Interpretation and Use of Penetrometer Data to describe Soil Compaction in Vineyards.

A portable recording penetrometer was used for in situ field measurements of soil strengths in existing experiments with known profile characteristics. The data reported include effects of soil preparation methods, tractor wheel compaction and soil moisture on soil strength, as well as a case study in a productioll'vineyard. The penetrometer proved to be a useful instrument in identifying and quantifying soil compaction problems and the effects of soil management systems in vineyards. The data revealed that serious subsoil compaction can exist which may result in very poor vine performance and even death of the vines

Beyond dogmatism: Rationality in theology and science

Beyond dogmatism: Rationality in theology and scienceThe justification of cognitive claims in theology can be dealt with adequately only if the epistemological issues of metaphorical reference, experiential adequacy and explanatory progress are seen as crucial problems for the more encompassing problem of rationality in theology. To claim some form of reality depiction the theologian will have to argue for a plausible theory of reference on the basis of interpreted religious experience. In this discussion important analogies between the rationality of theological theorizing and the rationality of science are revealed. Thusexplanatory progress in theology shows itself to be a form of inference to the best explanation, and the rationahty of both theology and science is therefore determined by certain epistemic values

A virtual element method for transversely isotropic elasticity

This work studies the approximation of plane problems concerning transversely isotropic elasticity, using a low-order virtual element method (VEM). The VEM is an alternative finite element method characterised by complete freedom in determining element geometries that are otherwise polygonal in two dimensions, or polyhedral in three. Transversely isotropic materials are characterised by an axis of symmetry perpendicular to a plane of isotropy, and have applications ranging from fibre reinforcement to biological materials. The governing equations of the transversely isotropic elasticity problem are derived and a virtual element formulation of the problem is presented along with a sample implementation of the method. This work focuses on the treatment of near-incompressibility and near-inextensibility. These are explored both for homogeneous problems, in which the plane of isotropy is fixed; and non-homogeneous problems, in which the fibre directions defining the plane of isotropy vary with position. In the latter case various options are explored for approximating the non-homogeneous terms at an element level. The VEM approximations are shown through a range of numerical examples to be robust and locking-free, for a selection of element geometries, and fibre directions corresponding to mild and strong inhomogeneity

In search of Hercules: Democracy, constitutionalism and the South African Constitutional Court

African Studies Seminar series. Paper presented 7 October 1996The Interim Constitution of South Africa which came into effect on 27 April 1994 established a new law-government relationship characterised by constitutionalism, a relationship which will be confirmed by the final Constitution. Constitutionalism subordinates the decisions and actions of a democratically elected legislature to the constitution and the body responsible for enforcing it (2) In South Africa, this body is the Constitutional Court (3). Constitutionalism is a fundamental element of liberal legal ideology, and a widely accepted model of liberal democracy, as it is argued that only in this way can certain rights which are fundamental to the successful operation of a democracy be protected from the transient will of the majority (4). However, in both the African and the South African contexts the merits of constitutionalism are not that readily accepted. Okoth-Ogendo documents the "emphatic rejection of the classical notion of constitutionalism" (5) by the majority of African states, and Nolutshungu points out that the idea of constitutionalism was not one "easily found in the discourse of the South African liberation movement" (6). And indeed when the eleven judges on the new South African Constitutional Court, in the first case before them, unanimously declared the death penalty unconstitutional (7), it provoked a public outcry and wide-spread condemnation of the decision as undemocratic and contrary to the will of the majority, accompanied by calls for a referendum on the issue (8). This illustrated that a large number of South Africans might not understand or like the system of constitutionalism, as they believe that democracy means that the majority gets what it wants. This tension between constitutionalism and popular democracy is noted by Dennis Davis when he asks : "can it not be argued that a body that has not been elected, and is not otherwise politically responsible to an electorate, is undermining democracy by telling a democratically elected body what it can and cannot do ?" (9). This paper will argue that there is indeed a tension between constitutionalism and the aims of popular democracy, and that the commitment to constitutionalism on the part of all the significant political parties in South Africa is a central feature of the elite-pacted nature of the transition to democracy. Du Plessis and Corder note the growing enthusiasm, in the late eighties, for human rights and constitutionalism in National Party (NP) and government circles, as a result of the realisation that this can be a very effective way of protecting vested interests during and after the transition (10). During the process of negotiations, the model of democracy proposed by the African National Congress (ANC) changed dramatically from an emphasis on a strong central state, popular democracy and a high degree of participation, to a commitment to decentralisation of power, liberal democracy and constitutionalism. It will also be argued, however, that constitutionalism is not inherently incompatible with popular democratic ideology, and that it can in fact be a way of broadening the base of popular participation in government as well as a way of entrenching government accountability, especially in the arena of human rights. This view of constitutionalism accommodates the popular democratic demand for a central role for civil society in the process of democratisation and the subsequent consolidation of democracy (11). The purpose of this paper is thus clearly not to condemn constitutionalism. On the contrary, it is based on an acceptance of the need for the protection of human rights and the development of a human rights culture in the context of the heterogeneous and historically strife-torn South African society. There is reason for concern, however, about the legitimacy of constitutionalism as a system of government in the eyes of the majority of South Africans, as illustrated by public reaction to the death penalty decision and other decisions that affect the criminal law (12), and it is therefore important to investigate the possibility of reconciling constitutionalism, as an institution of liberal democracy, and the aims of popular democracy in South Africa. A central assumption of this paper is that the solution to the tension between constitutionalism and popular democratic ideology in South Africa lies in the concept of human rights, particularly social and economic rights, as it can expand the base of civil society participation in government and entrench government accountability, but this will depend on the level of legal mobilisation (13) in civil society and, importantly, on the way in which the Constitution is interpreted...

