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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

An Investigation of Basic Probability Operations Using AND and OR Operations

Tsoi, Joannie January 2007 (has links)
The purpose of this thesis was to observe people’s abilities to compute probability problems at a fundamental level. The problems in this study were presented in an abstract format to ensure non-ambiguity in its interpretation. The study was administered to university level students. The focus was to determine people’s ability to answer probability questions that combined the probabilities of two single events, using the most basic types of operations: AND and OR. The study found that while most people were able to compute AND type probability questions, most had trouble with OR operations. Of special interest was a switching strategy that was employed in computing OR operations as the probability of a single event varied. The study also revealed that statistically sophisticated people were able to adopt the mindset of people who were statistically naïve. Further research is required in order to develop a better framework in understanding people’s logical process of computing these basic probability questions as well as its application to our everyday lives.
72

Meaning Construction: Cognitive Processes of Conceptual Interaction

Ran, Bing January 2007 (has links)
This thesis proposes a theoretical framework explaining cognitive processes of meaning construction through conceptual interactions. It was noted that while the nine models or theories (Fuzzy Sets, Selective Modification model, Amalgam theory, Concept Specialization model, Composite Prototype Model, Dual-Process model, Constraint model, CARIN model, and Coherence Theory) in literature on conceptual combination offered insights on the problem of how people understand conceptual combinations, most of them assumed a schematic representation of our knowledge of concepts. However, it is possible that our minds represent knowledge in less structured ways and that schematic structure may not necessarily play a role in making sense of conceptual combinations. In this thesis, I attempted to make fewer assumptions about how knowledge is represented to explain the cognitive processes of conceptual combinations. I assume that concepts are related to other concepts, and knowledge can be represented by associations among concepts. Based on this assumption, the meaning of a conceptual combination is constructed through interactions between these associated concepts. It is proposed that the cognitive processes involved in meaning construction start from a distinction between different roles each component concept plays (head or modifier), and then a system of associations are activated contingently, prototypically, and efficiently with the goal of forming a cognitive field (analytically represented as a closed cycle) to connect head and modifier in a balanced way. The balanced system of concepts is strengthened further by reconciling remaining tensions in the field. Experimental results confirmed that component concepts in a combination activate associations contingently, and prototypicality and balance are major factors influencing whether an association will be activated by the combination to construct the meaning. Head / Modifier and Novelty were also studied as moderating variables. The experimental results indicated that head is a stronger moderator for association activation than modifier, and novelty was not found to be a significant moderator in association activation. Implications of these findings are discussed and future research is identified.
73

The Effect of Prior Commitment on Group Conflict in Judgemental Tasks

Kay, Min Beom 27 July 2007 (has links)
Previous research has identified commitment as one of the major contributing factors in group conflict and this study extends this line of research by considering group conflict as a result of varying members’ prior commitment for groups working on judgmental tasks with a unanimous decision rule. The goal of the group working on a judgmental task is to reach consensus but unanimous decision rule further complicates the decision making process as it requires every member to agree with group’s decision. Given this setting, prior commitment was expected to result in higher group conflict and this elevated level of conflict to have more negative affect on the group. With three judgmental cases formulated, subjects were divided into post-decision and pre-decision groups. In the post-decision groups, each subject was individually presented with each case first and committed to his own decision. With these prior commitments, subjects reached a unanimous decision through a group discussion. In the pre-decision groups, subjects reached a group decision without any prior commitment to their own decisions. Results showed signs of prior commitment contributing to group conflict. Furthermore, the post-experimental questionnaire showed that higher group conflict translates to more negative affects on the perceived performance, the extent to which members agree with the group’s decision, feeling toward other members and willingness to work with the same group.
74

