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Articles 301 - 330 of 823
Full-Text Articles in Computer Sciences
Advancing The Effectiveness Of Non-Linear Dimensionality Reduction Techniques, Michael S. Gashler
Advancing The Effectiveness Of Non-Linear Dimensionality Reduction Techniques, Michael S. Gashler
Theses and Dissertations
Data that is represented with high dimensionality presents a computational complexity challenge for many existing algorithms. Limiting dimensionality by discarding attributes is sometimes a poor solution to this problem because significant high-level concepts may be encoded in the data across many or all of the attributes. Non-linear dimensionality reduction (NLDR) techniques have been successful with many problems at minimizing dimensionality while preserving intrinsic high-level concepts that are encoded with varying combinations of attributes. Unfortunately, many challenges remain with existing NLDR techniques, including excessive computational requirements, an inability to benefit from prior knowledge, and an inability to handle certain difficult conditions …
Improving The Effectiveness Of Machine-Assisted Annotation, Paul L. Felt
Improving The Effectiveness Of Machine-Assisted Annotation, Paul L. Felt
Theses and Dissertations
Annotated textual corpora are an essential language resource, facilitating manual search and discovery as well as supporting supervised Natural Language Processing (NLP) techniques designed to accomplishing a variety of useful tasks. However, manual annotation of large textual corpora can be cost-prohibitive, especially for rare and under-resourced languages. For this reason, developers of annotated corpora often attempt to reduce annotation cost by offering annotators various forms of machine assistance intended to increase annotator speed and accuracy. This thesis contributes to the field of annotated corpus development by providing tools and methodologies for empirically evaluating the effectiveness of machine assistance techniques. This …
Performance Evaluation Of Optimal Rate Allocation Models For Wireless Networks, Ryan Michael Padilla
Performance Evaluation Of Optimal Rate Allocation Models For Wireless Networks, Ryan Michael Padilla
Theses and Dissertations
Convex programming is used in wireless networks to optimize the sending or receiving rates of links or flows in a network. This kind of optimization problem is formulated into a rate allocation problem, where each node in the network will distributively solve the convex problem and all links or flows will converge to their optimal rate. The objective function and constraints of these problems are represented in a simplified model of contention, interference, and sending or receiving rates. The Partial Interference model is an optimal rate allocation model for use in wireless mesh networks that has been shown to be …
Automated Fingertip Detection, Joseph G. Butler
Automated Fingertip Detection, Joseph G. Butler
Theses and Dissertations
One of the oldest biometrics that has been used to uniquely identify a person is their fingerprint. Recent developments in research on fingerprint collection have made it possible to collect fingerprint data from a stand-off digital image. Each of the techniques developed so far have relied on either a very controlled capture environment to ensure only a single fingertip is collected or manual cropping of the image down to the fingertip. The main body of the research focuses on extracting the fingerprint itself. If fingerprint collection via digital image is ever to be fielded in the real world on such …
Wifu Transport: A User-Level Protocol Framework, Randall Jay Buck
Wifu Transport: A User-Level Protocol Framework, Randall Jay Buck
Theses and Dissertations
It is well known that the transport layer protocol TCP has low throughput and is unfair in wireless mesh networks. Transport layer solutions for mesh networks have been primarily validated using simulations with simplified assumptions about the wireless network. The WiFu Transport framework complements simulator results by allowing developers to easily create and experiment with transport layer protocols on live networks. We provide a user-space solution that is flexible and promotes code reuse while maintaining high performance and scalability. To validate WiFu Transport we use it to build WiFu TCP, a decomposed Tahoe solution that preserves TCP semantics. Furthermore, we …
Improving Filtering Of Email Phishing Attacks By Using Three-Way Text Classifiers, Alberto Trevino
Improving Filtering Of Email Phishing Attacks By Using Three-Way Text Classifiers, Alberto Trevino
Theses and Dissertations
