The comparative advantage of dryland soybean production in Brits, North West

The effect of policy on the South African soybean industry is analysed, using the policy analysis matrix. The absence of effective protection from cheap imports of soy-cake and -oil, as well as the ineffectiveness of the processing industry, lead to relatively low farmgate prices of soybeans in South Africa. This could result in producers using their resources for more profitable crops, thus depriving the South African feed industry to benefit from more full fat soy in feed rations.Crop Production/Industries,

Numerical simulations of rotating Rayleigh-Bénard convection

The Rayleigh-Bénard (RB) system is relevant to astro- and geophysical phenomena, including convection in the ocean, the Earth’s outer core, and the outer layer of the Sun. The dimensionless heat transfer (the Nusselt number Nu) in the system depends on the Rayleigh number Ra=ßg¿L 3/(¿¿) and the Prandtl number Pr=¿/¿. Here, ß is the thermal expansion coefficient, g the gravitational acceleration, ¿ the temperature difference between the bottom and top, and ¿ and ¿ the kinematic viscosity and the thermal diffusivity, respectively. The rotation rate H is used in the form of the Rossby number Ro=(ßg¿/L)/(2H). The key question is: How does the heat transfer depend on rotation and the other two control parameters: Nu(Ra, Pr, Ro)? Here we will answer this question by giving a summary of our result

Phe161 and Arg166 variants of p-hydroxybenzoate hydroxylase Implications for NADPH recognition and structural stability

AbstractPhe161 and Arg166 of p-hydroxybenzoate hydroxylase from Pseudomonas fluorescens belong to a newly discovered sequence motif in flavoprotein hydroxylases with a putative dual function in FAD and NADPH binding [1]. To study their role in more detail, Phe161 and Arg166 were selectively changed by site-directed mutagenesis. F161A and F161G are catalytically competent enzymes having a rather poor affinity for NADPH. The catalytic properties of R166K are similar to those of the native enzyme. R166S and R166E show impaired NADPH binding and R166E has lost the ability to bind FAD. The crystal structure of substrate complexed F161A at 2.2 Å is indistinguishable from the native enzyme, except for small changes at the site of mutation. The crystal structure of substrate complexed R166S at 2.0 Å revealed that Arg166 is important for providing an intimate contact between the FAD binding domain and a long excursion of the substrate binding domain. It is proposed that this interaction is essential for structural stability and for the recognition of the pyrophosphate moiety of NADPH

Determination of ADSL capacity in a generic exchange environment

Please read the abstract in the front matter this documentDissertation (M Eng (Electronic Engineering))--University of Pretoria, 2006.Electrical, Electronic and Computer Engineeringunrestricte

Efficient point-based simulation of four-way coupled particles in turbulence at high number density

In many natural and industrial applications, turbulent flows encompass some form of dispersed particles. Although this type of multiphase turbulent flow is omnipresent, its numerical modeling has proven to be a remarkably challenging problem. Models that fully resolve the particle phase are computationally very expensive, strongly limiting the number of particles that can be considered in practice. This warrants the need for efficient reduced order modeling of the complex system of particles in turbulence that can handle high number densities of particles. Here, we present an efficient method for point-based simulation of particles in turbulence that are four-way coupled. In contrast with traditional one-way coupled simulations, where only the effect of the fluid phase on the particle phase is modeled, this method additionally captures the back-reaction of the particle phase on the fluid phase, as well as the interactions between particles themselves. We focus on the most challenging case of very light particles or bubbles, which show strong clustering in the high-vorticity regions of the fluid. This strong clustering poses numerical difficulties which are systematically treated in our work. Our method is valid in the limit of small particles with respect to the Kolmogorov scales of the flow and is able to handle very large number densities of particles. This methods paves the way for comprehensive studies of the collective effect of small particles in fluid turbulence for a multitude of applications

Design of a Gigabit DSL modem using super orthogonal complete complementary codes

This paper describes the preliminary design and simulation towards a gigabit digital subscriber line modem that provides multi-user interference-free communication in a far-end crosstalk dominated environment by incorporating super orthogonal complete complementary spreading into the existing xDSL modem architecture. This is in contrast to existing vectoring and dynamic spectral management techniques that use joint processing and pre-processing of each user's signal to mitigate far-end crosstalk. A novel code allocation algorithm is introduced to provide all users with equal data rate ratios, even with bad line profiles and high-required data rates. Preliminary simulation results show that 1 Gbps aggregate throughput can be obtained for the system over a single pair of 0.5 mm copper wire over a distance from 180 to 150 m, depending on whether ADSL2+ or VDSL2 Profile 30a service bands are avoided, if present.The National Research Foundation of South Africa (Grant reference TP1207183332), Telkom and Bytes Universal Systems.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2161-39152017-11-30Electrical, Electronic and Computer Engineerin