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Multidisciplinary Design Optimization with Mixed Integer Quasiseparable Subsystems
Get PDFNumerous hierarchical and nonhierarchical decomposition strategies for the optimization of large scale systems, comprised of interacting subsystems, have been proposed. With a few exceptions, all of these strategies have proven theoretically unsound. Recent work considered a class of optimization problems, called quasiseparable, narrow enough for a rigorous decomposition theory, yet general enough to encompass many large scale engineering design problems. The subsystems for these problems involve local design variables and global system variables, but no variables from other subsystems. The objective function is a sum of a global system criterion and the subsystems' criteria. The essential idea is to give each subsystem a budget and global system variable values, and then ask the subsystems to independently maximize their constraint margins. Using these constraint margins, a system optimization then adjusts the values of the system variables and subsystem budgets. The subsystem margin problems are totally independent, always feasible, and could even be done asynchronously in a parallel computing context. An important detail is that the subsystem tasks, in practice, would be to construct response surface approximations to the constraint margin functions, and the system level optimization would use these margin surrogate functions. The present paper extends the quasiseparable necessary conditions for continuous variables to include discrete subsystem variables, although the continuous necessary and sufficient conditions do not extend to include integer variables
Quantitative Relative Comparison of CFD Simulation Uncertainties for a Transonic Diffuser Problem
Get PDFDifferent sources of uncertainty in CFD simulations are illustrated by a detailed study of two-dimensional, turbulent, transonic flow in a converging-diverging channel. Runs were performed with the commercial CFD code GASP using different turbulence models, grid levels, and flux-limiters to see the effect of each on the CFD simulation uncertainties. Two flow conditions were studied by changing the exit pressure ratio: the first is a complex case with a strong shock and a separated flow region, the second is the weak shock case with no separation. The uncertainty in CFD simulations has been studied in terms of four contributions: (1) discretization error, (2) error in geometry representation, (3) turbulence model, and (4) the downstream boundary condition. In this paper, we have quantified the relative contribution and the importance of each source of uncertainty and shown the level of scatter in results that a well informed CFD user may obtain in a typical design activity. The nozzle efficiency results obtained in this study showed that the range of variation for the strong shock case was much larger than that observed in the weak shock case. The discretization errors were up to 6% and the relative uncertainty originating from the selection of different turbulence models was as large as 9% for the strong shock case. Furthermore, the results demonstrated that grid convergence is not achieved with grid levels that have moderate mesh sizes and showed that highly refined grids are required to obtain solutions with an acceptable level of accuracy in design problems that involve simulations of complex flow fields. The results illustrated the interaction of different sources of uncertainty and showed that the magnitudes of numerical errors are influenced by the physical models used
Usability of Tablet PC as a Remote Control Device for Biomedical Data Visualization
Get PDFInteraction through multi-platform user interfaces (MPUIs), is increasingly being used in battlefield applications, telemedicine, classroom education, and engineering applications. Some of the uniqueness of these non-traditional user interfaces lies in the division of information between multiple displays and the remote control of information (e.g., using one computer to control a remote display). We preformed an exploratory study to compare three different setups: a Tablet PC with a traditional desktop, a Tablet PC with a large screen display (LSD) combination, and a desktop computer. The results showed that many users preferred the familiar Microsoft Windows widgets available on the Tablet PC; users often had difficulty generalizing their experiences' when using the Tablet PC; and the form factor of the Tablet PC worked in favor and against the user in different conditions. Our results indicate that while there are yet problems to overcome, generic handheld devices can make highly effective remote controls for virtual environments
Evaluation of a Location Linked Notes System
Get PDFWe present a location-aware messaging system that lets users read and post notes tied to a particular location. We developed multiple clients (desktop, PDA and cell phone) so that users could choose the most contextually-appropriate device to interact with the system. We allowed remote access and authoring to avoid imposing artificial restrictions on users. We report on our initial evaluation of the system. The goal of the evaluation was to explore novel potential uses of the system and to identify users' preferences regarding the different system features. In our evaluation, we found that users were receptive of this system for leaving and receiving location-targeted reminders. They also overwhelmingly approved of the remote access and authoring capability, and suggested scenarios where these features would be crucial. We discuss our experiences building the system and our findings from the initial evaluation
