5,698 research outputs found
Intergranular Cracking In Alloy 690 With Nb, Mo, And Hf Additions: In Situ Sem High Temperature Deformation Study
No full textThe microstructure behavior during high temperature deformation of Ni-base alloys based on alloy 690 modified with Nb, Mo, and Hf additions were studied. Optical and electron microscopy were used to characterize these materials and the results were compared with Calphadbased modeling results. The alloys behavior was studied between 500 and 1000 °C using an in-situ high temperature deformation test. The role of precipitates on the grain boundary morphology and their effect on grain boundary sliding and the mechanism of ductility-dip cracking are discussed. Both, undulated grain boundaries and primary intra-granular precipitates improved the alloy DDC resistance. © 2012 Trans Tech Publications, Switzerland.706-709945950The Minerals, Metals and Materials Society (TMS),NSFArkoosh, M.A., Fiore, N.F., (1972) Metallurgical Transactions, 3, p. 2235Rhines, F.N., Wray, P.J., (1961) Transactions of the ASM, 54, p. 117Haddrill, D.M., Baker, R.G., (1965) British Welding Journal, p. 411Ii Noecker, F.F., Dupont, J.N., (2009) Welding Journal, 88, p. 7Nissley, N.E., Lippold, J.C., (2009) Welding Journal, 88, p. 131Ramirez, A.J., Lippold, J.C., (2004) Mat. Sci. and Eng. A, 380, p. 259Gifkins, R.C., (1994) Materials Characterization, 32, p. 59Langdon, T.G., (2006) Materials Science, 41, p. 597Ramirez, A.J., Lippold, J.C., (2005) Hot Cracking Phenomena in Welds, p. 19. , edited by T. Böllinghaus, H. HeroldCollins, M.G., Ramirez, A.J., Lippold, J.C., (2004) Welding Journal, 83, p. 39Yamaguchi, S., (1980) Phil. Trans. R. Soc. Lond. A, 295, p. 122Ramirez, A.J., Garzón, C.M., (2008) Hot Cracking Phenomena in Welds, 2, p. 427. , edited by T. Böllinghaus, H. Herold, C. Cross, J.C. LippoldZimina, L.N., Burova, N.N., Makushok, O.V., (1986) Met. Sci. and Heat Treatment, 28 (2), p. 130Duhl, J.M., Sullivan, C.P., (1971) Journal of Metals, pp. 38-40Torres, E.A., Paternella, F.G., Caram, R., Ramirez, A.J., (2009) 8 th International Conference on Trends in Welding Research, p. 354. , Pine-Mountain, GA-USAUnfried S, J., (2010) Mathematical Modelling of Weld Phenomena, 9, p. 983. , edited by Maney. H CerjakH K D H Bhadeshia and E KozeschnikPigrova, G.D., (2005) Metal Science and Heat Treatment, 47 (11-12), p. 544Torres, E.A., Caram, R., Ramirez, A.J., (2010) Materials Science Forum, 638-642, p. 2858Unfried S, J., Torres, E.A., Ramirez, A.J., (2011) Hot Cracking Phenomena in Welds, 3. , edited by T. Böllinghaus, H. Herold C. Cross, in pressAfonso, C.R.M., Lippold, J.C., Ramirez, A.J., (2010) Metallurgical Transactions A, , submitted t
Modeling And Characterization Of As-welded Microstructure Of Solid Solution Strengthened Ni-cr-fe Alloys Resistant To Ductility-dip Cracking Part I: Numerical Modeling
No full textThis work aims the numerical modeling and characterization of as-welded microstructure of Ni-Cr-Fe alloys with additions of Nb, Mo and Hf as a key to understand their proven resistance to ductility-dip cracking. Part I deals with as-welded structure modeling, using experimental alloying ranges and Calphad methodology. Model calculates kinetic phase transformations and partitioning of elements during weld solidification using a cooling rate of 100 K.s -1, considering their consequences on solidification mode for each alloy. Calculated structures were compared with experimental observations on as-welded structures, exhibiting good agreement. Numerical calculations estimate an increase by three times of mass fraction of primary carbides precipitation, a substantial reduction of mass fraction of M23C6 precipitates and topologically closed packed phases (TCP), a homogeneously intradendritic distribution, and a slight increase of interdendritic Molybdenum distribution in these alloys. Incidences of metallurgical characteristics of modeled as-welded structures on desirable characteristics of Ni-based alloys resistant to DDC are discussed here. © 2014 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.202297305Arkoosh, M.A., Fiore, N.F., (1972) Metall. Trans., 