No description available.

The uncountable number of tools for the creation of synthetic terrains poses as a challenge for simulation interoperability. The permutations of tools, elevation maps, and software settings leads to combinations of poorly correlated virtual terrains. An important issue in distributed simulations is the lack of line-of-sight correlation. For example, in military networked simulations, consistent intervisibility between simulated entities is crucial for a fair-fight, especially when simulations include direct-fire weapons. The literature review presented in the Chapter Two discusses a multitude of interoperability issues caused by discrepant terrain representations and rendering engines noncompliant to any standard image generation process. Furthermore, the literature review discusses past research that strived for measuring (or mitigating) the correlation issues between terrain databases. Based on previous research, this thesis proposes a methodology for analysis of line-of-sight correlation between a pair of terrain databases. All the mathematical theory involved in the methodology is discussed in the Chapter Three. In addition, this thesis proposes a new method for measuring the roughness of a visual terrain database. This method takes into account the 3D dispersion of the vectors normal to the polygons in the terrain's mesh. Because the vectors normal to the polygons are conveniently stored in most visual databases, the roughness calculation suggested here is fast and does not require sampling the terrain's elevation. In order to demonstrate the proposed method, twin terrain databases and a tool were created as part of this thesis. The goal of this tool is to extract data from the terrain databases for statistical analysis. The tool is open source and its source code is provided with this thesis. The Chapter Four includes an example of statistical analysis using an open source statistic software. The line-of-sight correlation analysis discussed here includes the terrain's geometry only (terrain's culture is not addressed). Human factors were not taken into consideration.

Traditional viewshed analyses distinguish between those areas which can be seen from a given observation point and those which cannot be seen. Given a surface digital elevation model (DEM) and observer properties (location and height), the algorithm computes whether or not each target cell is within the observer's line-of-sight. Just as significant and robust (although yet not commercially available) would be a tool that could search local neighborhoods of the observer to determine if different tower placements could achieve significantly improved viewsheds. This thesis customizes the popular ArcGIS software to demonstrate the implementation of such a tool. The use of different sampling methods specifies locations to site observation points throughout the Virginia Tech central campus, characterized by having large open areas in an otherwise urban environment. Analysis of the viewsheds calculated both before and after applying the optimization tool determined the amount of coverage gained by moving the observer short distances across the ground. In large open areas (Drillfield, parking lots), optimization achieved minimal gain, however in areas near buildings, significant increases in visible area were possible by moving the observer to the top of a nearby building. This research rejects the common belief that the best location for an observer or transmitter in open areas is always at the highest elevation point. However, in settings with tremendous vertical differences over small horizontal distances (ground to roof), the belief is justified. / Master of Science

No description available.

No description available.

Position location has become one of the more important tasks for improving communication and networking performance for future commercial wireless systems. It is also the enabling technology for many control and sensing applications envisioned by the wireless sensor networks (WSN). Despite its meaningfulness and many algorithms being developed in the past several years, position location in harsh propagation environments remains to be a challenging issue, due mainly to the lack of sufficient infrastructure support and the prominent phenomenon of non-line-of-sight (NLOS) signal propagation. Recently, adopting the concept of collaborative position location has attracted much research interest due to its potential in overcoming the abovementioned two difficulties. In this work, we approach collaborative position location from two different angles. Specifically, we investigate the optimal performance of collaborative position location, which serves as a theoretical performance benchmark. In addition, we developed a computationally efficient algorithm for collaborative position location and incorporated an effective NLOS mitigation method to improve its performance in NLOS-dense environments. Overall, our work provides insight into both theoretical and practical aspects of collaborative position location. / Ph. D.

This thesis describes the design and implementation of an innovative drawing interpretation tool for the sight-impaired. The move towards Graphical User Interfaces in today's computer era presents many challenges to those with impaired vision. Although there are many tools to aid this group in reading and writing text-based electronic documents, few software packages are available to help the sight-impaired interpret electronic images. This new tool, known as ImagePilot 2.0, processes electronic image files that contain line drawings and produces audio feedback to guide the user through the drawing. ImagePilot 2.0 receives input through a pointing device, thereby providing the user with a means of examining a drawing interactively, and serving as an aid for recognizing the outlines of familiar shapes and objects. In this study, a "line drawing" is a simple image that contains line segments and curves, without any shading or colors. It can be represented as a 2-dimensional array of picture elements (pixels), in which each pixel is either black or white. The drawing is represented by a pattern of black (foreground) pixels against a white background. Typically, groups of connected foreground pixels represent segments or curves that are associated with a single object. ImagePilot 2.0 makes it possible for a sight-impaired user to interrogate such an image. Line drawings can be stored in many different electronic formats. ImagePilot 2.0 supports valid Graphic Interchange Format (GIF) files. If the foreground image regions in the file are wider than one pixel in width, a Zhang-Suen thinning algorithm is applied to thin the drawing. The tool identifies the separate regions in the drawing and decides on the best starting point for each region. Once a starting point is chosen, the drawing is processed using a modified chain-coding algorithm. The audio feedback consists of two types of audio cues, verbal and tone, along with stereo playback. Verbal feedback guides the user with a set of verbal cues played through the speakers. The tone feedback uses three tones representing above, level, and below the horizontal. The left and right speakers provide left and right directional information at each level. Speed is a critical factor in image analysis and interpretation applications. While the tool is receiving and processing input, it must also respond to the user within an acceptable amount of time. ImagePilot 2.0 uses multi-threading and multi-tasking techniques to achieve higher performance speeds. After design and implementation, two groups of people tested the tool. The tool demonstrated the ability to help the user find and trace the segments in the test drawings with high efficiency and acceptable response time. This tool is written in pure Java, and complies with Sun's Java API specification 1.1.7 released in October 1998. The tool functions on systems with multimedia capabilities that have a Java Virtual Machine (JVM) and Java Media Framework (JMF) installed. / Master of Science

