Fuel manipulation with herbicide treatments to reduce fire hazard in young pine (Pinus elliottii × P. caribaea) plantations in south-east Queensland, Australia

Wildfire represents a major risk to pine plantations. This risk is particularly great for young plantations (generally less than 10 m in height) where prescribed fire cannot be used to manipulate fuel biomass, and where flammable grasses are abundant in the understorey. We report results from a replicated field experiment designed to determine the effects of two rates of glyphosate (450 g L–1) application, two extents of application (inter-row only and inter-row and row) with applications being applied once or twice, on understorey fine fuel biomass, fuel structure and composition in south-east Queensland, Australia. Two herbicide applications (~9 months apart) were more effective than a once-off treatment for reducing standing biomass, grass continuity, grass height, percentage grass dry weight and the density of shrubs. In addition, the 6-L ha–1 rate of application was more effective than the 3-L ha–1 rate of application in periodically reducing grass continuity and shrub density in the inter-rows and in reducing standing biomass in the tree rows, and application in the inter-rows and rows significantly reduced shrub density relative to the inter-row-only application. Herbicide treatment in the inter-rows and rows is likely to be useful for managing fuels before prescribed fire in young pine plantations because such treatment minimised tree scorch height during prescribed burns. Further, herbicide treatments had no adverse effects on plantation trees, and in some cases tree growth was enhanced by treatments. However, the effectiveness of herbicide treatments in reducing the risk of tree damage or mortality under wildfire conditions remains untested.

Biomass for aviation fuel production in the Fitzroy Basin, Queensland: a preliminary assessment of native and plantation forest potential

SummaryThis scoping study assesses the contribution that woody biomass could make to feedstock supply for an aviation biofuel industry in Queensland. The inland 600?900 mm rainfall zone, including the Fitzroy Basin region, is identified as an area that is particularly worthy of closer study as it has potential for supply of woody biomass from existing native regrowth (brigalow and other species) as well as from new plantings. New analyses carried out for this study of Corymbia citriodora subsp. variegata trials suggest biomass plantings could produce harvestable yield of aboveground dry mass of about 85 t ha?1 over a 10-year rotation at relatively low-rainfall (600?750 mm mean annual precipitation) sites and about 115 t ha?1 at medium-rainfall (750?900 mm) sites. Estimates of productivity for native regrowth suggest potential productivity should be around 40 t ha?1 during the initial decade after clearing when systems are managed for bioenergy rather than grazing. In this paper, potential production systems are described, and sustainability issues are briefly considered. It is concluded that more detailed studies focused particularly on biomass production would be worthwhile, and further research requirements are briefly discussed.

Ignition delay studies on hydrocarbon fuel with and without additives

Single pulse shock tube facility has been developed in the High Temperature Chemical Kinetics Lab, Aerospace Engineering Department, to carry out ignition delay studies and spectroscopic investigations of hydrocarbon fuels. Our main emphasis is on measuring ignition delay through pressure rise and by monitoring CH emission for various jet fuels and finding suitable additives for reducing the delay. Initially the shock tube was tested and calibrated by measuring the ignition delay of C2H6-O2 mixture. The results are in good agreement with earlier published works. Ignition times of exo-tetrahdyrodicyclopentadiene (C10H16), which is a leading candidate fuel for scramjet propulsion has been studied in the reflected shock region in the temperature range 1250 - 1750 K with and without adding Triethylamine (TEA). Addition of TEA results in substantial reduction of ignition delay of C10H16.

A new approach to thermochemical calculations of condensed fuel-oxidizer mixtures

A simple method of calculating the elemental stoichiometric coefficient, φe has been developed, which can easily be applied to multicomponent fuel-oxidizer compositions. The method correctly predicts whether a mixture is fuel lean, fuel rich, or stoichiometrically balanced. The total composition of oxidizing (or reducing) elements of the mixture appears to be related to the thermochemistry of the system. For the reaction of ammonium perchlorate and an organic fuel the heat of reaction varies linearly with the total composition of oxidizing elements. The physical significance of such a correlation based on thermochemical reasoning is highlighted in the paper.

On trade-off solution pairs in a special type of transportation problem

Abstract is not available.

Storage stability of solid rocket fuel. 1. Effect of temperature

Ageing behaviour of polystyrene (PS)/ammonium perchlorate (AP) propellent leading to ballistic changes has been studied. It follows a zero-order kinetic law. Ageing behaviour leading to change in burning rate ( ) in the temperature range of 60–200 ° C was found to remain the same. The dependence of the change of the average thermal decomposition (TD) rate at 230 and 260°C on the change in burning rate for the propellant aged at 100 ° C in air suggests that the slow TD of the propellant is the cause of ageing. The safe-life (for a pre-assigned burning-rate change limit) at 25 ° C in air has been calculated as a function of the rate of change.

Altruism, Trade Policy, and the Optimality of Foreign Aid

There are many studies in the literature that deal with the welfare effects of income transfers between nations in a general equilibrium setting. An important impetus for this extensive literature was the demonstration of the transfer paradox; that the donor country could actually gain from a transfer of income to another, and that the recipient could lose as a result of the gift. The reason for this paradoxical result is that the transfer gives rise to a terms-of-trade effect that may be especially beneficial to the donor and detrimental to the recipient. Subsequently, many papers have established conditions under which this paradox will or will not occur. Early work by Samuelson (1954) was followed by demonstrations of paradoxes by Gale (1974), Ohyama (1974), Brecher and Bhagwati (1982) and Bhagwati, Brecher and Hatta 1983, 1985, and Dixit (1983)) among others.1 More recently, many studies have examined whether or not foreign aid — tied and untied — can be welfare improving for both the donor and the recipient (see, for example, Turunen-Red and Woodland (1988), Kemp and Wong (1993), Schweinberger (1990), Hatzipanayotou and Michael (1995), Lahiri and Raimondos-Moller 1995, 1997, Djajić, Lahiri and Raimondos-Møller 1996a, 1996b, and Lahiri, Raimondos-Møller, Wong and Woodland 1997.2

Competition for aid and trade policy

This paper considers the optimal allocation of a given amount of foreign aid between two recipient countries. It is shown that, given consumer preferences, a country following a more restrictive trade policy would receive a smaller share of the aid if the donor country maximises its own welfare in allocating aid. If, on the other hand, the donor country allocates aid in order to maximize the sum of the welfare of the two recipient countries, the result is just the opposite. Finally, we analyze the situation where the recipient countries compete with each other for the given amount of aid. It is shown that this competition tends to lower the level of optimal tariffs in the recipient countries.

Correcting trade distortions in a small open economy

This paper considers the second-best strategy of correcting a wide variety of trade distortions in a small open economy with perfect competition in all markets. Using the tools of duality, we obtain some general properties of the structure and the levels of the optimal taxlsubsidy rates. The paper also analyzes the welfare effects of unilateral piecemeal trade policy reforms when some of the quota distortions—imposed by the foreign countries—are unalterable. It is shown that the merits of unilateral trade policy reforms that are emphasized in the literature crucially depend on the absence of unalterable foreign imposed quotas.