Duval

A further complication which not infrequently appears is the occurrence of a phase transition within the adsorbed film. Detailed investigation of a number of step-like isotherms by Rouquerol, Thorny and Duval, and by others has led to the discovery of a kink, or sub-step within the first riser, which has been interpreted in terms of a two-dimensional phase change in the first molecular layer. 

D. S. Duvall and W. A. Rubey, "Laboratory Evaluation of High Temperature Destmction of Kepone and Related Pesticides," EPA-600/2-76-299, NTIS, Springfield, Va., Dec. 1976. 

One, the CLEAR process, was investigated by Duval Corporation near Tucson, Arizona (29). It involves leaching copper concentrated with a metal chloride solution, separation of the copper by electrolysis, and regeneration of the leach solution in a continuous process carried out in a closed system. Elemental sulfur is recovered. Not far from the Duval plant, Cypms Mines Corporation operated a process known as Cymet. Sulfide concentrates undergo a two-step chloride solution leaching and are crystallized to obtain cuprous chloride crystals. Elemental sulfur is removed during this stage of the process. 

J. C. Mack and M. L. Duvall, "Performance and Economics of Minnelusa Polymer Floods," paper presented at the 1984 Mountain Regional Meeting of S ociety of Petroleum Engineers, Casper, Wyo., May 21—23,1984. 

Relative to the difficulties in establishing shock compression, as a serious science, Duvall [4] has observed ... 

G.E. Duvall, in Response of Metals to High Velocity Deformation (edited by P.G. Shewmon and V.F. Zackay), Interscience, New York 1961, pp. 165-202. 

The basic concepts of shock and particle velocities are well illustrated by an example first introduced by Duvall and Band (1968). Here we assume that a string of beads of diameter d, mass m, and spaced a fixed distance / apart on a smooth (frictionless) wire is impacted by a rigid, massive piston at velocity v. Each bead is assumed to undergo perfectly elastic, rigid-body motion upon impact with its neighbor. 

We express our gratitude to Orval E. Jones, George E. Duvall, and Dennis B. Hayes whose unpublished notes have instructed a generation of shock-wave scientists and engineers at Sandia and elsewhere. This excellent source of information figures prominently in this chapter. The figures were skillfully drawn by Kay Lang. 

W. Band and G.E. Duvall, Physical Nature of Shock Propagation, Amer. J. Phys. 29, 780(1961). 

G.E. Duvall, Shock Waves in the Study of Solids, Appl. Mech. Rev. 15, 849 (1962). G.E. Duvall and G.R. Fowles, Shock Waves, in High Pressure Physics and Chemistry, Vol. 2 (edited by R.S. Bradley), Academic Press, New York, 1963, p. 209. 

The shock-induced micromechanical response of <100>-loaded single crystal copper is investigated [18] for values of (WohL) from 0 to 10. The latter value results in W 10 Wg at y = 0.01. No distinction is made between total and mobile dislocation densities. These calculations show that rapid dislocation multiplication behind the elastic shock front results in a decrease in longitudinal stress, which is communicated to the shock front by nonlinear elastic effects [pc,/po > V, (7.20)]. While this is an important result, later recovery experiments by Vorthman and Duvall [19] show that shock compression does not result in a significant increase in residual dislocation density in LiF. Hence, the micromechanical interpretation of precursor decay provided by Herrmann et al. [18] remains unresolved with existing recovery experiments. 

To answer questions regarding dislocation multiplication in Mg-doped LiF single crystals, Vorthman and Duvall [19] describe soft-recovery experiments on <100)-oriented crystals shock loaded above the critical shear stress necessary for rapid precursor decay. Postshock analysis of the samples indicate that the dislocation density in recovered samples is not significantly greater than the preshock value. The predicted dislocation density (using precursor-decay analysis) is not observed. It is found, however, that the critical shear stress, above which the precursor amplitude decays rapidly, corresponds to the shear stress required to disturb grown-in dislocations which make up subgrain boundaries. 

G.E. Duvall, Propagation of Plane Shock Waves in a Stress-Relaxing Medium, in Stress Waves in Anelastic Solids (edited by H. Kolsky and W. Prager), Springer-Verlag, Berlin, 1964, pp. 20-32. 

J.E. Flinn, G.E. Duvall, G.R. Fowles, and R.F. Tinder, Initiation of Dislocation Multiplication in Lithium Fluoride Monocrystals Under Impact Loading, J. Appl. Phys. 46, 3752-3759 (1975). 

S.E. Arione and G.E. Duvall, Temperature Dependence of the Precursor Amplitude in <111 > Lithium Fluoride, in Shock Waves in Condensed Matter (edited by Y.M. Gupta), Plenum, New York, 1986, pp. 299-302. 

G.E. Duvall, Shock Compression Chemistry in Materials Synthesis and Processing, National Materials Advisory Board NMAB-414, National Academy Press, Washington, DC, 1984. 

T.J. Ahrens and G.E. Duvall, Stress Relaxation Behind Elastic Shock Waves in Rocks, J. Geophys. Res. 71, 4349-4360 (1966). 

---