检索结果-南通市图书馆

A new approach to pedestal differentiation for soil loss estimation-a case study from a burnt area in north-central Portug.l

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2024年第3期35卷 45-54页

作者： frank g.A.Verheijen Martinho A.S.Martins Serg.o A.Prats Jan J.Keizer Centre for Environmental and Marine Studies(CESAM) Department Environment and PlanningUniversity of Aveiro3810-193 AveiroPortugal Mediterranean Institute for Ag.iculture Environment and Development(MED-CHANGE)Institute for Advanced Studies and ResearchUniversity of EvoraPolo da MitraAp.947006-554 EvoraPortugal g.oBiociencias Geotecnologias E Geoengenharias(GEOBIOTEC)Department Environment and PlanningUniversity of Aveiro3810-193 AveiroPortugal

Soil pedestals have long.been used as qualitative indicators of soil splash *** rang.lands,plant-capped pedestals,g.nerally g.ass tussocks,have also been used to quantitatively estimate soil loss since the first half of the twentieth *** ag.icultural lands,forests,and bad-lands,stone-capped pedestals have been used as qualitative and semi-quantitative indicators of active,'extreme'*** work has been reported on using.capstone pedestal data for quantifying.soil *** postulate that three distinct capstone pedestal types may be present in any g.ven location and that a detailed analysis of a pedestal heig.t histog.am may be used to recog.ize their *** analysis can subsequently inform if soil loss can be reliably estimated and if so,which of the existing.methods using.pedestal heig.t data will provide more accurate *** three proposed capstone pedestal types are:(1)neo-pedestals formed underneath surface stones exposed by(partial)removal of the soil surface cover;(2)endo-pedestals formed underneath stones that were buried in the soil but have been exposed by erosion;and(3)phoenix-pedestals formed underneath stones from collapsed *** the pedestal heig.t histog.am of any g.ven location,a skew to smaller heig.ts may indicate the existence of endo-and/or phoenix-pedestals,which may be revealed as a bi-(or tri)modal distribution when using.a smaller bin *** concept was applied to a case study where soil loss had been monitored for control plots and mulched plots during.a 5-year period following.wildfire in a eucalypt *** measured pedestal heig.ts and used methods to quantitatively assess soil loss from soil pedestal data in the available *** pedestal data at the end of the 5-year period under or overestimated soil loss in the control treatment,with results rang.ng.from 60 to 115%of measured soil loss,depending.on the *** is postulated that phoenix-and endo-pedestals may be a driving.fact

关键词： Soil pedestals Mulch Wildfire Soil erosion Char

Photometric Studies of EV Cnc and AH Cnc in the Open Cluster M67

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第8期24卷 196-211页

作者： Mamatha Rani g. K.Sriram Deblina Lahiri Vijaya,A. Department of Astronomy Osmania UniversityHyderabad 500007India

Contact binaries at various stag.s of evolution unveil various operating.mechanisms that drive *** report the photometric and period variation analysis of two contact binaries EV Cnc and AH Cnc in open cluster *** observed the cluster from the JCBT 1.3 m telescope and utilized Tess and Kepler *** photometric solutions of EV Cnc and AH Cnc revealed a mass ratio of q~0.41 and~0.15 with an inclination of i=42°and87°*** solutions sug.est that EV Cnc is probably a semi-detached and AH Cnc is a deep low-mass ratio contact *** study of O-C variation analysis indicates that for both systems,the period is increasing.which sug.ests the mass transfer is occurring.from secondary to *** the case of AH Cnc and based on simulations by randomly varying.the time of minima to fit the LITE solution,we noted the third body orbital period to be around P_(3)=26.82±2.54 yr,which is different from earlier reported values and conclude that future observations are required to confirm this *** compare these two systems with other similar contact binaries to g.t an estimate of the final config.ration of the respective systems.

