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Multi-exponential model to describe pressure-dependent P-and S-wave velocities and its use to estimate the crack aspect ratio

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第2期14卷 385-395页

作者： Mihály Dobróka Norbert Péter Szabó Tünde Edit Dobróka Mátyás Krisztián Baracza Department of Geophysics University of MiskolcMiskolc-Egyetemváros3515Hungary MTA-ME Geoengineering Research Group University of MiskolcMiskolc-Egyetemváros3515Hungary Research Institute of Applied Earth Sciences University of MiskolcMiskolc-Egyetemváros3515Hungary

We present new quantitative model describing the pressure dependence of acoustic P-and S-wave *** that a variety of individual mechanisms or defects(such as cracks,pore collapse and grain crushing)can contribute to the pressure-dependent change of the wave velocity,we order a characteristic pressure to all of them and allow a series of exponential terms in the description of the(Pand S-waves)velocity-pressure *** estimate the parameters of the multi-exponential rock physical model in inversion procedures using laboratory measured P-and S-wave velocity *** is known,the conventional damped least squares method gives acceptable results only when one or two individual mechanisms are *** the number of exponential terms leads to highly nonlinear ill-posed inverse *** to this reason,we develop the spectral inversion method(SIM)in which the velocity amplitudes(the spectral lines in the characteristic pressure spectrum)are only considered as *** characteristic pressures(belonging to the velocity amplitudes)are excluded from the set of inversion unknowns,instead,they are defined in a set of fixed positions equidistantly distributed in the actual interval of the independent variable(pressure).Through this novel linear inversion method,we estimate the parameters of the multi-exponential rock physical model using laboratory measured P-and S-wave velocity *** characteristic pressures are related to the closing pressures of cracks which are described by well-known rock mechanical relationships depending on the aspect ratio of elliptical *** gives the possibility to estimate the aspect ratios in terms of the characteristic pressures.

关键词： Multi-exponential rock physical model Spectral inversion method(SIM) Crack aspect ratio Characteristic pressures

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Vanishing torsion of parametric curves

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第4期8卷 593-595页

作者： JUHSZ Imre Department of Descriptive Geometry University of MiskolcMiskolc-Egyetemváros H-3515Hungary

We consider the class of parametric curves that can be represented by combination of control points and basis func- tions. A control point is let vary while the rest is held fixed. It’s shown that the locus of the moving control point that yields points of zero torsion is the osculating plane of the corresponding discriminant curve at its point of the same parameter value. The special case is studied when the basis functions sum to one.

关键词：参数曲线没影点挠率判别曲线

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Prediction of Dynamic and Aerodynamic Characteristics of the Centrifugal Fan with Forward Curved Blades

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Journal of Thermal Science 2013年第6期22卷 517-521页

作者： Jií Polansky László Kalmár Roman Gápár Univerzitní 8 306 14 PlzeňCzech Republic miskolc-egyetemváros MiskolcHungary

The main aim of this paper is determine the centrifugal fan with forward curved blades aerodynamic characteristics based on numerical modeling. Three variants of geometry were investigated. The first, basic "A" variant contains 12 blades. The geometry of second "B" variant contains 12 blades and 12 semi-blades with optimal length[1]. The third, control variant "C" contains 24 blades without semi-blades. Numerical calculations were performed by CFD Ansys. Another aim of this paper is to compare results of the numerical simulation with results of approximate numerical procedure. Applied approximate numerical procedure [2] is designated to determine characteristics of the turbulent flow in the bladed space of a centrifugal-flow fan impeller. This numerical method is an extension of the hydro-dynamical cascade theory for incompressible and inviscid fluid flow. Paper also partially compares results from the numerical simulation and results from the experimental investigation. Acoustic phenomena observed during experiment, during numerical simulation manifested as deterioration of the calculation stability, residuals oscillation and thus also as a flow field oscillation. Pressure pulsations are evaluated by using frequency analysis for each variant and working condition.

