scholarly journals Influence of the Permeability of the Longwall Goaf Zones on the Location of an Area With Explosive Methane Concentration Levels

2020 ◽  
Vol 3 (1) ◽  
pp. 238-247
Author(s):  
Magdalena Tutak ◽  
Dorota Palka
Keyword(s):  
Oxygen Concentration ◽  
Preventive Measures ◽  
Concentration Level ◽  
Practical Importance ◽  
Hard Coal ◽  
Endogenous Fire ◽  
The One ◽  
Roof Rocks ◽  
The Impact ◽  
Concentration Levels

AbstractOne of the basic ventilation hazards and, at the same time most dangerous, in hard coal mines is the methane hazard. During the exploitation process using the longwall system with the breaking down of roof rocks, methane is released into mining excavations from both mined coal and the one left in goaves. Significant amounts of methane also flow from the underworked and overworked seams, through cracks and fissures formed in the rock mass. When accumulated at an explosive concentration level in goves and at an appropriate oxygen concentration level and the occurrence of a trigger (e.g. a spark or endogenous fire), methane may either explode or ignite. These are immensely dangerous phenomena. Therefore, the possibility of their occurrence should be limited. The article presents the results of the research aimed at determining the impact of the permeability of goaf zones on the distribution of methane and oxygen concentration levels in these goaves. The study was carried out for the longwall ventilated with the Y system. The model analysis was conducted, the results of which allowed the authors to determine these distributions. On their basis, both the location and size of the areas in which hazardous methane concentrations could occur were designated. The results are of great practical importance as they indicate areas in goaves where preventive measures should be implemented.

scholarly journals A Review on Historical Tsunamis in the Canary Islands: Implications for Tsunami Risk Reduction

Geosciences ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 222
Author(s):  
Inés Galindo ◽  
Carmen Romero ◽  
Esther Martín-González ◽  
Juana Vegas ◽  
Nieves Sánchez
Keyword(s):  
Canary Islands ◽  
Preventive Measures ◽  
High Population Density ◽  
Documentary Sources ◽  
Geological Processes ◽  
Tsunami Risk ◽  
The One ◽  
The Impact ◽  
First Time ◽  
La Gomera

The analysis of the historical documentary sources together with evidence from the geological record is essential to understand the impact and processes triggered by tsunamis on the Canary Islands. This archipelago has been affected by tsunamis caused by different geological processes, of which the most studied have been those generated by prehistoric mega-landslides. However, there is also evidence of those produced by distant tsunamigenic sources. An exhaustive review of all documentation available was made, identifying the existence of at least four seismically triggered tsunami episodes (1755, 1761, 1941 and 1969), the majority with an epicenter in the Azores-Gibraltar boundary. In this work, several tsunamis are cited for the first time, such as the one produced by the Argaga (La Gomera) landslide in 2020. Other episodes historically identified as tsunamis are discarded as they corresponded to other geological events. The effects of most historic tsunamis have gone unnoticed, having occurred in epochs of sparsely populated coastal areas. But their study allows us to infer the need for the archipelago authorities to establish preventive measures to avoid possible damage from tsunamis, especially if we consider the presently high population density of the Canarian littoral.

scholarly journals Determination of the Zone Endangered by Methane Explosion in Goaf with Caving of Longwalls Ventilated on „Y“ System

2016 ◽  
Vol 24 (4) ◽  
pp. 247-251 ◽  
Author(s):  
Jarosław Brodny ◽  
Magdalena Tutak
Keyword(s):  
Oxygen Concentration ◽  
Underground Mining ◽  
Ventilation System ◽  
Hard Coal ◽  
Methane Drainage ◽  
Endogenous Fire ◽  
Flow Through ◽  
Selection Of ◽  
Sufficient Oxygen

Abstract One of the most dangerous and most commonly present risks in hard coal mines is methane hazard. During exploitation by longwall system with caving, methane is emitted to mine heading from the mined coal and coal left in a pile. A large amount of methane also flows from neighboring seams through cracks and fissures formed in rock mass. In a case of accumulation of explosive methane concentration in goaf zone and with appropriate oxygen concentration and occurrence of initials (e.g. spark or endogenous fire), it may come to the explosion of this gas. In the paper there are presented results of numerical analysis of mixture of air and methane streams flow through the real heading system of a mine, characterized by high methane hazard. The aim of the studies was to analyze the ventilation system of considered heading system and determination of braking zones in goaf zone, in which dangerous and explosive concertation of methane can occur with sufficient oxygen concentration equal to at least 12%. Determination of position of these zones is necessary for the selection of appropriate parameters of the ventilation system to ensure safety of the crew. Analysis of the scale of methane hazard allows to select such a ventilation system of exploitation and neighboring headings that ensures chemical composition of mining atmosphere required by regulation, and required efficiency of methane drainage. The obtained results clearly show that numerical methods, combined with the results of tests in real conditions can be successfully used for the analysis of variants of processes related to ventilation of underground mining, and also in the analysis of emergency states.