Surface Partitioning for 3+2-axis Machining

Roman Flores, Armando January 2007 (has links)
Despite the inbuilt advantages offered by 5-axis machining, the manufacturing industry has not widely adopted this technology due to the high cost of machines and insufficient support from CAD/CAM systems. Companies are used to 3-axis machining and the operators are in many cases not yet ready for 5-axis machining in terms of training and programming. An effective solution for this 5 axis problem is a graduated migration through the use of 3+2-axis machining. The objective of this research is to develop and implement a machining technique that uses the simplicity of 3-axis tool positioning and the flexibility of 5-axis tool orientation, to machine complex surfaces. This technique, 3+2-axis machining, divides a surface into patches and then machines each patch using a fixed tool orientation. The tool orientation and section boundaries are determined to minimize the overall machining time. For each section the tool orientation is different but remains constant while machining this section. The number of patches selected for machining has a direct impact on the machining time. If the number of patches is small, the shape of the tool may vary greatly from that of the surface, which can result in smaller side-step distances. In contrast, a large number of patches leads to a better match between the tool and the workpiece, but it also leads to many re-orientations of the part as the tool moves between patches. Also, if the number of patches is large, the size of the patches will be reduced which will result in shorter tool passes that limit the tools ability to achieve the commanded feed rate. The optimum number of patches is a compromise between increasing the side step associated with large patches and the increase in time due to re-orientation of part and tool movement between patches. To find the optimal partition, a series of simulation tests are conducted to find the partition that would lead to the smallest machining time. This work presents the application of well known methods from Pattern Recognition and newly developed methods by the current author that were adapted for surface machining and boundary identification. This work also presents the methodology required to generate tool paths for 3+2-axis machining, which includes an explanation of the procedures required to determine an appropriate tool orientation, feed direction, tool path trajectory and tool parameters for patch-by-patch machining. These parameters are determined independently for each patch and aim at reducing the time required to machine a surface while maintaining the surface specifications. This work presents the surface partitioning scheme and the method of selecting optimum number of partitions along with actual machining experiments. Machining tests on four different surfaces were conducted to demonstrate the efficiency of the proposed technique. The results show that 3+2-axis machine reduced machining times over 3-axis ball nose machining and 5-axis machining using the “Sturz” method. Also, since the tool axis remains fixed during cutting, the tool offers constant feed rates and a better surface finish compared to simultaneous 5-axis.
75

Emergence and Influence of Expertise in Group Decision Making: A Judgmental Task

Tajeddin, Golnaz January 2007 (has links)
This thesis investigates the emergence and influence of expertise in group decision making while performing a judgmental task. Previous studies focused on intellective tasks or compared the group performance with the performance of the best individual in the group. In this study, performance feedbacks are provided to groups to help group members compare the individual performances and identify the expert. Laboratory experiments were conducted in which the task was to select a proverb that Canadians would like the most from the list of four proverbs from countries other than Canada. The four proverbs for each question were guaranteed to have equal selection probability based on the pretest survey. 18 four-person cooperative groups were asked to perform the task for eight iterations each. One member in each group was selected randomly to be the expert. Groups received performance feedbacks that reinforced the expert at the end of each iteration. The amount of information conveyed to each group regarding the expertise level of each group member was measured with a novel application of information analysis that captures the expert's gradual emergence. Experiment results supported the hypotheses of this study that (1) group members recognize the expert when working on a judgmental task with performance feedback and (2) while performing a judgmental task, the expert has more influence on the group decision making compared to others.
76

Trade-off between Innovation and Sustainability: Perceptions from Students from Developed and Developing Countries

Zhang, Yang January 2008 (has links)
This study investigated the human perception of certain social values to improve national well-being. It focused on the relative importance of two values, innovation and sustainability. Finally, it examined the possibility of a perceived trade-off between these two values by identifying whether a value change occurred among people from developed and developing countries under both constrained (forced-choice) and unconstrained (free-choice) rating conditions. The perceived importance of social values was measured in a survey using an eleven point rating scale. The perceived trade-off and the value change were identified by analyzing rating responses of the survey from test to retest. The analysis found that participants experienced a significant value change from test to retest and participants had different value preference depending on their country type, either developed or developing. This study consisted of two parts. The exploratory pilot study was conducted based on the Management Sciences Student Survey. This survey gathered information about the importance of selected social values from sixteen graduate students in the Department of Management Sciences at the University of Waterloo. The confirmatory main study was conducted using a web-based survey, Global Representative Value Change Survey. It collected information about the importance of the social values from close to three hundred students at the university at both test (Time One) and retest (Time Two). In this way, it enabled the researcher to identify a value change over time that was primarily attributed to a salience manipulation of innovation and sustainability trade-off. With a focus on the trade-off, the results revealed that all participants from developed and developing countries experienced a significant value change under the unconstrained condition, while very few significant value changes took place under the constrained condition. This study implies that people tend to maintain their value consistency and are not inclined to trade-off innovation for sustainability. If these values can co-exist in harmony and without compromise, people are prepared to give due consideration to sustainability, but not at the compromise to innovation. Implications are highlighted for educators, policy makers, and managers of technological innovation and change.
77

