2979008
Strategies for designing distributed systems: case studies in the design of an air traffic management system
The air traffic management system in the USA is an example of a distributed problem-solving system. It has elements of both cooperative and competitive problem-solving. It includes complex organizations such as Flight Operations Centers, the FAA Air Traffic Control Systems Command Center (ATCSCC), and traffic management units at en route centers that focus on daily strategic planning, as well as individuals concerned more with immediate tactical decisions (such as air traffic controllers and pilots). The design of this system has evolved over time to rely heavily on the distribution of tasks and control authority in order to keep cognitive complexity manageable for any one individual operator, and to provide redundancy (both human and technological) to serve as a safety net to catch the slips or mistakes that any one person or entity might make. Within this distributed architecture, a number of different conceptual approaches have been applied to deal with cognitive complexity and to provide redundancy. These approaches can be characterized in terms of the strategy for distributing: (1) control or responsibility, (2) knowledge or expertise, (3) access to data, (4) processing capacity, and (5) goals and priorities. This paper will provide an abstract characterization of these alternative strategies for distributing work in terms of these 5 dimensions, and will illustrate and evaluate their effectiveness in terms of concrete realizations found within the National Airspace System.
14822422
Knowledge-based search tactics for an intelligent intermediary system
Research on the nature of knowledge-based systems for bibliographic information retrieval is summarized. Knowledge-based search tactics are then considered in terms of their role in the functioning of a semantically based search system for bibliographic information retrieval, EP-X. This system uses such tactics to actively assist users in defining or refining their topics of interest. It does so by applying these tactics to a knowledge base describing topics in a particular domain and to a database describing the contents of individual documents in terms of these topics. This paper, then, focuses on the two central concepts behind EP-X: semantically based search and knowledge-based search tactics.
7962345
Online Library Catalog Systems: An Analysis of User Errors
Abstract A study of 30 first-time users of LCS, the online library catalog system at the Ohio State University, was conducted. Subjects were provided with the online and offline help available to users of this system and were asked to conduct four standard searches (author, title, subject, etc.). While conducting the online searches, the subjects were asked to “think aloud”. A detailed analysis of errors and associated verbal protocols provided insights into the design features and mental processes contributing to the commission of errors. Of particular significance are: (1) the profound influence that incorrect mental representations have on the viewing and interpretation of online and offline help and instructions; and (2) the snowballing effects of a misconception as a user tries to seek and interpret additional information in attempts to recover from an error.
61905558
Adaptive teaching strategies to improve student learning in problem-based learning environments
The purpose of this study is to investigate the use of adaptive teaching strategies and resource allocation to enhance training in cooperative learning settings. The Biology Sleuth is a multi-media learning environment developed as a testbed to vary the distribution of critical resources and the use of teaching strategies, and to study their effects on group dynamics and individual learning. Students work in a cooperative environment, aided by various resources including a knowledge-base, each other, the software, and the teacher. This study examines the effects of two teaching and resource allocation strategies in this environment and suggests these strategies can have a large impact on both group dynamics and individual learning.
18116859
In search of knowledge-based search tactics
Knowledge-based search tactics are discussed in terms of their role in the functioning of a semantically-based search system for bibliographic information retrieval. This prototype system, EP-X, actively assists users in defining or refining their topics of interest. It does so by applying search tactics to a knowledge-base describing topics in a particular domain and a database describing the contents of individual documents.
This paper reviews the empirical studies that lead to the two central concepts implemented in EP-X:Semantically-based search;Knowledge-based search tactics.
29630397
Coping with the Complexities of Multiple-Solution Problems: A Case Study
A model is proposed to account for the expertise of a skilled immunohematologist in solving multiple-solution problems. These problems, which he must deal with daily, are concerned with ensuring the safe transfusion of blood into patients. This model suggests that he copes with this difficult class of problems by: (1) Using patterns in the data to simplify the problem, hypothesizing the number of primitive solutions necessary to account for the test results and, when possibles, decomposing the problem into a set of less complex, single-solution problems. Such decompositions then enable more powerful reasoning processes; (2) making use of a mixture of data-driven and hypothesis-driven processes in order to reduce the chances that heuristic (and therefore error-prone) methods and cognitive biases will lead away from critical data; (3) Relying on a mixture of confirmatory and rule-out processes to provide converging evidence, thus reducing the changes of error; (4) uncovering his own errors through the use of “error models” that identify the conditions where one of his processes is likely to make an error (similar to the use of student models by expert tutors to diagnose mistakes made by students).
16502051
Parallelization and integration of fire simulations in the Uintah PSE
A physics-based stand-alone serial code for fire simulations is integrated in a unified computational framework to couple with other disciplines and to achieve massively parallel computation. Uintah, the computational framework used, is a component-based visual problem-solving environment developed at the University of Utah. It provides the framework for large-scale parallelization for different applications. The integration of the legacy fire code in Uintah is built on three principles: I) Develop different reusable physics-based components that can be used interchangeably and interact with other components, 2) reuse the legacy stand-alone fire code (written in Fortran) as much as possible, and 3) use components developed by third parties, specifically non-linear and linear solvers designed for solving complex-flow problems. A helium buoyant plume is simulated using the Nirvana machine at Los Alamos National Laboratory. Linear scalability is achieved up to 128 processors. Issues related to scaling beyond 128 processors are also discussed.
58774786
Challenges in Indexing Electronic Text and Images
1517725
Virtual Smoke: an interactive 3D flow visualization technique
A technique is given for computer visualization of simultaneous three-dimensional vector and scalar fields such as velocity and temperature in reacting fluid flow fields. The technique, which is called Virtual Smoke, simulates the use of colored smoke for experimental gaseous fluid flow visualization. However, it is noninvasive and can animate, in particular, the dynamic behaviors of steady-state or instantaneous flow fields obtained from numerical simulations. Virtual Smoke is based on volume seeds and volume seedlings, which are direct volume visualization methods previously developed for highly interactive scalar volume data exploration. Data from combustion simulations are used to demonstrate the effectiveness of Virtual Smoke.<<ETX>>