scholarly journals The Mechanisms of Endogenous Fires Occurring in Extractive Waste Dumping Facilities

2020 ◽  
Vol 12 (7) ◽  
pp. 2856
Author(s):  
Krzysztof Gogola ◽  
Tomasz Rogala ◽  
Małgorzata Magdziarczyk ◽  
Adam Smoliński
Keyword(s):  
Waste Management ◽  
Ground Surface ◽  
Coal Extraction ◽  
Hard Coal ◽  
Coal Waste ◽  
Waste Dumps ◽  
Endogenous Fire ◽  
Natural Aggregates ◽  
The One ◽  
Modern Technologies

The processes of hard coal extraction and processing are accompanied by the generation of a considerable amount of post-mining extractive waste, which in most cases is deposited on the ground surface. In the past, such waste was disposed of by deposition in bings and spoil piles of various kinds. The application of modern technologies makes it possible to recycle, reuse or reclaim extractive waste in engineering works or as a substitute of natural aggregates used for the construction of different kinds of banks and embankments. Regardless of whether the waste is deposited or reused, the basic target method of waste management consists of depositing it on the ground surface. This form of extractive waste management is always associated with the risk of the occurrence of coal self-heating phenomena, which may consequently lead to an endogenous fire. Therefore, it is of critical importance to apply appropriate technologies for the construction of coal waste embankments on the one hand, and on the other hand to recognize the mechanisms responsible for the occurrence of fires in extractive waste dumps, which constitutes the subject matter of this paper.

scholarly journals Impact of type of the roof rocks on location and range of endogenous fires particular hazard zone by in goaf with caving

2018 ◽  
Vol 29 ◽  
pp. 00005 ◽  
Author(s):  
Magdalena Tutak ◽  
Jarosław Brodny
Keyword(s):  
Occupational Safety ◽  
Heating Process ◽  
Coal Oxidation ◽  
Self Heating ◽  
Geological Conditions ◽  
Hazard Zone ◽  
Endogenous Fire ◽  
Roof Rocks ◽  
The Impact

Hazard of endogenous fires is one of the basic and common presented occupational safety hazards in coal mine in Poland and in the world. This hazard means possibility of coal self-ignition as the result of its self-heating process in mining heading or its surrounding. In underground coal-mining during ventilating of operating longwalls takes place migration of parts of airflow to goaf with caving. In a case when in these goaf a coal susceptible to self-ignition occurs, then the airflow through these goaf may influence on formation of favorable conditions for coal oxidation and subsequently to its self-heating and self-ignition. Endogenous fire formed in such conditions can pose a serious hazards for the crew and for continuity of operation of mining plant. From the practical point of view a very significant meaning has determination of the zone in the goaf with caving, in which necessary conditions for occurence of endogenous fire are fulfilled. In the real conditions determination of such a zone is practically impossible. The main aim of the analysis was to determine the impact of type of the roof rocks forming the goaf on the location and range of endogenous fires particular hazard zone by in these goaf. For determined mining-geological conditions, the critical value of velocity of airflow and oxygen concentration in goaf, conditioning initiation of coal oxidation process were determined.

Static and Dynamic Studies of Gasoline in View of its Octane Number and its Toxic Effect

2013 ◽  
Vol 12 (7) ◽  
pp. 451-459
Author(s):  
Ashraf Yehia El-Naggar ◽  
Mohamed A. Ebiad
Keyword(s):  
Toxic Effect ◽  
Aromatic Hydrocarbons ◽  
Octane Number ◽  
Liquid Fuel ◽  
Positive Impact ◽  
Hydrocarbon Composition ◽  
Different Temperatures ◽  
Different Seasons ◽  
The One ◽  
The Impact

Gasoline come primarily from petroleum cuts, it is the preferred liquid fuel in our lives. Two gasoline samples of octane numbers 91 and 95 from Saudi Arabia petrol stations were studied. This study was achieved at three different temperatures 20oC, 30oC and 50oC representing the change in temperatures of the different seasons of the year. Both the evaporated gases of light aromatic hydrocarbons (BTEX) of gasoline samples inside the tank were subjected to analyze qualitatively and quantitatively via capillary gas chromatography. The detailed hydrocarbon composition and the octane number of the studied gasoline samples were determined using detailed hydrocarbon analyzer. The idea of research is indicating the impact of light aromatic compounds in gasoline on the toxic effect of human and environment on the one hand, and on octane number of gasoline on the other hand. Although the value of octane number will be reduced but this will have a positive impact on the environment as a way to produce clean fuel.

