Mineral nutrition of fruit trees

xvi, 435 hlm.: ill.; 24 cm

A simple method for assessing fuel moisture content and fire danger rating

The flammability of wildland vegetation is strongly dependent upon the moisture content of fine dead fuels. Consequently, assessing the moisture content of these fuels to within a reasonable degree of accuracy is an important part of wildland fire management. Estimates of fine fuel moisture content can also be combined with information on wind speed, vegetation type and drought effects to provide a measure of fire potential or fire danger rating. For example, the moisture content of eucalypt litter is an important consideration in determining fire danger rating in the forests of southeastern Australia. This paper describes a simple and intuitive linear index, which provides an equivalent measure of the moisture content of eucalypt litter. Despite its simplicity, the so-called fuel moisture index, defined as FMI = 10-0.25(T-H), where T is temperature and H is relative humidity, is shown to be remarkably effective at reproducing the results of a more sophisticated model for the moisture content of eucalypt litter. In previous work the fuel moisture index was combined with information on wind speed U to provide a simple fire danger index F. Under the restrictive assumption of constant fuel availability, F was shown to compare favourably with other measures of fire danger rating that feature in the literature. In this paper we extend the definition of F to incorporate the effects of variable fuel availability. This is done very simply by multiplying F by the drought factor to obtain the index FD. The drought factor, which is determined through knowledge of antecedent rainfall, is used to describe fuel availability in forest fuel types. The utility of the index FD is tested by comparing its value with the McArthur Mark 5 Forest Fire Danger Index (FFDI) using data from two automatic weather stations. Moreover, by converting grass curing, which is used to describe fuel availability in grassland fuels, to an equivalent drought factor the index FD is also compared with the McArthur Mark 4 Grassland Fire Danger Index (GFDI). The comparisons indicate that FD provides a plausible measure of fire danger rating for forest fuels and grassland fuels in particular. The structure of the two McArthur indices with respect to the fuel moisture index is also investigated. It is shown that when viewed in terms of the (FMI, U) phase plane, the McArthur indices have a very simple geometric characterisation: constant FFDI corresponds to straight lines and constant GFDI corresponds to cubic curves in the (FMI, U) plane. This confirms that FMI is a unifying variable which permits a simpler conceptualisation of fire danger rating, at least as it is treated in the McArthur schemes. Hence, characterising fire danger rating in terms of FMI could have a pedagogical advantage over other methods and could provide fire management personnel with a simpler and more intuitive method for assessing fire potential

A simple index for assessing fire danger rating

Fire danger rating systems are used to assess the potential for bushfire occurrence, fire spread and difficulty of fire suppression. Typically, fire danger rating systems combine meteorological information with estimates of the moisture content of the fuel to produce a fire danger index. Fire danger indices are used to declare fire bans and to schedule prescribed burns, among other applications. In this paper a simple fire danger index F that is intuitive and easy to calculate is introduced and compared to a number of fire danger indices pertaining to different fuel types that are used in an operational setting in Australia and the United States. The comparisons suggest that F provides a plausible measure of fire danger rating and that it may be a useful pedagogical tool in the context of fire danger and fire weather

A simple index for assessing fuel moisture content

Assessing fuel moisture content to within a reasonable degree of accuracy is an important part of wildland fire management. In this paper we introduce a fuel moisture index that provides a simple and intuitive method for assessing fuel moisture content. The method can be quickly and easily applied in a field setting to provide a dimensionless measure of fuel moisture content. We compare the index with predictions from several models for fuel moisture content and conclude that it provides an equivalent measure of fuel moisture content for a number of fuel types. We go on to briefly discuss how the index could be used to construct a simple and intuitive fire danger index

Overview of new MAST physics in anticipation of first results from MAST Upgrade

The mega amp spherical tokamak (MAST) was a low aspect ratio device (R/a  =  0.85/0.65 ~ 1.3) with similar poloidal cross-section to other medium-size tokamaks. The physics programme concentrates on addressing key physics issues for the operation of ITER, design of DEMO and future spherical tokamaks by utilising high resolution diagnostic measurements closely coupled with theory and modelling to significantly advance our understanding. An empirical scaling of the energy confinement time that favours higher power, lower collisionality devices is consistent with gyrokinetic modelling of electron scale turbulence. Measurements of ion scale turbulence with beam emission spectroscopy and gyrokinetic modelling in up-down symmetric plasmas find that the symmetry of the turbulence is broken by flow shear. Near the non-linear stability threshold, flow shear tilts the density fluctuation correlation function and skews the fluctuation amplitude distribution. Results from fast particle physics studies include the observation that sawteeth are found to redistribute passing and trapped fast particles injected from neutral beam injectors in equal measure, suggesting that resonances between the m  =  1 perturbation and the fast ion orbits may be playing a dominant role in the fast ion transport. Measured D–D fusion products from a neutron camera and a charged fusion product detector are 40% lower than predictions from TRANSP/NUBEAM, highlighting possible deficiencies in the guiding centre approximation. Modelling of fast ion losses in the presence of resonant magnetic perturbations (RMPs) can reproduce trends observed in experiments when the plasma response and charge-exchange losses are accounted for. Measurements with a neutral particle analyser during merging-compression start-up indicate the acceleration of ions and electrons. Transport at the plasma edge has been improved through reciprocating probe measurements that have characterised a geodesic acoustic mode at the edge of an ohmic L-mode plasma and particle-in-cell modelling has improved the interpretation of plasma potential estimates from ball-pen probes. The application of RMPs leads to a reduction in particle confinement in L-mode and H-mode and an increase in the core ionization source. The ejection of secondary filaments following type-I ELMs correlates with interactions with surfaces near the X-point. Simulations of the interaction between pairs of filaments in the scrape-off layer suggest this results in modest changes to their velocity, and in most cases can be treated as moving independently. A stochastic model of scrape-off layer profile formation based on the superposition of non-interacting filaments is in good agreement with measured time-average profiles. Transport in the divertor has been improved through fast camera imaging, indicating the presence of a quiescent region devoid of filament near the X-point, extending from the separatrix to ψ n ~ 1.02. Simulations of turbulent transport in the divertor show that the angle between the divertor leg on the curvature vector strongly influences transport into the private flux region via the interchange mechanism. Coherence imaging measurements show counter-streaming flows of impurities due to gas puffing increasing the pressure on field lines where the gas is ionised. MAST Upgrade is based on the original MAST device, with substantially improved capabilities to operate with a Super-X divertor to test extended divertor leg concepts. SOLPS-ITER modelling predicts the detachment threshold will be reduced by more than a factor of 2, in terms of upstream density, in the Super-X compared with a conventional configuration and that the radiation front movement is passively stabilised before it reaches the X-point. 1D fluid modelling reveals the key role of momentum and power loss mechanisms in governing detachment onset and evolution. Analytic modelling indicates that long legs placed at large major radius, or equivalently low at the target compared with the X-point are more amenable to external control. With MAST Upgrade experiments expected in 2019, a thorough characterisation of the sources of the intrinsic error field has been carried out and a mitigation strategy developed