Visualizing Case Studies
Get PDFCase studies contain valuable information about development records. They are, however, usually presented as textual documents. Here we begin an initial design for viewing case study data. A prototype for viewing case study data is created using information visualization techniques for the purpose of testing against existing techniques. The evaluations show that the new design is just as usable as existing techniques, making it suitable for future development. Future work may show our design can accomplish tasks both faster and more efficiently
Variability of User Interaction with Multi-Platform News Feeds
Get PDFThe development of the World Wide Web (WWW) and proliferation of web enabled devices have allowed various news agencies to enrich their traditional method of distribution of news through TV, radio and print with simultaneous broadcast through the Web. The varying nature of devices through which the Web is accessed warrants different ways to feed the same content. This precipitates some variation in the way users interact with the news feeds. In this paper, we investigate how mental models and information scent affect this variation and user interaction on the whole. We present results from a preliminary survey conducted to capture the current news gathering behavior of general population and verify our assumptions. We then present observations from the study conducted using BBC news site over laptop, PDA and a cell phone
Search Tool Implementation for Historical Archive
Get PDFDr. Linda Arnold's archival project "Mexican-American War and the Media" is an underutilized resource. Providing contrasting primary sources on the War, it is the only archive of its kind. In order to make the archive's massive amount of information more accessible to researchers and students, I added search functionality to the site. Several tools were implemented and tested. Perlfect, a Perl-based open-source approach, was determined to be the best option. This report includes an outline of the steps taken to implement the search tool, a user's manual, a developer's manual, and options for future work. The archive may be accessed at http://www.majbill.vt.edu/history/mxamwar/index.htm
You've Got Mail! Calendar, Weather and More: Customizable Phone Access to Personal Information
Get PDFWe present a design and a prototype of a system that provides access to calendar, email, weather, and news information over a phone using a VoiceXML interface. The system provides quick access to personal information, while enabling but not requiring interactivity. As one major application, we envision the system being used while commuting to work. At home, users define their preferences regarding content and order of presentation using a website. On the road, the personalized audio feed plays like a radio news show. Instead of commercials, the user is reminded of today's meetings, deadlines and listens to the email inbox
Comparing Classroom Note Taking across Multiplatform Devices
Get PDFMany educators have suggested that note taking can be beneficial for the students' educational growth. Note taking is the core activity for students in a classroom and there been a large amount of research conducted, both from industry and from academia, into facilitating the note taking process. As such, there are many available systems for taking notes. However, what has not been given as much attention is how different devices, such as Tablet PCs and PDAs, effect this task. In this paper, we study students' current note taking behavior and the changes caused by the use of different platforms for this activity. Our goal is to provide ideas and general design guidelines for future note taking systems
Implementation of Motion Without Movement on Real 3D Objects
Get PDFResearchers have developed a technique such that when the colors of a static image are toggled on a screen, the illusion of continuous movement in a certain direction is produced. This phenomenon is known as motion without movement. In our research we aim to extend the applications of this technique and apply it to real three-dimensional objects. In order to achieve the projection of images onto three-dimensional shapes, we use projectors called shader lamps, which apply an algorithm to a two-dimensional image so that it appears undistorted when projected onto a three-dimensional object. The resulting effect is that a static object appears to be moving continuously in a desired direction. In addition to applying the motion without movement technique to entire objects, we also examine its use on parts of an image as small as a pixel. Using a technique called optical flow, we determine the exact movement oparts of an image by taking a second image similar to the original, where image shapes have moved and determine in which direction. Finally, we extend the motion without movement technique beyond its previous applications to use on color rather than solely grayscale images, thus producing even more realistic results