The theories of extrusion are examined; considerable limitations exist in the analysis of extrusion conditions using either the semi-empirical approach, which is based on the assumption of homogeneous straining, or the slip-line approach. More information is required on the basic extrusion parameters such as yield stress and friction coefficient an...
The extrusion pressures determined for beryllium and mild steel over a wide range of reductions in area at temperatures between 750ºC and 1050ºC are significantly lower than those reported previously. This is attributed to better control of temperature in the work reported, the effects of container friction were assessed and the coefficient of fric...
A technique for the hot extrusion of beryllium powder within a mild steel sheath has been developed. Limitations exist with this technique in the control of extruded dimensions, particularly on complex sections or where the sheath thickness is greater than about 0.020 inch. The use of pre-consolidated powder billets is recommended to reduce the dan...
A technique for the extrusion and sintering of beryllium oxide to produce high density, fine-grained, high strength material were modified and improved. This resulted in beryllium oxide (250 p.p.m. Fe) which after extrusion and sintering for 5 hours at 1400oC in nitrogen, had an average grain size 6 pts, a mean modulus of rupture equal to 34.840 p....
Published in BBA - Biomembranes
Published in BBA - Biomembranes
Published in American Journal of Orthodontics
Ce mémoire de Thèse se divise en deux parties. La première traite du problème de la déformation interne associée au déplacement des nappes superficielles. Sans privilégier un modèle par rapport à d'autres, on tente dans un premier temps de synthétiser les principaux mécanismes de mise en place géologiquement réalistes, puis de déterminer leur champ...
"April 1, 1991." / Spruce: an example for understanding and controlling conifer somatic embryogenesis ; Stages of zygotic and somatic embryo development ; Initiation of embryogenic callus from megagametophytes of loblolly pine ; Chemical composition of developing ovules of loblolly pine-1. Ionic composition and concentration / R. Nagmani ... [et al...
La dégradation des propriétés mécaniques à haute température est reliée principalement à la recristallisation et à la coalescence des précipités. La solution proposée pour éviter, ou limiter, ces phénomènes est de bloquer les joints de grains par des dispersoïdes et de durcir la matrice par de petits précipites stables thermiquement, dont les éléme...
