Double-step generation of ellipses

The principle of double-step incremental generation of nonparametric curves on a discrete plane is used to develop a double-step algorithm for scan converting ellipses in sixteen separate segments. The algorithm iterates only half as many times as current algorithms, while each iteration demands the same number of operations or slightly fewer operations than M. Pitteway's (1967, 1985) algorithm (previously the fastest one). This marked gain in the speed of scan conversion is due to the fact that the middle pixel in a two-step increment is obtained without computation     

TEM study of PLZT ceramics

The microscopic structures of PLZT(7.9/70/30 and x/65/35, x = 7 or 8) ceramics were studied by means of transmission electron microscopy. The presence of micro-regions in PLZTs was first verfied.     

Heat extraction efficiency of a concentric glass tubular evacuated collector

The results of detailed measurements and calculations of the properties of Sydney University/Nitto Kohki evacuated collector tubes have been used to develop a formula for the instantaneous heat extraction efficiency η of a collector panel incorporating the evacuated tubes. The instantaneous efficiency depends on ambient temperature, mean fluid temperature in the collector, solar flux and the design of the manifold used to extract heat from the glass absorber tubes. Manifold design determines the mean temperature difference between absorber tube surface and mean fluid temperature for given operating conditions, and strongly affects the efficiency η of a collector panel. Neither changes in the number of evacuated tubes per unit area of collector, nor variations in solar flux, significantly alter the efficiency decrement Δ η₀ associated with a particular manifold design. Calculated efficiencies agree well with experimental results for collector panels incorporating manifolds of various designs. The formula for efficiency η allows detailed analysis of the relative importance of various energy loss mechanisms in a collector.     

Effects of thymectomy and glucocorticoid therapy on peripheral lymphocytes in myasthenia gravis

Clinical manifestations and peripheral blood lymphocyte subset changes were studied in patients with myasthenia gravis (MG) to elucidate the mechanism of clinical improvement following treatment, with thymectomy (Tx) or glucocorticoid (GC) therapy. The changes found were: 1. There was a significant increase in percentages of CD3+, CD29+ CD4+ cells and CD4/CD8 ratio and a significant decrease in percentages of CD8+ and CD16,56+ cells in patients who had never been treated with any immune therapy. 2. After Tx or GC therapy, CD3+ and CD4+, CD29+ cells were decreased, but the number CD19+ and CD16, CD56 cells did not change. 3. Tx had a special effect on CD8+ cells. In most of the patients who showed clinical improvement after Tx, CD8+ cells were increased and CD4/CD8 ratio wad decreased. 4. Anti-acetylcholine receptor (AChRAb) titers were markedly decreased after GC therapy. These results indicate that there were obvious abnormalities in cell-mediated immunity in addition to those in humoral immunity in myasthenia gravis. These abnormalities tended to be normalized after Tx or GC therapy.     

A numerical investigation on the geometry dependence of the crack growth resistance in CT specimens

The influence of the specimen thickness B and the ligament length b on the J _R -curves is numerically investigated for CT specimens. The thickness effect is taken into account with 2-D analyses by dividing a plain sided specimen into a plane stress part and a plane strain part. The fracture process is controlled by experimentally determined critical values of the crack tip opening displacement for crack growth initiation (CTOD_i) and the crack tip opening angle for stable crack growth (CTOA_C). It is shown that for the global behaviour of a plain sided specimen, the B/b ratio is essential. The difference between the geometry dependence of the initiation value of the J-integral and the geometry dependence of the slope of the J _R -curves is also shown.     

Single g-pulses and segregation in virtual µg Bridgman growth environments. A complementary two-dimensional approach

The binomial single g-pulses — dopant segregation in a generic virtual µg Bridgman growth arrangement is discussed here with the help of a time dependent two-dimensional scheme. To attain this objective, the so-called solid composition drop distribution has been previously defined enabling a global two-dimensional information of the segregation impact in each virtually grown crystal. Based on this parameter it has been concluded that, at equal g-dose, solid segregation is independent on the shape of the single external pulse and that, for single g-pulses of equal g-dose, compositional variations are practically independent on the activity time but depend on the crystal growth rate. Finally, taking into account all these set of results, the pertinence of the g-dose as the only self-consistent parameter to describe the segregation impact has been discussed.