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Combustion characteristics of low-quality lignite for different bed material sphericities in a circulating fluidized bed boiler:A numerical study

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Particuology 2024年第7期90卷 364-382页

作者： Barışgürel gülşah Karaca Dolgun Osmanipek Ali Keçebaş Department of Mechanical Engineering Engineering FacultySüleyman Demirel UniversityÇünürIspartaTurkey Department of Energy Systems Engineering Technology FacultyMuğla SıtkıKoçman UniversityKötekliMenteşeMuğlaTurkey

This study delves into the combustion behavior of various lignite types within a circulating fluidized bed boiler(CFBB),with a primary focus on the impact of different bed material sphericity ratios(0.5,0.7,and 0.9).Utilizing bed material with a sphericity ratio of 0.9 sourced from theÇan power plant and verified through experimentation,the research reveals several key findings.Notably,furnace temperatures tended to rise with higher sphericity ratios,albeit with variations between lignite types,particularly highlighting the complexity of this relationship in the case of gLi-Tunçbilek lignite.Pressure levels in the combustion chamber remained consistent across different sphericity ratios,indicating minimal influence on pressure dynamics.improved combustion efficiency,especially at the bottom of the boiler,was observed at lower sphericity levels(0.5 and 0.7)forÇan lignite,as reflected in CO_(2) mole fractions.While NO_(x) emissions generally decreased with lower sphericity,the sensitivity to sphericity varied by lignite type,with ilgın lignite showcasing low NO_(x) but high SO_(2) emissions,underscoring the intricate interplay between lignite properties,sphericity,and emissions.Overall,this study advances our understanding of CFBB combustion dynamics,offering insights valuable for optimizing performance and emissions control,particularly in lignite-based power.

关键词： Circulating fluidized bed boiler Computational particle fluid dynamics method Particle sphericity ratios NO_(x)and SO_(2)emissions Energy production efficiency

Phase composition,conductivity,and sensor properties of cerium-doped indium oxide

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Nano Materials Science 2024年第2期6卷 193-200页

作者： M.i.ikim g.N.gerasimov V.F.gromov O.J.ilegbusi L.i.Trakhtenberg N.N.Semenov Federal Research Center for Chemical Physics of RAS MoscowRussia University of Central Florida OrlandoFLUSA Moscow institute of Physics and Technology(State University) DolgoprudnyMoscow RegionRussia Lomonosov Moscow State University MoscowRussia

The hydrothermal synthesis of in_(2)O_(3)and CeO_(2)–in_(2)O_(3)is investigated as well as the properties of sensor layers based on these compounds.During the synthesis of in_(2)O_(3),intermediate products in(OH)_(3)and inOOH are formed,which are the precursors of stable cubic(c-in_(2)O_(3))and metastable rhombohedral(rh-in_(2)O_(3))phases,respectively.A transition from c-in_(2)O_(3)to rh-in_(2)O_(3)is observed with the addition of CeO_(2).The introduction of cerium into rh-in_(2)O_(3)results in a decrease in the sensor response to hydrogen,while it increases in composites based on c-in_(2)O_(3).The data on the sensor activity of the composites correlate with XPS results in which CeO_(2)causes a decrease in the concentrations of chemisorbed oxygen and oxygen vacancies in rh-in_(2)O_(3).The reverse situation is observed in composites based on c-in_(2)O_(3).Compared to in_(2)O_(3)and CeO_(2)–in_(2)O_(3)obtained by other methods,the synthesized composites demonstrate maximum response to H_(2)at low temperatures by 70–100℃,and have short response time(0.2–0.5 s),short recovery time(6–7 s),and long-term stability.A model is proposed for the dependence of sensitivity on the direction of electron transfer between in_(2)O_(3)and CeO_(2).

关键词： Cerium oxide indium oxide Nanocomposite Hydrothermal method Cubic phase Rhombohedral phase Sensor response Conductivity Hydrogen Response/recovery time

Height-diameter models for King Boris fir(Abies borisii regis Mattf.) and Scots pine(Pinus sylvestris L.) in Olympus and Pieria Mountains, greece

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Journal of Mountain Science 2024年第5期21卷 1475-1490页

