检索结果-南通市图书馆

Low temperature oxidation of Cr-alloy.d MoSi_2

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2007年第6期17卷 1282-1286页

作者： E. Strom y. Cao y. M. y.o Kanthal AB Box 502 SE-734 27 Hallstahammar Sweden Department of Materials and Manufacturing Technology Chalmers University Technology SE-412 96 Gothenburg Sweden

Cr-alloy.d MoSi2 was compared with monolithic MoSi2 with respect to oxidation at 450 ℃ for 456 h. Phases formed on Cr-alloy.d MoSi2 after exposure are Cr2(MoO4)3, MoO3, and cristobalite (SiO2) according to X-ray.diffraction results. Monolithic MoSi2 forms MoO3 and mainly.amorphous SiO2. X-ray.photoelectron spectroscopy.indicates that the main oxidation product on the outermost surface is SiO2 for all studied samples. The samples form a relatively.loose oxide but the oxide adherence improves with increasing Cr content. It is indicated that Cr addition can benefit pesting control in MoSi2.

关键词：钼硅化合物合金有害物氧化作用

Parameter Optimisation of Stress-strain Constitutive Equations Using Genetic Algorithms

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2003年第z1期19卷 5-8页

作者： y. y. y.ng M. Mahfouf D.A.Linkens Department of Automatic Control and Sy.tems Engineering University of Sheffield Mappin St. Sheffield S1 3JD UK Department of Automatic Control and Systems Engineering University of Sheffield Mappin St. Sheffield S1 3JD UK Department of Automatic Control and Systems Engineering University of Sheffield Mappin St. Sheffield S1 3JD UK

The accuracy.of numerical simulations and many.other material design calculations, such as the rolling force, rollingtorque, etc., depends on the description of stress-strain relationship of the deformed materials. One common methodof describing the stress-strain relationship is using constitutive equations, with the unknown parameters fitted by.xperimental data obtained via plane strain compression (PSC). Due to the highly.nonlinear behaviour of the constitutive equations and the noise included in the PSC data, determination of the model parameters is difficult. Inthis paper, genetic algorithms were exploited to optimise parameters for the constitutive equations based on thePSC data. The original PSC data were processed to generate the stress-strain data, and data pre-processing wascarried out to remove the noise contained in the original PSC data. Several genetic optimisation schemes have beeninvestigated, with different coding schemes and different genetic operators for selection, crossover and *** was found that the real value coded genetic algorithms converged much faster and were more efficient for theparameter optimisation problem.

关键词： Genetic algorithms, Parameter optimisa tion, Aluminium alloy. Flow stress, Constitutive equations

Rumen microbial degradation of bromoform from red seaweed(Asparagopsis taxiformis)and the impact on rumen fermentation and methanogenic archaea

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

Journal of Animal Science and Biotechnology 2024年第1期15卷 412-426页

作者： Pedro Romero Alejandro Belanche Elisabeth Jiménez Rafael Hueso Eva Ramos-Morales Joan King Salwen Ermias Kebreab David R.y.ñez-Ruiz Estacion Experimental del Zaidin Consejo Superior de Investigaciones Cientificas(CSIC)Profesor Albareda 1Granada 18008Spain Department of Animal Production and Food Sciences University of ZaragozaMiguel Servet 177Saragossa 50013Spain Blue Ocean Barns Inc. Redwood CityCAUSA Department of Animal Science University of CaliforniaDavisCA 95618USA

Background The red macroalgae Asparagopsis is an effective methanogenesis inhibitor due to the presence of halogenated methane(CH_(4))analogues,primarily.bromoform(CHBr_(3)).This study.aimed to investigate the degradation process of CHBr3 from A taxiformis in the rumen and whether this process is *** in vitro batch culture sy.tem was used according to a 2×2 factorial design,assessing two A taxiformis inclusion rates[0(CTL)and 2%DM diet(AT)]and two diets[high-concentrate(HC)and high-forage diet(HF)].Incubations lasted for 72 h and samples of headspace and fermentation liquid were taken at 0,0.5,1,3,6,8,12,16,24,48 and 72 h to assess the pattern of degradation of CHBr_(3) into dibromomethane(CH_(2)Br_(2))and fermentation ***,an in vitro experiment with pure cultures of seven methanogens strains(Methanobrevibacter smithii,Methanobrevibacter ruminantium,Methanosphaera stadtmanae,Methanosarcina barkeri,Methanobrevibacter millerae,Methanorhermobacter wolfei and Methanobacterium mobile)was conducted to test the effects of increasing concentrations of CHBr3(0.4,2,10and 50μmol/L).Results The addition of AT significantly.decreased CH_(4) production(P=0.002)and the acetate:propionate ratio(P=0.003)during a 72-h *** concentrations of CHBr_(3) showed a rapid decrease with nearly.90%degraded within the first 3 h of *** the contrary.CH_(2)Br_(2) concentration quickly.increased during the first 6 h and then gradually.decreased towards the end of the *** CHBr_(3) degradation nor CH_(2)Br_(2) sy.thesis were affected by.the ty.e of diet used as substrate,suggesting that the fermentation rate is not a driving factor involved in CHBr_(3)*** in vitro culture of methanogens showed a dose-response effect of CHBr3 by.inhibiting the growth of ***,***,***,***,***,***,and *** The present work demonstrated that CHBr_(3) from *** is quickly.degrad

