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An analysis of the geomechanical processes in coal mining using the Velenje mining method
Gregor Jeromel, Milan Medved, Jakob Likar, 2010, original scientific article

Abstract: With in-depth geomechanical analyses of sub-level mining using the longwall mining method we can identify the relationships between the physical and mechanical parameters of geological materials, depending on the intensity of the coal extraction. The extent and the intensity of the mining operations impose impacts on the stresses and cause deformation changes in the rocks and in the coal seams on a broader area of excavations. The method of sub-level coal extraction requires multi-caving of the hanging-wall layers, which are recompressed, and in sub-level stoping each represents a hanging wall. The repeating processes of caving-in and compression, from the aspect of the theory of plasticity, have been relatively little researched because every such process brings about structural changes in natural, multi-caved and recompressed materials in the hanging wall. The intensity of the coal extraction has direct impacts on the surrounding and distant mining areas. Extensive stress and deformation changes in the surrounding area, and in the mine, represent a safety hazard for the employees, since the supporting system in the mine roadway could collapse. Therefore, a controlled excavation of the coal, and a good understanding of the geomechanical properties of all the materials and processes involved, is extremely important for planning and managing economic production, while also ensuring safe mining operations. A numerical model that allows for in-depth analyses of the geomechanical processes that occur in the hanging wall, the footwall and in the coal seam during sub-level coal excavation, is broadly applicable and highly relevant for analysing the intensity and the level of the caving processes in sub-level coal mining, and for making realistic plans for coal excavation with workers’ safety in mind.
Keywords: coal mining, sub-level mining method, longwall coal mining method, carving processes, finite-difference method, FLAC, mathematical model
Published: 11.06.2018; Views: 437; Downloads: 65
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Heuristic approach to inventory control with advance capacity information
Marko Jakšič, Borut Rusjan, 2009, original scientific article

Abstract: There is a growing trend of information sharing within modern supply chains. This trend is mainly stimulated by recent developments in information technology and the increasing awareness that accurate and timely information helps firms cope with volatile and uncertain business conditions. We model a periodic-review, single-item, capacitated stochastic inventory system, where a supply chain member has the ability to obtain advance capacity information (‘ACI’) about future supply capacity availability. ACI is used to reduce the uncertainty of future supply and thus enables the decision-maker to make better ordering decisions. We develop an easily applicable heuristic based on insights gained from an analysis of the optimal policy. In a numerical study we quantify the benefits of ACI and compare the performance of the proposed heuristic with the optimal performance. We illustrate the conditions in which the procedure is working well and comment on its practical applicability.
Keywords: inventories, supply, stochastic processes, operations research, heuristics
Published: 30.11.2017; Views: 493; Downloads: 257
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Synchronous bursts on scale-free neuronal networks with attractive and repulsive coupling
Qingyun Wang, Guanrong Chen, Matjaž Perc, 2011, original scientific article

Abstract: This paper investigates the dependence of synchronization transitions of bursting oscillations on the information transmission delay over scale-free neuronal networks with attractive and repulsive coupling. It is shown that for both types of coupling, the delay always plays a subtle role in either promoting or impairing synchronization. In particular, depending on the inherent oscillation period of individual neurons, regions of irregular and regular propagating excitatory fronts appear intermittently as the delay increases. These delay-induced synchronization transitions are manifested as well-expressed minima in the measure for spatiotemporal synchrony. For attractive coupling, the minima appear at every integer multiple of the average oscillation period, while for the repulsive coupling, they appear at every odd multiple of the half of the average oscillation period. The obtained results are robust to the variations of the dynamics of individual neurons, the system size, and the neuronal firing type. Hence, they can be used to characterize attractively or repulsively coupled scale-free neuronal networks with delays.
Keywords: synchronization, neuronal networks, noise, stochastic processes, scale-free networks, information transmission delay
Published: 19.06.2017; Views: 596; Downloads: 307
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Comparing algebraic and numerical solutions of classical diffusion process equations in computational financial mathematics
Andreas Ruffing, Patrick Windpassinger, Stefan Panig, 2001, original scientific article