作者： Dimitrios i.RAPTiS Dimitra PAPADOPOULOU Angeliki PSARRA Athanasios A.FALLiAS Aristides g.TSiTSANiS Vassiliki KAZANA Renewable Natural Resource Management and Bioeconomy Laboratory Department of Forest and Natural Environment SciencesInternational Hellenic University66100 DramaGreece

in forest science and practice, the total tree height is one of the basic morphometric attributes at the tree level and it has been closely linked with important stand attributes. in the current research, sixteen nonlinear functions for height prediction were tested in terms of their fitting ability against samples of Abies borisii regis and Pinus sylvestris trees from mountainous forests in central greece. The fitting procedure was based on generalized nonlinear weighted regression. At the final stage, a five-quantile nonlinear height-diameter model was developed for both species through a quantile regression approach, to estimate the entire conditional distribution of tree height, enabling the evaluation of the diameter impact at various quantiles and providing a comprehensive understanding of the proposed relationship across the distribution. The results clearly showed that employing the diameter as the sole independent variable, the 3-parameter Hossfeld function and the 2-parameter N?slund function managed to explain approximately 84.0% and 81.7% of the total height variance in the case of King Boris fir and Scots pine species, respectively. Furthermore, the models exhibited low levels of error in both cases(2.310m for the fir and 3.004m for the pine), yielding unbiased predictions for both fir(-0.002m) and pine(-0.004m). Notably, all the required assumptions for homogeneity and normality of the associated residuals were achieved through the weighting procedure, while the quantile regression approach provided additional insights into the height-diameter allometry of the specific species. The proposed models can turn into valuable tools for operational forest management planning, particularly for wood production and conservation of mountainous forest ecosystems.

关键词： generalized nonlinear weighted regression Monte Carlo cross-validation Mountainous ecosystems Quantile regression Central greece

Exact solutions for magnetohydrodynamic nanofluids flow and heat transfer over a permeable axisymmetric radially stretching/shrinking sheet

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Chinese Physics B 2024年第2期33卷 108-114页

作者： U.S.Mahabaleshwar g.P.Vanitha L.M.Pérez Emad H.Aly i.Pop Department of Studies in Mathematics Davangere UniversityShivagangothriDavangereIndia Departamento de F´ısica FACIUniversidad de Tarapac´aCasilla 7DAricaChile Department of Mathematics Faculty of EducationAin Shams UniversityRoxyCairoEgypt Department of Mathematics Babes-Bolyai University400084 Cluj-NapocaRomania

We report on the magnetohydrodynamic impact on the axisymmetric flow of Al_(2)O_(3)/Cu nanoparticles suspended in H_(2)O past a stretched/shrinked sheet.With the use of partial differential equations and the corresponding thermophysical characteristics of nanoparticles,the physical flow process is illustrated.The resultant nonlinear system of partial differential equations is converted into a system of ordinary differential equations using the suitable similarity transformations.The transformed differential equations are solved analytically.impacts of the magnetic parameter,solid volume fraction and stretching/shrinking parameter on momentum and temperature distribution have been analyzed and interpreted graphically.The skin friction and Nusselt number were also evaluated.in addition,existence of dual solution was deduced for the shrinking sheet and unique solution for the stretching one.Further,Al_(2)O_(3)/H_(2)O nanofluid flow has better thermal conductivity on comparing with Cu/H_(2)O nanofluid.Furthermore,it was found that the first solutions of the stream are stable and physically realizable,whereas those of the second ones are unstable.

关键词： magnetohydrodynamic nanofluid stretching/shrinking sheet axisymmetric flow analytical solution suction/injection

Detection of 4p16.3 deletion and 11p15.5p15.4 gain in a boy by comparative genomic hybridization array:A case report

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World Journal of Clinical Cases 2024年第8期12卷 1517-1522页

作者： işın Kaya Medical genetics Bakırçay UniversityÇiğli Education ve Training Hospitalİzmir 35620Turkey

BACKgROUND Nonallelic homologous recombination(NAHR)of segmental duplications or low copy repeats(LCRs)result in DNA gain/loss and play an important role in the origin of genomic disorders.CASE SUMMARY A 3-year-old boy was referred for genetic analysis.Comparative genomic hybrid-ization array analysis revealed a loss of 3776 kb in the 4p16.3 chromosomal region and a gain of 3201 kb in the 11p15.5p15.4 chromosomal region.CONCLUSiON genomic imbalances caused by NAHR in LCRs result in deletion and duplication syndromes.

关键词： Wolf-Hirschhorn syndrome Silver-Russell syndrome Recurrent rearrangements Case report

Taxonomy,distribution,and contemporary exposure of terrestrial mammals to floods and human pressure across different areas for biodiversity conservation in China

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integrative Zoology 2024年第3期19卷 458-467页

作者： Roman SHARNUUD Eric i.AMECA MOE Key Laboratory for Biodiversity Science&Ecological Engineering College of Life SciencesBeijing Normal UniversityBeijingChina Climate Change Specialist group Species Survival CommissionInternational Union for Conservation of NatureGlandSwitzerland

