Fracture prediction in steady ideal plastic flows

The theory of ideal plastic flows is a powerful tool for the preliminary design of metal forming operations. The present paper develops an approach to include a fracture criterion in this design procedure. The fracture criterion is based on the workability diagram and an average value of the triaxiality factor. In the case of three dimensional flows, this fracture criterion is modified which leads to mathematical advantages. It is shown that in many cases the modified criterion coincides with the original criterion. Using the proposed approach fracture initiation in drawing and extrusion processes is predicted. In particular, it is demonstrated that fracture predictions may be carried out without having the solution for stress and strain in the plastic zone (it is only necessary to know that it exists). The maximum possible area reduction with no fracture is given by the solution to a quadratic equation (in general, it might be a transcendental equation).     

The Effect of Moisture Content on the Conversion of Ergosterol to Vitamin D in Shiitake Mushrooms

The distribution of ergosterol in different parts of shiitake mushrooms was studied in order to optimize the conversion of ergosterol to vitamin D₂ during drying. The effect of moisture on the conversion of ergosterol to vitamin D₂ was also investigated by adjusting the moisture content of fresh mushrooms to different levels in a large vacuum desiccator and subjecting them to UV irradiation at 290-320 nm wavelength, for 2 h. The moisture, ergosterol and vitamin D₂ contents were determined using standard procedures. It was found that the ergosterol content on a dry matter basis of fresh shiitake mushroom was highest in the gills (10.6 ± 0.99 mg/g DM), followed by the cap or pileus (5.34 ± 0.64 mg/g DM) and was least in the stalk or stipe (2.97 ± 0.56). The moisture content had a marked influence on the conversion of ergosterol to vitamin D₂, the best conversion taking place at a moisture content of about 70% on a wet basis.     

Optoviscosimetry of a Liquid Film by the Method of a Dispersed Magnetic Sublayer

A magnetooptical method of measurement of viscosity, which is based on recording the optical response (induced by the magnetic-field pulses) of a two-layer system resulting from the sedimentation of ferroparticles dispersed in the liquid under study, has been proposed. The procedure has been described and the results of measurement of the rheokinetics of a number of media, including polymer compositions formed into a thin film, in heating, evaporation, and polymerization have been presented.     

Conservation of water resources problems of small rivers in Russia

Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 8, pp. 1–5, August, 1994.     

New titanium applications on the Boeing 777 airplane

When rolled out for its first customer in 1995, the 777 will be the first new Boeing commercial airplane in more than ten years. Since the introduction of the last two Boeing planes, the 767 and 757, the science and technology of titanium alloys has come a long way. Some of the advances have led to new applications of titanium\3-with its accompanying performance benefits\3-on the 777.