Appearance Of Knots Research Articles

Classical and Relativistic Conservation of Momentum Flux in Radio-Galaxies

A new set of laws of motion for turbulent jets propagating in an intergalactic medium characterized by a decreasing density is derived by applying conservation of momentum flux both in the classical and relativistic framework. Two characteristic features of radio-galaxies, such as oscillations and curvature, are modeled by a classical helicoidal jet. A third feature of a radio-galaxy, the appearance of knots, is explained as an effect due to the theory of images.

Estimation of sawn face width of Sugi (Cryptomeria japonica D. Don) logs by cross-sectional shape with approximation profile

In sawing systems producing high quality lumber from medium diameter sugi (Cryptomeria japonica D. Don) logs, operators must carefully decide the amount of setworks taking into consideration the sawn face width and appearance of knots so that the work efficiency often suffers considerable reduction. A simple mathematical method to estimate the sawn face width on the basis of cross-sectional shape with an approximation profile was proposed. Ninety cross-sectional shapes were measured using a newly developed measuring device and estimated as a circle or an ellipse, where 89% of the cross-sectional shapes fit the ellipses. The error margin in 72–75% of the sawn face width estimates was 2.0 cm or less, which was equal to the conventional value achieved by skilled operators.