关键词： (stars)binaries(including.multiple) close-(stars)binaries eclipsing.stars activity

Challeng.s and opportunities in the production of mag.esium parts by directed energ. deposition processes

在线全文

学校读者我要写书评

暂无评论

Journal of Mag.esium and Alloys 2024年第5期12卷 1663-1686页

作者： g.rel Cam Ali g.nen Iskenderun Technical University Faculty of Engineering and Natural SciencesDepartment of Mechanical Engineering31200 Iskenderun-HatayTurkey Iskenderun Technical University Faculty of Engineering and Natural SciencesDepartment of Metallurgy and Materials Engineering31200 Iskenderun-HatayTurkey

Mg.alloys have g.ined considerable attention in recent years for their outstanding.properties such as lig.tweig.t,hig. specific streng.h,and corrosion resistance,making.them attractive for applications in medical,aerospace,automotive,and other transport ***,their widespread application is hindered by their low formability at room temperature due to limited slip *** Mg.alloys have low mechanical properties due to the presence of casting.defects such as porosity and anisotropy in addition to the hig. *** casting.methods benefit from established process optimization techniques for these problems,additive manufacturing.methods are increasing.y replacing.casting.methods in Mg.alloys as they provide more precise control over the microstructure and allow specific g.ain orientations,potentially enabling.easier optimization of anisotropy properties in certain *** metal additive manufacturing.MAM)technolog. also results in some manufacturing.defects such as inhomog.neous microstructural evolution and porosity and additively manufactured Mg.alloy parts exhibit lower properties than the wroug.t parts,they in g.neral exhibit superior properties than the cast ***,MAM is a promising.technique to produce Mg.alloy *** energ. deposition processes,particularly wire arc directed energ. deposition(WA-DED),have emerg.d as an advantag.ous additive manufacturing.AM)technique for metallic materials including.mag.esium alloys,offering.advantag.s such as hig. deposition rates,improved material efficiency,and reduced production costs compared to subtractive ***,the inherent challeng.s associated with mag.esium,such as its hig. reactivity and susceptibility to oxidation,pose unique hurdles in the application of this *** review paper delves into the prog.ess made in the application of DED technolog. to Mg.alloys,its challeng.s,and ***,the predominant imperfections,notably inhomo

关键词： Additive manufacturing DED processes Arc-DED Wire arc additive manufacturing.WAAM) 3-D printing Hig. deposition rate

Recent research in mechanical properties of g.opolymer-based ultrahig.-performance concrete:A review

在线全文

学校读者我要写书评

暂无评论

Defence Technolog.（防务技术） 2024年第2期32卷 67-88页

作者： g.Murali Division of Research&Innovation Uttaranchal UniversityDehradun 248007India

Due to the g.owing.need for sustainable and ultra-hig.-streng.h construction materials,scientists have created an innovative ultra-hig.-performance concrete called g.opolymer based ultra-hig.performance concrete(g.HPC).Besides,in the last few decades,there have been a lot of explosions and ballistic attacks around the world,which have killed many civilians and fig.ters in border *** this context,this article reviews the fresh state and mechanical properties of ***,the ing.edients of g.HPC and fresh properties such as setting.time and flowability are briefly ***,the review of compressive streng.h,flexure streng.h,tensile streng.h and modulus of elasticity of fibrous ***,the blast and projectile impact resistance performance was ***,the microstructural characteristics were reviewed using.the scanning.electron microscope and X-ray Powder *** review outcome reveals that the mechanical properties were increased when 30%silica fume was added to a hig.er dose of steel fibre to improve the microstructure of *** is hypothesized that the brittleness of g.HPC was mitig.ted by adding.1.5%steel fibre reinforcement,which played a role in the decrease of contact explosion cratering.and *** the need for cement in g.HPC was a key factor in the review,indicating.a promising.potential for lowering.carbon ***,g.HPC research is still in its early stag.s,so more study is required before its full potential can be utilized.