The Internet has been plagued with endless spam for over 15 years. However, in the last five years spam has morphed from an annoying advertising tool to a social engineering attack vector. Much of today's unwanted email tries to deceive users into replying with passwords, bank account information, or to visit malicious sites which steal login credentials and spread malware. These email-based attacks are known as phishing attacks. Much has been published about these attacks which try to appear real not only to users and subsequently, spam filters. Several sources indicate traditional content filters have a hard time detecting phishing …
Infinitesimal Perturbation Analysis For The Capacitated Finite-Horizon Multi-Period Multiproduct Newsvendor Problem, Brigham Bond Wilson
Infinitesimal Perturbation Analysis For The Capacitated Finite-Horizon Multi-Period Multiproduct Newsvendor Problem, Brigham Bond Wilson
Theses and Dissertations
An optimal ordering scheme for the capacitated, finite-horizon, multi-period, multiproduct newsvendor problem was proposed by cite {shao06} using a hedging point policy. This solution requires the calculation of a central curve that divides the different ordering regions and a vector that defines the target inventory levels. The central curve is a nonlinear curve that determines the optimal order quantities as a function of the initial inventory levels. In this paper we propose a method for calculating this curve and vector using spline functions, infinitesimal perturbation analysis (IPA), and convex optimization. Using IPA the derivatives of the cost with respect to …
Feasibility Of Tcp For Wireless Mesh Networks, Richard Lloyd Lee
Feasibility Of Tcp For Wireless Mesh Networks, Richard Lloyd Lee
Theses and Dissertations
When used in a wireless mesh network, TCP has shortcomings in the areas of throughput and fairness among traffic flows. Several methods have been proposed to deal with TCP's weakness in a wireless mesh, but most have been evaluated with simulations rather than experimentally. We evaluate several major enhancements to TCP – pacing, conservative windows, and delayed ACKs – to determine whether they improve performance or fairness in a mesh network operating in the BYU Computer Science building. We also draw conclusions about the effectiveness of wireless network simulators based on the accuracy of reported simulation results.
Using Agent-Based Models To Understand Multi-Operator Supervisory Control, Yisong Guo
Using Agent-Based Models To Understand Multi-Operator Supervisory Control, Yisong Guo
Theses and Dissertations
As technology advances, many practical applications require human-controlled robots. For such applications, it is useful to determine the optimal number of robots an operator should control to maximize human efficiency given different situations. One way to achieve this is through computer simulations of team performance. In order to factor in various parameters that may affect team performance, an agent-based model will be used. Agent-based modeling is a computational method that enables a researcher to create, analyze, and experiment with models composed of agents that interact within an environment [12]. We construct an agent-based model of humans interacting with robots, and …
Analysis And Characterization Of Author Contribution Patterns In Open Source Software Development, Quinn Carlson Taylor
Analysis And Characterization Of Author Contribution Patterns In Open Source Software Development, Quinn Carlson Taylor
Theses and Dissertations
Software development is a process fraught with unpredictability, in part because software is created by people. Human interactions add complexity to development processes, and collaborative development can become a liability if not properly understood and managed. Recent years have seen an increase in the use of data mining techniques on publicly-available repository data with the goal of improving software development processes, and by extension, software quality. In this thesis, we introduce the concept of author entropy as a metric for quantifying interaction and collaboration (both within individual files and across projects), present results from two empirical observational studies of open-source …
Commit Patterns And Threats To Validity In Analysis Of Open Source Software Repositories, Alexander Curtis Maclean
Commit Patterns And Threats To Validity In Analysis Of Open Source Software Repositories, Alexander Curtis Maclean
Theses and Dissertations
In the course of studying the effects of programming in multiple languages, we unearthed troubling trends in SourceForge artifacts. Our initial studies suggest that programming in multiple languages concurrently negatively affects developer productivity. While addressing our initial question of interest, we discovered a pattern of monolithic commits in the SourceForge community. Consequently, we also report on the effects that this pattern of commits can have when using SourceForge as a data-source for temporal analysis of open source projects or for studies of individual developers.
