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| Registros recuperados: 66 | |
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| Doole, Graeme J.; Pannell, David J.. |
| Simulation models are valuable tools in the analysis of complex, highly constrained economic systems unsuitable for solution by mathematical programming. However, model size may hamper the efforts of practitioners to efficiently identify the most valuable configurations. This paper investigates the efficacy of a new metaheuristic procedure, compressed annealing, for the solution of large, constrained systems. This algorithm is used to investigate the value of incorporating a sown annual pasture, French serradella (Ornithopus sativa Brot. cv. Cadiz), between extended cropping sequences in the central wheat belt of Western Australia. Compressed annealing is shown to be a reliable means of considering constraints in complex optimisation problems in... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Combinatorial optimisation; Crop rotation; Simulated annealing; Research Methods/ Statistical Methods; C63; Q15. |
| Ano: 2007 |
URL: http://purl.umn.edu/10438 |
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| Bennett, Anne L.; Pannell, David J.. |
| Spatial distribution of weeds in a crop is patchy. Traditional boom sprayers waste herbicide by applying it to areas where weed density is already low. A new technology, Weed Activated Spray Process (WASP), uses sensors to detect the presence of weeds and control spray nozzles accordingly. The economic benefits of this technology to extensive crop farmers in Western Australia are investigated using a model based on the economics of information. Existing technology is likely to reduce profits because the weed density at which it switches off spraying is too high. Even if sensitivity to low densities could be improved, likely benefits of pre‐crop usage would still be very low or negative. |
| Tipo: Journal Article |
Palavras-chave: Crop Production/Industries. |
| Ano: 1998 |
URL: http://purl.umn.edu/117284 |
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| Pannell, David J.. |
| A biologically realistic model of crop yield response to herbicide application is presented. It includes functions for weed mortality from herbicide application and yield loss due to surviving weeds. The optimal herbicide rate and two types of decision thresholds are derived theoretically and illustrated with empirical examples. Responses of the various decision criteria to changes in parameters are also examined theoretically and empirically. A multidimensional threshold for weeds based on weed density and weed-free yield is presented. The issue of farmers using other than officially recommended herbicide rates is discussed. |
| Tipo: Journal Article |
Palavras-chave: Risk and Uncertainty. |
| Ano: 1990 |
URL: http://purl.umn.edu/22352 |
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| Pannell, David J.; Kingwell, Ross S.; Schilizzi, Steven. |
| Bugs are an unavoidable aspect of mathematical programming (MP) modelling. In this paper we discuss the prevention and diagnosis of bugs in MP models. The topic is rarely addressed in the literature but is crucial to the success of modelling projects, especially for large models. We argue that finding a bug and understanding unexpected results (whether or not due to a bug) are very closely related activities. We identify different types of bugs and suggest practical strategies for dealing with each. Adopting procedures for prevention of bugs is essential, especially for large models. We outline the prevention strategies we have adopted and found successful for the MIDAS and MUDAS models. |
| Tipo: Journal Article |
Palavras-chave: Research Methods/ Statistical Methods. |
| Ano: 1996 |
URL: http://purl.umn.edu/12306 |
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| Llewellyn, Rick S.; Lindner, Robert K.; Pannell, David J.; Powles, Stephen B.. |
| Perceptions are known to play an important role in the innovation adoption decision. Once influential perceptions have been identified, there is the potential for information to influence adoption by changing these perceptions. In this paper, the influence of an extension workshop targeting grain growers’ perceptions known to be associated with the adoption of integrated weed management and herbicide resistance management has been measured using regression analysis. Consistent with a Bayesian learning framework, the greatest influence on grower perceptions and intended adoption behaviour was observed where information could be delivered with a high degree of certainty and validity. |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Crop Production/Industries; Farm Management. |
| Ano: 2003 |
URL: http://purl.umn.edu/57911 |
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| Marsh, Sally P.; Curatolo, April; Pannell, David J.; Park, Geoff; Roberts, Anna M.. |
| Investment in natural resource management (NRM) by regional organisations in Australia has been widely criticised for failing to achieve substantial environmental outcomes. The Investment Framework for Environmental Resources (INFFER) is a tool for developing and prioritising projects to address environmental issues such as water quality and biodiversity decline, environmental pest impacts and land degradation. It aims to achieve the most valuable environmental outcomes with the available resources. During 2008 and 2009 INFFER has been implemented with a number of catchment management organisations (CMOs) throughout Australia. In this paper, we report on lessons from and implications of this experience. Data on implementation were collected in formal and... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Research and Development/Tech Change/Emerging Technologies. |
| Ano: 2010 |
URL: http://purl.umn.edu/59100 |
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| Marsh, Sally P.; Pannell, David J.. |
| In most states of Australia, agricultural extension policies and practices have increasingly been based on considerations of private/public goods, user pays and cost recovery. In addition, the delivery of extension has been strongly influenced by changing administrative structures and a change in the paradigm within which the extension community operates. These changes have had major impacts, including more extension being delivered by the private sector. There are positive aspects to the changes and, for some issues, they are appropriate. However, we have a number of reservations, particularly about the effectiveness of current extension systems in assisting the adoption of complex environmental and farming system technologies. |
| Tipo: Journal Article |