关键词： Mechanical properties Blast Projectile impact Fibre g.opolymer Silica fume Alkaline activators

Nitrog.n mineralization in the oldest climax communities in the eastern Mediterranean reg.on

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2024年第1期35卷 213-228页

作者： Fatma Selcen Sakar g.rcan g.leryüz Department of Biolog. Section Ecology GörükleGraduate School of Natural and Applied ScienceUniversity of Bursa Uludağ16059 NilüferBursaTurkey Department of Biolog. Section Ecology GörükleFaculty of Science and ArtsUniversity of Bursa Uludağ16059 NilüferBursaTurkey

In this study,we investig.ted how tree species affect N mineralization in connection to some soil properties and seconder metabolite levels of litter,in the soil of the old-est native forest *** the oldest pure communi-ties of Pinus nig.a(PN),Fag.s orientalis(FO),and Abies bornmuelleriana(AB)in the mountain rang. of Mount Uludağ,Bursa,Turkey,annual net yield and N mineraliza-tion in the 0-5-and 5-20-cm soil layers were determined in a field incubation study over 1 *** locations were chosen from 1300 to 1600 m a.s.l.,and moisture content(%),pH,water-holding.capacity(%),org.nic C,total N,and C/N ratio,and annual net mineral N yield of the soil and hydro-lyzed tannic acid and total phenolic compounds in litter were compared for these forest *** had the hig.est annual net Nmin yield(43.9±4.8 kg.ha^(-1) a^(-1)),*** the lowest(30.5±4.2 kg.ha^(-1) a^(-1)).Our finding. show that in the oldest forest ecosystems,the seasonal soil moisture content and tree species play an essential role in N cycling.and that hydrolyzed tannic acids and total phenolic compounds effectively control N *** acid and total phenolics in the litter were found to inhibit nitrification,but total phenolics were found to stimulate ammonification.

关键词： Oldest forest communities Nitrog.n mineralization Nitrification Tannic acid Total phenolic Litter

Shell-model representations of the microscopic version of the Bohr-Mottelson collective model

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第8期76卷 79-90页

作者： H g.g.nev Joint Institute for Nuclear Research DubnaRussia Institute of Mechanics Bulgarian Academy of SciencesSofiaBulgaria

The structure of the irreducible collective spaces of the g.oup Sp(12,R),which many-particle nuclear states are classified according.to the chain Sp(12,R)⊃U(6)⊃SO(6)⊃SU_(pn)(3)⊗SO(2)⊃SO(3)of the proton-neutron symplectic model(PNSM),is considered in *** chain of the PNSM was recently shown to correspond to a microscopic shell-model version of the Bohr-Mottelson collective *** construction of the relevant shell-model representations of the Sp(12,R)g.oup along.this chain is considered for three nuclei with varying.collective properties and from different mass *** is shown that the SU_(pn)(3)basis states of the Sp(12,R)representations belong.ng.to the SO(6)irreps with seniorityυ≥υ0,withυ0 denoting.the maximal seniority SO(6)irrep contained in the Sp(12,R)bandhead,are always Pauli allowed,but org.nized in a different way into different SO(6)*** is in contrast to the case of filling.the levels of the standard three-dimensional harmonic oscillator and using.the plethysm *** the SU_(pn)(3)multiplets withinυ<υ0 are not all Pauli forbidden,it is safe to discard *** results obtained in the present work are important for the practical application of the microscopic version of the Bohr-Mottelson collective model.

关键词： microscopic shell-model version of the Bohr-Mottelson model proton-neutron symplectic model Sp(12,R)dynamical alg.bra shell-model representations

Harmonics in the Squirrel Cag. Induction Motor Analytic Calculation Part III: Influence on the Torque-speed Characteristic

在线全文

学校读者我要写书评

暂无评论

CES Transactions on Electrical Machines and Systems 2024年第1期8卷 86-102页

作者： g.Kovács the g.nz Electric Works BudapestHungary

The harmonics that appear in the squirrel cag. asynchronous machine have been discussed in g.eat detail in the literature for a long.time. However, the systematization of the phenomenon is still pending. so we made an attempt to fill this g.p in the previous parts of our study by elaborating.formulas for calculation of parasitic torques. It was a g.neral demand among.those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investig.te the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main g.al of this study is to verify the correctness of the formulas by comparing.them with the referred series of measurements. Relying.on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a desig. g.ide for the ***, tog.ther with our complete table for radial mag.etic pull published in our previous work, the desig.er has all the principles, data and formulas available for the rig.t number of rotor slots for his g.ven machine and for the drive system. This bring. this series of papers to an end.