Computer Aided Geometric Design, Thomas W. Sederberg
Computer Aided Geometric Design, Thomas W. Sederberg
Faculty Publications
This semester is the twenty-fourth time I have taught a course at Brigham Young University titled, "Computer Aided Geometric Design." When I first taught such a course in 1983, the field was young enough that no textbook covered everything that I wanted to teach, and so these notes evolved. The field now has matured to the point that several semesters worth of valuable material could be compiled. These notes, admittedly biased towards my own interests, reflect my personal preferences as to which of that material is most beneficial to students in an introductory course. I welcome anyone who has an …
A Synthetic Document Image Dataset For Developing And Evaluating Historical Document Processing Methods, Daniel Walker, William Lund, Eric Ringger
A Synthetic Document Image Dataset For Developing And Evaluating Historical Document Processing Methods, Daniel Walker, William Lund, Eric Ringger
Faculty Publications
Document images accompanied by OCR output text and ground truth transcriptions are useful for developing and evaluating document recognition and processing methods, especially for historical document images. Additionally, research into improving the performance of such methods often requires further annotation of training and test data (e.g., topical document labels). However, transcribing and labeling historical documents is expensive. As a result, existing real-world document image datasets with such accompanying resources are rare and often relatively small. We introduce synthetic document image datasets of varying levels of noise that have been created from standard (English) text corpora using an existing document degradation …
A General Model For Continuous Noninvasive Pulmonary Artery Pressure Estimation, Robert Anthony Smith
A General Model For Continuous Noninvasive Pulmonary Artery Pressure Estimation, Robert Anthony Smith
Theses and Dissertations
Elevated pulmonary artery pressure (PAP) is a significant healthcare risk. Continuous monitoring for patients with elevated PAP is crucial for effective treatment, yet the most accurate method is invasive and expensive, and cannot be performed repeatedly. Noninvasive methods exist but are inaccurate, expensive, and cannot be used for continuous monitoring. We present a machine learning model based on heart sounds that estimates pulmonary artery pressure with enough accuracy to exclude an invasive diagnostic operation, allowing for consistent monitoring of heart condition in suspect patients without the cost and risk of invasive monitoring. We conduct a greedy search through 38 possible …
Framework To Secure Cloud-Based Medical Image Storage And Management System Communications, Timothy James Rostrom
Framework To Secure Cloud-Based Medical Image Storage And Management System Communications, Timothy James Rostrom
Theses and Dissertations
Picture Archiving and Communication Systems (PACS) have been traditionally constrained to the premises of the healthcare provider. This has limited the availability of these systems in many parts of the world and mandated major costs in infrastructure for those who employ them. Public cloud services could be a solution that eases the cost of ownership and provides greater flexibility for PACS implementations. This could make it possible to bring medical imaging services to places where it was previously unavailable and reduce the costs associated with these services for those who utilize them. Moving these systems to public cloud infrastructure requires …
A Speculative Approach To Parallelization In Particle Swarm Optimization, Matthew Gardner, Andrew Mcnabb, Kevin Seppi
A Speculative Approach To Parallelization In Particle Swarm Optimization, Matthew Gardner, Andrew Mcnabb, Kevin Seppi
Faculty Publications
Particle swarm optimization (PSO) has previously been parallelized primarily by distributing the computation corresponding to particles across multiple processors. In these approaches, the only benefit of additional processors is an increased swarm size. However, in many cases this is not efficient when scaled to very large swarm sizes (on very large clusters). Current methods cannot answer well the question: “How can 1000 processors be fully utilized when 50 or 100 particles is the most efficient swarm size?” In this paper we attempt to answer that question with a speculative approach to the parallelization of PSO that we refer to as …
Quality Selection For Dynamic Adaptive Streaming Over Http With Scalable Video Coding, Travis L. Andelin
Quality Selection For Dynamic Adaptive Streaming Over Http With Scalable Video Coding, Travis L. Andelin
Theses and Dissertations
Video streaming on the Internet is increasingly using Dynamic Adaptive Streaming over HTTP (DASH), in which the video is converted into various quality levels and divided into two-second segments. A client can then adjust its video quality over time by choosing to download the appropriate quality level for a given segment using standard HTTP. Scalable Video Coding (SVC) is a promising enhancement to the DASH protocol. With SVC, segments are divided into subset bitstream blocks. At playback, blocks received for a given segment are combined to additively increase the current quality. Unlike traditional DASH, which downloads segments serially, this encoding …
Fast Spheroidal Weathering With Colluvium Deposition, Mckay T. Farley
