Hydrological Interpretation of Basin Morphology

Completion Report OWRT Agreement No. 14-31-0001-5002 OWRT Project A-049-ALASHydrologic processes in a particular basin are governed by three groups of factors: input regimes of mass and energy, the nature of mass and energy transfer and transformation, and the biophysical characteristics of the basin. This third group provides the structural or morphological framework in which hydrologic processes are taking place and, as such, contributes significantly to the uniqueness of specific basin response.The work upon which this completion report is based was supported by funds provided by the U. S. Department of the Interior, Office of Water Research and Technology as authorized under the Water Resources Research Act of 1964, Public Law 88-379, as amended

Hydrometeorological Literature Review for the Delta-Clearwater Creek Area

Completion Report State of Alaska Department of Natural Resources Reimbursable Service Agreement Dated August 19, 1977Phase One of this study consists of a search for existing hydrometeorological data or other information relevant to environmental baseline studies of the Delta-Clearwater Creek agricultural development project. A general summary of this literature search is presented below; a detailed annotated bibliography immediately follows the summary. Phase Two consists initially of a preliminary analysis, based on existing information, of the local water budget, the groundwater regime, and the potential for transport of agricultural chemicals into the water system. Finally, evaluation and comments on the adequacy or sufficiency of existing data and recommendation for future work are made. Selected charts, diagrams, or tables of data have been included in the text where such information is relevant, but not voluminous.This project and report were supported through a contract from the State of Alaska, Department of Natural Resources

PDDL2.1: An extension of PDDL for expressing temporal planning domains

In recent years research in the planning community has moved increasingly towards application of planners to realistic problems involving both time and many types of resources. For example, interest in planning demonstrated by the space research community has inspired work in observation scheduling, planetary rover ex ploration and spacecraft control domains. Other temporal and resource-intensive domains including logistics planning, plant control and manufacturing have also helped to focus the community on the modelling and reasoning issues that must be confronted to make planning technology meet the challenges of application. The International Planning Competitions have acted as an important motivating force behind the progress that has been made in planning since 1998. The third competition (held in 2002) set the planning community the challenge of handling time and numeric resources. This necessitated the development of a modelling language capable of expressing temporal and numeric properties of planning domains. In this paper we describe the language, PDDL2.1, that was used in the competition. We describe the syntax of the language, its formal semantics and the validation of concurrent plans. We observe that PDDL2.1 has considerable modelling power --- exceeding the capabilities of current planning technology --- and presents a number of important challenges to the research community

The Automatic Inference of State Invariants in TIM

As planning is applied to larger and richer domains the effort involved in constructing domain descriptions increases and becomes a significant burden on the human application designer. If general planners are to be applied successfully to large and complex domains it is necessary to provide the domain designer with some assistance in building correctly encoded domains. One way of doing this is to provide domain-independent techniques for extracting, from a domain description, knowledge that is implicit in that description and that can assist domain designers in debugging domain descriptions. This knowledge can also be exploited to improve the performance of planners: several researchers have explored the potential of state invariants in speeding up the performance of domain-independent planners. In this paper we describe a process by which state invariants can be extracted from the automatically inferred type structure of a domain. These techniques are being developed for exploitation by STAN, a Graphplan based planner that employs state analysis techniques to enhance its performance

Extending the exploitation of symmetries in planning

Highly symmetric problems result in redundant search effort which can render apparently simple problems intractable. Whilst the potential benefits of symmetry-breaking have been explored in the broader search community there has been relatively little interest in the exploitation of this potential in planning. An initial exploration of the benefits of symmetry-breaking in a Graphplan framework, by Fox and Long in 1999 (Fox and Long 1999) yielded promising results but failed to take into account the importance of identifying and exploiting new symmetries that arise during the search process. In this paper we extend the symmetry exploitation ideas described in (Fox and Long 1999) to handle new symmetries and report results obtained from a range of planning problems

Exploiting a graphplan framework in temporal planning

Graphplan (Blum and Furst 1995) has proved a popular and successful basis for a succession of extensions. An extension to handle temporal planning is a natural one to consider, because of the seductively time-like structure of the layers in the plan graph. TGP (Smith and Weld 1999) and TPSys (Garrido, Onaindía, and Barber 2001; Garrido, Fox, and Long 2002) are both examples of temporal planners that have exploited the Graphplan foundation. However, both of these systems (including both versions of TPSys) exploit the graph to represent a uniform flow of time. In this paper we describe an alternative approach, in which the graph is used to represent the purely logical structuring of the plan, with temporal constraints being managed separately (although not independently). The approach uses a linear constraint solver to ensure that temporal durations are correctly respected. The resulting planner offers an interesting alternative to the other approaches, offering an important extension in expressive power

Plan permutation symmetries as a source of inefficiency in planning

This paper briefly reviews sources of symmetry in planning and highlights one source that has not previously been tackled: plan permutation symmetry. Symmetries can be a significant problem for efficiency of planning systems, as has been previously observed in the treatment of other forms of symmetry in planning problems. We examine how plan permutation symmetries can be eliminated and present evidence to support the claim that these symmetries are an important problem for planning systems

Progress in AI Planning Research and Applications

Planning has made significant progress since its inception in the 1970s, in terms both of the efficiency and sophistication of its algorithms and representations and its potential for application to real problems. In this paper we sketch the foundations of planning as a sub-field of Artificial Intelligence and the history of its development over the past three decades. Then some of the recent achievements within the field are discussed and provided some experimental data demonstrating the progress that has been made in the application of general planners to realistic and complex problems. The paper concludes by identifying some of the open issues that remain as important challenges for future research in planning

Planning with generic types

Domain-independent, or knowledge-sparse, planning has limited practical appli-cation because of the failure of brute-force search to scale to address real prob-lems. However, requiring a domain engineer to take responsibility for directing the search behavior of a planner entails a heavy burden of representation and leads to systems that have no general application. An interesting compromise is to use domain analysis techniques to extract features from a domain description that can exploited to good effect by a planner. In this chapter we discuss the process by which generic patterns of behavior can be recognized in a domain, by automatic techniques, and appropriate specialized technologies recruited to assist a planner in efficient problem solving in that domain. We describe the in-tegrated architecture of STAN5 and present results to demonstrate its potential on a variety of planning domains, including two that are currently beyond the problem-solving power of existing knowledge-sparse approaches