关键词：弯曲叶片离心风机气动特性特性预测数值模拟几何形状数值计算数值方法

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A new model for thermal conductivity of“continuous matrix/dispersed and separated 3D-particles”type composite materials and its application to WC-M(M=Co,Ag)systems

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Journal of Materials Science & Technology 2022年第2期97卷 123-133页

作者： Shiyi Wen Yong Du Jing Tan Yuling Liu Peng Zhou Jianzhan Long George Kaptay State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Hunan Provincial Key Defense Laboratory of High Temperature Wear-Resisting Materials and Preparation Technology Hunan University of Science and TechnologyXiangtan 411201China State Key Laboratory of Cemented Carbide Zhuzhou 412000China University of miskolc MiskolcEgyetemváros3515Hungary

In the present work a new thermal conductivity model is developed for two-phase composite materials,which are consisted of a continuous matrix and dispersed 3 D-particles separated from each other by the matrix as a function of grain size and volume ratio of the dispersed particles at different *** model is applied to reproduce experimental thermal conductivity values of cemented carbide systems WC-Co and *** agreement was found between measured thermal conductivity data originating from both this work and recent literature and the calculated ones only using semi-empirical parameters for the interfacial thermal resistance(ITR)values at WC/Co,WC/Ag and WC/WC interfaces as a function of ***,the temperature and grain size dependence of the thermal conductivity for WC is established for the first *** model works well for the case when the matrix(Ag)has a higher thermal conductivity compared to that of the WC particles and also for the case when the matrix(Co)has a lower thermal conductivity compared to that of the WC *** new model forms a physically sound basis for further development/materials design of cemented carbides and particlereinforced composite materials.

关键词： Thermal conductivity WC-Co WC-Ag Modeling Cemented carbides Composite materials

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Preliminary analysis on roles of metal–organic compounds in the formation of invisible gold

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Acta Geochimica 2021年第6期40卷 1050-1072页

作者： Medet Junussov Mádai Ferenc Kristály Ferenc Tòth Tivadar Fintor Krisztián Muránszky Gábor Prekob Ádám Hámor-VidóMária Department of Mineralogy and Petrography Institute of Mineralogy and GeologyFaculty of Earth Sciences and EngineeringUniversity of MiskolcMiskolc-Egyetemváros 3515Hungary Institute of Mineralogy and Geology Faculty of Earth Sciences and EngineeringUniversity of MiskolcMiskolc-Egyetemváros 3515Hungary Department of Mineralogy and Geochemistry Faculty of Science and InformaticsUniversity of SzegedAradi vértank tere 1Szeged 6720Hungary Institute of Chemistry Faculty of Material Sciences and EngineeringUniversity of MiskolcMiskolc-Egyetemváros 3515Hungary Department of Geology and Meteorology Institute of Geography and Earth SciencesFaculty of SciencesUniversity of PécsVasvári pál utcaPecs 7622Hungary

The paper comprises new analytical data on the nature and occurrence of gold in solid pyrobitumen,closely associated with the main gold-bearing sulfide arsenic ores of the Bakyrchik gold deposit(Kazakhstan),related to post-collisional magmatic-hydrothermal *** mineralization of the deposit occurs mainly in the form of an“invisible”type of gold in the structures of arsenian pyrite and arsenopyrite,and the form of gold-organic compounds of pyrobitumen in carbonaceous-terrigenous sequences of Carboniferous *** and electron microscopic analysis,Raman and FT-Infrared analysis,mineralogical and three-step sequential extraction analysis(NH2OHHCl,H2O2,HNO3?HCl)has been carried out using 9 ore samples(from 3 different types of ores)for a comprehensive study of pyrobitumen and sulfide arsenic ores focusing mainly on organic *** sequentially extracted precious metal content of pyrobitumen reaches up to 7 ppm gold and other metals like Ag 4 ppm,Pt 31 ppb,and Pd 26 ppb,forming metal–organic compounds,while arsenic sulfide minerals incorporate 11 ppm gold,39 ppm Ag,0.49 ppm *** enrichment of gold associating with organic matter and sulfide ore minerals was confirmed in this *** matter was active in the migration of gold and the capture of gold by ***,the reductive organic matter agent released gold,most likely for the sulfide arsenic ore *** was a decisive factor in the concentration,transportation,and preservation of gold in the deposit.