3, p. 2235. , 10.1007/BF02643237Yeniscavich, W., (1966) Weld. J., 45, pp. 344sHemsworth, B., Boniszewski, T., Eaton, N.F., (1969) Met. Constr. Br. Weld. J., 1, p. 5Rhines, F.N., Wray, P.J., (1961) Trans. ASM., 54, p. 117Abralov, M.A., Abdurakhmanov, R.U., (1974) Automation Welding, 27, p. 7Haddrill, D.M., Baker, R.G., (1965) Br. Weld J., 12, p. 411Ramirez, A.J., Lippold, J.C., (2004) Mater. Sci. Eng. A, 380, p. 259. , 10.1016/j.msea.2004.03.074Noecker, I.I.F.F., Dupont, J.N., (2009) Weld. J., 88, pp. 7sYoung, G.A., Capobianco, T.E., Penik, M.A., Morris, B.W., McGee, J.J., (2008) Weld. J., 87, pp. 31sCollins, M.G., Ramirez, A.J., Lippold, J.C., (2004) Weld. J., 83, pp. 39sNishimoto, K., Saida, K., Okauchi, H., (2006) Sci. Technol. Weld. Joining, 11, p. 471. , 10.1179/174329306X94318Nishimoto, K., Saida, K., Okauchi, H., (2006) Sci. Technol. Weld. Joining, 11, p. 462. , 10.1179/174329306X94309Nippes, E.F., Savage, W.F., Bystram, B.J., (1955) Weld. J., 23, pp. 183sNissley, N.E., Lippold, J.C., (2008) Weld. J., 87, pp. 257sChabenat, A., Pierron, D., Thomas, A., Faure, F., Guyon, C., (2004), Appl. No. 10/639,680. United States Patent Pub. No. US 2004/0115086 A1, June 17Kiser, S.D., Zhang, R., Baker, B.A., (2009) Proc. 8th Int. Conf. of Trends in Welding Research, p. 639Ramirez, A.J., Sowards, J.W., Lippold, J.C., (2006) J. of Mat. Proces. Tech., 179, p. 212. , 10.1016/j.jmatprotec.2006.03.095Ramirez, A.J., Lippold, J.C., (2004) Mater. Sci. Eng. A, 25, p. 245. , 10.1016/j.msea.2004.03.075Nissley, N.E., Lippold, J.C., (2009) Weld. J., 88, pp. 131sTorres, E.A., Caram, R., Ramirez, A.J., (2010) Mater. Sci. Forum, 638-642, p. 2858. , 10.4028/www.scientific.net/MSF.638-642.2858Unfried, J., Ramirez, A.J., (2012) Mater. Sci. Forum, 706-709, p. 945. , 10.4028/www.scientific.net/MSF.706-709.945Unfried, J., Torres, E.A., Ramirez, A.J., (2011) Hot Cracking Phenomena in Welds III, p. 295. , 1st ed. Springer-Verlag Berlin 10.1007/978-3-642-16864-2-15Saunders, N., Fahrmann, M., Small, C.J., (2000) Proc. 9th Int. Symp. of Superalloys 2000, pp. 803-811. , 10.7449/2000/Superalloys-2000-803-811Saunders, N., (1996) Proc. 8th Int. Symp. of Superalloys 1996, p. 115. , PA, USA (eds. R.D.K. Kissinger et al.)Engström, A., Höglund, L., Ågren, J., (1994) Metall. Mat. Trans. A, 25, p. 1127. , 10.1007/BF02652288Kaufman, L., Nesor, H., (1974) Metall. Mat. Trans. A, 5, p. 1617. , 10.1007/BF02646333Ramirez, A.J., Garzón, C.M., (2008) Hot Cracking Phenomena in Welds II, p. 427. , 1st ed. Springer-Verlag Berlin 10.1007/978-3-540-78628-3-22Saunders, N., Li, X., Miodownik, A.P., Schillé, J.-P., (2004) J. Mater. Sci., 39, p. 7237. , 10.1023/B:JMSC.0000048737.32055.7aHou, Q.Y., He, Y.Z., Zhang, Q.A., Gao, J.S., (2007) Mater. Des., 28, p. 1982. , 10.1016/j.matdes.2006.04.005Zimina, L.N., Burova, N.N., Makushok, O.V., (1986) Met. Sci. Heat Treat., 28, p. 130. , 10.1007/BF00717535Dahl, J.M., Danesi, W.F., Dunn, R.G., (1973) Metall. Trans., 4, p. 1087. , 10.1007/BF02645612Unfried, J., Fonseca, S.E.B., Afonso, C.M.R., Ramirez, A.J., (2010) Mathematical Modelling of Weld Phenomena 9, pp. 983-996Kraft, T., Exner, H.E., (1998) Mater. Sci. Technol., 14, p. 377. , 10.1179/mst.1998.14.5.377Raghavan, M., Mueller, R., Vaughn, G.A., Floreen, S., (1984) Metall. Mat. Trans. A., 15, p. 783. , 10.1007/BF02644553Perricone, M.J., Dupont, J.N., (2006) Metall. Trans. A, 37, p. 1267. , 10.1007/s11661-006-1078-7(2009) Technical Bulletin of Inconel Alloy 690, , PCC Energy GroupRadrakrisnha, C., Prasad-Rao, K., (1997) J. Mater. Sci., 32, p. 1977. , 10.1023/A:101854191511
Modeling And Characterization Of As-welded Microstructure Of Solid Solution Strengthened Ni-cr-fe Alloys Resistant To Ductility-dip Cracking Part Ii: Microstructure Characterization