Abstract: We revise the interrelations between the classical Black Scholes equation, the diffusion equation and Burgers equation. Some of the algebraic properties the diffusion equation shows are elaborated and qualitatively presented. The related numerical elementary recipes are briefly elucidated in context of the diffusion equation. The quality of the approximations to the exact solutions is compared throughout the visualizations. The article mainly is based on the pedagogical style of the presentations to the Novacella Easter School 2000 on Financial Mathematics.
Keywords: diffusion processes, diffusion equations
Published: 14.06.2017; Views: 419; Downloads: 293
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Eliminating knowledge bottlenecks using fuzzy logic
Maja Zajec, Davorin Kofjač, Matjaž Roblek, 2013, original scientific article

Abstract: In the formation of new processes, innovations generated by people possessing the right knowledge and talent play a crucial role. Our starting point was the fact that every new change in processes can alter the knowledge structure of a work position or work role. This means that a person can become a knowledge bottleneck in the process. If this person is found on a critical path, the process cannot produce the output in a desired form, extent or quality, unless the bottleneck is removed. For this reason, we developed a decision model founded on fuzzy logic. The result of the fuzzy model is knowledge estimation based on deviation between the required and actual knowledge. For faster decision making, we made a presentation of allocated people on desired roles using the heat map technique. Therefore, the employers make better decisions on actual knowledge allocation, acquiring missing knowledge, or defining knowledge required for the future, which makes them more competitive.
Keywords: knowledge allocation, knowledge management, business processes
Published: 30.12.2015; Views: 774; Downloads: 250
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The contents of Cu, Mn, Zn, Cd, Cr, and Pb at different stages of the winemaking process
Janja Kristl, Marjan Veber, Metka Slekovec, 2003, original scientific article

Abstract: In samples taken during different stages of winemaking process (from grapes, crushed grapes, pressed pomace, must deposit, deposit of lees, must before and after clarification and wine) the Cu, Mn and Zn contents were determined by flame atomic absorption spectrometry (FAAS) and the Cd, Pb and Cr contents were determined by electrothermal atomic absorption spectrometry (ETAAS). Grapes, crushed grapes, pressed pomace, must deposit and deposit of lees were microwave digested with nitric acid, hydrofluoric acid and hydrogen peroxide solution, while for must and wine no special treatments were necessary. The highest contents of Cu, Mn, Zn, Pb, Cd and Cr were determined in the pressed pomace, lees, and in white grape varieties also in must deposit. Mean values obtained of dry weight (pressed pomace, lees, must deposit) were 63 mg/kg, 300 mg/kg, 184 mg/kg for Cu, 11 mg/kg, 15 mg/kg, 134 mg/kg for Mn, 14 mg/kg, 35 mg/kg, 17 mg/kg for Zn, 0.3 mg/kg, 0.5 mg/kg, 0.6 mg/kg for Pb, 0.5 mg/kg, 1.0 mg/kg, 1.8 mg/kg for Cr, 15.4 µg/kg, 24.4 µg/kg, 13.0 µg/kg for Cd. The Cu content was decreasing from the grapes to the bottled wine, whereas the Mn, Zn, Cd, Cr and Pb contents in the bottled wine were higher than in musts in all investigated white and red grape varieties. In ten wine samples the following contents were determined: Cu; mean 0.12 mg/L (range: 0.06-0.30 mg/L), Mn; mean 1.04 mg/L (range: 0.60-1.78 mg/L), Zn; mean 0.50 mg/L (range: 0.13-1.03 mg/L), Cd; mean 0.34 µg/L (range: 0.08-1.04 µg/L), Cr; mean 17.0µg/L (range: 5.2-25.1 µg/L) and Pb; mean 25.3 µg/L (range: 16.4-37.8 µg/L).
Keywords: viticulture, chemical processes, chemical elements, chemical analysis
Published: 10.07.2015; Views: 1078; Downloads: 89
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Enhancing the effectiveness of training through information feedback
Blaž Rodič, Gozdana Miglič, Goran Vukovič, Bruno Završnik, Robert Leskovar, 2009, original scientific article

