检索结果-南通市图书馆

Application of rare earths in fluid catalytic cracking： A review

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 Rare Earths 2017年第10期35卷 941-956页

作者： aaron Akah Research and Development Center Saudi Aramco Dhahran 31311 Saudi Arabia

The need for more active and hydrothermally stable fluid catalytic cracking（FCC）catalysts to combat the effect of metal contaminants has led to an increase in demand for rare earth *** earth oxides enhance catalyst activity and prevent the loss of acid sites during the FCC unit operation,especially when heavy residue with high metal content is used as *** this paper,a review was carried out to show the effects of rare earth elements on the structure,activity,and stability of FCC ***,the use of rare earth elements as vanadium traps was analyzed in conjunction with the mechanism of catalyst deactivation by *** objective was to elucidate the interaction of vanadium species with the zeolite component of the FCC catalysts and the role of rare earth elements in countering the deleterious effects of vanadium on the FCC catalysts.

关键词： FCC catalyst rare earth vanadium trap zeolites

Comparisons of jOULE 1 rocket thermospheric wind observations in high latitudes with GITM simulations

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2017年第3期60卷 412-418页

作者： DENG Yue LARSEN Miguel F RIDLEY aaron j ZHAN TianYu Department of Physics University of Texas at Arlington Department of Physics Clemson University Center for Space Environment Modeling The University of Michigan

4 Summary and conclusion The jOULE sounding rocket 1 experiment was carried out at Poker Flat Research Range in Alaska around 1200 UT on March 27th,2003 with two instrumented rockets and one chemical tracer *** the released TMA trails,neutral wind measurements from approximately 85 to 160 km altitude showed a vertically propagating wave and a jet structure around 120 km *** shears appeared at the bottom side of the jet with Richardson numbers close to or smaller than the critical value of 0.25,which implies the possible existence of Kelvin-Helmholtz instabilities caused by the vertical shear in the fast flows.

关键词： target tracking parallel vision processor MRID skipping searching image processing

Co-author Weighting in Bibliometric Methodology and Subfields of a Scientific Discipline

在线全文

学校读者我要写书评

暂无评论

journal of Data and Information Science 2020年第3期5卷 84-96页

作者： Lawrence Smolinsky aaron j Lercher Department of Mathematics Louisiana State UniversityBaton RougeLA 70803USA Middleton Library Louisiana State UniversityBaton RougeLA 70803USA

Purpose: To give a theoretical framework to measure the relative impact of bibliometric methodology on the subfields of a scientific discipline, and how that impact depends on the method of evaluation used to credit individual scientists with citations and publications. The authors include a study of the discipline of physics to illustrate the method. Indicators are introduced to measure the proportion of a credit space awarded to a subfield or a set of ***/methodology/approach: The theoretical methodology introduces the notion of credit spaces for a discipline. These quantify the total citation or publication credit accumulated by the scientists in the discipline. One can then examine how the credit is divided among the subfields. The design of the physics study uses the American Physical Society print journals to assign subdiscipline classifications to articles and gather citation, publication, and author information. Credit spaces for the collection of Physical Review journal articles are computed as a proxy for ***: There is a substantial difference in the value or impact of a specific subfield depending on the credit system employed to credit individual *** limitations: Subfield classification information is difficult to obtain. In the illustrative physics study, subfields are treated in groups designated by the Physical Review journals. While this collection of articles represents a broad part of the physics literature, it is not all the literature nor a random *** implications: The method of crediting individual scientists has consequences beyond the individual and affects the perceived impact of whole subfields and institutions. Originality/value: The article reveals the consequences of bibliometric methodology on subfields of a disciple by introducing a systematic theoretical framework for measuring the consequences.

关键词： Citation analysis Bibliometrics Research evaluation Co-author

Dietary fibre effects and the interplay with exogenous carbohydrases in poultry nutrition

在线全文

学校读者我要写书评

暂无评论

Animal Nutrition 2024年第1期16卷 231-240页

作者： Michael R.Bedford Birger Svihus aaron j.Cowieson AB Vista Feed Ingredients Ltd MarlboroughUnited Kingdom Norwegian University of Life Sciences ÅsNorway DSM Nutritional Products KaiseraugstSwitzerland

