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Individual effect of Y and Nd on the microstructure formation of Mg-Y-Nd alloys processed by severe plastic deformation and their effect on the subsequent mechanical and corrosion properties

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Journal of Magnesium and Alloys 2023年第2期11卷 509-521页

作者： Maria Zemkova Peter Minarik jan Dittrich jan Bohlen Robert Kral Charles University Department of Physics of MaterialsKe Karlovu 512116PragueCzechia University of Zilina Research CentreUniverzitna8215/1Zilina01026Slovakia Institute of Material and Process Design Helmholtz-Zentrum Hereon21502GeesthachtGermany

This work investigated the effect of sole yttrium and neodymium alloying on the microstructure formation during severe plastic deformation by equal channel angular pressing(ECAP) and an impact on the mechanical strength and corrosion resistance of binary Mg-3Y and Mg-3Nd *** results are compared with a ternary Mg-4Y-3Nd alloy,which represents a simplified version of the commercially successful WE43 *** extensive study comprises a thorough microstructural analysis performed by scanning and transmission electron microscopy,including electron backscatter diffraction and texture analysis performed by X-ray *** is shown that the presence of Nd primarily caused precipitation during the processing of the Mg-3Nd alloy,while Y remained dissolved in the magnesium matrix in the Mg-3Y *** difference resulted in a significantly smaller average grain size in the Mg-3Y alloy(~0.77 nm) than in the Mg-3Nd alloy(~1.3 μm) after the final step of the processing and formation of a slightly different ***,the composition and the processing affected the mechanical and corrosion properties of the investigated materials,measured by compression deformation tests,microhardness measurement,and electrochemical impedance *** study shows that the ECAP-processed W3 sample exhibits a surprisingly good combination of ultrafine-grain structure,weak crystallographic texture,high strength,and high corrosion resistance compared with the other investigated *** attributes make this material very interesting for utilisation in the industry and/or medicine.

关键词： Magnesium Rare earth elements Microstructure Texture Mechanical strength Corrosion

Contribution to Encyclopedia of Thermal Stresses

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Journal of Thermal Science 2015年第3期24卷 215-220页

作者： jan TALER Pawel OCLON Institute of Thermal Power Engineering Faculty of Mechanical EngineeringCracow University of TechnologyPoland

This paper lists the contribution in the international interdisciplinary reference – Encyclopedia of Thermal Stresses(ETS). The ETS, edited by the world famous expert in field of Thermal Stresses – Professor Richard Hetnarski from Rochester Institute of Technology, was published by Springer in 2014. This unique Encyclopedia, subdivided into 11 volumes is the most extensive and comprehensive work related to the Thermal Stresses topic. The entries were carefully prepared by specialists in the field of thermal stresses, elasticity, heat conduction, optimization among others. The Polish authors' contribution within this work is significant; over 70 entries were prepared by them.

关键词： Thermal stresses heat conduction thermodynamics

A Comparison of Experimental and Numerical Studies Performed on a Low-Pressure Turbine Blade Cascade at High-Speed Conditions, Low Reynolds Numbers and Various Turbulence Intensities

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Journal of Thermal Science 2013年第5期22卷 413-423页

作者： jan Michalek Petr Straka VZLU - Aerospace Research and Test Establishment Beranovych 130 19500 PragueCzech Republic

This paper focuses on a comparison of experimental and numerical investigations performed on a low-pressure mid-loaded turbine blade at operating conditions comprised of a wide range of Math numbers （from 0.5 - 1.1）, Reynolds numbers （from 0.4e＋5 - 3.0e＋5）, flow incidence （-15 - 15 degrees） and three levels of free-stream tur- bulence intensities （2, 5 and 10%）. The experimental part of the work was performed in a high-speed linear cas- cade wind tunnel. The increased levels of turbulence were achieved by a passive grid placed at the cascade inlet. A two-dimensional flow field at the center of the blade was traversed pitch-wise upstream and downstream the cascade by means of a five-bole probe and a needle pressure probe, respectively. The blade loading was measured using the surface pressure taps evenly deployed at the blade mid-span along the suction and the pressure side. The inlet turbulence was investigated using the constant temperature anemometer technique with a dual sensor probe. Experimentally evaluated values of turbulent kinetic energy and its dissipation rate were then used as inputs for the numerical simulations. An in-house code based on a system of the Favre-averaged Navier-Stokes equation closed by a two-equation k-co turbulence model was adopted for the predictions. The code utilizes an algebraic model of bypass transition valid both for attached as for separated flows taking in account the effect of free-stream turbulence and pressure gradient. The resulting comparison was carried out in terms of the kinetic en- ergy loss coefficient, distributions of downstream wakes and blade velocity. Additionally a flow visualization was performed by means of the Schlieren technique in order to provide a further understanding of the studied phe- nomena. A few selected cases with a particular interest in the attached and separated flow transition are compared and discussed.

