling process It was necessary to use lacustrine chalk as an activator of the self-solidification process. The presence of calcium will allow the formation of cement phases which will be able to strongly bond the skeletal grains. Also, the addition of reagipsum to the composition of the mixture would contribute to the improvement of the physico-mechanical parameters. The elevated SO4 2– ion in the mixture during the solidification allows for the crystallization of the sulphate phases in the pore space to form bridges between the ash and clay minerals. The use of mixtures in land reclamation unfavourably transformed by opencast mining in the Bełchatów region would result in measurable ecological and economic benefits and would largely solve the problem of waste disposal from the from the operation and processing of lignite energy.

Go to article

Authors and Affiliations

Elżbieta Hycnar
Marek Waldemar Jończyk
Tadeusz Ratajczak
Download PDF Download RIS Download Bibtex

Abstract

At the end of 2018, when the Hučivá Cave (Hučivá diera, Rausch Keller) was explored in Tatranská Lomnica, profile deposits in rear areas of the cave were found disturbed by an amateur excavation. One stone artefact was first found in back-dirt clay-layer material at the excavation pit, later joined by four more specimens from the cleaned pit profile. The Typological analysis of the artefacts shows, that their closest parallels are found in inventories of the Magdalenian culture. Hučivá is the only cave in the whole Tatras with documented prehistoric settlement and the only Slovak cave with evidence of the Magdalenian culture. The discovery provides new information concerning subsistence strategies of late Pleistocene hunters in High Tatra Mountain landscapes. In light of this discovery, the possibility of seasonal movements along the northern slopes of this mountains range to the east and then south, through the mountain passes to the upper Spiš region should now be considered.

Go to article

Authors and Affiliations

Paweł Valde-Nowak
Marián Soják
Download PDF Download RIS Download Bibtex

Abstract

An unsustainable energy mix and energy overconsumption contribute to negative processes such as environmental pressure or energy dependency. The aim of the article is to assess the European Union countries situation in terms of sustainable energy consumption. Eurostat was were used in the analyses. The research was based on synthetic indicators for 2017 data. A non-standard method was used. In accordance with the assumptions of sustainable energy consumption, six indicators were proposed: primary energy consumption (2005=100), final energy consumption (2005=100), share of renewable energy in energy consumption, deficit/surplus in the 2020 renewable energy sources consumption target, energy import dependency (%), greenhouse gas emissions intensity of energy consumption (2000=100). The share of renewable energy in energy consumption and deficit/ surplus in the 2020 renewable energy sources consumption target are stimulants, other features are destimulants. The European Union countries were classified into four groups due to the situation in terms of sustainable energy consumption (first class – favorable situation, second class – quite favorable situation, third class – rather unfavorable situation, fourth class – unfavorable situation). According to the results in twelve countries the situation was identified as favorable or quite favorable, while in the other sixteen countries as rather unfavorable and unfavorable. However, all countries have entered the path of necessary changes. It is important to continue monitoring and analyzing the progress of European Union countries in the field of energy and climate policy.

Go to article

Authors and Affiliations

Luiza Julita Ossowska
Dorota Agnieszka Janiszewska
Download PDF Download RIS Download Bibtex

Abstract

The amount of waste from washing dolomite aggregates increases continuously. Aggregates are washed to remove clayey pollutants.They consist of a large amount of clay minerals and carbonates. Their properties and amount depends on the type of raw material and type of washing technology. Utilization of waste from washing aggregates is common problem and has not been sought out yet. Their usage as the raw material in ceramics might be environmentally friendly way to utilize them.

This paper presents technological properties, phase composition and microstructure analysis of materials made of waste sludge from washing dolomite aggregates. Research was divided into three parts: technological properties analysis, phase composition analysis and microstructure analysis.

Samples made of waste dolomite sludge were formed in laboratory clay brick vacuum extruder and fired at 900, 1000 and 1100°C. For final materials, apparent density, open porosity, water absorption, compressive strength and durability were examined. Results of technological research suggest the possibility of the application of the waste sludge from washing aggregates in building ceramics technology as bricks materials. Waste sludge from washing dolomite aggregates can be used as the main raw material of building ceramics masses. Without any additional technological operations (e.g. drying or grinding), the material with satisfactory properties was obtained. According to durability results all obtained materials can be used for masonry protected against water penetration and without contact with soil and ground water and also for masonry subjected to passive exposure (F0 – according to the standard EN 771-1).

Go to article

Authors and Affiliations

Ewelina Kłosek-Wawrzyn
Grzegorz Łój
Anna Bugaj
Wojciech Wons
Keywords HTAC gas combustion
Download PDF Download RIS Download Bibtex

Abstract

HTAC (High Temperature Air Combustion) technology is one of the most important achievements in combustion engineering of recent years. The main idea of the technology is to organize combustion in such a way that reaction takes place in almost whole volume of combustion chamber with very uniform gas and temperature field. It can be done by preheating air above the ignition temperature of fuel, separation of air and fuel nozzles and by high recirculation inside the combustion chamber. Uniform and moderated temperatures result in very low thermal NO emission, and on the other hand, long enough rcsiclcncc time in the chamber results in low CO and incomplete products emission. In this paper authors present simple mathematical model which allows for estimation of influence of air temperature and flue gas recirculation rate on final emission on NO and CO.
Go to article

