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Preparation of bead metal single crystals by electron beam heating J. Vac. Sci. Technol. A 23, 1535 (2005); 10.1116/1.2101793 Why is iridium the best substrate for single crystal diamond growth? MODES IN SMALL FERRITE-FILLED WAVEGUIDES 2391to have comparable amplitudes. Since 1/;1 must decay rapidly in the transverse plane, hz= 1/;2 is a good approximation and is valid even at the boundary, to order k o 2 /(32, which is quite small for small waveguide and p,+ significantly larger than p,-.Therefore neglecting the axial component of e inEq. (4) is justified for the propagating volume mode as its effect is only to perturb the approximate solution slightly. The method outlined in this Appendix is of value in determining the limit of validity of the approximate solution presented in the text.A study of the brittle fracture of iridium is made using the scanning electron microscope. Except where macroscopic imperfections are present, cracks can only be nucleated after extensive work-hardening. Plastic relaxation of the crack is inhibited because impurities substantially increase the critical resolved shear stress. Brittle fracture in iridium is thus basically an impurity effect.

Current practice in the design of reinforced soil is to calculate the long-term strength of a reinforcement damaged during installation by multiplying the two partial safety factors RFID and RFCR. This procedure assumes that there is no synergy between them. To test this hypothesis, stepped isothermal method creep-rupture tests were performed on a polyester geosynthetic in its undamaged and damaged states. The geosynthetic chosen and the method of damage were specifically chosen to yield a 30% reduction in strength with the minimum of scatter. From simple tensile testing, the reduction factor for installation damage, RFID, was measured to be 1.42. Stepped isothermal method tests on the undamaged geosynthetic gave a creep-rupture characteristic with RFCR = 1.70 for 106 hours (114 years). Thus, the predicted reduction factor for the long-term strength of the damaged geosynthetic is (RFCR)(RFID) = 2.41. The measured reduction factor was 2.26, 7% less than predicted. It is recommended that the practice of using (RFCR)(RFID) is upheld in the knowledge that the prediction will be slightly conservative.

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