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Energy & Environmental Materials 2024年第5期7卷 341-348页

作者： Pan Li Jiang Zhong Yanqing Fu Zhentao Du Lan Jiang yi Han jan Luxa Bing Wu Zdenek Sofer Qiliang Wei Weiyou Yang School of Resources Environment and MaterialsState Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite StructuresGuangxi UniversityNanning 530004China Institute of Micro/Nano Materials and Devices Ningbo University of TechnologyNingbo 315211China Department of Inorganic Chemistry University of Chemistry and Technology PragueTechnická516628Prague 6Czech Republic

Anion exchange membrane fuel cell(AEMFC)technology is attracting intensive attention,due to its great potential by using non-precious-metal catalysts(NPMCs)in the cathode and cheap bipolar plate materials in alkaline ***,in such case,the kinetics of hydrogen oxidation reaction(HOR)in the anode is two orders of magnitude sluggish than that of acidic electrolytes,which is recognized as the grand challenge in this ***,we report the rationally designed Ni nanoparticles encapsulated by N-doped graphene layers(Ni@NG)using a facile pyrolysis *** on the density functional theory calculations and electrochemical performance analysis,it is witnessed that the rich Pyridinic-N within the graphene shell optimizes the binding energy of the intermediates,thus enabling the fundamentally enhanced activity for HOR with robust *** a proof of concept,the resultant Ni@NG sample as the anode with a low loading(1.8 mg cm^(-2))in AEMFCs delivers a high peak power density of 500 mW cm^(-2),outperforming all of those of NPMC-based analogs ever reported.

关键词： anion-exchange-membrane fuel cells density functional calculations hydrogen oxidation reaction Ni-based non-precious-metal catalysts pyridinic N-doped graphene

A new GIS-compatible methodology for visibility analysis in digital surface models of earth sites

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Geoscience Frontiers 2021年第4期12卷 21-33页

作者： Katerina Ruzickova jan Ruzicka jan Bitta VSB–Technical University of Ostrava Czech Republic

As a GIS tool,visibility analysis is used in many areas to evaluate both visible and non-visible *** analysis builds on a digital surface model describing the terrain morphology,including the position and shapes of all objects that can sometimes act as visibility ***,some barriers,for example vegetation,may be permeable to a certain *** extensive research and use of visibility analysis in different areas,standard GIS tools do not take permeability into *** article presents a new method to calculate visibility through partly permeable *** method is based on a quasi-Monte Carlo simulation with 100 iterations of visibility *** iteration result represents 1%of vegetation permeability,which can thus range from 1%to 100%visibility behind vegetation *** main advantage of the method is greater accuracy of visibility results and easy implementation on any GIS *** incorporation of the proposed method in GIS software would facilitate work in many fields,such as architecture,archaeology,radio communication,and the military.

关键词： Digital surface model Visibility analysis Topographic data processing Obstacle object Permeability

The effect of Tyrophagus putrescentiae on Fusarium poae transmission and fungal community in stored barley in a laboratory experiment

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Insect Science 2014年第1期21卷 65-73页

作者： jan Hubert Marta Nesvorna jan Kopecky Crop Research Institute Praha 6 Czech Repubfic

The effect of Tyrophagus putrescentiae on Fusarium poae transmission and fungal community composition was studied in nonsterile barley grain. The experiments included following treatments： control barley without mites; barley containing l0 or 50 mites without preincubation on E poae （Tpl0 and TpS0）; barley containing 10 or 50 mites after preincubation on E poae （FTp 10 and FTp50）. The number of mites, suc cessful transfer of E poae, and changes in the fungal communities were examined after 21 d of experiment. Increase of deoxynivalenol （DON） content in the barley was chosen as a criterion of successful Epoae transfer. The preincubation of T. putrescentiae on Epoae increased DON level approximately to 800 and 300μg/kg of grain for FTpl0 and FTpS0, respectively. T. putrescentiae population growth in FTpl0 was lower than in Tpl0, while no difference was found between FTp50 and Tp50. Fungal communities were compared by amplification, cloning and sequencing of ITS fragments, and operational taxonomic units （OTU） analysis. The OTU analysis did not support the transfer ofF. poae via mites. From the analyzed clones, only 13 cloned sequences clustered with E poae in an OTU defined at distance level 0.07. The related clones originated from FTpl0, Tpl 0, Tp50 and control treatments, but not from FTp50. However, the presence of E poae in FTp50 was confirmed by PCR amplification with specific primers. The observation may be explained by different effect of mite population density, that is, in the high density, （FTp50 treatment） the fungus was overgrazed, while the lower population density （FTp 10） supported E poae transfer.

关键词： barley deoxinivalenol (DON) Fusariumpoae mites mycotoxin storage

Stability Problems in Road and Pipeline Constructions and Their Mitigation——Examples from Sakhalin and Azerbaijan

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Journal of Mountain Science 2011年第2期8卷 307-313页

作者： NOVOTNY jan ARCADIS Geotechnika a.s. Charles University in Prague Faculty of Natural Science

The paper gives two examples of larger construction projects with typical stability problems. The first example is from Sakhalin Island in the Russian Far East. It is connected with a construction of oil and gas pipelines through the mountainous terrain in Makarov region. The region has an active geotectonic history and is highly affected by uncontrolled erosion and extensive landslips. Basic principles of landslide hazard mitigation are presented. The second example is from a motorway construction in Azerbaijan. This motorway leads from Baku to Russia through a seismo-tectonically active area at the toe of Caucasian mountains and in some places is situated in deep cuts at the toe of high slopes. This unsuitable routing, together with seismic activity, led to a slope stability failure of a slope affected by recent tectonic movements near the village of Devechi. Stability conditions and designed remedy measures are presented.

关键词： Stability problems Roads Pipelines Mitigation Sakhalin Azerbaijan

Non-Hermitian degeneracies of internal–external mode pairs in dielectric microdisks

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Photonics Research 2019年第4期7卷 464-472页

作者： CHANG-HWAN yi JULIUS KULLIG MARTINA HENTSCHEL jan WIERSIG Institut für Physik Otto-von-Guericke-Universit?t Magdeburg Institut für Physik Technische Universit?t Ilmenau

Open quantum and wave systems can exhibit non-Hermitian degeneracies called exceptional points, where both the eigenvalues and the corresponding eigenstates coalesce. Previously, such exceptional points have been investigated in dielectric microcavities in terms of optical modes which are well confined inside the cavity. However,beside these so-called "internal modes" with a relatively high quality factor, there exists another kind of mode called "external modes," which have a large decay rate and almost zero intensity inside the cavity. In the present paper, we demonstrate the physical significance of the external modes via the occurrence of exceptional points of internal–external mode pairs for transverse electric polarization. Our numerical studies show that these exceptional points can be achieved by either a boundary deformation of the microdisk or by introducing absorption into a circular cavity.

关键词： electric optical wave can via Our be

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