A comprehensive understanding of the role of dietary fibre in non-ruminant animal production is *** and conflated definitions of fibre coupled with significant analytical complexity,interact with poorly defined host and microbiome *** fibre is known to influence gut development,feed intake and passage rate,nutrient absorption,microbiome taxonomy and function,gut p H,endogenous nutrient loss,environmental sustainability,animal welfare and *** significant gaps persist in our understanding of fibre in non-ruminant animal production,there is substantial interest in optimizing the fibre fraction of feed to induce high value phenotypes such as improved welfare,live performance and to reduce the environmental footprint of animal production *** order to achieve these aspirational goals,it is important to tackle dietary fibre with the same level of scrutiny as is currently done for other critical nutrient classes such as protein,minerals and *** chemical,mechanical and nutritional role of fibre must be explored at the level of monomeric sugars,oligosaccharides and polysaccharides of varying molecular weight and decoration,and this must be in parallel to standardisation of analytical tools and definitions for *** further complicate subject,exogenous carbohydrases recognise dietary fibre as a focal substrate and have varying capacity to generate lower molecular weight carbohydrates that interact differentially with the host and the enteric *** short review article will explore the interactive space between dietary fibre and exogenous carbohydrases and will include their nutritional and health effects with emphasis on functional development of the gut,microbiome modulation and host metabolism.

关键词： Fibre Carbohydrase Nutrition Microbiome Gastro-intestinal development Feed

The impact of salps(Salpa thompsoni)on the Antarctic krill population(Euphausia superba):an individual-based modelling study

在线全文

学校读者我要写书评

暂无评论

Ecological Processes 2023年第1期12卷 680-695页

作者： Bruno Walter Pietzsch aaron Schmidt jürgen Groeneveld Dominik Bahlburg Bettina Meyer Uta Berger Faculty of Environmental Sciences Institute of Forest Growth and Forest Computer SciencesTechnische Universität Dresden01062 DresdenGermany Department of Ecological Modelling Helmholtz Centre for Environmental Research-UFZLeipzigGermany Section Polar Biological Oceanography Alfred Wegener Institute Helmholtz Centre for Polar and Marine ResearchBremerhavenGermany Institute for Chemistry and Biology of the Marine Environment(ICBM) Carl-Von-Ossietzky UniversityOldenburgGermany Helmholtz Institute for Marine Functional Biodiversity(HIFMB) OldenburgGermany

Background Krill(Euphausia superba)and salps(Salpa thompsoni)are key macrozooplankton grazers in the Southern Ocean ***,due to differing habitat requirements,both species previously exhibited little spatial *** ongoing climate change-induced seawater temperature increase and regional sea ice loss,salps can now extend their spatial distribution into historically krill-dominated areas and increase rapidly due to asexual reproduction when environmental conditions are *** the potential effects on krill is crucial,since krill is a species of exceptional trophic significance in the Southern Ocean food *** impacts on krill could trigger cascading effects on its predators and *** address this question,we combined two individual-based models on salps and krill,which describe the whole life cycle of salp individuals and the dynamic energy budget of individual *** resulting new model PEKRIS(PErformance of KRIll ***)simulates a krill population for 100 years under varying chlorophyll-a concentrations in the presence or absence of *** All of the investigated krill population properties(abundance,mean length,and yearly egg production)were significantly impacted by the presence of *** the other hand,salp density was not impacted if krill were *** medians of krill population properties deviated during variable maximum chlorophyll-a density per year when salps were introduced by−99.9%(−234 individuals per 1000 m3)for krill density,−100%(−22,062 eggs per 1000 m3)for krill eggs and−0.9%(−0.3 mm)for mean length of *** If both species compete for the same food resource in a closed space,salps seem to inhibit krill *** simulation studies should investigate whether this effect prevails if different phytoplankton sizes and consumption preferences of krill are ***,direct predation of the two species or consumption of krill fecal pellets by salps could c

关键词： Euphausia superba Salpa thompsoni Individual-based model Food competition Population dynamics DEB theory

同方期刊数据库

Closed-loop drip irrigation control using a hybrid wireless sensor and actuator network

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2011年第3期54卷 577-588页

作者： FRANZEN aaron Department of Biosystems and Agricultural Engineering Oklahoma State University

In this research, a closed-loop drip irrigation control hybrid wireless sensor and actuator network (HWSAN) prototype were developed and deployed in a crop field for soil property precise measurement and precision irrigation in accordance with the measured soil property. The HWSAN was composed of a wireless sensor and actuator network (WSAN) used for in-field soil property monitoring and irrigation control and a laboratory supervising system. The WSAN included ten sensor nodes, five irrigation control nodes, a central node, a gateway and a cellular modem. The laboratory supervising system was formed by a web-server. The system could automatically sample soil properties including soil moisture, electrical conductivity, and nearsurface temperature at four different depths underground and transmit field data through cellular network to the web-server. Closed-loop control was achieved through the control nodes listening uploading packets from its paired sensor nodes to control drip irrigation. Results from the quality of service (QoS) evaluation included: the data packet transmission rate was 84.76%, data accuracy rate was greater than 97% and no in-field data transmission errors.

