Effects of intensity and frequency of defoliation on a mixture of guinea grass (Panicum maximum cv. Coloniao) and Verano stylo (Stylosanthes hamata cv. Verano) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Plant Science at Massey University

A study was conducted in a glasshouse to determine the effect of defoliation treatments comprising combinations of two intensities (7.5 cm and 15.0 cm cutting height) and three frequencies (2, 3 and 6 weeks) on production, botanical composition and crude protein of a Guinea grass (Panicum maximum cv. Coloniao) / Verano stylo (Stylosanthes hamata cv. Verano) sward. Total cumulative yield was reduced with more intense defoliation and decreased as the sward was defoliated more frequently. A similar response was observed for cumulative grass yield. In legume, cumulative yield was reduced at hard intensity but was not influenced by defoliation frequency. The proportion of the legume component in the sward was not influenced by defoliation intensity but increased with increasing defoliation frequency due more to depressed grass growth rather than a promotion in legume growth. Defoliation intensity and defoliation frequency had no effect on legume branch number. Similarly, branch size was not influenced by defoliation frequency but increased with less intense defoliation. Both defoliation intensity and defoliation frequency influenced grass tiller number. It was increased with more intense defoliation. The sward defoliated at moderate frequency resulted in the highest tiller number. Tiller number was not different between very frequent and infrequent defoliation. Intensity and frequency of defoliation also influenced average tiller size. It was reduced with more intense defoliation and decreased with increasing defoliation frequency. Percent crude protein content of both grass and legume was not influenced by defoliation intensity but was reduced with less frequent defoliation. The percent crude protein content in the legume which was more than double that in the grass indicates that Verano stylo has important contributions in the development and management of a legume-based tropical pasture

A covariantisation of M5-brane action in dual formulation

We construct a manifestly diffeomorphic M5-brane action in dual formulation coupled to an eleven-dimensional supergravity target space. The covariantisation is carried out by using (generalised) PST technique with 5 auxiliary scalar fields, which are obtained by using a geometrical consideration as a reduction of an auxiliary 4-form of Maznytsia-Preitschopf-Sorokin. As is typical in PST-covariantised theory, our construction possesses as usual the two local PST symmetries. By using one of the local PST symmetries, the action can be reduced to the non-manifestly covariant M5-brane action in dual formulation constructed earlier by the authors. The discussion on double dimensional reduction to D4-brane, and on the comparison of on-shell action then easily follows.Comment: 26 page

The M5-brane action revisited

We construct an alternative form of the M5-brane action in which the six-dimensional worldvolume is subject to a covariant split into 3+3 directions by a triplet of auxiliary fields. We consider the relation of this action to the original form of the M5-brane action and to a Nambu-Poisson 5-brane action based on the Bagger-Lambert-Gustavsson model with the gauge symmetry of volume preserving diffeomorphismsComment: 26 pages, v2: minor corrections, references added and update

Signals of a new phase in N=2 gauge theory with a magnetic field on the three-sphere

We study the effect of a magnetic field on N=2 super-Yang-Mills on S^3 at strong coupling using the gauge/gravity correspondence. As in previous work that dealt with the theory in infinite volume, we find that increasing the magnetic field pushes the system into the confined phase. However, we in addition also find that, within the class of configurations with the same symmetry as those which describe the ground state at vanishing magnetic field, a mass gap appears in the spectrum. This suggests the existence of a new phase with so far unexplored symmetry structure. We provide suggestions for the physical properties of this phase.Comment: 28 page

Particle swarm optimisation with applications in power system generation

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 12/06/2007.Today the modern power system is more dynamic and its operation is a subject to a number of constraints that are reflected in various management and planning tools used by system operators. In the case of hourly generation planning, Economic Dispatch (ED) allocates the outputs of all committed generating units, which are previously identified by the solution of the Unit Commitment (UC) problem. Thus, the accurate solutions of the ED and UC problems are essential in order to operate the power system in an economic and efficient manner. A number of computation techniques have progressively been proposed to solve these critical issues. One of them is a Particle Swarm Optimisation (PSO), which belongs to the evolutionary computation techniques, and it has attracted a great attention of the research community since it has been found to be extremely effective in solving a wide range of engineering problems. The attractive characteristics of PSO include: ease of implementation, fast convergence compared with the traditional evolutionary computation techniques and stable convergence characteristic. Although the PSO algorithms can converge very quickly towards the optimal solutions for many optimisation problems, it has been observed that in problems with a large number of suboptimal areas (i.e. multi-modal problems), PSO could get trapped in those local minima, including ED and UC problems. Aiming at enhancing the diversity of the traditional PSO algorithms, this thesis proposes a method of combining the PSO algorithms with a real-valued natural mutation (RVM) operator to enhance the global search capability and investigate the performance of the proposed algorithm compared with the standard PSO algorithms and other algorithms. Prior to applying to ED and UC problems, the proposed method is tested with some selected mathematical functions where the results show that it can avoid being trapped in local minima. The proposed methodology is then applied to ED and UC problems, and the obtained results show that it can provide solutions with good accuracy and stable convergence characteristic with simple implementation and satisfactory calculation time. Furthermore, the sensitivity analysis of PSO parameters has been studied so as to investigate the response of the proposed method to the parameter variations, especially in both ED and UC problems. The outcome of this research shows that the proposed method succeeds in dealing with the PSO' s drawbacks and also shows the superiority over the traditional PSO algorithms and other methods in terms of high quality solutions, stable convergence characteristic, and robustness.Royal Thai Government; King Mongkut's Institute of Technology North Bangko