198,825 research outputs found
Nanoscale Depth Profiling of Residual Stresses Due to Fine Surface Finishing
No full textMechanical polishing is commonly used for both surface finishing and metallographic sample preparation for a broad range of materials. However, polishing causes local deformation and induces residual stress, which has an important effect on many surface phenomena. Until recently, it has not been possible to quantify the nanoscale depth variation of polishing-induced plastic deformation (eigenstrain) and the associated residual stress. In this study, the magnitude and depth of polishing-induced residual stress are evaluated directly by focused ion beam milling and digital image correlation using the micro-ring-core geometry method. Depth-resolved residual stress profiles are obtained with sub-micrometer resolution at the surface of a titanium alloy sample that is subjected to various polishing steps. It is found that electrochemical polishing and polishing with colloidal silica do not induce any significant residual stress. However, polishing with diamond slurry leads to the formation of compressive residual stresses of up to 300 MPa, which extend deeper into the material when larger diamond particles are used. This study paves the way for further research on polishing and its effect on surface properties
Neoproterozoic to Early Paleozoic sequences of Congo Shield: comparison of Congo Basin with the surrounding marginal basins
No full textIn the Chap. 6, E. Kadima, D. Delvaux, M. Everaerts, S. Sebagenzi, and F. Lucazeau focus on these lowermost Neoproterozoic to Cambrian succession beneath the centre of the Congo Basin and use this to better constrain the early evolution of the Congo Basin. These authors draw on earlier work of Kadima and reinterpret the old drill core and seismic data, especially from the two fully cored, deep stratigraphic wells Gilson-1: 4,563 m and Mbandaka-1: 4,350 m) that appear to terminate in carbonates that contain intriguing evaporitic-like minerals at the base of the Congo Basin. With this information, they then correlate the successions with the carbonate-siliciclastic sequences along the peripheral margins of the Congo Basins (mentioned in the earlier chapters). The main findings of this work are the recognition of possible major Neoproterozoic (mechanical) rifts that underlie the overlying, but poorly dated, Phanerozoic cover, which they interpret as thermal subsidence sequences. This is an important contribution towards unravelling the origin of the Congo basin
Overbevolking: cijfers en feiten; gevolgen en remedie - Jan-Pieter Everaerts
No full textSzakdolgozatomhoz forrásnyelvi szövegnek egy társadalomtudományi cikket választottam, melynek témája a túlnépesedés. A tudományos értekezés az „Overbevolking: cijfers en feiten, gevolgen en remedie” címet viseli és írója a belga Jan-Pieter Everaerts, aki a „De Groene Belg” című online magazin kiadója. A 18 oldalas áttekintésből 14 oldalt fordítottam le, amely a következő fejezeteket taglalja: a Föld és annak egyenetlen népességeloszlása, a Föld népességének története, a túlnépesedés, mint relatív és abszolút fogalom, a túlnépesedés negatív és pozitív következményei, mi akadályozza meg, hogy racionális vitát folytassanak a túlnépesedésről, és végül a túlnépesedés problémáinak lehetséges megoldásai. A tanulmány funkcionális stílusrétege alapján tudományos szöveg, a kifejezésmódja alapján leíró szöveg, a tárgyi tartalom alapján társadalomtudományi szöveg. Katharina Reiss fordításközpontú szövegtipológiája alapján pedig a tartalomközpontú szövegek stílusjegyeit hordozza. Fordításomat példákkal támasztom alá és ezen példák alapján mutatom be a fordítási átváltási műveleteket. Ezt követően a terminusjegyzék és a felhasznált irodalom listája zárja dolgozatomat.D.É.Fordító és tolmácsMSc/M
Transverse fatigue behaviour and residual stress analyses of double sided FSW aluminium alloy joints
No full textFriction stir welding (FSW) since its invention has been attracting relevant interest for joining aluminium alloys. Due to the nature of this process, the materials can be joint without melting. Thanks to this peculiar characteristic, the issues associated with the cooling from liquid phase are avoided or considerably reduced, such as cracking, porosity, and defects. However, as well as other well-established welding techniques, the FSW process gives rise to formation of residual stress in the welding region and surrounding volume: heat and thermo-mechanical affected zones. Presence of residual stress in a mechanical component is well-known to affect its performance, particularly regarding fatigue at high number of cycles. Another aspect that influences the fatigue life is the underlying microstructure. In this work, we firstly study the residual stress field and the underlying microstructural features arising in FSW butt joints and their effect on the fatigue performance of this type of weldments. The evaluation of residual stress field is carried out by means of modern experimental techniques. In the first instance, synchrotron X-ray powder diffraction was employed for two-dimensional full field maps of residual stress. Corroboration of these measurements was done by exploiting the capability of focused ion beam and digital image correlation (FIB-DIC), which is able to deliver pointwise absolute measurement of residual stress. A set of FSW samples were then tested under uniaxial fatigue loading at several loading ranges, in the high cycle fatigue regime, in order to understand whether the severity of loads affects the crack path and life endurance. Fractographic and electron backscattered diffraction (EBSD) analysis then revealed crack nucleation site and propagation mechanisms with the respect of the underlying microstructure. Outcome of these experimental studies is then thoroughly discussed
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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