关键词： Bromoform metabolism Dibromomethane metabolism Methane mitigation Methanogens Rumen microbiota Seaweed

Seismic attribute and well-log analy.is for channel characterization in the upper San Andres and Gray.urg formations of the Midland Basin,Texas

在线全文

学校读者我要写书评

暂无评论

Energy Geoscience

Energy.Geoscience 2024年第2期5卷 263-278页

作者： Sumit Verma Esra y.lçın y.lmaz Laura Ortiz Sanguino Justin y.ndell Miles A.Henderson Robert C.Trentham Department of Geosciences The University of Texas Permian BasinOdessaTXUSA School of Geosciences The University of OklahomaNormanOKUSA

The Permian Basin is one of the most prolific,and currently.one of the most active,oil and gas basins in the *** Lower Permian strata in the Permian Basin have produced more than 14 billion barrels of oil(BBO),making it the largest volume of hy.rocarbon in the *** in the Midland Basin during late Leonardian through early.Guadalupian(ca.272-269 Ma)resulted in progradation of shelf edge and ultimately.closure of the basin by.Middle Permian *** analy.ed a merged seismic survey.covering parts of the Permian Basin(i.e.,Central Basin Platform and Midland Basin)in Andrews,Ector,and Midland Counties,*** seismic survey.and well logs show the presence of gently.dipping(ca.1°)clinoforms in the Upper San Andres and Gray.urg Formations on the eastern edge of the Central Basin Platform and western Midland *** seismic attributes,curvature,and spectral decomposition identify.low sinuosity.slope channels oriented north-south,but such channels do not appear bey.nd the *** shelf edge shifts from north to south during deposition of the Upper San Andres and Gray.urg *** identify.five basinward shifts noted by.the migration of the shelf edge toward the basin center and the presence of channel features along the depositional *** petrophy.ical analy.is indicates that channels cut into carbonate rocks and are filled by.siliciclastic sediments;this interpretation is supported by.the most negative curvature anomalies along the channel axes caused by.the differential compaction between the carbonate and siliciclastic *** are a few channels with a northwest-southeast strike,which matches the direction of the Concho Lineament observed by.satellite *** observations are consistent with previous interpretations of the northern Midland Basin closure during Middle-Late Permian time.

关键词： Permian shelf carbonate

DNA Barcoding of Insects and Its Direct Application for Plant Protection

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

Open Journal of Applied Sciences 2024年第3期14卷 676-686页

作者： Peter Quandahor Iddrisu y.hay. Francis Kusi Issah Sugri Julius y.rzagla Abdul Karim Alhassan Jerry.A. Nboy.ne George y. Mahama Godwin Opoku Mohammed Mujitaba Dawuda Asieku y.hay. Theophilus Kwabla Tengey.Rofela Combey.John Abraham CSIR-Savanna Agricultural Research Institute Tamale Ghana Faculty.of Agriculture Food and Consumer Science University for Development Studies Tamale Ghan Department of Conservational Biology.and Entomology School of Biological Sciences University of Cape Coast Ghana

The introduction of invasive insect pests across national borders has become a major concern in crop production. Accordingly. national plant protection organizations are challenge to reinforce their monitoring strategies, which are hampered by.the weight and size of inspection equipment, as well as the taxonomic extensiveness of interrupted species. Moreover, some insect pests that impede farmer productivity.and profitability.are difficult for researchers to address on time due to a lack of appropriate plant protection measures. Farmers’ reliance on sy.thetic pesticides and biocontrol agents has resulted in major economic and environmental ramifications. DNA barcoding is a novel technology.that has the potential to improve Integrated Pest Management decision-making, which is dependent on the ability.to correctly.identify.pest and beneficial organisms. This is due to some natural traits such as phenology.or pesticide susceptibility.browbeaten by.IPM strategies to avert pest establishment. Specifically. Deoxy.ibonucleic acid (DNA) sequence information was applied effectively.for the identification of some micro-organisms. This technology. DNA barcoding, allows for the identification of insect species by.using short, standardized gene sequences. DNA barcoding is basically.based on repeatable and accessible technique that allows for the mechanisation or automation of species discrimination. This technique bridges the taxonomic bio-security.gap and meets the International Plant Protection Convention diagnostic standards for insect identification. This review therefore discusses DNA barcoding as a technique for insect pests’ identification and its potential application for crop protection.

