Modification and improvements to cooled blades Patent

Modification and improvement of turbine blades for maximum cooling efficienc

Modelling the wheat sector in South Africa

In this study, the structure of the South African wheat market is analysed using economic theory and econometric modelling techniques. The model is used to make baseline projections regarding the supply and use of wheat in South Africa and to analyse the impacts of various policy alternatives on the wheat sector for the period 2004–2008. Results indicate that the area harvested in the summer as well as winter region will decrease over time. Domestic consumption will marginally increase over time, which will result in higher levels of imports. The ability of the model to simulate policy shocks is illustrated by means of simulating the impact of the elimination of the wheat import tariff on the wheat sector.Industrial Organization,

Integrability of the critical point of the Kagom\'e three-state Potts mode

The vicinity of the critical point of the three-state Potts model on a Kagom\'e lattice is studied by mean of Random Matrix Theory. Strong evidence that the critical point is integrable is given.Comment: 1 LaTex file + 3 eps files 7 page

Heavy Meson Production in NN Collisions with Polarized Beam and Target -- A new facility for COSY

The study of near--threshold meson production in pp and pd collisions involving polarized beams and polarized targets offers the rare opportunity to gain insight into short--range features of the nucleon--nucleon interaction. The Cooler Synchrotron COSY at FZ--J\"ulich is a unique environment to perform such studies. Measurements of polarization observables require a cylindrically symmetrical detector, capable to measure the momenta and the directions of outgoing charged hadrons. The wide energy range of COSY leads to momenta of outgoing protons to be detected in a single meson production reaction between 300 and 2500 MeV/c. Scattering angles of protons to be covered extend to about $45^{\circ}$ in the laboratory system. An azimuthal angular coverage of the device around 98% seems technically achievable. The required magnetic spectrometer could consist of a superconducting toroid, providing fields around 3 T.Comment: 6 pages, 1 figure, submitted to Czechoslovak Journal of Physic

The valvula cerebelli of the spiny eel, Macrognathus aculeatus, receives primary lateral-line afferents from the rostrum of the upper jaw

In the spiny eel, Macrognathus aculeatus, anterodorsal and (to a lesser degree) anteroventral lateralline nerves project massively to the granular layer of the valvula cerebelli, throughout its rostrocaudal extent. The posterior lateral-line nerve terminates in the corpus cerebelli. Thus, valvula and corpus cerebelli are supplied with mechanosensory input of different peripheral origins. An analysis of the taxonomic distribution of experimentally determined primary lateral-line input to the three parts of the teleostean cerebellum reveals that the eminentia granularis always receives such input, and that the corpus cerebelli is the recipient of primary lateral-line input in many teleosts. The valvula, however, receives primary lateral-line afferents in only two examined species. In M. aculeatus, the massive lateral-line input to the valvula probably originates in mechanoreceptors located in the elongated rostrum of the upper jaw, a characteristic feature of mastacembeloid fishes. This projection to the valvula may therefore represent a unique specialization that arose with the evolution of the peculiar rostrum

Spectral Models of Convection-Dominated Accretion Flows

For small values of the dimensionless viscosity parameter, namely $\alpha\lesssim 0.1$, the dynamics of non-radiating accretion flows is dominated by convection; convection strongly suppresses the accretion of matter onto the central object and transports a luminosity $\sim 10^{-3}-10^{-2} \dot M c^2$ from small to large radii in the flow. A fraction of this convective luminosity is likely to be radiated at large radii via thermal bremsstrahlung emission. We show that this leads to a correlation between the frequency of maximal bremsstrahlung emission and the luminosity of the source, $\nu_{\rm peak} \propto L^{2/3}$. Accreting black holes with X-ray luminosities $10^{-4} L_{Edd}\gtrsim L_X(0.5-10{\rm keV}) \gtrsim 10^{-7}L_{Edd}$ are expected to have hard X-ray spectra, with photon indices $\Gamma\sim2$, and sources with $L_X\lesssim 10^{-9}L_{Edd}$ are expected to have soft spectra, with $\Gamma\sim3.5$. This is testable with {\it Chandra} and {\it XMM}.Comment: final version accepted by ApJ; significant modifications from previous versio

Order-by-disorder in classical oscillator systems

We consider classical nonlinear oscillators on hexagonal lattices. When the coupling between the elements is repulsive, we observe coexisting states, each one with its own basin of attraction. These states differ by their degree of synchronization and by patterns of phase-locked motion. When disorder is introduced into the system by additive or multiplicative Gaussian noise, we observe a non-monotonic dependence of the degree of order in the system as a function of the noise intensity: intervals of noise intensity with low synchronization between the oscillators alternate with intervals where more oscillators are synchronized. In the latter case, noise induces a higher degree of order in the sense of a larger number of nearly coinciding phases. This order-by-disorder effect is reminiscent to the analogous phenomenon known from spin systems. Surprisingly, this non-monotonic evolution of the degree of order is found not only for a single interval of intermediate noise strength, but repeatedly as a function of increasing noise intensity. We observe noise-driven migration of oscillator phases in a rough potential landscape.Comment: 12 pages, 13 figures; comments are welcom

Facilitating decision-making in agriculture by using a system of models

This article presents a deterministic farm-level model developed to link to an existing partial equilibrium sector-level model of the grain and livestock sectors of South Africa. The objective is to create a linked system of models consisting of a sector- and farm-level model with the capability to analyse the likely effects of changes in policies and markets at both the sector and representative farm level in South Africa. A representative farm in the Free State Province is used to validate the farm-level model. The farm-level model is used to simulate a baseline as well as two scenarios of the representative farm for the period 2003 to 2010. Results indicate that the farm-level model simulates the representative farm rather accurately compared to historical data. The baseline and scenario results indicate that the linked system of models can be useful for policy and business decision-makers to analyse the impact of change in policies and markets at both the sector- and farm level.Farm Management,

Modelling the impact of the ‘Fast Track’ land reform policy on Zimbabwe’s maize sector

This paper attempts to analyze the impacts of the ‘fast track’ land reform policy on maize production in Zimbabwe through the construction of a partial equilibrium model that depicts what could have happened if no further policy shifts had taken place after 2000. The resimulated baseline model was used to make projections based on the various trends of exogenous variables in 2000. This means that the model generated an artificial data set based on what the maize market would have looked like under a set of the pre-2000 existent policy conditions. The ‘fast track’ land reform policy was thus assessed based on the performance of the baseline model using a range of “what if” assumptions. Commercial area harvested was 39 % less than what could have been harvested in 2001, and declining by negative 80.57 % in 2007. Results showed total maize production was 61.85 % and 43.88 % less than what could have been produced in the 2002 and 2005 droughts, respectively. This may imply that droughts would have been less severe if the ‘fast track’ land reform was not implemented. Therefore, the ‘fast track’ land reform had a negative effect on maize production. Thus, the econometric model system developed provided a basis through which the effects of the FTLRP on the maize market may be analyzed and understood.‘fast track’ land reform programme, partial equilibrium model, maize, Zimbabwe, Crop Production/Industries, Land Economics/Use,