Publications
A Cargo Planning, Analysis, and Configuration System for the International Space Station
Abstract
As the Crew Station Operations Division at NASA plans and integrates cargo, the people involved will go through a process of settling what they want to bring with what they can bring. The determination of what can be flown requires an analysis guided by the following questions: Will our stowage fit? What does it weigh? Will anything break if we load it according to the current plan? Based on the analysis, decisions are made as to where racks, stowage provisions, and thousands of pieces of hardware will be located. Flight 7A.1 is the first MPLM flight to be planned and integrated using a Common Lisp application called the Cargo Planning and Analysis System (CPACS). This paper describes my early experience with Common Lisp and outlines some of the features of Common Lisp that were utilized in the development of the CPACS.
Application of Sweeping Techniques to Reverse Engineering (PDF 670 KB)
Abstract
As 3-D scanning systems become faster and less expensive, the reverse engineering process--recreating mathematical models from physical parts--is gaining more attention. Many physical parts are created by combining a series of sweeping operations within CAD/CAM systems. By applying these sweeping techniques in the reverse, one can recreate mathematical models of many parts. This investigation of the reverse engineering process presents an approach for recovering three types of swept surfaces. Translational sweeps are found by recovering a profile curve and a trajectory curve. Rotational sweeps are found by recovering a profile curve and an axis of rotation. Free- form swept surfaces are found by slicing the data into a set of contours along an axis and skinning a surface over the section curves. These recovery techniques all depend on an approach presented for recovering curves by projecting a set of points onto a slicing plane for curve approximation. This approach to recovering the three types of swept surfaces is demonstrated on a number of examples that include data collected from parts scanned with a Minolta Vivid 900 3-D scanner.
Open Domain Question Answering on the WWW
Abstract
The appeal of being able to type a question into the computer and receive an answer has been renewed by the broad availability of information on the World Wide Web (WWW). Ideally, a question answering system that uses the WWW as its knowledge base would be able to answer a broad range of questions. Practically, the size and unstructured nature of the WWW makes this a very difficult task. Examining three recent systems, FAQ Finder, START, and MULDER will reveal different approaches and challenges to using WWW resources as a knowledge base for a QA system. The FAQ Finder System (Burke, et al., 1997), developed at the University of Chicago, uses FAQ files and the WordNet lexicon as its knowledge base. START was developed by Boris Katz et al. and uses sentence level natural language processing to match questions with sentence representations stored in its knowledge base. The digested sentences can be derived from and refer to resources on the WWW (Katz, 1997). MULDER (Cody Kwok et al., 2001) developed at the University of Washington, attempts to find answers using search engines that index the WWW. This paper details how these systems create a knowledge base using WWW resources and match natural language questions with structures in the knowledge base to generate answers.
Optimizing Search: The 8 Puzzle
Abstract
Solving an 8-puzzle involves moving the puzzle from a starting state to a solution state with many options in between. This paper explores breadth-first search, depth-first search, hill-climbing, and the optimization of A* using the profiling tools provided with CMU Common Lisp.