No full textIn part II of this work is evaluated the as-welded microstructure of Ni-Cr-Fe alloys, which were selected and modeled in part I. Detailed characterization of primary and secondary precipitates, subgrain and grain structures, partitioning, and grain boundary morphology were developed. Microstructural characterization was carried out using optical microscopy, SEM, TEM, EBSD, and XEDS techniques. These results were analyzed and compared to modeling results displaying a good agreement. The Hf additions produced the highest waviness of grain boundaries, which were related to distribution of Hf-rich carbonitrides. Experimental evidences about Mo distribution into crystal lattice have provided information about its possible role in ductility-dip cracking (DDC). Characterization results of studied alloys were analyzed and linked to their DDC resistance data aiming to establish relationships between as-welded microstructure and hot deformation performance. Wavy grain boundaries, primary carbides distribution, and strengthened crystal lattice are metallurgical characteristics related to high DDC resistance. © 2014 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.202307315Unfried, J., Ramirez, A.J., (2012) Mater. Sci. Forum, 706-709, p. 945. , 10.4028/www.scientific.net/MSF.706-709.945Unfried, J., Torres, E.A., Ramirez, A.J., (2011) Hot Cracking Phenomena in Welds III, p. 295. , 1st ed. Springer-Verlag Berlin 10.1007/978-3-642-16864-2-15Ramirez, A.J., Garzón, C.M., (2008) Hot Cracking Phenomena in Welds II, p. 427. , Springer-Verlag Berlin 10.1007/978-3-540-78628-3-22Ramirez, A.J., Sowards, J.W., Lippold, J.C., (2006) J. Mater. Process. Technol., 179, p. 20. , 10.1016/j.jmatprotec.2006.03.095Nissley, N.E., Lippold, J.C., (2008) Weld. J., 87, pp. 257sKiser, S.D., Zhang, R., Baker, B.A., (2009) Proc. 8th Int. Conf. of Trends in Welding Research, p. 639. , Pine-Mountain GA, USAHou, Q.Y., He, Y.Z., Zhang, Q.A., Gao, J.S., (2007) Mater. Des., 28, p. 1982. , 10.1016/j.matdes.2006.04.005Hemsworth, B., Boniszewski, T., Eaton, N.F., (1969) Met. Constr. Br. Weld. J., 1, p. 5Rhines, F.N., Wray, P.J., (1961) Trans. ASM, 54, p. 117Abralov, M.A., Abdurakhmanov, R.U., (1974) Automation Welding, 27, p. 7Haddrill, D.M., Baker, R.G., (1965) Br. Weld J., 12, p. 411Ramirez, A.J., Lippold, J.C., (2004) Mater. Sci. Eng. A, 380, p. 259. , 10.1016/j.msea.2004.03.074Ii, F.F.N., Dupont, J.N., (2009) Weld. J., 88, pp. 62sTorres, E.A., Caram, R., Ramirez, A.J., (2010) Mater. Sci. Forum, 638-642, p. 2858. , 10.4028/www.scientific.net/MSF.638-642.2858Zimina, L.N., Burova, N.N., Makushok, O.V., (1986) Met. Sci. Heat Treat., 28, p. 130. , 10.1007/BF00717535Kotval, P.S., Venables, J.D., Calder, R.W., (1972) Metall. Trans., 3, p. 453Dahl, J.M., Danesi, W.F., Dunn, R.G., (1973) Metall. Trans., 4, p. 1087. , 10.1007/BF02645612Duhl, J.M., Sullivan, C.P., (1971) J. Met., 23, p. 38Jena, A.K., Chatuverdi, M.C., (1984) J. Mat. Sci., 19, p. 3121. , 10.1007/BF00549796Mulford, R.A., Kocks, U.F., (1979) Scr. Metall., 13, p. 729. , 10.1016/0036-9748(79)90145-5Chabenat, A., Pierron, D., Thomas, A., Faure, F., Guyon, C., (2004), Appl. No. 10/639,680. United States patent Pub. No. US 2004/0115086 A1Nissley, N.E., Lippold, J.C., (2009) Weld. J., 88, pp. 131sPerricone, M.J., Dupont, J.N., (2006) Metall. Trans. A, 37, p. 1267. , 10.1007/s11661-006-1078-7Kraft, T., Exner, H.E., (1998) Mater. Sci. Technol., 14, p. 377. , 10.1179/mst.1998.14.5.377Kou, S., (2003) Welding Metallurgy, p. 145. , 2nd ed. John Wiley & Sons NYMehrabian, R., Flemings, M.C., (1970) Metall. Trans., 1, p. 455. , 10.1007/BF02811556Alburquerque, V.H.D., Silva, C.C., Menezes, T.I., Farias, J.P., Tavares, J.M., (2011) Microsc. Res. Tech., 74, p. 36. , 10.1002/jemt.20870Donachie, M.J., Donachie, S.J., (2002) Superalloys: A Technical Guide, p. 37. , 2nd ed. ASM International USAStiller, K., (1992) Surf. Sci., 266, p. 402. , 10.1016/0039-6028(92)91053-ELim, Y.S., Kim, J.S., Kim, H.P., Cho, H.D., (2004) J. Nucl. Mater., 335, p. 108. , 10.1016/j.jnucmat.2004.07.038Radrakrisnha, C., Prasad-Rao, K., (1997) J. Mater. Sci., 32, p. 1977. , 10.1023/A:1018541915113Song, K., Aindow, M., (2008) Mater. Sci. Eng. A, 479, p. 365. , 10.1016/j.msea.2007.09.055Rios, P.R., (1987) Acta Metall., 35, p. 2805. , 10.1016/0001-6160(87)90280-XSong, K., Aindow, M., (2007) Metall. Mater. Trans. A, 38, p. 1. , 10.1007/s11661-006-9032-2Ramakrishnan, K.N., Venkadesan, S., Murthy, K.P.N., (1995) Scr. Metall. Mater., 32, p. 685. , 10.1016/0956-716X(95)91586-EUnfried, J., Afonso, C.M.R., Ramirez, A.J., (2009) Acta Microsc., 18, p. 191Young, G.A., Capobianco, T.E., Penik, M.A., Morris, B.W., McGee, J.J., (2008) Weld. J., 87, pp. 31
