The added mass coefficient of a dispersion of spherical gas bubbles in liquid

Models published in the two-phase flow literature for the added mass coefficient of a dilute bubbly dispersion are discussed and compared. It is shown that the differences between the models are mainly due to the different ways in which the added mass is defined. Also, approximate expressions for the added mass coefficient of non-dilute bubbly dispersions are given. Finally, the use of the models in an equation for the average motion of the bubbles is briefly discussed

Ductile transition in nylon-rubber blends: influence of water

On nylon 6 and nylon 6/EPDM blends the influence of water on the glass transition temperature, mechanical properties, and the ductile transition temperature was studied. Blends of 10% and 20% were prepared with a particle size of 0.3 µm and the tensile properties, flexural moduli, torsion moduli, and notched izod impact strength were studied as functions of water concentration. The ductile transition temperature in polyamides can be lowered by plasticizing the nylon and by a rubber particle-induced process; both processes show some synergistic effects

Software Reuse in Agile Development Organizations - A Conceptual Management Tool

The reuse of knowledge is considered a major factor for increasing productivity and quality. In the software industry knowledge is embodied in software assets such as code components, functional designs and test cases. This kind of knowledge reuse is also referred to as software reuse. Although the benefits can be substantial, software reuse has never reached its full potential. Organizations are not aware of the different levels of reuse or do not know how to address reuse issues. This paper proposes a conceptual management tool for supporting software reuse. Furthermore the paper presents the findings of the application of the management tool in an agile development organization

The distribution of ATP within tomato (Lycopersicon esculentum Mill.) embryos correlates with germination whee as total ATP concentration does not

The distribution of ATP in tomato seeds was visualized by monitoring the luminescence of frozen sections on top of a gel containing all the components of the luciferase reaction, but excluding ATP. ATP was imaged in germinating tomato seeds at intervals of 3, 6, 17, 24 and 48 h and in seeds with primary or secondary dormancy. ATP was present mainly in the embryo and concentrated in the radicle tip towards the completion of germination. In contrast to germinating seeds, ATP was distributed more evenly in dormant seeds. For germination, the ratio of ATP concentration in the radicle tip versus cotyledons was decisive, rather than the absolute concentration

Optimization of image-guided radiotherapy (IGRT) for lung cancer

Senan, S. [Promotor]Slotman, B.J. [Promotor]Sörnsen De Koste, J.R. van [Copromotor

Op soek na ’n duidelike reformatoriese paradigma vir kerklike gesag

In search of a clear reformed paradigm on ecclesiastical authorityThis article represents an effort to investigate the claim from different viewpoints that Jesus Christ is the real and sole authority in church polity. It is maintained in this article that different systems of church government replace in reality the ius divinum with a ius humanum. The church can only be governed by the authority of Jesus Christ in a ministry where the grounds for ecclesiastical decisions and directions are clearly pointed out from the Scriptures

Het die reformasie die leer gered en aanbidding verloor?

Little information is available on the relation between doctrine and liturgy during and after the Reformation. The concept “doctrine” relates to what is, since Emanuel Kant, labelled as theory and “liturgy” refers to practice as if these concepts were not related. This article investigates the validity of this perception. It asserts that this may be true in a tradition in the wake of Zwingli’s reformation, and concludes that liturgy must be subservient to what the congregation believes (doctrine) otherwise liturgy impedes on religious and sacramental belief and experience. Afrikaans Churches inherited doctrine and liturgy from the Reformed Churches in the Netherlands who followed the liturgical concepts of Zwingli. The latter rejected the concept that Christ is present in holy communion, and confined his liturgy to the Roman pedagogical pronaus (pre-mass). Zwingli’s liturgy (prayer, etc.) is dominated by a pedagogical sermon (good or bad) by a trained minister (dominus). He viewed the Lord’s Supper as an objective way of preaching the sacrifice and atonement on Calvary and not as a covenantal communion. He restricted this celebration to four times a year. By contrast, Roman and Eastern Orthodox Churches thrived because liturgy served their confessions of faith. Calvin followed the custom of the ancient churches, the structure of the Missa Romanun and absolute unity between Word and Sacrament. He was not allowed to realise his liturgical concepts (except singing Psalms) in Geneva. In the current struggle for “liturgical renewal” in reformed churches in South Africa the indissoluble relation between faith (doctrine) and experiencing and expressing faith (liturgy) should be restored and utilised in order to succeed and survive