关键词： wireless sensor network drip irrigation soil property monitoring precision agriculture

The kinetics of static recovery by dislocation climb

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2022年第1期8卷 973-982页

作者： aaron A.Kohnert Laurent Capolungo Materials Science and Technology Division Los Alamos National LaboratoryLos AlamosNMUSA

The initial microstructure of a wide range of structural materials is conditioned by thermo-mechanical treatments such as hot-working,tempering,or solution *** the elevated temperatures associated with these treatments the dislocation microstructure evolves,usually decreasing in density through a process known as static *** its technological relevance,static recovery is not fully characterized from a theoretical standpoint,with even the controlling mechanisms subject to *** this study,a climb-enabled discrete dislocation dynamics(DDD)capability is leveraged to explore the kinetics of static recovery in pure Fe when controlled by dislocation *** data from these simulations is used to develop a revised static recovery law,and provides the parameters appropriate for predictive microstructure models in *** law differs from previous analytical derivations invoking climb of dislocations,following the logarithmic trends typical of experimental observations where prior work did *** comparison between the recovery law derived from DDD to experimental recovery data in alpha Fe shows strong agreement across a range of temperatures,and suggests that climb is the controlling mechanism for static recovery in pure metals.

关键词： dislocation law treatment

Calculation and interpretation of classical turning surfaces in solids

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

npj Computational Materials 2021年第1期7卷 229-238页

作者： aaron D.Kaplan Stewart j.Clark Kieron Burke john P.Perdew Department of Physics Temple UniversityPhiladelphiaPA 19122USA Centre for Materials Physics Durham UniversityDurham DH13LEUK Departments of Chemistry and Physics University of CaliforniaIrvineCA 92697USA Departments of Physics and Chemistry Temple UniversityPhiladelphiaPA 19122USA

Classical turning surfaces of Kohn–Sham potentials separate classically allowed regions(CARs)from classically forbidden regions(CFRs).They are useful for understanding many chemical properties of molecules but need not exist in solids,where the density never decays to *** equilibrium geometries,we find that CFRs are absent in perfect metals,rare in covalent semiconductors at equilibrium,but common in ionic and molecular *** all materials,CFRs appear or grow as the internuclear distances are uniformly *** can also appear at a monovacancy in a *** with several approximate density functionals and codes confirm these behaviors.A classical picture of conduction suggests that CARs should be connected in metals,and disconnected in wide-gap insulators,and is confirmed in the limits of extreme compression and ***,many semiconductors have no CFR at equilibrium,a key finding for density functional ***,a strong correlation with insulating behavior can still be ***,equilibrium bond lengths for all cases can be estimated from the bond type and the sum of the classical turning radii of the free atoms or ions.

关键词： turning solids expanded

Ectomycorrhizal and Saprotrophic Fungal Communities Vary Across mm-Scale Soil Microsites Differing in Phosphatase Activity

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

Pedosphere 2019年第3期29卷 344-359页

作者： aaron GODIN Denise BROOKS Sue j. GRAYSTON Melanie D. jONES Biology Department University of British Columbia Okanagan campus Kelowna V1V 1V7 (Canada) Department of Forest & Conservation Sciences Faculty of Forestry University of British Columbia Vancouver V6T 1Z4 (Canada)

To understand nutrient cycling in soils, soil processes and microorganisms need be better characterized. To determine whether specific trophic groups of fungi are associated with soil enzyme activity, we used soil imprinting to guide mm-scale sampling from microsites with high and low phosphatase activities in birch/Douglas-fir stands. Study 1 involved sampling one root window per site at 12 sites of different ages(stands);study 2 was conducted at one of the stem-exclusion stands, at which 5 root windows had been installed. Total fungal and ectomycorrhizal(EM) fungal terminal-restriction fragment length polymorphism(TRFLP)fingerprints differed between high-and low-phosphatase activity microsites at 8 of 12 root windows across 12 sites. Where differences were detected, fewer EM fungi were detected in high-than low-phosphatase activity microsites. Using 5 root windows at one site,next-generation sequencing detected similar fungal communities across microsites, but the ratio of saprotrophic to EM fungal reads was higher in high-phosphatase activity microsites in the two windows that had low EM fungal richness. In windows with differences in fungal communities, both studies indicated that EM fungi were less successful than saprotrophic fungi in colonizing fine-scale,organic matter-rich microsites. Fine-scale sampling linked with in situ detection of enzyme activity revealed relationships between soil fungal communities and phosphatase activity that could not be observed at the scales employed by conventional approaches, thereby contributing to the understanding of fine-scale phosphorus cycling in forest soils.

关键词： ectomycorrhizae fine scale fungal communities phosphatase root windows saprotrophic fungi soil imprinting