44,011 research outputs found
Influence of grain structure and slip planarity on fatigue crack growth in low alloying artificially aged 2xxx aluminium alloys
No full textThe fatigue crack growth behaviour under constant amplitude loading of three low alloying artificially aged 2xxx aluminium alloys with distinct microstructures is analysed. Fatigue crack growth tests show a correlation between fatigue performance and the occurrence of crack closure. Fractography and fracture surface measurements show that rougher surfaces give higher closure levels suggesting a dominating influence of RICC in these alloys. The relationship between the crack path and the microstructure, i.e. grain structure and slip planarity, is assessed semi-quantitatively. A criterion to evaluate the propensity for slip band formation is derived and reasonable correlation is found between the fatigue fracture behaviour of the three alloys and this criterion. <br/
Assessment of Self-Archiving in Institutional Repositories: Depositorship and Full-Text Availability
No full textThis research evaluates the success of open access self-archiving in several well-known institutional repositories. Two assessment factors have been applied to examine the current practice of self-archiving: depositorship and the availability of full text. This research discovers that the rate of author self-archiving is low and that the majority of documents have been deposited by a librarian or administrative staff. Similarly, the rate of full-text availability is relatively low, except for Australian repositories. By identifying different practices of self-archiving, repository managers can create new strategies for the operation of their repositories and the development of archiving policies
Assessment of mixed mode loading on macroscopic fatigue crack paths in thick section Al-Cu-Li alloy plate
No full textHigh strength, wrought 7xxx (Al-Zn-Mg) and Al-Li based alloys show a propensity for fatigue macroscopic crack deflections aligned along grain boundaries. The present work reports a study on a 3rd generation Al-Li based alloy in the form of a thick AA2297 (Al-Cu-Li alloy) plate, where it was found that although the lithium containing material may indeed be more susceptible to mixed mode grain boundary failure (and by implication crack deflection in conventional tests), the AA2297 alloy fatigue behaviour is mechanistically and functionally equivalent to 7xxx alloy behaviour. It is shown that crack paths are controlled by a combination of crack loading mixity (KII/KI ratio) and maximum strain energy release rates (expressed as Keq.max). Increasing KII/KI ratio is seen to favour sustained grain boundary failure. Crack growth rate behaviour is discussed in terms of extrinsic and intrinsic components of crack growth resistance. It is shown that the present approach can be successfully applied to predict crack deflection / crack paths for a range of sample geometries and orientations on a range of high strength orthotropic aluminium alloys, including 3rd generation Al-Li based alloys and well-established 7xxx alloys
Information Literacy and Librarian-Faculty Collaboration: A Model for Success:
No full textIn the age of information explosion and technological advancement, issues of information storage, organization, access, and evaluation have become necessarily important in our societies. Addressing issues of information literacy and designing how they can be best integrated in students' learning process are of critical importance. Library professionals in the United States, particularly in the academia, have realized the importance of information literacy and have attempted in various ways to address these issues. The ultimate goal is to make information literacy an integral part of the academic curriculum, thus helping students to succeed not only during their years in college but also for their lifelong career choices. This article will look at ways of how information literacy can best be incorporated into students' academic experience, and how this process can make students' learning meaningful and successful. Specifically, the author will examine the model of librarian-faculty collaboration in integrating information literacy into the curriculum, as demonstrated in the Ohio Five Colleges' Information Literacy Program.Publisher version of this article is available at: http://www.white-clouds.com/iclc/cliej/cl24.ht
Embrittlement of Al-Li-Cu-Mg alloys at slightly elevated temperatures: microstructural mechanisms of hardening
