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A genetic algorithm with memory for mixed discrete-continuous design optimization
Get PDFThis paper describes a new approach for reducing the number of the fitness function
evaluations required by a genetic algorithm (GA) for optimization problems with
mixed continuous and discrete design variables. The proposed additions to the GA
make the search more effective and rapidly improve the fitness value from generation
to generation. The additions involve memory as a function of both discrete and
continuous design variables, multivariate approximation of the fitness function in
terms of several continuous design variables, and localized search based on the
multivariate approximation. The approximation is demonstrated for the minimum
weight design of a composite cylindrical shell with grid stiffeners
RGML: A Markup Language for Characterizing Requirements Generation Processes
Get PDFIn this paper we present the Requirements Generation Markup Language (RGML). The RGML supports the formal characterization of (a) the physical structure of a requirements generation process, (b) individual activities inherent to that process, and (c) artifacts produced and consumed during the generation process. The inclusion of templates, application instantiation, and the expression of temporally-based pre- and post-conditions increase the flexibility of RGML and its ability to capture variations in requirements generation processes.
We envision the RGML as providing the specification basis for (automatically) producing interactive environments that lead (or guide) the requirements engineer through a structured set of integrated activities that foster the evolution of quality requirements
Reinforcing Reachable Routes
Get PDFThis paper studies the evaluation of routing algorithms from the perspective of reachability routing, where the goal is to determine all paths between a sender and a receiver. Reachability routing is becoming relevant with the changing dynamics of the Internet and the emergence of low-bandwidth wireless/ad-hoc networks. We make the
case for reinforcement learning as the framework of choice to realize reachability routing, within the confines of the current Internet infrastructure. The setting of the reinforcement learning problem offers several advantages,including loop resolution, multi-path forwarding capability, cost-sensitive routing, and minimizing state overhead,
while maintaining the incremental spirit of current backbone routing algorithms. We identify research issues in reinforcement learning applied to the reachability routing problem to achieve a fluid and robust backbone routing framework. This paper also presents the design, implementation and evaluation of a new reachability routing algorithm that uses a model-based approach to achieve cost-sensitive multi-path forwarding; performance assessment of the algorithm in various troublesome topologies shows consistently superior performance over classical reinforcement learning algorithms. The paper is targeted toward practitioners seeking to implement a reachability routing algorithm
Scenario/Class Diagram Synthesis
Get PDFThe scenario-synthesis problem in requirements analysis is explored in this report.The approach suggested by Khriss et al.is adapted for the domain of Digital Libraries. The results of the synthesis along with the entire transformation process are elaborated in this report
Generalized Linear Product Homotopy Algorithms and the Computation of Reachable Surfaces
Get PDFIn this paper, we apply a homotopy algorithm to the problem of finding points in a
moving body that lie on specific algebraic surfaces for a given set of spatial
configurations of the body. This problem is a generalization of Burmester's
determination of points in a body that lie on a circle for five planar positions. We focus
on seven surfaces that we term "reachable" because they correspond to serial chains with
two degree-of-freedom positioning structures combined with a three degree-of-freedom
spherical wrist. A homotopy algorithm based on generalized linear products is used to
provide a convenient estimate of the number of solutions of these polynomial systems. A
parallelized version of this algorithm was then used to numerically determine all of the
solutions
PRESERVATION OF ETDs ON NDLTD Version 1.0
Get PDFTheses and dissertations published at a university are important research resources. ETDs (Electronic Theses and Dissertations) are simply the theses and dissertations published in electronic form (e.g., in PDF). Many universities are implementing a requirement that theses and dissertations be submitted in electronic form, thus making it easier for other people to access these works. These ETDs typically are archived on a server at each local university. We have developed a mirroring system which will store additional copies of remote ETDs, and thus will preserve and enhance access to them. The local archive of ETDs will be updated regularly. If someday the university (Publisher) fails to provide access to one of its ETDs or an ETD copy is corrupted, the user will still have access to another copy of ETD. The above system will be used for NDLTD (Networked Digital Library of Theses and Dissertations).
NDLTD is an initiative to encourage the creation of ETDs by student authors, and to make ETDs easily accessible to students via World Wide Web, thus improving graduate education. There are currently over 150 members in NDLTD. Users can browse or search ETDs through the NDLTD website. The NDLTD website also provides a union catalog to search for ETDs.