The Influence of Disintegration of Hard Coal Varieties of Different Metamorphism Grade on the Amount of Sorbed Ethane / Wpływ rozdrobnienia odmian węgla kamiennego o różnym stopniu metamorfizmu na ilości sorbowanego etanu

2013 ◽  
Vol 58 (2) ◽  
pp. 449-463 ◽  
Author(s):  
Mieczysław Żyła ◽  
Agnieszka Dudzińska ◽  
Janusz Cygankiewicz
Keyword(s):  
Sorption Isotherms ◽  
Electron Donors ◽  
Hard Coal ◽  
Coal Surface ◽  
Compact Layer ◽  
Compact Structure ◽  
Small Surface ◽  
Mining Works ◽  
The Impact ◽  
Content Of Oxygen

Ethane constitutes an explosive gas. It most often accompanies methane realizing during exploitation and mining works. In this paper the results of ethane sorption have been discussed on three grain classes of six selected hard coal samples collected from active Polish coalmines. On the basis of obtained results, it has been stated that the tested hard coals prove differentiated sorption power with reference to ethane. Te extreme amount of ethane is sorbed by low carbonized hard coal from “Jaworzno” coalmine. This sort of coal shows great porosity, and great content of oxygen and moisture. The least amount of ethane is sorbed by hard coal from “Sośnica” coalmine. This sort of coal possesses relatively a great deal of ash contents. Together with the process of coal disintegration, the amount of sorbed ethane increases for all tested coal samples. Between tested coals there are three medium carbonized samples collected from “Pniówek”, “Chwałowice” “Zofiówka” coalmines which are characterized by small surface values counted according to model BET from nitrogen sorption isotherms determined at the temperature of 77.5 K. The samples of these three coals prove the highest, from between tested coals, increase of ethane sorption occurring together with their disintegration. These samples disintegrated to 0,063-0,075 mm grain class sorb ethane in the amount corresponding with the sorption quantity of low carbonized coal from “Jaworzno” coalmine in 0.5-0.7 mm grain class. It should be marked that the low carbonized samples collected from “Jaworzno” and Wesoła” coalmines possess large specific surface and great porosity and belong to coal group of “loose” spatial structure. Regarding profusion of sorbed ethane on disintegrated medium carbonized samples from “Pniówek”, “Zofiówka”, “Chwałowice” coalmines it can be supposed that in the process of coal disintegration, breaking their “compact’ structure occurs. Loosened structure of medium carbonized coals results in increasing accessibility of ethane particles to sorption centres both electron donors and electron acceptors which are present on hard coal surface. The surface sorption centre increase may result in formation a compact layer of ethane particles on coal surface. In the formed layer, not only the strengths of vertical binding of ethane particles with the coal surface appear but also the impact of horizontal strengths appears which forms a compact layer of sorbed ethane particles. The surface layer of ethane particles may lead to explosion.

The Development of Agritourism in the Podkarpackie Voivodeship in the Light of International and National Conditions

2017 ◽  
Vol 13 ◽  
pp. 244-261
Author(s):  
Mariola Tracz ◽  
Małgorzata Bajgier-Kowalska ◽  
Radosław Uliszak
Keyword(s):  
Development Strategy ◽  
Current State ◽  
Central Statistical ◽  
Central Statistical Office ◽  
Tourism Resources ◽  
The One ◽  
The Impact ◽  
District Offices ◽  
Socio Economic Factors

Podkarpackie Voivodeship is one of the regions of Poland in which the number of agritourism entities is very high. Therefore tourism plays a significant role in its development strategy. The aim of the paper is to identify the current state of agritourism and the changes that have occurred in the region in the years 2000–2016. Specific objectives are to determine the distribution of agritourism farms and their offer, together with a comprehensive analysis of the environmental and socio-economic factors, as well as the impact of the Slovak-Ukrainian border. The report was developed on the statistical materials from the Polish Central Statistical Office, Podkarpackie Agricultural Advisory Centre in Boguchwała and data collected from municipalities and district offices that is published on their websites, as well as through interviews with 100 owners of agritourism farms in the Podkarpackie Voivodeship. The research has shown, on the one hand, the decline in the number of farms in the region and, on the other hand, the increase in the diversity of the tourist offer of these entities. Distribution of agritourism farms is closely linked to the attractiveness of natural environment and quality of secondary tourism resources. Traditional agritourism has not yet fully used its countryside, as well as cross-border advantages of its location.