A significant research focus is placed on identifying animal species and areas at future risk to human-induced alterations of the environment and long-term changes in climatic conditions.Yet,the extent to which exposure to extreme climatic events and intense human pressure can increase the risk of harmful impacts on species remains poorly investigated.Focusing on terrestrial mammals in China,one of the world’s megadiverse countries,we investigated patterns of contemporary exposure to floods and human pressures and determined their taxonomic representation and distribution across three major area-based conservation schemes,namely,national nature reserves(NNRs),priority areas for biodiversity conservation(PABCs),and key biodiversity areas(Kbas).Among the 440 species assessed with moderate or high exposure to floods,327(∼75%)also qualified as moderate or high in exposure to intense human pressure.These species mainly belong to the orders Chiroptera,Eulipotyphla,and Rodentia.Likewise,there were 305,311,and 311 species with moderate or high exposure to flood and intense human pressure represented across NNRs,PABCs,and Kbas,respectively.Our findings support the prioritization of Kbas for expansion of site-based protection efforts such as NNRs in China,considering threats to species from exposure to adverse effects from both extreme climate and human pressure.

关键词： conservation floods human pressure mammals taxonomy

Effect of solidification cooling rate on microstructure and tribology characteristics of Zn-4Si alloy

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international Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 362-373页

作者： F.Akbari M.golkaram S.Beyrami g.Shirazi K.Mantashloo R.Taghiabadi M.Saghafi Yazdi i.Ansarian Department of Metallurgy and Material Science Imam Khomeini International University(IKIU)Qazvin ***Iran

The main objective of this work was to modify the microstructure and enhance the tribological properties of a new Zn-4Si al-loy through a high solidification cooling rate(SCR).According to the results,by increasing the SCR from 2.0 to 59.5℃/s the average size of primary Si particles and that of the grains reduced from 76.1 and 3780μm to less than about 14.6 and 460μm,respectively.Augment-ing the SCR also enhanced the microstructural homogeneity,decreased the porosity content(by 50%),and increased the matrix hardness(by 36%).These microstructural changes enhanced the tribological behavior.For instance,under the applied pressure of 0.5 MPa,an in-crease in the SCR from 2.0 to 59.5℃/s decreased the wear rate and the average friction coefficient of the alloy by 57%and 23%,respect-ively.The wear mechanism was also changed from the severe delamination,adhesion,and abrasion in the slowly-cooled alloy to the mild tribolayer delamination/abrasion in the high-cooling-rate-solidified sample.

关键词： zinc-silicon alloy primary silicon solidification cooling rate tribology sliding wear

Electro-Optical Model of Soiling Effects on Photovoltaic Panels and Performance implications

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Energy Engineering 2024年第2期121卷 243-258页

作者： A.Asbayou g.P.Smestad i.ismail A.Soussi A.Elfanaoui L.Bouhouch A.ihlal Laboratory of Materials and Renewable Energies University Ibn ZohrAgadir80000Morocco Sol ideas Technology Development San José95150USA

in this paper,a detailed model of a photovoltaic(PV)panel is used to study the accumulation of dust on solar panels.The presence of dust diminishes the incident light intensity penetrating the panel’s cover glass,as it increases the reflection of light by particles.This phenomenon,commonly known as the“soiling effect”,presents a significant challenge to PV systems on a global scale.Two basic models of the equivalent circuits of a solar cell can be found,namely the single-diode model and the two-diode models.The limitation of efficiency data in manufacturers’datasheets has encouraged us to develop an equivalent electrical model that is efficient under dust conditions,integrated with optical transmittance considerations to investigate the soiling effect.The proposed approach is based on the use of experimental current-voltage(i-V)characteristics with simulated data using MATLAB/Simulink.Our research outcomes underscores the feasibility of accurately quantifying the reduction in energy production resulting from soiling by assessing the optical transmittance of accumulated dust on the surface of PV glass.

关键词： Photovoltaics solar energy optical transmittance soiling dust PV performance

AN OPTiMAL CONTROL PROBLEM FOR A LOTKA-VOLTERRA COMPETiTiON MODEL WiTH CHEMO-REPULSiON

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Acta Mathematica Scientia 2024年第2期44卷 721-751页

作者： Diana i.HERNÁNDEZ Diego A.RUEDA-gOMEZ Élder J.ViLLAMiZAR-ROA Universidad industrial de Santander Escuela de MatemáticasA.A.678BucaramangaColombia

in this paper we study a bilinear optimal control problem for a diffusive Lotka-Volterra competition model with chemo-repulsion in a bounded domain of ℝ^(ℕ),N=2,3.This model describes the competition of two species in which one of them avoid encounters with rivals through a chemo-repulsion mechanism.We prove the existence and uniqueness of weak-strong solutions,and then we analyze the existence of a global optimal solution for a related bilinear optimal control problem,where the control is acting on the chemical signal.Posteriorly,we derive first-order optimality conditions for local optimal solutions using the Lagrange multipliers theory.Finally,we propose a discrete approximation scheme of the optimality system based on the gradient method,which is validated with some computational experiments.

关键词： Lotka-Volterra chemo-repulsion optimal control optimality conditions