The Open Archives Initiative (OAI) is dedicated to solving problems of digital library interoperability. OAI has developed a metadata harvesting protocol to support streaming of metadata from one repository to another, ultimately to a provider of user services such as browsing, searching, or annotation. An OAI harvester implements the OAI protocol for metadata harvesting.
We use an OAI harvester to harvest metadata about ETDs and then a simple web crawler is used to get the actual data and store it on a local machine. This ensures that we have a local copy of data even if the publisher of data is somehow unable to provide us with data. Our OAI harvester harvests metadata, which was not harvested since the last time it was run. Hence, updating the mirror site is easily accomplished. This is a very effective scheme, which can be used to mirror any collection of data, provided the collection has an associated OAI server
Building Digital Libraries from Simple Building Blocks
Get PDFMetadata harvesting has been established by the Open Archives Initiative (OAI) as a
viable mechanism for connecting a provider of data to a purveyor of services. The Open
Digital Library (ODL) model is an emerging framework which attempts to break up the
services into appropriate components based also on the basic philosophy of the OAI
model. This framework has been applied to various projects and evaluated for its
simplicity, extensibility and reusability to support the hypothesis that digital libraries
(DLs) should be built from simple Web Service-like components instead of as monolithic
software applications
Persistent virtual identity in community networks: Impact to social capital value chains
Get PDFCommunity networks are digital infrastructures designed to strengthen bonds and build social capital between members of a community, facilitating accomplishment of goals. As we consider how community network implementations can be improved, we recognize the potential that social translucence and activity notification introduces to other forms of CSCW. We investigate how the underlying notion of persistent virtual identity---established at logon---impacts user perception of community networks and their social capital production process. To approach this question, we introduce a design model that reconciles various computer-mediated communication research contributions with support for typical community network scenarios of use. Using this model, we perform an inspection on existing community network implementations. Based on the insight gained through this analysis, we introduce a generic prototype that allows survey of user reaction to community network design elements under differing conditions of persistent virtual identity implementation and usage motivation---the results frame a value-chain understanding of conceptual tradeoffs
Snap2Diverse: Coordinating Information Visualizations and Virtual Environments
Get PDFThe field of Information Visualization is concerned with improving with how users perceive, understand, and interact with visual representations of data sets. Immersive Virtual Environments (VEs) excel at providing researchers and designers a greater comprehension of the spatial features and relations of their data, models, and scenes. This project addresses the intersection of these two fields where information is visualized in a virtual environment. Specifically we are interested in visualizing abstract information in relation to spatial information in the context of a virtual environment. We describe a set of design issues for this type of integrated visualization and demonstrate a coordinated, multiple-views system supporting 2D and 3D visualization tasks such as overview, navigation, details-on-demand, and brushing-and-linking selection. Software architecture issues are discussed with details of our implementation applied to the domain of chemical information and visualization. Lastly, we subject our system to an informal usability evaluation and identify usability issues with interaction and navigation that may guide future work in these situations
Immersive Virtual Environments for University Education: Views from the Classroom
Get PDFEducation has long been touted as an important application
area for immersive virtual environments (VEs).
VEs can allow students to visualize and interact with
complex three-dimensional (3D) structures, perform
virtual experiments,#157; view scenes with natural head and
body movements, and experience environments that
would be otherwise inaccessible because of distance (the
surface of the Moon), scale (a complex molecule), or
danger (a sunken ship). Many researchers have explored
the use of VEs for education [1, 2], with some degree of
success. However, few VE systems have been deployed
for actual classroom use, and little is known about effective
methods for employing VEs in real-world settings
(the work of Johnson et al. is a notable exception [4]).
In this paper, we describe three VE applications developed
to teach university students concepts in the areas
of computer graphics, building structures, and computer
networking, and discuss our experience in using
them as integral parts of appropriate classes at Virginia
Tech. We differ from Johnson et al. in our focus on postsecondary
education and in our use of VEs as tools
within a traditional lecture-based class. We present our
observations of what worked and what did not, and offer
guidelines for others wishing to incorporate VEs into the
classroom