Surveying adherence of dental clinic patients to preventive measures in oral cavity

2019 ◽  
Vol 24 (2) ◽  
pp. 167-172 ◽  
Author(s):  
T. V. Kudryavtseva ◽  
V. V. Tachalov ◽  
E. S. Loboda ◽  
L. Yu. Orekhova ◽  
E. Yu. Nechai ◽  
...  
Keyword(s):  
Oral Cavity ◽  
Working Conditions ◽  
Oral Hygiene ◽  
Preventive Measures ◽  
Periodontal Diseases ◽  
Dental Health ◽  
Developed Countries ◽  
Dental Clinic ◽  
The Many ◽  
The Impact

Relevance. Periodontal diseases are a medical and social problem due to the wide spread among the population of developed countries and the impact on the quality of life. Among the many factors that are important in the development of inflammatory periodontal diseases, an important role is played by adherence to the recommendations of the dentist in respecting oral hygiene. Aim of the work was to study the adherence of patients of the dental clinic to compliance with preventive measures in the oral cavity.Materials and methods. A total of 98 patients of dental clinic, 62 female (medial age 38,6 ± 14,0 years) and 36 male (medial age 37,2±13,1 years) participated in survey. The study participants flled in the profle and answered questions about age, gender, harmful working conditions and bad habits, frequency of visits to the dental clinic, attitudes to the prevention of dental diseases, knowledge about the means and methods of oral hygiene.Results. As a result of the study, it was found that in the vast majority of cases, respondents are employed in production that does not adversely affect their health (91%), only 8% of patients indicated harmful working conditions.Conclusions. The study revealed that, despite the recommendations of the dentist, patients are not always committed to the implementation of preventive measures in the oral cavity. Dentists need to motivate patients to use not only the usual methods and means of hygiene, but also additional ones necessary for maintaining dental health.

Laughter on the Fringes

2019 ◽  
Author(s):  
Anna Peterson
Keyword(s):  
The Other ◽  
Literary Canon ◽  
Autobiographical Writing ◽  
Treasure Trove ◽  
Old Comedy ◽  
Other Hand ◽  
Aggressive Humor ◽  
The One ◽  
The Individual ◽  
The Impact

This book examines the impact that Athenian Old Comedy had on Greek writers of the Imperial era. It is generally acknowledged that Imperial-era Greeks responded to Athenian Old Comedy in one of two ways: either as a treasure trove of Atticisms, or as a genre defined by and repudiated for its aggressive humor. Worthy of further consideration, however, is how both approaches, and particularly the latter one that relegated Old Comedy to the fringes of the literary canon, led authors to engage with the ironic and self-reflexive humor of Aristophanes, Eupolis, and Cratinus. Authors ranging from serious moralizers (Plutarch and Aelius Aristides) to comic writers in their own right (Lucian, Alciphron), to other figures not often associated with Old Comedy (Libanius) adopted aspects of the genre to negotiate power struggles, facilitate literary and sophistic rivalries, and provide a model for autobiographical writing. To varying degrees, these writers wove recognizable features of the genre (e.g., the parabasis, its agonistic language, the stage biographies of the individual poets) into their writings. The image of Old Comedy that emerges from this time is that of a genre in transition. It was, on the one hand, with the exception of Aristophanes’s extant plays, on the verge of being almost completely lost; on the other hand, its reputation and several of its most characteristic elements were being renegotiated and reinvented.

Freedom of Expression versus Privacy and the Right to Reputation

2017 ◽  
Author(s):  
Dirk Voorhoof
Keyword(s):  
Public Interest ◽  
Freedom Of Expression ◽  
Media Freedom ◽  
Investigative Journalism ◽  
The Public ◽  
The Right Of Privacy ◽  
The One ◽  
Grand Chamber ◽  
The Right ◽  
The Impact

The normative perspective of this chapter is how to guarantee respect for the fundamental values of freedom of expression and journalistic reporting on matters of public interest in cases where a (public) person claims protection of his or her right to reputation. First it explains why there is an increasing number and expanding potential of conflicts between the right to freedom of expression and media freedom (Article 10 ECHR), on the one hand, and the right of privacy and the right to protection of reputation (Article 8 ECHR), on the other. In addressing and analysing the European Court’s balancing approach in this domain, the characteristics and the impact of the seminal 2012 Grand Chamber judgment in Axel Springer AG v. Germany (no. 1) are identified and explained. On the basis of the analysis of the Court’s subsequent jurisprudence in defamation cases it evaluates whether this case law preserves the public watchdog-function of media, investigative journalism and NGOs reporting on matters of public interest, but tarnishing the reputation of public figures.

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