Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item Exploring the Contributions of Word Knowledge and Figural Reasoning Ability to College Students' Performance on a Measure of Relational Reasoning with Words(2021) Zhao, Hongyang; Alexander, Patricia; Human Development; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Word knowledge has long been considered as one of the most important predictors of reading comprehension, academic achievement, and social development. However, it was relatively narrowly conceptualized and measured as either the number of words individuals know the general meaning of (i.e., breadth) or the simple association between two words (i.e., depth). The problem with such a one-sided view is that the existing measures of word knowledge is limited in revealing the quality of word knowledge, which is characterized by both depth and breadth. In this investigation, by comparison, quality of word knowledge was conceptualized as individuals’ fine-grained understanding of the word meanings as they systematically identified semantic similarities and differences among a group of words. It is believed that through deliberate comparisons among word sets, individual’s understanding of the intricacy, subtlety in the meaning of words can be revealed. Therefore, this study offered a new approach in assessing the word knowledge quality informed by a theoretical model of relational reasoning and its four resulting forms (Alexander & DRLRL, 2012). A novel measure of word knowledge quality, Relational Reasoning with Words (R2W2) was developed and validated in this study. Moreover, the unique contributions of relational reasoning ability and word knowledge to college students’ performance on R2W2 were also analyzed. With a sample that involved 338 participants from four US universities, the study found that R2W2 was a reliable and valid measure for word knowledge quality with sound psychometric properties on the item level. In addition, word knowledge was found to contribute to college students’ performance on R2W2 more than relational reasoning ability. Implications for future research and practice are also presented and discussed.Item The compositional character of visual correspondence(2004-08-06) Ogale, Abhijit Satishchandra; Aloimonos, Yiannis; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Given two images of a scene, the problem of finding a map relating the points in the two images is known as the correspondence problem. Stereo correspondence is a special case in which corresponding points lie on the same row in the two images; optical flow is the general case. In this thesis, we argue that correspondence is inextricably linked to other problems such as depth segmentation, occlusion detection and shape estimation, and cannot be solved in isolation without solving each of these problems concurrently within a compositional framework. We first demonstrate the relationship between correspondence and segmentation in a world devoid of shape, and propose an algorithm based on connected components which solves these two problems simultaneously by matching image pixels. Occlusions are found by using the uniqueness constraint, which forces one pixel in the first image to match exactly one pixel in the second image. Shape is then introduced into the picture, and it is revealed that a horizontally slanted surface is sampled differently by the two cameras of a stereo pair, creating images of different width. In this scenario, we show that pixel matching must be replaced by interval matching, to allow intervals of different width in the two images to correspond. A new interval uniqueness constraint is proposed to detect occlusions. Vertical slant is shown to have a qualitatively different character than horizontal slant, requiring the role of vertical consistency constraints based on non-horizontal edges. Complexities which arise in optical flow estimation in the presence of slant are also examined. For greater robustness and flexibility, the algorithm based on connected components is generalized into a diffusion-like process, which allows the use of new local matching metrics which we have developed in order to create contrast invariant and noise resistant correspondence algorithms. Ultimately, it is shown that temporal information can be used to assign correspondences to occluded areas, which also yields ordinal depth information about the scene, even in the presence of independently moving objects. This information can be used for motion segmentation to detect new types of independently moving objects, which are missed by state-of-the-art methods.