Fast Spheroidal Weathering With Colluvium Deposition, Mckay T. Farley
Theses and Dissertations
It can be difficult to quickly and easily create realistic sandstone terrain. Film makers often need to generate realistic terrain for establishing the setting of their film. Many methods have been created which address terrain generation. One such method is using heightmaps which encode height as a gray-value in a 2d image. Most terrain generation techniques don't admit concavities such as overhangs and arches. We present an algorithm that operates on a voxel grid for creating 3d terrain. Our algorithm uses curvature estimation to weather away the terrain. We speed up our method using a caching mechanism that stores the …
Carry And Expand: A New Nomadic Interaction Paradigm, Richard B. Arthur
Carry And Expand: A New Nomadic Interaction Paradigm, Richard B. Arthur
Theses and Dissertations
People are nomadic; traveling from place to place. As a user travels, he may need access to his digital information, including his data, applications, and settings. A convenient way to supply this access is to have the user carry that digital information in a portable computer such as a laptop or smart phone. As Moore's Law continues to operate, devices such as smart phones can easily perform the computing necessary for a user's work. Unfortunately, the amount of data a human can receive and convey through such devices is limited. To receive more information humans require more screen real estate. …
A Foveated System For Wilderness Search And Rescue In Manned Aircraft, Carson D. Fenimore
A Foveated System For Wilderness Search And Rescue In Manned Aircraft, Carson D. Fenimore
Theses and Dissertations
Wilderness search and rescue can be assisted by video searchers in manned aircraft. The video searcher's primary task is to find clues on the ground. Due to altitude, it may be difficult to resolve details on the ground with a standard video camera. As the video streams at a constant frame rate, the searcher may become distracted by other tasks. While handling these tasks the searcher may miss important clues or spend extra time flying over the search area; either outcome decreases both the effectiveness of the video searcher and the chances of successfully finding missing persons. We develop an …
Modeling And Designing Fair Rate Control For Wireless Mesh Networks With Partial Interference, Lei Wang
Modeling And Designing Fair Rate Control For Wireless Mesh Networks With Partial Interference, Lei Wang
Theses and Dissertations
Internet rate control protocols, such as TCP, encounter severe performance problems in wireless mesh networks. Because wireless networks use shared communication channels, contention and interference can significantly degrade flow throughput and fairness. Existing research takes either an engineering-based or optimization-based approach to solve the performance problems. The engineering-based approach usually solves a specific observed problem, but does not necessarily optimize the overall performance. The optimization-based approach mathematically models the network to find the optimal resource allocation among competing flows. The model can lead to a distributed rate control algorithm with performance guarantees, but relatively little work has been done to …
Improving Multi-Label Classification By Avoiding Implicit Negativity With Incomplete Data, Derrall L. Heath
Improving Multi-Label Classification By Avoiding Implicit Negativity With Incomplete Data, Derrall L. Heath
Theses and Dissertations
Many real world problems require multi-label classification, in which each training instance is associated with a set of labels. There are many existing learning algorithms for multi-label classification; however, these algorithms assume implicit negativity, where missing labels in the training data are automatically assumed to be negative. Additionally, many of the existing algorithms do not handle incremental learning in which new labels could be encountered later in the learning process. A novel multi-label adaptation of the backpropagation algorithm is proposed that does not assume implicit negativity. In addition, this algorithm can, using a naive Bayesian approach, infer missing labels in …
Hykss: Hybrid Keyword And Semantic Search, Andrew J. Zitzelberger
Hykss: Hybrid Keyword And Semantic Search, Andrew J. Zitzelberger
Theses and Dissertations
The rapid production of digital information makes the task of locating relevant information increasingly difficult. Keyword search alleviates this difficulty by retrieving documents containing keywords of interest. However, keyword search suffers from a number of issues such ambiguity, synonymy, and the inability to handle semantic constraints. Semantic search helps resolve these issues but is limited by the quality of annotations which are likely to be incomplete or imprecise. Hybrid search, a search technique that combines the merits of both keyword and semantic search, appears to be a promising solution. In this work we introduce HyKSS, a hybrid search system driven …
Fast Relabeling Of Deformable Delaunay Tetrahedral Meshes Using A Compact Uniform Grid, David C. Frogley
Fast Relabeling Of Deformable Delaunay Tetrahedral Meshes Using A Compact Uniform Grid, David C. Frogley
Theses and Dissertations
