检索结果-南通市图书馆

A mechanistic study of cO removal on a small H-saturated platinum cluster

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science china chemistry 2008年第12期51卷 1187-1196页

作者： FORREY robert c Department of Physics Pennsylvania State University Berks Campus Reading PA 19610 USA

cO poisoning to platinum catalysts has long been recognized as one of the major technical obstacles in heterogeneous catalysis and its successful removal represents a significant challenge to a wide variety of applications. Using density functional theory (DFT), we performed systematic theoretical calcula-tions to explore the cO removal mechanisms, in the presence of hydrogen, via oxidation by oxygen to form cO2 or reduction by hydrogen to form formaldehyde using a subnano Pt cluster as a model for catalyst nanoparticles. We show that cO oxidation is both thermochemically and kinetically difficult at low H coverage but becomes very exothermic with a moderate activation barrier at high H coverage, suggesting that the oxidation can be carried out readily at elevated temperatures. Doping the Pt cluster with Ru can significantly improve the oxidation thermochemical energy and moderately reduce the activation barrier. The results are consistent with experimental observations. We found that cO reduction by hydrogen to form formaldehyde is moderately endothermic. However, the reaction is predicted to be kinetically difficult due to the relatively high activation barriers associated with the sequential H attacks to the cO molecule.

关键词： cluster Pt-Au alloy full H-saturation cO oxidation cO hydrogenation density functional theory

Endangered species and nature conservation: science issues and challenges

在线全文

学校读者我要写书评

暂无评论

Integrative Zoology 2008年第2期3卷 75-82页

作者： robert c.SZARO US Geological Survey Biological Resources DisciplineRestonVirginiaUSA

The issues and challenges facing us in ensuring the survival of as many species and ecosystems as possible call fora renewed research focus to address how to improve management strategies and policy making now and into thefuture. The key issues to be addressed by activities of the International Union of Forest Research Organization’s(IUFRO) Task Force on Endangered Species and Nature conservation include such issues as: (i) preventing speciesfrom being listed by maintaining species populations at sufficient levels that they do not require listing;(ii) recoveringthreatened and endangered species;(iii) developing management practices and strategies;(iv) balancingactions affecting suites of threatened or endangered species;(v) developing conservation strategies for specieswithout definitive taxonomic treatments;(vi) dealing with global change;(vii) dealing with invasive species;and(viii) restoring critical habitats.

关键词： endangered species management practices nature conservation restoration science issues

SUSTAINABLE STRATEGIES FOR THE REHABILITATION OF AN HISTORIc STATE OFFIcE BUILDING

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 Green Building 2014年第4期9卷 23-42页

作者： robert c.Burns AIA LEED AP

When the commonwealth of Virginia determined to renovate the Ninth Street Office Building for continued use as badly needed office space,it was confronted with many *** only does the prime location of the 11-story building on Richmond’s capitol Square come into play,but also the complications inherent in the rehabilitation of any iconic 110-year old building for contemporary *** the commonwealth’s mandate to meet a minimum threshold for sustainability,and we have the recipe for a challenging,but ultimately rewarding,*** article will describe the historic evolution of the project along with a discussion of the process necessary to design and implement a sustainable building solution within the context of an historic building,including identification of potential sustainable strategies and the implementation of an appropriate approach to arrive at the final solution.

关键词： Historic rehabilitation adaptive reuse public projects sustainable strategies embodied energy

Reconstruction Residuals Based Long-term Voltage Stability Assessment Using Autoencoders

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 Modern Power Systems and clean Energy 2020年第6期8卷 1092-1103页

作者： Haosen Yang robert c.Qiu Houjie Tong the Department of Electrical Engineering Center for Big Data and Artificial IntelligenceShanghai Jiaotong UniversityShanghai 200240China School of Electronic Information and communication Huazhong University of Science and TechnologyWuhan 430000China IEEE

Real-time voltage stability assessment(VSA)has long been an extensively research *** recent years,rapidly mounting deep learning methods have pushed online VSA to a new height that large amounts of learning algorithms are applied for VSA from the perspective of measurement *** learning methods generally require a large dataset which contains measurements in both secure and insecure states,or even unstable ***,in practice,the data of insecure or unstable state is very rare,as the power system should be guaranteed to operate far away from voltage *** this circumstance,this paper proposes an autoencoder based method which merely needs data of secure state to evaluate voltage stability of a power *** principle of this method is that an autoencoder purely trained by secure data is expected to only create precise reconstruction for secure data,while it fails to rebuild data of insecure ***,the residual of reconstruction is effective in indicating ***,to develop a more accurate and robust algorithm,long short-term memory(LSTM)networks combined with fully-connected(Fc)layers are used to build the autoencoder,and a moving strategy is introduced to bias the features of testing data toward the secure feature *** experiments and comparison with traditional machine learning algorithms demonstrate the effectiveness and high accuracy of the proposed method.

