The article presents the methodology for assessing the longevity of hard coal mines. Based on international experts’ assessments, important criteria for determining mine viability have been presented. The results refer to Polish coal mines in the area of the Upper Silesian Coal Basin, however, the methodology itself can be applied to other geological and mining conditions of mines elsewhere.
The results of structural analyses carried out using the MICMAC method for factors related to the mining geo-environment that may determine the longevity of individual hard coal mines are presented. The analyses were based on the results of expert surveys carried out using the Delphi method. The experts participating in the survey came from various countries and had extensive experience related to work or cooperation with hard coal mining. The criterion factors examined were assigned to two systems (groups) for which structural analysis was performed. The first group includes factors related to the level of exploitation hampering, while the second group includes factors related to hard coal quality and the availability of resources. As a result of the analyses the following were determined: the key factors which have the most significant influence on the system, result and goal factors, factors affecting the system and autonomous factors which have little effect on the system.
The obtained results allowed to determine which factors should be taken into account in the process of determining the longevity of a hard coal mine.
The purpose of this work is to present a theoretical analysis of top orthogonal to bottom arrays of conducting electrodes of infinitesimal thickness (conducting strips) residing on the opposite surfaces of piezoelectric slab. The components of electric field are expanded into double periodic Bloch series with corresponding amplitudes represented by Legendre polynomials, in the proposed semi-analytical model of the considered two-dimensional (2D) array of strips. The boundary and edge conditions are satisfied directly by field representation, as a result. The method results in a small system of linear equations for unknown expansion coefficients to be solved numerically. A simple numerical example is given to illustrate the method. Also a test transducer was designed and a pilot experiment was carried out to illustrate the acoustic-wave generating capabilities of the proposed arrangement of top orthogonal to bottom arrays of conducting strips.
Environmental factors and the addition of adjuvants to the spray tank mix may interfere with glyphosate efficiency in hairy fleabane control. The objective of this study was to evaluate the effect of air temperature and the addition of ammonium sulfate (NH4)2SO4 to glyphosate in the control of glyphosate-resistant (GR) and -susceptible (GS) hairy fleabane. Treatments consisted of air temperatures of 12°C and 25°C, six doses of glyphosate from zero to 2,880 g · ha−1, the presence or absence of (NH4)2SO4 in the spray solution, and one GS and another GR biotype. At the lowest tested dose (180 g · ha−1), control of the GR biotype was 91% and 20% when the plants were kept at 12°C and 25°C, respectively, reducing the resistance factor (RF) by 9.30 times and was associated to the reduction of temperature. The addition of (NH4)2SO4 increased the control by 10−20% at high glyphosate doses and at 25°C. The resistance of hairy fleabane to glyphosate was completely reversed when the plants were maintained at 12°C. At this temperature, resistant plants were controlled even at doses well below that recommended for the control of this species. At 25°C, a dose four times higher than that recommended was required for satisfactory control. At the field level, under situations of low temperatures, it was possible to improve the efficacy of glyphosate applications in hairy fleabane control, if there were no other mechanisms of resistance involved.
Wind and solar radiation are intermittent with stochastic fluctuations, which can influence the stability of operation of the hybrid system in the grid integrated mode of operation. In this research work, a smoothing control method for mitigating output power variations for a grid integrated wind/PV hybrid system using a battery and electric double layer capacitor (EDLC) is investigated. The power fluctuations of the hybrid system are absorbed by a battery and EDLC during wide variations in power generated from the solar and wind system, subsequently, the power supplied to the grid is smoothened. This makes higher penetration and incorporation of renewable energy resources to the utility system possible. The control strategy of the inverter is realized to inject the power to the utility system with the unity power factor and a constant DC bus voltage. Both photovoltaic (PV) and wind systems are controlled for extracting maximum output power. In order to observe the performance of the hybrid system under practical situations in smoothing the output power fluctuations, one-day practical site wind velocity and irradiation data are considered. The dynamic modeling and effectiveness of this control method
Bacterial adsorption on mineral surface is one of the key steps in bioleaching process. The bacteria adsorb on the mineral surface via the extracellular polymeric substances (EPS) layer. In this paper, the behavior of glucuronic acid, one of the key substances in EPS layer, adsorbed on the pyrite surface is studied using DFT and electrochemical methods. Adsorption capacity of glucuronic acid is stronger than that of water. Glucuronic acid adsorbs on pyrite surfaces and it follows a mixed type of interactions (physisorption and chemisorption). Adsorption of glucuronic acid on pyrite surface followed Langmuir’s adsorption isotherm with adsorption standard free energy of –27.67kJ mol–1. The structural and electronic parameters were calculated and discussed.