We address the problem of fast relabeling of deformable Delaunay tetrahedral meshes using a compact uniform grid, with CPU parallelization through OpenMP. This problem is important in visualizing the simulation of deformable objects and arises in scientific visualization, games, computer vision, and motion picture production. Many existing software tools and APIs have the ability to manipulate 3D virtual objects. Prior mesh-based representations either allow topology changes or are fast. We aim for both. Specifically, we improve the efficiency of the relabeling step in the Delaunay deformable mesh invented by Pons and Boissonnat and improved by Tychonievich and Jones. The relabeling …
Modeling Wireless Networks For Rate Control, David C. Ripplinger
Modeling Wireless Networks For Rate Control, David C. Ripplinger
Theses and Dissertations
Congestion control algorithms for wireless networks are often designed based on a model of the wireless network and its corresponding network utility maximization (NUM) problem. The NUM problem is important to researchers and industry because the wireless medium is a scarce resource, and currently operating protocols such as 802.11 often result in extremely unfair allocation of data rates. The NUM approach offers a systematic framework to build rate control protocols that guarantee fair, optimal rates. However, classical models used with the NUM approach do not incorporate partial carrier sensing and interference, which can lead to significantly suboptimal performance when actually …
Naive Bayesian Spam Filters For Log File Analysis, Russel William Havens
Naive Bayesian Spam Filters For Log File Analysis, Russel William Havens
Theses and Dissertations
As computer system usage grows in our world, system administrators need better visibility into the workings of computer systems, especially when those systems have problems or go down. Most system components, from hardware, through OS, to application server and application, write log files of some sort, be it system-standardized logs such syslog or application specific logs. These logs very often contain valuable clues to the nature of system problems and outages, but their verbosity can make them difficult to utilize. Statistical data mining methods could help in filtering and classifying log entries, but these tools are often out of the …
Experimental Performance Evaluation Of Atp (Ad-Hoc Transport Protocol) In A Wireless Mesh Network, Xingang Zhang
Experimental Performance Evaluation Of Atp (Ad-Hoc Transport Protocol) In A Wireless Mesh Network, Xingang Zhang
Theses and Dissertations
It is well known that TCP performs poorly in wireless mesh networks. There has been intensive research in this area, but most work uses simulation as the only evaluation method; however, it is not clear whether the performance gains seen with simulation will translate into benefits on real networks. To explore this issue, we have implemented ATP (Ad-hoc Transport Protocol), a transport protocol designed specifically for wireless ad hoc networks. We have chosen ATP because it uses a radically different design from TCP and because reported results claim significant improvement over TCP. We show how ATP must be modified in …
Rendering Realistic Cloud Effects For Computer Generated Films, Cory A. Reimschussel
Rendering Realistic Cloud Effects For Computer Generated Films, Cory A. Reimschussel
Theses and Dissertations
This work addresses the problem of rendering clouds. The task of rendering clouds is important to film and video game directors who want to use clouds to further the story or create a specific atmosphere for the audience. While there has been significant progress in this area, other solutions to this problem are inadequate because they focus on speed instead of accuracy, or focus only on a few specific properties of rendered clouds while ignoring others. Another common shortcoming with other methods is that they are not integrated into existing rendering pipelines. We propose a solution to this problem based …
A Study Analyzing Five Instructional Methods For Teaching Software To Junior High Students, Scott Ronald Bartholomew
A Study Analyzing Five Instructional Methods For Teaching Software To Junior High Students, Scott Ronald Bartholomew
Theses and Dissertations
If you ask 5 different teachers what the best way to teach a new technology to a student is you will get 5 different answers. (Bork, 2001; Cheong, 2008; Egal, 2009; Howell, 2001) What is the best way to teach a new computer software application to a student? In the technological world we live in today the effective transfer of technological knowledge is paramount. With varying opinions even among the leaders of national technology teacher associations (Haynie, 2005) there is a large level of ambiguity in relation to best practices in technology teaching. This study evaluates five commonly used methods …
Flexible Storylines, Ivan Dmitrievich Romashka
Flexible Storylines, Ivan Dmitrievich Romashka
Theses and Dissertations
A long-standing goal of computer-based entertainment is the creation of a story where a user is in control of portions of the storyline. These non-linear stories give a user an opportunity to adapt the story to his or her interests, schedule and needs. The Internet has made non-linear video a reality. Different approaches have been taken to create and play non-linear video stories. They suffer from lack of simplicity, smoothness, and television-like experience in story creation and presentation. Flexible Storylines provide a way to easily create and present non-linear video stories. The creation of these stories is done using a …