No full textWhen underaged, damage tolerant Al-Li based alloys are exposed to slightly elevated temperatures (60 to 100ºC), their strength increases and toughness decreases. To study the first stages of this process, 8090 sheet in three underaged heat treatment conditions, including T3, T81 and a multi-stage temper, was exposed for 1000 h at 70°C. Using a model for strengthening in combination with a quantitative analysis of differential scanning calorimetry data, it is shown that strengthening can be explained by an increase in the volume fraction of the delta' phase and, to a lesser extent, to the formation of Guinier-Preston (GPB) zones. For the T3 temper, coarsening of delta' precipitates is the main strengthening mechanism during exposure at 70ºC. The solvus of delta' and GPB, which to a large extent defines this embrittlement, is discussed. Toughness reduction during exposure at slightly elevated temperatures can be minimised via a multi stage temper or via a reduction of the Li content of the alloy
Factors to Assess Self-Archiving in Institutional Repositories
No full textThis paper proposes a group of factors that may be used to assess the success of open access self-archiving. It concentrates on self-archiving in institutional repositories. The authors emphasize the importance of examining content materials, particularly the availability of full text versus abstracts and the deposits archived by authors versus by others.Peer reviewe
Applying the NISO Metasearch Initiative Scheme to Enhance E-Resources Management at Rutgers University Library
No full textThis paper discusses problems in the management of library e-resources and attempts to identify potential solutions to the problems. By describing an e-resources enhancement project taken by Rutgers University Libraries, this paper points to the importance of providing contextually-rich metadata and reorganizing the accessibility of e-resources on a library’s website. It introduces how this Rutgers project adopted the National Information Standards Organization Metasearch Initiative to support the identification of appropriate e-collections for metaseaching. The outcomes of the project have facilitated a dynamic display of relevant e-resources to library users as an effective way of automatic access to library e-collections.Peer reviewe
A Metadata Manager's Role in Collaborative Projects: The Rutgers University Libraries Experience
No full textPurpose – This article discusses the roles and responsibilities of a metadata manager in collaborative digital projects.
Methodology – It describes the general requirements for metadata management, and introduces some scenarios in the practices of digital projects by the Rutgers University Libraries to support the generalized definition. A workflow of metadata management is illustrated.
Practical implications – With an explicit definition of the roles and responsibilities of the metadata manager, many other digital libraries that need to develop a new or optimize the existing workflow may find the Rutgers experience useful as reference.
Originality – Very few articles have explored this topic although the functions of metadata in the development of digital projects have been talked extensively.Peer reviewe
Microstructure and strengthening of Al-Li-Cu-Mg alloys and MMCs: II. Modelling of yield strength
No full textA detailed quantitative model for the strengthening of monolithic alloys and composites due to precipitation strengthening, solution strengthening, grain and subgrain strengthening, strengthening by dislocations and load transfer to ceramic inclusions is presented. The model includes a newly derived description of the effect of a precipitate free zone (PFZ) around the reinforcing phase incorporating strain hardening of the PFZ. The model is successfully applied to model the experimental data for the proof strengths of four Al Li Cu Mg type alloys and composites aged to obtain a wide range of microstructures and all strengthening contributions are quantified. It is shown that PFZ formation in the 8090 MMC causes a drastic reduction in the proof strength (about 100 MPa), but it has little influence on the time required for peak ageing. In all alloys strengthening due to GPB zones is more important than strengthening due to delta' (Al3Li) phase
Macropsis zizhongi Li, Dai et Li
No full textMacropsis zizhongi Li, Dai et Li, nom. nov. Macropsis gracilis Li et Liang, 2005: 578 –579, nom. preocc. (nec Macropsis gracilis Dubovskiy, 1966: 97) Distribution. China (Heilongjiang prov.). Etymology. The species is named in honour of Prof. Li Zizhong, the first author of the original species name.Published as part of Li, Hu, Dai, Ren-Huai, Li, Zi-Zhong & Yu, Dmitri, 2012, Taxonomic study of Chinese species of the genus Macropsis (Hemiptera: Cicadellidae: Macropsinae): new species, new records, synonymy and replacement name, pp. 41-62 in Zootaxa 3420 on page 61, DOI: 10.5281/zenodo.21216
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