Drag Reduction by Applying Speedstrips on Rowing Oars
No full textAbstractThe objective of this study was to determine the advantage of the application of speedstrips to rowing oars for a lightweight single sculler. The research method comprehended three steps: (1) the analysis of the rowing oar movement, (2) the determination of the change in drag and (3) the composition of a rowing model to establish the advantage that could be achieved. The parameters needed for the model: boat velocity, oar angle velocity and power delivered by the rower, were recorded on a real single sculler. The change in drag due to speedstrips on cylinders was determined by performing wind tunnel experiments. The rowing model (Matlab) simulates a race by using real stroke data of a world-class rower as input, while calculating the drag with the coefficients determined by the wind tunnel experiments. The output of the model is the final advantage by the application of speedstrips to rowing oars. Speedstrips induce a 0.1% advantage over a 2000 m race under calm wind conditions. The advantage increases up to .4% with a headwind velocity of 5 m s-1. For bigger boats, the advantage could be even more significant
Drag and Power-loss in Rowing Due to Velocity Fluctuations
No full textAbstractThe flow motions in the turbulent boundary layer between water and a rowing boat initiate a turbulent skin friction. Reducing this skin friction results in better rowing performances. A Taylor-Couette (TC) facility was used to verify the power losses due to velocity fluctuations PV′ in relation to the total power , as a function of the velocity amplitude A. It was demonstrated that an increase of the velocity fluctuations results in a tremendous decrease of the velocity efficiency eV . The velocity efficiency eV for a typical rowing velocity amplitude A of 20 – 25% was about 0.92 – 0.95%. Suppressing boat velocity fluctuations with 60% will increase boat speed with 1.6%. Riblet surfaces were applied on the inner and outer cylinder wall to indicate the drag reducing ability of such surfaces. The results of the measurements at constant velocity are identical as the results reported earlier, while the experimental configuration was different. This confirms once more the consistency of the TC-system for drag studies. The maximum drag reduction DR was 3.4% at a Reynolds number Res 4.7 × 104, which corresponds to a shear velocity in this TC-system with water of V 4.7 m/s. For typical rowing velocity fluctuations, the riblets maintain to reduce the drag with 2.8% and corresponds to a averaged velocity increase of 0.9%. The drag reducing ability of riblets is partly lost due to velocity fluctuations with high amplitudes (A > 20%). From these results, it is concluded that the friction coefficient Cf will vary within one cycle. Higher acceleration/deceleration leads to a additional level of turbulent kinetic energy
A.J. Cronin. A doctor into lifelong writer
No full textReality and fiction might be strictly coexistent in the narrative world. The author of this article, after a deep reading of A.J. Cronin’s novels, has tried to find out the right key to penetrate into the novelist’s intricate world. After many interrogatives on A.J. Cronin both as a man and writer, the author , finally, has been able to grasp from the pages of the novelist, the suffering of a man who has made of his romance the history of his own life
Computing with cables: Towards massively parallel neuro computers
No full textElectrical Engineering, Mathematics and Computer Scienc
Radio Frequency Interference Mitigation in Radio Astronomy