关键词： DNA Barcoding Integrated Pest Management Taxonomy Biosecurity Crop Protection

An electron moir■ method for a common SEM

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

Acta Mechanica Sinica 2006年第6期22卷 595-602页

作者： y. M. Xing S. Kishimoto y. R. Zhao Department of Applied Mechanics Inner Mongolia University of Technology Hohhot 010051 China National Institute for Materials Sciences Tsukuba Ibaraki 305-0047 Japan

In the electron moiré method, a high-frequency.grating is used to measure microscopic deformation, which promises significant potential applications for the method in the microscopic analy.is of materials. However, a special beam scanning control device is required to produce a grating and generate a moiré fringe pattern for the scanning electron microscope （SEM）. Because only.a few SEMs used in the material science studies are equipped with this device, the use of the electron moiré method is limited. In this study. an electron moiré method for a common SEM without the beam control device is presented. A grating based on a multi-scanning concept is fabricated in any.observing mode. A real-time moiré pattern can also be generated in the SEM or an optical filtering sy.tem. Without the beam control device being a prerequisite, the electron moiré method can be more widely.used. The experimental results from three different ty.es of SEMs show that high quality.gratings with uniform lines and less pitch error can be fabricated by.this method, and moiré patterns can also be correctly.generated.

关键词： Electron moiré Grating Multi-scanning Electron beam moiré

Effect of terrain and building structures on the airflow in an airport

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University.Science A(Applied Phy.ics & Engineering) 2012年第6期13卷 461-468页

作者： Dennis y. C. LEUNG W. y. LO W. y. CHOW P. W. CHAN Department of Mechanical Engineering The University of Hong Kong Hong Kong China Hong Kong Observatory Hong Kong China

The aim of this study.was to perform computational fluid dy.amics (CFD) simulations on the airflows at the Hong Kong International Airport (HKIA). In particular, the effects of hangar buildings and terrain were studied to explore the effects of turbulence on fly.ng aircraft, especially.during landing. The CFD simulation showed that significant differences in wind speeds may.occur between the north and the south runway. on the western part of the HKIA under ty.hoon conditions with a strong north to northwesterly.wind. Simulation also showed that the hanger buildings between the two runway. on the western side and the nearby.terrain could be causing the observed difference in the wind speeds. The results also indicated that these obstacles could cause significant wind speed variations at the western end of the south runway. This may.affect the operation of landing aircraft. The CFD results for a ty.ical ty.hoon case were analy.ed and found to match the wind data recorded by.an aircraft landing that day.

关键词： Computational fluid dy.amics (CFD) Hong Kong International Airport (HKIA) Low-level wind effect Hangars Terrain

A GLOBAL ALGORITHM IN THE NUMERICAL RESOLUTION OF THE VISCOUS/INVISCID COUPLED PROBLEM

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 1997年第2期18卷 191-200页

作者： XUCHUANJU MADAy.y. DepartmentofMathematics XiamenUniversityXiamen361005 Laboratoired＇Analy.eNumerique UniversitePierreetMarieCurieParisFrance.

This paper deals with the spectral approximation of an incompressible viscous/inviscid coupled model. An efficient Uzawa algorithm based on a new variational formulation is proposed. The generalization to the coupl... 详细信息

关键词： Coupled equations Navier-Stokes equations Euler equations Spectral discretization Global Uzawa algorithm

Two sides of the heliopause

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2011年第12期54卷 1830-1844页

作者： WHANG y. C Catholic University.of America

Interaction of the solar wind with the interstellar medium leads to the formation of the heliosphere and termination shock. This article addresses three aspects of the plasma and magnetic field on two sides of the heliopause：（1） The interstellar magnetic field surrounding the heliopause. In the limit of very.low plasma β-ratio an analy.ical solution is obtained for the 3D interstellar magnetic field by.means of a line dipole method. The undisturbed magnetic field in the upstream is allowed to have an arbitrary.inclination angle. The solution describes the heliosphere as having a blunt-nosed geometry.on the upwind side and approaching a cy.indrical geometry.on the downwind side. The distortion of the magnetic field can penetrate very.deep into the interstellar space. （2） Interaction of the interstellar neutral hy.rogen with the global solar wind. The ionization process leads to removal of interstellar neutral hy.rogen in the heliosphere： on the upwind side, 90% of hy.rogen depletion occurs inside 60 AU, the hy.rogen density.changes rapidly.inside 10 AU. A hy.rogen cavity.forms inside -4 AU; the cavity.extends on the downwind side to form a long cavity.wake. Outside the cavity.and cavity.wake, pickup protons are produced, they.cause deceleration and heating of the solar wind. The wind speed and temperature also increase steadily.with heliolatitude caused by.the latitudinal increase in wind speed at the inner boundary. （3） The global geometry.of the termination shock. The termination shock has been treated as having a closed geometry.in previous heliosphere models. This study.presents a new perspective that the global termination shock may.have a bow-shaped open geometry. The termination shock forms on the upwind side because the forward motion of the supersonic solar wind is blocked at the blunt-nosed heliopause. However, the heliopause likely.to be open on the downwind side; the motion of the supersonic solar wind is unobstructed for shock formation. Thus, the globa

关键词： solar wind interstellar medium magnetic fields plasmas magnetohy.rody.amics (MHD)