Die behoefte aan ’n wyer artikel 2(3) van die Wet op Testamente 7 van 1953 (soos gewysig): ’n Kritiese beskouing

Uit teks: Die Hoogste Hof van Appél se uitspraak in Bekker v Naude en Andere 2003(5) SA 173 (HHA) het die posisie aangaande die toepassing van artikel 2(3) van die Wet op Testamente 7 van 1953 (soos gewysig) duidelik uiteengesit en alle onsekerheid uit die weg geruim

Low Thermal Expansion Coatings for Carbon/Carbon Composites

Two classes of materials are considered for low expansion protective coatings for carbon/carbon composites. They include composites containing particles which undergo allotropic phase transformations accompanied by negative volume changes with increasing temperature and anisotropic oxides which demonstrate low expansion due to microcracking. Conditions for failure of coatings by either cracking or spallation due to thermal mismatch are evaluated

Applying an instructional design method to serious games - experiences and lessons learned

The ABCDE method, used internationally to treat seriously ill patients, is a complex skill that is commonly trained in face-to-face-courses. In the abcdeSlM game, used as a preparation for these courses, players treat patients in a virtual emergency department. We applied the Four Component Instructional Design theory to redesign the existing game. In this article, we describe how the components of this instructional design theory can be applied to a serious game for medical education

Mechanical properties of wood-derived silicon carbide aluminum-alloy composites as a function of temperature

The mechanical behavior [i.e., stiffness, strength, and toughness (K_(IC))] of SiC Al–Si–Mg metal–ceramic composites (50:50 by volume) was studied at temperatures ranging from 25 to 500 °C. The SiC phase was derived from wood precursors, which resulted in an interconnected anisotropic ceramic that constrained the pressure melt-infiltrated aluminum alloy. The composites were made using SiC derived from two woods (sapele and beech) and were studied in three orthogonal orientations. The mechanical properties and corresponding deformation micromechanisms were different in the longitudinal (LO) and transverse directions, but the influence of the precursor wood was small. The LO behavior was controlled by the rigid SiC preform and the load transfer from the metal to the ceramic. Moduli in this orientation were lower than the Halpin–Tsai predictions due to the nonlinear and nonparallel nature of the Al-filled pores. The LO K_(IC) agreed with the Ashby model for the K_(IC) contribution of ductile inclusions in a brittle ceramic

Acquiring high-resolution wind measurements by modifying radiosonde sounding procedures

High-resolution wind measurements are crucial for the understanding of dynamic processes in the atmosphere. In the troposphere and lower stratosphere, radiosondes provide a good vertical resolution of a few metres, but the wind data are usually low-pass filtered by the manufacturer in order to suppress disturbances in the data caused by the spurious motions of the sonde. As an example, the filter within the standard processing of Vaisala radiosondes becomes effective at vertical scales below 300 m for an ascent rate of 5 m s−1. We describe a method for increasing the usable resolution of radiosonde wind measurements. The main ideas are to avoid self-induced motions of the balloon by keeping it in the subcritical Reynolds number range, to avoid typical pendulum motions of a 15 s period by using a shorter string, and to use data from a descending balloon in order to avoid disturbances from the wake of the balloon affecting temperature and humidity measurements due to the decreased string length. We demonstrate that our changes in hardware and software allow for artefact-free wind data down to scales of 50 m, while the remaining disturbances on even smaller scales are removed. Accordingly, the usable resolution of the wind data has been increased by a factor of 6, compared to the standard data output, at relatively low cost.</p

High-temperature hardness of Ga_(1−x)In_xAs

Substantial solid‐solution strengthening of GaAs by In acting as InAs_4 units has recently been predicted for an intermediate‐temperature plateau region. This strengthening could account, in part, for the reduction of dislocation density in GaAs single crystals grown from the melt. Hardness measurements at high temperatures up to 900 °C have been carried out on (100) GaAs, Ga_(0.9975)In_(0.0025)As, and Ga_(0.99)In_(0.01)As wafers, all of which contain small amounts of boron. Results show a significant strengthening effect in In‐doped GaAs. A nominally temperature‐independent flow‐stress region is observed for all three alloys. The In‐doped GaAs shows a higher plateau stress level with increasing In content. The results are consistent with the solid‐solution strengthening model. The magnitude of the solid‐solution hardening is sufficient to explain the reduction in dislocation density with In addition

Marangoni shocks in unobstructed soap-film flows

It is widely thought that in steady, gravity-driven, unobstructed soap-film flows, the velocity increases monotonically downstream. Here we show experimentally that the velocity increases, peaks, drops abruptly, then lessens gradually downstream. We argue theoretically and verify experimentally that the abrupt drop in velocity corresponds to a Marangoni shock, a type of shock related to the elasticity of the film. Marangoni shocks induce locally intense turbulent fluctuations and may help elucidate the mechanisms that produce two-dimensional turbulence away from boundaries.Comment: 4 pages, 5 figures, published in PR

Some Cautionary Remarks on Abelian Projection and Abelian Dominance

Some critical remarks are presented, concerning the abelian projection theory of quark confinement.Comment: Talk presented at LATTICE96(topology) plenary session, uses psfig and espcrc2 package

The Finite Field Kakeya Problem

A Besicovitch set in AG(n,q) is a set of points containing a line in every direction. The Kakeya problem is to determine the minimal size of such a set. We solve the Kakeya problem in the plane, and substantially improve the known bounds for n greater than 4.Comment: 13 page