The subject of my contribution is the cognition in the jurisprudence. It focuses on the question of the methods used in the jurisprudence to achieve knowledge of the law and the importance of the language in this process. My considerations focus on the evaluative position of the jurist. It is based on the assumption that the choice of a view requires not only an evaluation but also a kind of hierarchization. Therefore the important question is which evaluations are displaced by jurisprudence, and which ones creep into the theoretical considerations. The arguments on this topic have been drawn from three texts by German jurists of the 19th century.
The aim of the study was to evaluate the visualization of the rabbit common calcanean tendon and adjacent structures in the high-field magnetic resonance imaging (MRI) of 1.5 T field strength and to compare the results with those previously obtained for the low-field MRI (0.25 T). Eight New Zealand rabbits were used in the post-mortem study and the results indicate that the high-field MRI provides more detailed images only in transverse scans, where the outer outline of the tendon was visualized more accurately. Other analysed structures were imaged with a resolution comparable to the low-field MRI.
Approximately 80% of water extracted from oil and gas deposits in Poland is disposed of by injection into the rock matrix. The aim of the model research was to predict both the hydrochemical reactions of water injected into wells for its disposal and the hydrogeochemical processes in the reservoir formation. The purpose of hydrogeochemical modeling of the hydrocarbon formation was also to determine the potential of formation waters, injection waters, and their mixtures to precipitate and form mineral sediments, and to determine the corrosion risk to the well. In order to evaluate saturation indices and corrosion ratios, the geochemical programs PHREEQC and DownHole SAT were used. The results of hydrogeochemical modeling indicate the possible occurrence of clogging in the well and the near-well zone caused mainly by the precipitation of iron compounds (iron hydroxide Fe(OH)3 and siderite FeCO3) from the formation water due to the presence of high pressures and temperatures (HPHT). There is also a high certainty of the precipitation of carbonate sediments (calcite CaCO3, strontianite SrCO3, magnesite MgCO3, siderite FeCO3) from the injection water within the whole range of tested pressures and temperatures. The model simulations show that temperature increase has a much greater impact on the potential for precipitation of mineral phases than pressure increase.
The infauna of the soft bottom of Nottinghambukta was studied quantitatively. The distribution of 5 most abundant species: Liocyma fluctuosa (Bivalvia), Dendrodoa grossularia (Ascidiacea), Priapulus caudatus and Halicryptus spinulosus (Priapulida) and Chone duneri (Polychaeta), in this Arctic estuary has been presented.
Flying bird counts were carried out at Esperanza Bay (62°24'S, 56°59'W), Antarctic Peninsula, between November 1989 and February 1990. Six breeding species (Oceanites oceanicus, Chionis alba, Catharacta lonnbergi, Catharacta maccormicki, Larus dominicanus and Sterna vittata) and six visitor species (Macronectes giganteus, Fulmarus glacialoides, Daption capense, Pagodroma nivea, Fregetta tropica and Phalacrocorax atriceps) were recorded. Kelp gull and Antarctic tern populations have decreased in relation to the data by previous authors, perhaps as a result of the increased activity at Esperanza Station. Cygnus melanocoryphus was recorded for the first time at Esperanza Bay.
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