关键词： Gold Pyrobitumen Bakyrchik Vitrinite Metal-organic compounds

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Application of machine learning algorithms to predict tubing pressure in intermittent gas lift wells

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Petroleum Research 2022年第2期7卷 246-252页

作者： Nagham Amer Sami Department of Petroleum Engineering Faculty of Earth ScienceUniversity of Miskolc3515MiskolcHungary

Tubing pressure at gas injection depth in intermittent wells is one of the most critical parameters for production engineers to evaluate the performance of the ***,monitoring of the tubing pressure is not usually carried out in real *** has been realized that the generally used correlations are not effective enough due to complexity of the intermittent process which involve many parameters and assumptions to develop such *** focus of this study is to utilize machine learning(ML)algorithms to develop a model that can accurately predict tubing pressure in artificial intermittent gas lift *** algorithms built on the field data provide a solution that is easy to use and universally applicable to the complex *** non-linear regression ML methods are employed in this study,namely,Decision Tree-regression(DT),Random Forest-regression(RF)and K Nearest Neighbors-regression(KNN).All the tubing pressures obtained from ML models were compared with the actual values to ensure the effectiveness of the *** developed models show that it can predict the pressure with more than 99.9%*** is an interesting result,as such outcome accuracy has not been reported usually in the open literature.

关键词： Machine learning Artificial intelligence Intermittent gas lift Tubing pressure Random forest Decision tree KNN

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Determination of Power Consumption for Suspension Mixing in Stirring Equipments and Stirred Ball Mills

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材料科学与工程（中英文A版） 2012年第7期2卷 572-578页

作者： Viktoria Mannheim Zoltan Simenfalvi Dept. of Chemical Machinery University of Miskolc Miskolc-Egyetemv6ros 3515 Hungary

This paper presents the theory for determination of power consumption for mixing in stirring equipments and the experimental results for a laboratory stirred mill. This work is concerned with mixing on the molecular scale of suspensions. The power consumption for mixing can be determined by a method based on the dimensional analysis. In this case the stirring equipments have similar geometry. The basic equation is known, but a specific mathematical form is unknown for mixing by professional literatures. Stirred mills are still up-to-date and relatively new ones and only few investigations have been previously published on the power consumption. During the experiments the main technical parameters have been systematically adjusted. The laboratory stirred mill is operating with turbulent flow. The dynamic viscosity of suspension can be calculated by rheological measurements. The survey data are represented in shear diagrams. According to the theoretical and experimental measurements, the absolute dynamic viscosity of suspension can be written in generally and mathematically form as well. In relationship of equations, the Stirrer Reynolds number and the Froude number can be identified. Industrial sizes can be determined by a new scale-up model on the basis of the laboratory measurements.

关键词：搅拌设备搅拌球磨机混合功耗测定实验室测量实验过程数学形式

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Caustics of developable surfaces

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Frontiers of Information Technology & Electronic Engineering 2022年第3期23卷 479-487页

作者： Miklos HOFFMANN Imre JUHASZ Ede TROLL Institute of Mathematics and Computer Science Eszterhazy Karoly UniversityEger 3300Hungary Department of Computer Graphics and Image Processing University of DebrecenDebrecen 4010Hungary Department of Descriptive Geometry University of MiskolcMiskolc 3515Hungary

While considering a mirror and light rays coming either from a point source or from infinity,the reflected light rays may have an envelope,called a caustic *** this paper,we study developable surfaces as *** caustic surfaces,described in a closed form,are also developable surfaces of the same type as the original mirror *** provide efficient,algorithmic computation to find the caustic surface of each of the three types of developable surfaces(cone,cylinder,and tangent surface of a spatial curve).We also provide a potential application of the results in contemporary free-form architecture design.