Authors and Affiliations

Kamil Malczyk
Andrzej Szlęk
Download PDF Download RIS Download Bibtex

Abstract

Canal connecting Elbląg with Ostróda was built in the XIX century to transport corn to the port of Elbląg. Due to economic and political changes it never played its economic function. Now it is a tourist attraction. The canal is thus of some tourist value which is difficult to assess. Tourist value of the Elbląg Canal was assessed with the travel cost method (TCM) within the study carried out in 2003. The study allowed for estimating the object’s value based on its usefulness expressed by inclination to payment. Three groups of users were distinguished when analysing the demand for recreational canal’s services: tourists using ships of the Elbląg–Ostróda Navigation Company, individual sailors and anglers. Total tourist value of the canal calculated as NPV of the annual value of canal’s services depends on adopted interest rate. At a rate of 3.2% the value is 328 thous. PLN (73.9 thous. euro), at a rate of 4% – 282 thous. PLN (63.5 thous. euro), while at 8% interest rate it decreases to 160 thous. PLN (36.0 thous. euro).

Go to article

Authors and Affiliations

Tadeusz Liziński
Marcin Bukowski
Download PDF Download RIS Download Bibtex

Abstract

Objectives: The aim of the study was to assess the relationship between body composition, nutritional status and physical ability in elderly outpatients.
Method:. In this cross-sectional study, demographic data and medical history were collected from patients aged ≥60 years followed in the Geriatric Outpatient Clinic from October 2010 to February 2014. Body composition was examined using a dual-energy X-ray absorptiometry. Physical performance was assessed by gait speed (GS), Timed Up & Go Test (TUG), Six Minute Walk Test (6MWT). The nutritional status was evaluated using the Mini Nutritional Assessment (MNA) and serum albumin level.
Results: Mean age (± SD) of 76 patients (64.47% men) was 71.93 ± 8.88 yrs. The most common diseases were: hypertension (89.47%), coronary heart disease (81.58%) and chronic heart failure (68.4%). In multiple regression analyses, the factors significantly affecting GS were: age (B = –0.017, p ≤0.0001), good nutritional status (B = 0.038, p <0.01) and percent of lower extremity fat (B = –0.009, p <0.05). Longer TUG time was associated with poorer nutritional status (B = –0.031, p <0.01), older age (B = 0.01, p <0.01) and a higher number of comorbidities (B = 0.034, p <0.05). 6MWT was influenced negatively by age (B = –3.805, p <0.01) and percent of lower extremity fat (B = –2.474, p <0.05).
Conclusions: Age and nutritional status remain a strong determinant of physical fitness deterioration. Different measures of physical performance are influenced by different elements of body composition — no single element of body composition was found determining the deterioration of all assessed parameters of physical fitness.
Identifying the relationship between body composition, nutritional status and physical performance can help elucidate the causes of disability and target preventive measures.
Go to article

Authors and Affiliations

Paulina Fatyga-Kotula
1
Barbara Wizner
2
Małgorzata Fedyk-Łukasik
2
Tomasz Grodzicki
2
Anna Skalska
2

  1. Department of Toxicology and Occupational Diseases, Jagiellonian University Medical College, Kraków, Poland
  2. Department of Internal Medicine and Gerontology, Jagiellonian University Medical College, Kraków, Poland
Download PDF Download RIS Download Bibtex

Abstract

This work aims to further compensate for the weaknesses of feature sparsity and insufficient discriminative acoustic features in existing short-duration speaker recognition. To address this issue, we propose the Bark-scaled Gauss and the linear filter bank superposition cepstral coefficients (BGLCC), and the multidimensional central difference (MDCD) acoustic feature extracted method. The Bark-scaled Gauss filter bank focuses on low-frequency information, while linear filtering is uniformly distributed, therefore, the filter superposition can obtain more discriminative and richer acoustic features of short-duration audio signals. In addition, the multi-dimensional central difference method captures better dynamics features of speakers for improving the performance of short utterance speaker verification. Extensive experiments are conducted on short-duration text-independent speaker verification datasets generated from the VoxCeleb, SITW, and NIST SRE corpora, respectively, which contain speech samples of diverse lengths, and different scenarios. The results demonstrate that the proposed method outperforms the existing acoustic feature extraction approach by at least 10% in the test set. The ablation experiments further illustrate that our proposed approaches can achieve substantial improvement over prior methods.
Go to article

Authors and Affiliations

Yunfei Zi
1
Shengwu Xiong
1

  1. School of Computer and Artificial Intelligence, Wuhan University of Technology Wuhan, China
Download PDF Download RIS Download Bibtex

Abstract

Agile Project Management is a topic that has become popular both in business and academia, since the publication of the Agile Manifesto – a historic landmark in this subject. In the next 20 years, there was a relevant scientific production that must be analyzed to provoke reflection about the knowledge built up in this period. In this sense, this study aims to analyze the relevant scientific literature on Agile Project Management through a systematic review and a bibliometric analysis of articles published in scientific journals with Digital Object Identifier, in English, from the Web of Science and Scopus databases, from 2001 to 2021. The research results enable us to gain insights into the characteristics of this knowledge domain, regarding its volume and evolutionary trend, main contributors (i.e. scientific journals, authors, and their affiliations), main studies, methods used, and its central thematic axes.
Go to article

Authors and Affiliations

Antonio Carlos Pacagnella Junior
1
Vinicius Romeiro da Silva
1

  1. State University of Campinas, School of Applied Sciences, Production Engineering Center (CENPRO), Brazil

This page uses 'cookies'. Learn more