关键词： Reconstruction loss autoencoders voltage stability long-short-term memory(LSTM) feature moving strategy

Application of the three-dimensional telegraph equation to cosmic-ray transport

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2016年第10期16卷 107-115页

作者： robert c. Tautz Ian Lerche Zentrum fur Astronomie und Astrophysik Technische Universitat Berlin HardenbergstraBe 36 D-10623 Berlin Germany Institut fur Geowissenschaften Naturwissenschaftliche Fakultat Ⅲ Martin-Luther-Universitat Halle D-06099 HalleGermany

An analytical solution to the three-dimensional telegraph equation is presented. This equation has recently received some attention but so far the treatment has been one-dimensional. By using the structural similarity to the Klein-Gordon equation, the telegraph equation can be solved in closed form. Illustrative examples are used to discuss the qualitative differences from the diffusion solution. A comparison with a numerical test-particle simulation reveals that some features of an intensity profile can be better explained using the telegraph approach.

关键词： plasmas -- turbulence -- magnetic field -- diffusion -- solar wind

Eastern Dharwar craton,India:continental lithosphere growth by accretion of diverse plume and arc terranes

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2012年第3期3卷 225-240页

作者： c.Manikyamba robert Kerrich National Geophysical Research Institute Council of Scientific and Industrial ResearchHyderabad 500 007India Department of Geological Sciences University of SaskatchewanSaskatoonSaskatchewan S7N 5E2Canada

Abstract Greenstone belts of the eastern Dharwar craton, India are reinterpreted as composite tecto- nostratigraphic terranes of accreted plume-derived and convergent margin-derived magmatic sequences based on new high-precision elemental data. The former are dominated by a komatiite plus Mg-tholeiitic basalt volcanic association, with deep water siliciclastic and banded iron formation （BIF） sedimentary rocks. Plumes melted at 〈90 km under thin rifted continental lithosphere to preserve intrao- ceanic and continental margin aspects. Associated alkaline basalts record subduction-recycling of Me- soarchean oceanic crust, incubated in the asthenosphere, and erupted coevally with Mg basalts from a heterogeneous mantle plume. Together, komatiites-Mg basalts-alkaline basalts plot along the Phanero- zoic mantle array in Th/Yb versus Nb/Yb coordinate space, representing zoned plumes, establishing that these reservoirs were present in the Neoarchean mantle. convergent margin magmatic associations are dominated by tholeiitic to calc-alkaline basalts compo- sitionally similar to recent intraoceanic arcs. As well, boninitic flows sourced in extremely depleted mantle are present, and the association of arc basalts with Mg-andesites-Nb enriched basalts-adakites documented from cenozoic arcs characterized by subduction of young （〈20 Ma）, hot, oceanic litho- sphere. consequently, cenozoic style ＂hot＂ subduction was operating in the Neoarchean. These diverse volcanic associations were assembled to give composite terranes in a subduction-accretion orogen at -2.7 Ga, coevally with a global accretionary orogen at -2.7 Ga, and associated orogenic gold mineralization.

关键词： continental lithospheregrowth Zoned plume Subduction-accretion Neoarchean mantle Geodynamics Eastern Dharwar craton

Ophiolites:Identification and tectonic significance in space and time

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2023年第6期14卷 380-385页

作者： Kent c.condie robert J.Stern Department of Earth&Environmental Science New Mexico Institute of Mining and TechnologySocorroNM 87801USA Geosciences Department University of Texas at DallasRichardsonTX 75080USA

