An algorithm for finding the position of a point relative to a fixed polygonal boundary

This article describes a method that determines the position of a point relative to a fixed boundary. Its advantage over the other existing algorithms described below is that in most cases it is necessary that only part of the algorithm be executed to determine the position of the point. A possible inconvenience of using this algorithm is that the contour boundary has to be entered as data. For problems where the boundary often changes the algorithm is not suitable in its present form. The applications envisaged here are to cases where the position of a very large number of points have to be determined relative to one fixed polygonal boundary whose shape is known in advance, for example, blanking out of contours in automatic contouring, or selecting drill holes which lie in the particular part of a mineral deposit.     

A rate-type constitutive model for soil with a critical state

A continuum representation for soil which incorporates the concepts of hypoelasticity and critical state theory is proposed. General, three-dimensional constitutive equations are formulated to relate specific volume, stress, rate of deformation and rate of change of stress, resulting in a mathematical material model which exhibits phenomenological features typical of soil response. The general constitutive equations are specialized to represent the particular cases of isotropic compression, constant, volume deformation, uniaxial compression and biaxial deformation. Methods are suggested for determining the model parameters to represent a specific soil using conventional triaxial test data. Comparisons of stress-strain response with published experimental data are shown.     

Associated and non-associated constitutive relations for undrained behaviour of isotropic soft clays

Incremental theory of plasticity has been used to derive associated and non-associated stress–strain relations for analysing the undrained stress-strain response of isotropic normally and lightly overconsolidated clays. A series of comparisons between the theoretical stress-strain-pore pressure response and laboratory test results for 3 in. × 6 in. samples of very high degree of repeatability and reproduceability have been described. From these comparisons it can be seen that both the associated and, non-associated Cam clay models appear to give consistently the best correlations between the theoretical results and the experimental observations.     

Composition of low energy cosmic radiation from silicon to nickel

The charge composition of the cosmic radiation for the elements withZ14 has been studied in a stack of nuclear emulsions exposed at Fort Churchill in July 1967. Particles stopping in the stack have been measured with a nuclear track photometer to determine the charge. Relative abundances are given for the elements silicon to nickel and comparison is made with other investigations.     

The dark-side illumination of Saturn's rings

Using Focas and Dollfus' (1969) measurements, the effective optical thickness of Saturn's rings along the cross-section studied is evaluated from intensity of radiation transmitted through the rings. The most probable value, including also the contribution of gaps, is 0.2. A large fraction of dark-side illumination is produced by single scattering in gaps having an optical thickness 10^–4 to 10^–3.