No full textThe next generation of radio telescopes is expected to be one to two orders of magnitude more sensitive than the current generation. Examples of such new telescopes are the Low Frequency Array (LOFAR), currently under construction in the Netherlands, and the Square Kilometer Array (SKA), currently in a concept study phase. Another trend is that technological advances in the fields of electronics and communications systems have led to a vast increase in radio communication applications and systems, and also to an increasing demand for radio spectrum. These two trends, more sensitive telescopes and a much denser spectrum use, imply that radio astronomy will become more vulnerable to interference from radio transmitters. Although protection criteria exist for radio astronomy, it becomes increasingly difficult to keep the radio astronomy frequency bands free from interference. In order to mitigate interference in radio astronomical data, filtering techniques can be used. In this thesis, modern array signal processing techniques have been applied to narrow-band multichannel interference detection and excision, and to narrow-band spatial interference filtering. By investigating the subspace structure of the telescope array output covariance matrices, new results were found, such as upper limits on interference residuals after excision and spatial filtering. The effect of bandwidth, extendedness of the interfering sources, and multipath effects on the detection and spatial filter effectiveness were studied as well. The advantage of a multichannel approach over a single telescope approach was demonstrated by using experimental data from the Westerbork Synthesis Radio Telescope (WSRT). As the performance of mitigation algorithms can be improved by calibration of the telescope gains and noise powers, calibration algorithms were developed. These algorithms were verified both for single and dual polarised arrays. Finally, a LOFAR interference mitigation strategy was developed.Electrical Engineering, Mathematics and Computer Scienc
A pre-post test evaluation of the impact of the PELICAN MDT-TME Development Programme on the working lives of colorectal cancer team members
No full textBackground: the PELICAN Multidisciplinary Team Total Mesorectal Excision (MDT-TME) Development Programme aimed to improve clinical outcomes for rectal cancer by educating colorectal cancer teams in precision surgery and related aspects of multidisciplinary care. The Programme reached almost all colorectal cancer teams across England. We took the opportunity to assess the impact of participating in this novel team-based Development Programme on the working lives of colorectal cancer team members.Methods: the impact of participating in the programme on team members' self-reported job stress, job satisfaction and team performance was assessed in a pre-post course study. 333/568 (59%) team members, from the 75 multidisciplinary teams who attended the final year of the Programme, completed questionnaires pre-course, and 6-8 weeks post-course.Results: across all team members, the main sources of job satisfaction related to working in multidisciplinary teams; whilst feeling overloaded was the main source of job stress. Surgeons and clinical nurse specialists reported higher levels of job satisfaction than team members who do not provide direct patient care, whilst MDT coordinators reported the lowest levels of job satisfaction and job stress. Both job stress and satisfaction decreased after participating in the Programme for all team members. There was a small improvement in team performance.Conclusions: participation in the Development Programme had a mixed impact on the working lives of team members in the immediate aftermath of attending. The decrease in team members' job stress may reflect the improved knowledge and skills conferred by the Programme. The decrease in job satisfaction may be the consequence of being unable to apply these skills immediately in clinical practice because of a lack of required infrastructure and/or equipment. In addition, whilst the Programme raised awareness of the challenges of teamworking, a greater focus on tackling these issues may have improved working lives furthe
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