Elliptical machines

An aluminum alloy cooling water conduit section was removed from a machine that made polyethylene sheeting. A large hole had formed just below a in. (1.9 cm) cooling water orifice. The designed orifice is shown in Fig. 8.11, with the elliptically shaped corroded hole just below. 

Figure fl.11 An aluminum cooling water conduit severely attacked by a caustic in service. The large circular hole in the machined face is corroded around its edges. The elliptical hole between the 6- and 7-in. ruler markings was formed by corrosion penetrating the conduit wall. 

A further peculiarity of conventional M/E membranes is that autoclaving produces uneven shrinkage between machine and transverse directions with the result that a disk which is circular before autoclaving becomes somewhat elliptical after auto-... 

Inasmuch as all samples were perfectly round 47 mm disks before "dry" autoclaving, the standard deviation of the measured diameters after autoclaving is a measure of ellipticity,/.e. uneven shrinkage in machine and transverse directions. 

Owing to the variety of units found in the literature and in software—e.g., mdeg and deg for ellipticity, and mm, cm or dm for path length—it is necessary to take care that experimental parameters are entered in the units requested by the machine software. 

The basic operation in most of the following schemes is modular multiplication. (Elliptic curve arithmetic, on which some of the schemes could be based instead, is not described here see, e.g., Kobl87].) It is assumed that is represented by the numbers 0,. .., n-1. A modular multiplication can be computed with one multiplication and one division. A multiplication of /-bit numbers on a machine with word length w can easily be performed with fZ/vvl word multiplications. Division takes a small number of word multiplications more. 

As the cloth or web falls into the liquor from the winch at the back of the machine, it tends to bunch up and lie in a heap for a short time. This is no disadvantage with wool or cotton materials, but tends to cause serious creases in acetate rayons and other thermoplastic fibres. To overcome this a long shallow machine with an elliptical winch has been designed (Fig. 13.24). The elliptical shape of the roller folds the material in wide layers which are free from random creases as it falls into the dye liquor. The... 

Vibration, Fig. 9 Mirror surface machining after suppressing undesirable vibration (a) Diamond cutting with vibration-suppressed machining center, (b) Aluminum alloy machined by ordinary cutting, (c) Hardened die steel machined by elliptical vibration cutting (Shamoto et al. 2005)... 

This programme was presented last year (ref. 2). The purpose of TERFIS 5 tests carried out in 1996 was to quantify the influence of residual stresses on crack initiation and growth in weldments. They were obtained on stainless steel 316 L tubes where a defect was machined in a welded joint. The tubes were submitted to a low uniform tension (29 Mpa) and to thermal stocks (ex in the case of a circunferential defect AT in the thickness 180°C and 10 cycles in the case of a semi-elliptic defect AT in the thickness 300°C and 1500 cycles). 

One of the effective ways to eliminate surfece cracks is crack-healing. Especially, that driven by oxidation of SiC can completely erase all surface cracks by a simple heat treatment. Ando et al. reported that a heat treatment at 1573 K for 1 h in air can completely heal a elliptical surface crack with surface length = 100 xm, which introduced by indentation in alumina reinforced by 15 vol.% SiC particles. Also, Osada et al. reported that the numerous surface cracks introduced by heavily machining can be completely healed by the same crack-healing treatment. 

Most CD spectrometers, although they actually measure differential absorbance, produce a CD spectrum in ellipticity, with imits 0, in millidegrees, versus rather than AA versus X. Most CD machines will perform the conversion from ellipticity to absorbance units on request. 

Formability of the polymer sheet blanks was evaluated by means of tensile tests and bi-axial circular (50mm) and elliptical (50/32mm) hydraulic bulge tests. The tensile tests were performed in a mechanical testing machine while the hydraulic bulge tests were performed in a universal sheet metal testing machine. Testing speed was constant and set to 5mm/min in both cases. 

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