Center For Materials Science Research Articles

Diffraction of sound pulses by a circular cylinder

The diffraction of sound pulses by a circular cylinder in a fluid medium is analyzed by applying the Poisson's summation formula and Laplace transform. The inverse Laplace transform is computed analytically by using a modified Cagniard method. This newly developed method avoids the tedious calculation of residues of complex-ordered Bessel functions. Because asymptotic approximations of the modified Bessel functions have been used, the solutions so obtained are good for the early-time transient waves or for pulses with short duration, for which the normal-mode solution is poorly convergent. Analytical solutions for the incident, reflected and diffracted pulses in the illuminated and shadow zones are obtained by a unified approach. Each pulse is represented by a ray integral with a unique arrival time which conforms to Fermat's principle. The numerical results obtained for an incident square pulse emitted by a line source resemble the actual experimental observations reported by others [G. R. Barnard and C. M. McKinney, J. Acoust. Soc. Am. 33, 226 (1961)] for the backscattering of a hard cylinder in water. [Supported by NSF through a grant to the Materials Science Center at Cornell University.]

PERSISTENCE AND EFFECTS OF LIGHT FUEL OIL IN SOIL

ABSTRACT The USDA-SCS Plant Materials Science Center at Big Flats, New York, was damaged by flood-borne oil in June 1972. Field plots were established in part of the damaged area to determine the effects of such contamination on soil properties and on crop production, and to assess the persistence of such contamination under northeastern conditions of soil and climate. Field crops (corn, oats, and soybeans) have been used as major indicator crops. Crop yield data have been collected and compared to published estimated yields for the same area and soil resource. Soil samples have been analyzed annually to determine the quantities of oil remaining in the soil. Greenhouse experiments have been conducted to determine a threshold level of economic damage, and the residual effects of such applications. The results indicate that oil penetration was slightly below 24 inches; that the initial levels of oil contamination were relatively low (0.2% by weight, or less), but spectacular in appearance; that shallow rooted crops were less susceptible to damage by residual oil than deep rooted crops; that some residual effect was reflected in growth of both crop plants and weeds one year after contamination; and that light fuel oils may affect crop growth at relatively low application rates. These effects may be minimized by the proper choices of crop species and soil management practices (tillage and fertilization). The results are supported by aerial photographs and field inspections of similar problem areas in the Big Flats area, made at one-year intervals.

Nucleation of voids in irradiated metals—III. Impurity effects : By K. C. Russell; Department of Metallurgy and Materials Science, Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, U.S.A.

Nucleation of voids in irradiated metals—III. Impurity effects : By K. C. Russell; Department of Metallurgy and Materials Science, Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, U.S.A.

Reequilibration Kinetics for Undoped and Lithium‐Doped Single Crystal Nickel Oxide

Journal of the American Ceramic SocietyVolume 56, Issue 7 p. 397-398 Reequilibration Kinetics for Undoped and Lithium-Doped Single Crystal Nickel Oxide J. NOWOTNY, J. NOWOTNYSearch for more papers by this authorJ. B. WAGNER JR., J. B. WAGNER JR.Search for more papers by this author J. NOWOTNY, J. NOWOTNYSearch for more papers by this authorJ. B. WAGNER JR., J. B. WAGNER JR.Search for more papers by this author First published: July 1973 https://doi.org/10.1111/j.1151-2916.1973.tb12702.xCitations: 16 Supported by the National Science Foundation by a postdoctoral fellowship to J. Nowotny under Grant No. GK-1137. At the time this work was done, the writers were with the Department of Materials Science and Materials Research Center, Northwestern University, Evanston, IL 60201. J. Nowotny is now with the Research Laboratories of Catalysis and Surface Chemistry, Polish Academy of Sciences, Krakow, Poland. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume56, Issue7July 1973Pages 397-398 RelatedInformation

Geometry of symmetrized states: Robert Gilmore. Center for Materials Science and Eingineering, Massachusetts Institute of Technology, Cambridge, Massachusetts

Geometry of symmetrized states: Robert Gilmore. Center for Materials Science and Eingineering, Massachusetts Institute of Technology, Cambridge, Massachusetts

Direct crystallization of extended‐chain crystals of polyethylene from the melt at high pressure

Journal of Polymer Science Part B: Polymer LettersVolume 8, Issue 3 p. 165-172 Article Direct crystallization of extended-chain crystals of polyethylene from the melt at high pressure P. D. Calvert, P. D. Calvert Department of Metallurgy and Materials Science, Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MassachusettsSearch for more papers by this authorD. R. Uhlmann, D. R. Uhlmann Department of Metallurgy and Materials Science, Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MassachusettsSearch for more papers by this author P. D. Calvert, P. D. Calvert Department of Metallurgy and Materials Science, Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MassachusettsSearch for more papers by this authorD. R. Uhlmann, D. R. Uhlmann Department of Metallurgy and Materials Science, Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MassachusettsSearch for more papers by this author First published: March 1970 https://doi.org/10.1002/pol.1970.110080305Citations: 25AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume8, Issue3March 1970Pages 165-172 RelatedInformation

New buildings

A five‐story concrete and glass laboratory, known as the Vannevar Bush Building, has been opened at Massachusetts Institute of Technology as part of its interdepartmental Center for Materials Science and Engineering. Costing $6 million, the new building houses facilities for preparation, purification, and evaluation of metals, insulators, semiconductors, and composite materials such as ceramics. A central analytical lab provides chemical evaluation methods, while physical methods include x‐ray analysis, optical and election microscopy, and electron microprobe analysis. Research will cover basic physics and chemistry of solids, materials of interest in electronics and optics, and properties of materials at high temperatures and pressures. High‐field superconductors and laser materials are also included.

Mass Transfer Problems in Ionic Crystals with Charge Neutrality

Both diffusional creep and sintering involve mass transport of the stoichiometric group of atoms AαBβ. The driving force in each case is external to the lattice, being applied mechanical stress in the case of diffusional creep and surface tension in the case of sintering. It is assumed that point defect mechanisms are involved in the diffusion process. Herring has considered the case of diffusional creep by lattice diffusion where charge effects are absent. The analogous case of creep by grain-boundary diffusion, which becomes the important process at small grain size, has also been treated. [A. L. Ruoff, Materials Science Center Rept. No. 298, Cornell University, Ithaca, New York; and R. L. Coble, J. Appl. Phys. 34, 1679 (1963)]. The diffusional creep of a polycrystalline specimen is here formulated exactly and terms which must be dropped to obtain Herring's expression (for either metallic or ionic crystals) are directly specified. It is then shown that Herring's equations apply to a pure ionic crystal when the conduction is purely ionic and space-charge effects can be ignored if the tracer diffusion coefficient D in Herring's equations is replaced by DM, and the atomic volume Ω in his equations is replaced by the molecular volume VM of the diffusing ``molecule'' of AαBβ. If A atoms have the smallest tracer diffusion coefficient DTa0, then DM=DTa0/faα, where fa is the correlation factor.

Lectures in materials science (the Cornell Materials Science Center lecture series; Leurgans, Paul, ed.)

Lectures in materials science (the Cornell Materials Science Center lecture series; Leurgans, Paul, ed.)