Ophiolites are fragments of oceanic lithosphere that are produced at spreading centers at ocean ridges,back arc basins,or forearcs during subduction initiation,and are key indicators of plate *** it is widely agreed that ophiolites are remnants of oceanic crust and associated depleted mantle preserved in orogens,the recognition of ophiolites and their tectonic significance is still a topic of discussion and *** propose that ophiolites can be recognized in the geologic record by some combination of genetically related pillow basalt,layered gabbro,sheeted dykes,podiform chromite,harzburgite or/and *** igneous rocks have either ocean-ridge basalt or immature oceanic arc basalt chemical *** a scoring system of 1–11 for ophiolite confidence level,scores of8 are considered confident,6–8 probable,andcores6 areconfident ophiolite(score of 8)is the Zunhua ophiolite in eastern china at 2550 Ma,and the oldest well documented sheeted dykes occur in the Jormua and Purtuniq ophiolites at 2000–1950 *** do not become geographically widespread until after 900 Ma,and most ophiolites of all ages formed in a forearc(subduction initiation)tectonic *** ophiolite production requires plate tectonics,subduction must have begun at least locally by 2700 Ma but did not become widespread until after 2000 *** abundance of ophiolites after 900 Ma may reflect better preservation of subduction-related ophiolites,or to an increasing global network of interconnected *** frequency peaks in the geologic record partially reflect geographic regions where ophiolites have been extensively studied rather than monitoring the production rate of ophiolites,but the scarcity of>900 Ma ophiolites is probably real.

关键词： Ophiolite Plate tectonics Subduction initiation Forearc Ocean ridge Tectonic setting Supercontinent

Impact of carbon-based nutrient enhancement on biofiltration performance for drinking water treatment

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 Environmental Sciences 2019年第8期31卷 124-131页

作者： Yu Zhao Liz Taylor-Edmonds robert c.Andrews Department of civil and Mineral Engineering University of Toronto

Incorporation of a carbon-based nutrient enhancementstrategy for drinking water biofiltration is an attractive option, especially for source waters which contain recalcitrant organics. This study compared biofilters that were operated in parallel and individually enhanced with amino acids(including alanine, phenylalanine, and tryptophan), inulin, and sucrose to increase biomass concentration and promote biodegradation of dissolved organic carbon(DOc) in the source water, including disinfection by-product(DBP) precursors. Biomass activity was characterized by measuring adenosine tri-phosphate(ATP), dissolved oxygen(DO) consumption, and through the use of laccase and esterase enzyme assays. Performance was evaluated in terms of headloss,turbidity, p H, DOc, UV254, and DBP formation potential(DBP FP). The introduction of carbonbased nutrients significantly increased biomass activity, where ATP values peaked at 976 ng/g of filter media, 853 ng/g, and 513 ng/g for amino acids, inulin, and sucrose-spiked biofilters,respectively, while a non-spiked control only reached 104 ng/g. DO utilization by the enhanced biofilters was significantly higher than the control, with a strong correlation between ATP and DO uptake observed for all filters(R^2> 0.74). Laccase and esterase enzyme activities of enhanced biofilters were also elevated(p > 0.05), suggesting greater biodegradation potential. Operational parameters such as headloss development and turbidity control were not impaired by carbon supplementation strategies or an increase in biomass concentration and activity. However, the enhancement strategy did not provide improvement in terms of source water carbon removal(DOc and UV254) or DBP FP when treated filters were compared to a control.

关键词： Biological filtration carbon enhancement Biomass Disinfection by-products Dissolved organic carbon

Deep Reinforcement Learning for Power System Applications: An Overview

在线全文

学校读者我要写书评

暂无评论

cSEE Journal of Power and Energy Systems 2020年第1期6卷 213-225页

作者： Zidong Zhang Dongxia Zhang robert c.Qiu Research center For Big Data Engineering And Technologies Shanghai Jiao Tong UniversityShanghai 200240China Department of Electrical and computer Engineering Tennessee Technological UniversityCookevilleTN 38505USA china Electric Power Research Institute Beijing 100192China

Due to increasing complexity, uncertainty and data dimensions in power systems, conventional methods often meet bottlenecks when attempting to solve decision and control prob- lems. Therefore, data-driven methods toward solving such prob- lems are being extensively studied. Deep reinforcement learning (DRL) is one of these data-driven methods and is regarded as real artificial intelligence (AI). DRL is a combination of deep learning (DL) and reinforcement learning (RL). This field of research has been applied to solve a wide range of complex sequential decision-making problems, including those in power systems. This paper firstly reviews the basic ideas, models, algorithms and techniques of DRL. Applications in power systems such as energy management, demand response, electricity market, operational control, and others are then considered. In addition, recent advances in DRL including the combination of RL with other classical methods, and the prospect and challenges of applications in power systems are also discussed.

关键词： Artificial intelligence deep reinforcement learning machine learning power system smart grids