关键词： Caustics Developable surface Reflected light rays Curve of regression

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Subject Area Risk Assessment of Four Hungarian Universities with a View to the QS University Rankings by Subject

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Journal of Data and Information Science 2022年第4期7卷 61-80页

作者： Péter Sasvári Anna Urbanovics Public Governance and International Studies University of Public ServiceHungary University of miskolc Hungary

Purpose:The aim of our paper is to investigate the role of a mentor leading a research team in the overall scientific performance of an academic institution and the possible risks of their departure with a special attention to their publication ***/methodology/approach:By using SciVal subject area data,we composed a formula describing the level of vulnerability of any given university in the case of losing any of its leading mentors,identifying other risk factors by dividing their careers into separate ***:It turns out that the higher field-weighed citation impact is,the better position universities reach in the rankings by subject and the vulnerability of institutions highly depends on the mentors,especially in view of their contribution to the topic *** limitations:The analysis covers the publication output of leading researchers working at four Hungarian universities,the scope of the analysis is worth being *** implications:Our analysis has the potential to give an applicable systemic approach as well as a data collection scheme to university managements so as to formulate an inclusive and comprehensive research strategy involving the introduction of a reward system aimed at publications and further encouraging national and international research ***/value:The methodology and the principles of risk assessment laid down in our paper are not restricted to measuring the vulnerability level of a limited group of academic institutions,they can be appropriately used for investigating the role of mentors or leading researchers at every university across the globe.

关键词： QS Rankings by Subject Scientific Competitiveness Risk Analysis Subject Area Exposure

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Mapping Structurally Controlled Alterations Sparked by Hydrothermal Activity in the Fatira–Abu Zawal Area,Eastern Desert,Egypt

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Acta Geologica Sinica(English Edition) 2023年第2期97卷 662-680页

作者： Mohamed BADAWI Mahmoud ABDELATIF Ali SHEBL Farid MAKROUM Ahmed SHALABY Norbert NéMETH Institute of Exploration Geosciences University of MiskolcMiskolc 3515Hungary Department of Geology Mansoura UniversityMansoura 35516Egypt Department of Geology South Valley UniversityQena 83523Egypt Department of Mineralogy and Geology University of DebrecenDebrecen 4032Hungary Department of Geology Tanta UniversityTanta 31527Egypt

The Eastern Desert of Egypt suffered a protracted period of deformation triggered by cratonization of the new juvenile crust known as the Arabian Nubian Shield(ANS),which has been proposed for potential gold discoveries associated with the corresponding tectonic *** Fatira area,on the border of Egypt’s Northern and Central Eastern Deserts,is covered with metavolcanic rocks twisted by a dextral relocation of the Fatira Shear Zone(FSZ)relative to the Barud magmatic *** recent study evaluated many deformed post-orogenic granitic intrusions and felsite dikes associated with promising mineralization localities,notably orogenic gold *** combination of various field observations and remote sensing data,followed by the analysis of aeromagnetic enhanced maps,allowed the differentiation of distinct lithologies,structural features,and hydrothermal alterations in the study ***,the integrated results obtained from the different interpretation techniques are utilized to identify and confirm the previously supposed mineralized localities in the Fatira and Abu Zawal areas and predict other matched *** final ASTER,Sentinel 2 hydrothermal alteration,and orientation entropy heat maps demonstrate the association between these mineralized regions and major structures related to the FSZ late stage of deformation rather than other structures studied throughout the area of interest.

关键词： gold granite island arc association Pan-African Orogeny Egypt

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