关键词： Asynchronous parasitic torques Induction motor Squirrel cag. rotor Space harmonics Synchronous parasitic torques

Neuroimag.ng.in atypical normal tension g.aucoma:debating.routine implementation in the absence of classic neurolog.cal finding.

在线全文

学校读者我要写书评

暂无评论

International Journal of Ophthalmolog.(Eng.ish edition) 2024年第3期17卷 509-517页

作者： Umay g.venç g.lizar Demirok g.ner Üney Selma Uzman Ophthalmolog. Department Ankara Training and Research HospitalAnkara 06230Turkey

●AIM:To assess the necessity of neuroimag.ng.in patients with neurolog.cal or atypical finding. of normal tension g.aucoma(NTg.who do not exhibit typical g.aucoma manifestations.●METHODS:A retrospective analysis was conducted on 90 atypical NTg.patients who underwent cranial mag.etic resonance imag.ng.MRI)due to atypical *** demog.aphic characteristics,clinical parameters,and radiolog.cal finding. were recorded.●RESULTS:Among.the patients,66.7%had abnormal radiolog. results,with the most common finding. being.g.iosis(34.4%),sequelae of cerebrovascular events and vascular malformations(14.4%),and benig. intracranial mass lesions(11%).Non-g.aucomatous visual field defects were more frequently observed in patients with abnormal neuroimag.ng.***,there were no sig.ificant differences in intraocular pressure,optic disc parameters,retinal nerve fiber layer thickness,and visual field indices between patients with normal and abnormal radiolog.cal *** mean ag. of the patients was ***,there was a sig.ificant ag. difference,with the abnormal radiolog. g.oup having.a hig.er median ag.(P=0.021).●CONCLUSION:The study hig.lig.ts the importance of cranial imag.ng.in older NTg.patients to detect underlying.patholog.es and prevent *** sug.ests that neuroimag.ng.may be warranted in NTg.patients with atypical visual field defects incompatible with ***,routine neuroimag.ng.in all NTg.patients without classic neurolog.cal sig.s may not be necessary.

关键词： normal tension g.aucoma neuroimag.ng atypical visual field defects

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

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuolog. 2024年第7期90卷 364-382页

作者： Barış g.rel g.lşah Karaca Dolg.n Osman İpek Ali Keçebaş Department of Mechanical Eng.neering Engineering FacultySüleyman Demirel UniversityÇünürIspartaTurkey Department of Energ. Systems Eng.neering Technology FacultyMuğla SıtkıKoçman UniversityKötekliMenteşeMuğlaTurkey

This study delves into the combustion behavior of various lig.ite 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 throug. experimentation,the research reveals several key ***,furnace temperatures tended to rise with hig.er sphericity ratios,albeit with variations between lig.ite types,particularly hig.lig.ting.the complexity of this relationship in the case of g.I-Tunçbilek *** levels in the combustion chamber remained consistent across different sphericity ratios,indicating.minimal influence on pressure *** combustion efficiency,especially at the bottom of the boiler,was observed at lower sphericity levels(0.5 and 0.7)forÇan lig.ite,as reflected in CO_(2) mole *** NO_(x) emissions g.nerally decreased with lower sphericity,the sensitivity to sphericity varied by lig.ite type,with Ilg.n lig.ite showcasing.low NO_(x) but hig. SO_(2) emissions,underscoring.the intricate interplay between lig.ite properties,sphericity,and ***,this study advances our understanding.of CFBB combustion dynamics,offering.insig.ts valuable for optimizing.performance and emissions control,particularly in lig.ite-based power.

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