Developing the music cognition competencies of both singers and instrumentalists is one of the goals of school music programs. Vocal and instrumental sight reading are used to indicate the level of development of cognitive skills in music. In this study, vocal and instrumental sight reading served as a basis for determining public school orchestra students' cognitive development in music. Vocal sight-reading and instrumental sight-reading performances of 143 orchestra students in 7th, 9th, and 11th grades were examined. Students' vocal sight-singing accuracy was tested using the Vocal Sight Reading Inventory (Henry, 1999). Students' instrumental sight-reading was assessed using the String Performance Rating Scale (Zdzinski & Barnes, 2002). The ANOVA procedure and the Welch test were applied to determine whether there was an improvement in students' vocal and instrumental sight reading with additional years of school orchestra experience. Results from ANOVA analyses indicated that the differences in students' instrumental sight-reading scores across the three grade levels were statistically significant [F (2,140) = 34.50], p < .01. A post hoc Bonferroni adjustment revealed that the differences between each of the groups were statistically significant (p < .05) in favor of older and more experienced students. For vocal sight reading, the Tamhane procedure revealed significant differences only between students at the 7th and 11th grade levels, also in favor of the older students (p < .05). Correlational analysis indicated that there was a strengthening of the relationship between students' vocal sight reading and instrumental sight reading as students progressed in grade level, indicating that they were continuing to develop their musicianship skills. The correlation between vocal sight-reading and instrumental sight-reading scores according to grade level were r = .36, p < .05 for 7th grade, r = .52, p < .01 for 9th grade, and r = .64, p < .01 for 11th grade. In this study I stressed the importance of both vocal sight-reading and instrumental sight-reading experiences for orchestra students and ultimately for all instrumental students. I also proposed theoretical models as to how the two skills are related and how they might be developed.

The focus of this study is on the relationships among three basic auditory representations as well as their interaction with a measure of overall musicianship (sight-singing) among a group of classical and non-classical university music students (N = 112) selected from three different universities. Students were enrolled in level one of an aural skills course at the time. Basic auditory representations included were tonic centrality, measured by Colwell’s (1968) Feeling for Tonal Center, tonal grouping, measured by Colwell’s (1968) Auditory-Visual Discrimination, and harmonic function grouping, measured by a revised version of Holahan, Saunders and Goldberg’s (2000) assessment. I evaluated relationships by correlating scores on each measure and also compared these relationships among classical and non-classical music students. The participants in this study were the most skilled at forming auditory representations of tonic centrality and non-classical musicians significantly (p = .002) outperformed classical musicians in this area. Tonic centrality was also most strongly correlated with overall musicianship (τ = .45, p < .001) within the sample, and this relationship appeared to be stronger among non-classical musicians (τ = .52, p < .001) than among classical musicians (τ = .39, p < .001). This difference may be accounted for by the increased reliance on grounding in a tonal center required by the musical activities of a typical non-classical music student. Given the changing balance of musical endeavors present in tertiary music schools today (Lehmann, Sloboda, & Woody, 2007), educators are encouraged to better understand the particular strengths non-classical musicians may bring to the classroom in terms of ear-based musical abilities. Likewise, music educators on each level are encouraged to incorporate ear-based activities such as improvisation and playing by ear to the benefit of musicians of all genres.

The ability to sight-read well is held as a highly regarded and important skill in music performance and education. Over the past 90 years, researchers have investigated several aspects of music sight-reading, especially those attributes possessed by skilled sight-readers. A significant and recurrent finding from this body of research is the relationship between sight-reading and rhythm recognition. Though these studies have found positive effects and correlations between rhythm recognition and sight-reading, they have been limited and indirect. The aim of this dissertation was to investigate the effects of (a) practicing rhythms on a single pitch and (b) practicing rhythms with full-range scales and their direct effects on sight-reading ability in saxophonists at the college level. The primary objective in this research was to determine if one method was more effective than another in developing sight-reading skills. The participants (N = 74) consisted of college students who were enrolled in saxophone lessons at a university in the southwestern United States. Participants were administered a sight-reading pre-test at the beginning of an 8-week treatment period. After pre-testing, students were blocked into two groups. The first treatment group was assigned to practice rhythms on a single pitch and the second treatment group was assigned to practice rhythms combined with full-range major scales. After the treatment period, participants were administered a sight-reading post-test. A 2-way mixed ANOVA was used to determine if there were differences between treatment groups, differences from pre-test to post-test, and if there was a significant interaction between treatment and time. There was no significant difference between treatment groups, F (1, 72) = .035, p = .852, partial η2 = .000028. There was a significant effect for time, indicating that both treatment groups improved from pre-to post test, F (1, 72) = 83.499, p < .001, partial η2 = .537. There was no significant interaction between treatment and time, F (1, 72) = .322, p = .572, partial η2 = .004.