关键词： low pressure turbine high-speed flow low Reynolds number flow separation transition RANS

Computational Modelling of Retrofitting a Coal Fired Boiler Type OP-230 for Predicting NOX Reduction

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Journal of Thermal Science 2018年第5期27卷 433-439页

作者： MOTYL Przemyslaw LACH jan Faculty of Mechanical Engineering Kazimierz Pulaski University of Technology and Humanities in RadomRadom 26-600poland Faculty of Engineering Management Bialystok University of TechnologyKleosin 16-001 Poland

This study focuses on a CFD modelling of biomass-derived syngas co-firing with coal in an older mid-sized PC-fired boiler of type OP-230 with low-emission burners on the front wall. The simulations were performed to determine whether the boiler can be retrofitted for the fulfilment of the prospective environmental protection regulations relating to levels of NO_X emissions. The improvement of the air staging via the dual-fuel technique was based on the indirect co-firing technology. The impact of two arrangements of dedicated syngas nozzles(below and above the existing coal burners), two syngas compositions and two heat replacements(5% and 15%) on the course of thermal processes in a furnace was tested. The reductions in NO_X emissions were predicted relative to the baseline when only coal is combusted. The highest reduction of about 38% was achieved with the syngas nozzles below the existing coal burners and 15% heat replacement. This arrangement of nozzles offers the residence time sufficient to co-fire coal with waste derived syngas. A lower reduction in NO_X emissions was obtained with the nozzles above the burners as the enlargement of local fuel rich zone near syngas injection becomes significant for 15% heat replacement. Results provide for the decreasing impact of methane content along with the increase of syngas heat input. The avoided CO_2 emissions through the syngas indirect co-firing with coal in the boiler are linear function of heat replacements.

关键词： boiler modelling co-firing biomass derived syngas NOX emission retrofitting

Effect of gear teeth finishing method on properties of teeth surface layer and its resistance to pitting wear creation

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Journal of Central South University 2016年第1期23卷 68-76页

作者： jan Zwolak Arkadiusz Palczak Department of Mechanics and Mechanical Engineering Faculty of Mathematics and Natural Sciences The University of Rzeszow Rejtana Ave. 16C Rzeszow 35-959 Poland

This work presented the characteristics of two gear teeth finishing methods, due to the properties of gear teeth surface layer obtained at the tooth working depth. These methods are: 1) the teeth carburization, hardening to a hardness of HRC 60-62 and then grinding, 2) the soft gear shaving as the final mechanical treatment and then carburizing and hardening to the hardness of HRC60-62. This work included the test results of the contact fatigue strength carried out on the circulating power system. The Wohler curves were plotted due to the obtained results, as the basis for the practical evaluation of the considered gear finishing methods. The parameters like volume distribution of the voids, content of the retained austenite, compressive residual stress value, but also the results of contact fatigue strength tests, are more favorable for the teeth shaving method than for the teeth grinding method.

关键词： gear teeth finishing treatment surface layer contact fatigue strength pitting

Heavy rockbursts due to longwall mining near protective pillars:A case study

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International Journal of Mining Science and Technology 2018年第5期28卷 799-805页

作者： Petr Konicek jan Schreiber Department of Geomechanics and Mining Research Institute of Geonics Czech Academy of Science

Rockburst represents a very dangerous phenomenon in deep underground mining in unfavourable conditions such as great depth, high horizontal stress, proximity of important tectonic structures, and unmined pillars. The case study describes a recorded heavy rockburst in the Czech part of the Upper Silesian Coal Basin, which occurred during longwall mining near the protective pillar. The artificial dividing of geological blocks and creation of mining protective pillars(shaft pillars, crosscut pillars etc.) is a dangerous task in light of rockbursts occurring mainly due to overstressing of remaining pillars. A simple model of this situation is presented. Natural and mining conditions are analysed and presented in detail as well as registered seismicity during longwall mining in the area. Recorded rockbursts in the area of interest are described and their causes discussed. Many rockbursts near protective pillars were recorded in this mining region. Methodical instructions for rockburst prevention in proximity of protective pillars as well as for gates driving were devised based on the evaluation of rockburst causes. The paper presents these principles for prevention.

关键词： Rockburst Rockburst prevention Hardcoal longwall mining Induced seismicity Protective pillar

Liver transplantation and liver resection as alternative treatments for primary hepatobiliary and secondary liver tumors: Competitors or allies?

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Hepatobiliary & Pancreatic Diseases International 2024年第2期23卷 111-116页

作者： jan Lerut Institute for Experimental and Clinical Research(IREC) Universitécatholique Louvain(UCL)Avenue Hippocrate 561200 Woluwe Saint PierreBrusselsBelgium

Although Starzl designed in the 1960’s liver transplantation(LT)to treat unresectable primary and also secondary liver tumors,transplantation still occupies a(too)small place in the respective therapeutic algorithms[1].Due to the lack of(any)selection criteria,the concept of transplantation became rapidly challenged because of the prohibitively high incidence of tumor recurrence[1–3].

关键词： liver tumors Liver

Experimental Study of Sand Bed Configurations in Front of a Vertical Wall Under Wave Action

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China Ocean Engineering 1998年第4期13卷 405-416页

作者： jan Chyan-Deng Professor Department of Hydraulics and Ocean Engineering National Cheng Kung University TainanTaiwan 70101 China.

When a 2-D progressive wave train normally or obliquely approaches a vertical wall and then is normally or obliquely reflected from it, the combination of the approaching and reflected waves may result in a standing wave or a short-crested wave in front of the wall. This paper presents the experimental observations of sand bed configurations under the action of these water waves in front of the wall. The geometry of sand ripples under these water waves in front of the vertical wall is presented as a function of flow parameters, such as the water particle semi-excursion and the mobility number.

关键词： sand bed wave action vertical sea wall bed form standing wave short-crested wave mobility number

The Axial and Radial Solid Loadings up the CFB-Riser

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Chinese Journal of Chemical Engineering 2000年第2期8卷 171-175页

作者： Kathleen Smolders jan Baeyens Chemical Engineering Department Katholieke Universiteit Leuven de Croylaan 46B-3001 HeverleeBelgiumChemical Engineering DepartmentKatholieke Universiteit Leuven de Croylaan 46B-3001 HeverleeBelgium

1 INTRODUCTIONThe determination of the solids hold-up and local solidfluxes is of paramount importance in the study ofthe hydrodynamics of a two-phase *** tech-niques have been used during the past decades(Table1).The... 详细信息

关键词： circulating fluidized beds solids loading axial and radial profiles