A virtual element method for hyperelasticity

This thesis studies the approximation of plane problems of hyperelasticity, using a loworder virtual element method (VEM). The VEM is an extension of the finite element method (FEM). It is characterised by considerable freedom with regard to element geometry, permitting arbitrary polygonal and polyhedral elements in two and three dimensions respectively. Furthermore, the local basis functions are not known explicitly on elements and take the simple form of piecewise-linear Lagrangian functions on element boundaries. All integrations are performed on element edges. The VEM formulation typically involves a consistency term, computed via a projection, and a stabilization term, which must be approximated. Problems concerning isotropic and transversely isotropic hyperelastic material models are considered. Examples of transversely isotropic materials, which are characterised by an axis of symmetry normal to a plane of isotropy, range from simple fibre-reinforced materials to biological tissues. To date, in the context of hyperelasticity, investigation of the performance of VEM has primarily focused on problems involving the isotropic neo-Hookean material model. Furthermore, there has been limited investigation into the behaviour of the VEM in the nearly incompressible and nearly inextensible limits. In this thesis a VEM formulation with a novel approach to the construction of the stabilization term is formulated and implemented for problems involving isotropic and transversely isotropic hyperelastic materials. The governing equations of hyperelasticity are derived and various isotropic and transversely isotropic constitutive models are presented. This is followed by presentation of the virtual element formulation of the hyperelastic problem and a possible approach to its practical implementation. Through a range of numerical examples, the VEM with the proposed stabilization term is found to exhibit robust and accurate behaviour for a variety of mesh types, including those comprising highly non-convex element geometries, and for problems involving severe deformations. Furthermore, the versatility of the proposed VEM formulation is demonstrated through its application to a range of popular isotropic and transversely isotropic material models for a wide variety of material parameters. Through this investigation the VEM is found to exhibit locking-free behaviour in the limiting cases of near-incompressibility and near-inextensibility, both separately and combined

Other experiences of planning for reconstruction and transformation: A narrative of planning and development histories in Hammanskraal-Temba

Hammanskraal-Temba is one of the areas in South Africa that experiences a multitude of problems, ranging from an informal settlement lacking services, a struggling local economy, unemployment and housing shortages, to land claims and border disputes. However, a study of the historical development of the area and the impact of development initiatives such as planning policies and legislation on the area indicated the wide range of experiences and interpretations of the role of planners and planning. In an attempt to highlight these interpretations and the various [hi]stories, an alternative approach towards local historic analysis is used and is illustrated by some extracts from the Hammanskraal-Temba case study. The article aims in particular to illustrate some other experiences of planning for reconstruction and transformation and their implications for planning and planners. The article is based on a paper delivered at the Planning History Study Group: Millennium Conference in May 2000, at the Howard College at the University of Natal in Durban. The conference focused on the role of planning and planners in reconstruction

Evolution, knowledge and Christian faith: Gerd Theissen and the credibility of theology

Evolution, knowledge and Christian faith: Gerd Theissen and the credibility of theologyIn this article the way in which Theissen uses the evolutionary paradigm as a comprehensive framework for interpreting not only central themes in theology but also the credibility of theology as such, is analysed from an epistemological point of view. Theissen's overall choice for critical rationalism is critized as an epistemological blurring of paradigms, and thus of models of rationality, and typified as a quest for realism and explanatory progress in theology instead. In interpreting the evolutionary paradigm for theology, Theissen does, however, open up exciting possibilities for retaining the scientific and cognitive status of theological statements

Narrative theology: An adequate paradigm for theological reflection?

As reflection on the religious claims embedded in stories, narrative theology touches the nerve of theology: what is the epistemological status of theological theories if they are based on discourse which is fundamentally narrative and metaphorical? This paper analyzes this question, along with the important differences between ‘pure’ and ‘impure’ narrative theology. Crucial problems arise from this and are discussed: the epistemological problem of determining criteria for assessing the truth claims of theological statements; and the hermeneutical criteria for distinguishing between good and bad receptions of Christianity’s classic text

Rasionaliteit en kreatiwiteit — ont-werp vir ’n kritiese, konstruktiewe teologie

“ ’n Nuwe tydsgewrig mag nuwe sienings van God, mens en wêreld bring, ’n nuwe tydsgees openbaar en die mens voor nuwe sake stel en gevolglik ’n nuwe wetenskapsidee eis. Verandering van tye impliseer dan ook verandering van wetenskapsidee.