Abstract: After the fall of the Berlin wall, the public administrations in Central and Eastern European countries have had to adapt to an enormous number of changes in a relatively short time. Their civil servants are still facing a constantly changing regulatory framework which needs implementation and enforcement, as well as new demands from the growing private sector and the citizens. These challenges can only be met if the civil servants are highly qualified and constantly updating their qualifications. A sound system of in-service training is therefore crucial to keep the public servants on equal footing with the rapidly changing environment. The research presented in this paper analyzed the practices of training evaluation as an information feedback in a branch of Slovene state administration. We analyzed the attitudes of employees towards evaluation with the assumption that there probably are notable differences between the attitudes of public servants depending on their demographic qualities. The results of the research, that 414 public servants have participated in, show that the position in the hierarchy has the strongest influence on their attitude towards evaluation. Empirical data also show that most of the employees are willing to participate in a continuous and objective training evaluation, but the leading public servants are less involved in the evaluation than expected.
Keywords: civil servants, evaluation processes, information feedback, goal oriented systems, public administration, training, training effectiveness
Published: 10.07.2015; Views: 839; Downloads: 67
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The applicability of an advanced oxidation process for textile finishing wastestreams & fate of persistent organic pollutants
Julija Volmajer Valh, Alenka Majcen Le Marechal, Boštjan Križanec, Simona Vajnhandl, 2012, original scientific article

Abstract: The trend of sustainable use of available water resources encourages textile finishing enterprises to implement efficient wastewater treatment technologies that enable water recycling, and not just itćs discharging into the local wastewater treatment plants (WWTP). This paper presents the results obtained from the H2O2/UV treatment of wastewater from Slovene textile finishing company. Laboratory scale decolouration experiments were performed on the most representative wastewater samples, collected in three months period. In general 80 % decolouration and 86 % total organic carbon (TOC) reduction was achieved. On the other hand, the use of ultraviolet (UV) radiation to degrade and destroy organic pollutants in textile wastewater could lead to the formation of toxic dioxins and dioxin-like compounds, groups of persistent organic pollutants, especially due to the presence of halogenated compounds in textile finishing processes. For these reasons, textile wastewater samples were analysed for any content of dioxins before and after the treatment with H2O2/UV.
Keywords: tekstilne odpadne vode, napredni oksidacijski procesi, H2O2/UV, dioksini, textile wastewater, advanced oxidation processes, H2O2/UV, ecological parameters, dioxins
Published: 10.07.2015; Views: 1047; Downloads: 34
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Aida Kamišalić Latifić, 2014, doctoral dissertation

Abstract: A medical process is a set of medical actions performed by healthcare professionals while making observations about signs and symptoms, ordering interventions, prescriptions, tests, and any other actions in order to solve a health problem that is affecting a particular patient. The objective is to offer a curative, chronic, palliative and/or symptomatic treatments. The capability of a physician to propose an appropriate treatment depends on his/her knowledge of similar clinical cases and by following advances in the treatment of particular diseases. Time is an important concept of the real world that has to be considered in regard to medical processes. Clinical Practice Guidelines (CPGs) are a narrative set of recommendations for treating patients suffering from a particular disease. By constantly referring to CPGs physicians can stay up to date with the best evidence-based medical care and with the recommendations of experts. The time dimension is, however, often omitted or only partially covered in CPGs. Some CPGs do contain certain recommendations considering time but often there are huge gaps that are supposed to be overcome by physicians’ own knowledge and experience. At the same time, healthcare centres hold healthcare records and information systems that register medical processes and patients data, including information about the times of any encounters, prescriptions, and other medical actions. Therefore healthcare records and information systems data can be a source for detecting temporal medical knowledge and sound evidence regarding healthcare. This thesis is centred on temporal knowledge acquisition and representation for the purposes of decision-making during medical processes. CPGs were analysed to obtain procedural knowledge models and Extended Timed Transition Diagrams defined for representations of the obtained knowledge. The data about the treatments of patients were analysed in order to detect temporal medical knowledge models that represented those medical procedures that were carried out while the data was being generated. These models thus provided an explicit representation of the time dimensions of past medical procedures. They could be used for complementing the knowledge provided by CPGs, for studying adherences to the CPGs and for representing a basic framework for medical procedural decision support systems development.
Keywords: knowledge acquisition, knowledge representation, temporal knowledge, decision-making, medical processes, procedural knowledge modelling
Published: 25.02.2014; Views: 1318; Downloads: 111
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