The Use Of Kullback-Leibler Divergence In Opinion Retrieval

Cen, Kun 24 September 2008 (has links)
With the huge amount of subjective contents in on-line documents, there is a clear need for an information retrieval system that supports retrieval of documents containing opinions about the topic expressed in a user’s query. In recent years, blogs, a new publishing medium, have attracted a large number of people to express personal opinions covering all kinds of topics in response to the real-world events. The opinionated nature of blogs makes them a new interesting research area for opinion retrieval. Identification and extraction of subjective contents from blogs has become the subject of several research projects. In this thesis, four novel methods are proposed to retrieve blog posts that express opinions about the given topics. The first method utilizes the Kullback-Leibler divergence (KLD) to weight the lexicon of subjective adjectives around query terms. Considering the distances between the query terms and subjective adjectives, the second method uses KLD scores of subjective adjectives based on distances from the query terms for document re-ranking. The third method calculates KLD scores of subjective adjectives for predefined query categories. In the fourth method, collocates, words co-occurring with query terms in the corpus, are used to construct the subjective lexicon automatically. The KLD scores of collocates are then calculated and used for document ranking. Four groups of experiments are conducted to evaluate the proposed methods on the TREC test collections. The results of the experiments are compared with the baseline systems to determine the effectiveness of using KLD in opinion retrieval. Further studies are recommended to explore more sophisticated approaches to identify subjectivity and promising techniques to extract opinions.
78

Cognitive repairs in decision-making by venture capitalists

Dilts, Andrew January 2009 (has links)
This paper examines cognitive repairs as they apply to the decision-making process used by venture capitalists, asking the question of “how could, or how do, cognitive repairs play a role in the decision-making process used by venture capitalists when evaluating a proposal for a new investment?” It begins by reviewing the well-documented concept of human decision-making biases and errors, and then shifts to an overview of the decision-making processes used by venture capitalists when evaluating a proposal for investment in a new venture. It then looks specifically at previous literature that identifies decision-making biases that venture capitalists fall prey to, and follows with reviewing the literature on cognitive repairs: organizational strategies that are used to compensate for or correct decision-making biases. Senior members of the venture capital industry were interviewed to empirically investigate this question, and it was found that while some strategies were in place to reduce human decision-making error, there was both room for and suggested evidence of a greater number of such errors. This leads to the suggestion that the increased use of cognitive repairs by venture capitalists could be beneficial, though this initial research is only of an exploratory format and warrants further investigation both more broadly and deeply.
79

Measuring the Stability of Query Term Collocations and Using it in Document Ranking

Alshaar, Rana January 2008 (has links)
Delivering the right information to the user is fundamental in information retrieval system. Many traditional information retrieval models assume word independence and view a document as bag-of-words, however getting the right information requires a deep understanding of the content of the document and the relationships that exist between words in the text. This study focuses on developing two new document ranking techniques, which are based on a lexical cohesive relationship of collocation. Collocation relationship is a semantic relationship that exists between words that co-occur in the same lexical environment. Two types of collocation relationship have been considered; collocation in the same grammatical structure (such as a sentence), and collocation in the same semantic structure where query terms occur in different sentences but they co-occur with the same words. In the first technique, we only considered the first type of collocation to calculate the document score; where the positional frequency of query terms co-occurrence have been used to identify collocation relationship between query terms and calculating query term’s weight. In the second technique, both types of collocation have been considered; where the co-occurrence frequency distribution within a predefined window has been used to determine query terms collocations and computing query term’s weight. Evaluation of the proposed techniques show performance gain in some of the collocations over the chosen baseline runs.
80

Innovation and Competition in Standard-Based Industries: An Analysis of the High Definition U.S. Home Video Market

Lee, William Seokwoo 22 January 2009 (has links)
This paper examines the competitive dynamics in a standard-based industry through a historical examination of the U.S. home video industry. It analyzes how the Blu-ray technology wins the battle of the high definition DVD market over HD-DVD technology, by focusing on the aspects of the first-mover advantages, network effects. The analysis suggests that the success in the network-based industry partially support to traditional argument on first-mover advantages; they were important only to the point that the first mover takes advantages of the lead time to develop a network of complementary products. This study illustrates that building a network of complementary products and installed base should be the primary goal to succeed in the standard setting competition.

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