Palavras-chave: Teaching/Communication/Extension/Profession. |
| Ano: 2000 |
URL: http://purl.umn.edu/117854 |
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| Hardaker, J. Brian; Patten, Louise H.; Pannell, David J.. |
| A programming technique, utility-efficient programming, is developed for farm planning under risk. The objective function is the parametric sum of two parts of the utility function in which the degree of risk aversion varies systematically with the parameter. This technique has several advantages over those previously available: a number of types of utility functions are applicable including ones exhibiting decreasing risk aversion; the degree of risk aversion can be limited to a plausible range; the form of the distribution for activity net revenues is flexible; and the technique can be used with available algorithms. The method is illustrated using a parametric linear programming algorithm. |
| Tipo: Journal Article |
Palavras-chave: Farm Management; Risk and Uncertainty. |
| Ano: 1988 |
URL: http://purl.umn.edu/22959 |
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| Pannell, David J.. |
| Australian research into the economics of privately and publicly funded weed control is reviewed. Of the published studies that consider farm-level problems, most have been simplistic. Complexities which affect a farmer's optimal control strategies for crop and pasture weeds are outlined. The determination of herbicide rates on an economic basis is proposed as an area for further work. The traditional economic threshold concept is not suitable for this purpose. Studies of the economics of public weed control programs are slightly more common than farm-level studies in the literature, although work on public weed problems has focussed on just a few weed species. Future directions for weed economics research are suggested. |
| Tipo: Journal Article |
Palavras-chave: Crop Production/Industries. |
| Ano: 1988 |
URL: http://purl.umn.edu/12278 |
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| Pannell, David J.; Hailu, Getu; Weersink, Alfons; Burt, Amanda. |
| The use by farmers of futures contracts and other hedging instruments has been observed to be low in many situations, and this has sometimes seemed to be considered surprising or even mysterious. We propose that it is, in fact, readily understandable and consistent with rational decision making. Standard models of the decision about optimal hedging show that it is negatively related to basis risk, to quantity risk, and to transaction costs. Farmers who have less uncertainty about prices have a lower optimal level of hedging. If a farmer has optimistic price expectations relative to the futures market, the incentive to hedge can be greatly reduced. And finally, farmers who have low levels of risk aversion have little to gain from hedging in terms of risk... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Hedging; Risk; Risk aversion; Flat payoff functions; Agricultural Finance. |
| Ano: 2007 |
URL: http://purl.umn.edu/9232 |
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| Chalak, Morteza; Pannell, David J.; Polyakov, Maksym. |
| Invasive species are significant threats to biodiversity, natural ecosystems and agriculture leading to large worldwide economic and environmental damage. Spread and control of invasive species are stochastic processes with important spatial dimensions. Most economic studies of invasive species control ignore spatial and stochastic aspects. This paper covers this gap in the previous studies by analysing a spatially explicit dynamic process of controlling invasive species in a stochastic setting. We show how stochasticity, spatial location of infestation and control can influence the spread, control efficiency and optimal control strategies. The main aim of this paper is to analyse the relationship between economic parameters and stochastic spatial... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Environmental Economics and Policy; Land Economics/Use. |
| Ano: 2011 |
URL: http://purl.umn.edu/115513 |
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| Pannell, David J.. |
| A broad range of information relevant to salinity is reviewed in order to critically evaluate existing and prospective policy responses. The review includes issues of hydrogeology, farmer perceptions and preferences, farm‐level economics of salinity management practices, spill‐over benefits and costs from salinity management, and politics. The technical challenge of preventing salinity is far greater than previously recognised. The farm‐level economics of currently available management practices for salinity prevention are adverse in many situations. Off‐site benefits from on‐farm practices are often small and long delayed. Past national salinity policies have been seriously flawed. While current policy proposals include positive elements, they have not... |
| Tipo: Journal Article |
Palavras-chave: Land Economics/Use. |
| Ano: 2001 |
URL: http://purl.umn.edu/117725 |
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| Pannell, David J.; Roberts, Anna M.; Park, Geoff; Curatolo, April; Marsh, Sally P.; Alexander, Jennifer. |
| This is a pre-publication version of: Pannell, D.J., Roberts, A.M., Park, G., Alexander, J., Curatolo, A. and Marsh, S. (2012). Integrated assessment of public investment in land-use change to protect environmental assets in Australia, Land Use Policy 29(2): 377-387. |
| Tipo: Working or Discussion Paper |
Palavras-chave: Environmental Economics and Policy; Resource /Energy Economics and Policy; Q20; Q50. |
| Ano: 2011 |
URL: http://purl.umn.edu/102455 |
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| Pannell, David J.. |
| Strategic‐basic research refers to basic research conducted in strategically selected areas expected to be of social benefit. Recent literature on the processes of basic research and its links to applied research has not been widely discussed in relation to agricultural research. This may have important implications for the question of the optimal allocation of research resources. The links are reviewed and combined into a framework for considering the allocation question. A numerical model suggests that only a small number of the model’s parameters substantially affect the optimal level of basic research, and that it is not important to identify the optimal solution precisely, since the benefit function is extremely flat around the optimum. |
| Tipo: Journal Article |
Palavras-chave: Resource /Energy Economics and Policy. |
| Ano: 1999 |
URL: http://purl.umn.edu/117033 |
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| Registros recuperados: 66 | |
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