Physical Sciences and Mathematics Commons^™

Improving Virtual Machine I/O Performance In Cloud Environments Via I/O Functionality Offloading, Sahan Bamunavita Gamage

Open Access Dissertations

In recent years there has been a rapid growth in the adoption of cloud computing. A key technology that drives cloud computing is virtualization. In addition to enabling multi-tenancy in cloud environments, virtualizing hosts in the cloud environments has made management of hardware resources increasingly flexible. An important consequence of virtualizing hosts in the cloud is the negative impact it has on the I/O performance of the applications running in the virtual machines.

In this dissertation, we address the important problem of alleviating the negative impact of virtualization on I/O of the virtual machines. First, we show that virtual machine …

Reasoning Across Language And Vision In Machines And Humans, Andrei Barbu

Open Access Dissertations

Humans not only outperform AI and computer-vision systems, but use an unknown computational mechanism to perform tasks for which no suitable approaches exist. I present work investigating both novel tasks and how humans approach them in the context of computer vision and linguistics. I demonstrate a system which, like children, acquires high-level linguistic knowledge about the world. Robots learn to play physically-instantiated board games and use that knowledge to engage in physical play. To further integrate language and vision I develop an approach which produces rich sentential descriptions of events depicted in videos. I then show how to simultaneously detect …

Improving Reuse In Software Development For The Life Sciences, Nicholas Vincent Iannotti

Open Access Dissertations

The last several years have seen unprecedented advancements in the application of technology to the life sciences, particularly in the area of data generation. Novel scientific insights are now often driven primarily by software development supporting new multidisciplinary and increasingly multifaceted data analysis. However, despite the availability of tools such as best practice frameworks, the current rate of software development is not able to keep up with the needs of scientists. This bottleneck in software development is largely due to code reuse generally not being applied in practice.

This dissertation presents Legwork, a class library of reuse-optimized design pattern implementations …

Response Of Plasma Facing Components In Tokamaks Due To Intense Energy Deposition Using Particle-In-Cell(Pic) Methods, Filippo Genco

Open Access Dissertations

Damage to plasma-facing components (PFC) due to various plasma instabilities is still a major concern for the successful development of fusion energy and represents a significant research obstacle in the community. It is of great importance to fully understand the behavior and lifetime expectancy of PFC under both low energy cycles during normal events and highly energetic events as disruptions, Edge-Localized Modes (ELM), Vertical Displacement Events (VDE), and Run-away electron (RE). The consequences of these high energetic dumps with energy fluxes ranging from 10 MJ/m2 up to 200 MJ/m2 applied in very short periods (0.1 to 5 ms) can be …

Mispronunciation Detection For Language Learning And Speech Recognition Adaptation, Zhenhao Ge

Open Access Dissertations

The areas of "mispronunciation detection" (or "accent detection" more specifically) within the speech recognition community are receiving increased attention now. Two application areas, namely language learning and speech recognition adaptation, are largely driving this research interest and are the focal points of this work.

There are a number of Computer Aided Language Learning (CALL) systems with Computer Aided Pronunciation Training (CAPT) techniques that have been developed. In this thesis, a new HMM-based text-dependent mispronunciation system is introduced using text Adaptive Frequency Cepstral Coefficients (AFCCs). It is shown that this system outperforms the conventional HMM method based on Mel Frequency Cepstral …

Enabling Richer Insight Into Runtime Executions Of Systems, Karthik Swaminathan Nagaraj

Open Access Dissertations

Systems software of very large scales are being heavily used today in various important scenarios such as online retail, banking, content services, web search and social networks. As the scale of functionality and complexity grows in these software, managing the implementations becomes a considerable challenge for developers, designers and maintainers. Software needs to be constantly monitored and tuned for optimal efficiency and user satisfaction. With large scale, these systems incorporate significant degrees of asynchrony, parallelism and distributed executions, reducing the manageability of software including performance management. Adding to the complexity, developers are under pressure between developing new functionality for customers …

Impact Of Network Protocols On Data Center Applications, Pawan Prakash

Open Access Dissertations

Data centers containing hundreds of thousands of servers have become the foundation of modern computing infrastructures. Enterprises are increasingly deploying new applications and moving existing applications to these large-scale data centers. These networked applications communicate via a set of conventional network protocols, which were originally designed for wide area networks. In this dissertation, we study the impact of different networking layer protocols on the performance of data center applications.

At the transport layer, we observe that bandwidth sharing via TCP in commodity data center networks, which are organized in multi-rooted tree topologies, can lead to severe unfairness under many common …

Improved Kernel Security Through Code Validation, Diversification, And Minimization, Dannie Michael Stanley

Open Access Dissertations

The vast majority of hosts on the Internet, including mobile clients, are running one of three commodity, general-purpose operating system families. In such operating systems the kernel software executes at the highest processor privilege level. If an adversary is able to hijack the kernel software then by extension he has full control of the system. This control includes the ability to disable protection mechanisms and hide evidence of compromise.

The lack of diversity in commodity, general-purpose operating systems enables attackers to craft a single kernel exploit that has the potential to infect millions of hosts. If enough variants of the …

Scholarly Collaboration In Engineering Education: From Big-Data Scientometrics To User-Centered Software Design, Hanjun Xian

Open Access Dissertations

Engineering education research has grown into a flourishing community with an-ever increasing number of publications and scholars. However, recent studies show that a significant amount of engineering education knowledge retains a clear disciplinary orientation. If the gaps in scholarly collaboration continue to be prevalent within the entire community, it will become increasingly difficult to sustain community memory. This will eventually inhibit the propagation of innovations and slow the movement of research findings into practice.

This dissertation studies scholarly collaboration in the engineering education research community. It provides a clear characterization of collaboration problems and proposes potential solutions. The dissertation is …

Dependence-Based Source Level Tracing And Replay For Networked Embedded Systems, Man Wang

Open Access Dissertations

Error detection and diagnosis for networked embedded systems remain challenging and tedious due to issues such as a large number of computing entities, hardware resource constraints, and non-deterministic behaviors. The run-time checking is often necessitated by the fact that the static verification fails whenever there exist conditions unknown prior to execution. Complexities in hardware, software and even the operating environments can also defeat the static analysis and simulations. Record-and-replay has long been proposed for distributed systems error diagnosis. Under this method, assertions are inserted in the target program for run-time error detection. At run-time, the violation of any asserted property …

Predictive Duty Cycling Of Radios And Cameras Using Augmented Sensing In Wireless Camera Networks, Joonhwa Shin

Open Access Dissertations

Energy efficiency dominates practically every aspect of the design of wireless camera networks (WCNs), and duty cycling of radios and cameras is an important tool for achieving high energy efficiencies. However, duty cycling in WCNs is made complex by the camera nodes having to anticipate the arrival of the objects in their field-of-view. What adds to this complexity is the fact that radio duty cycling and camera duty cycling are tightly coupled notions in WCNs.

Abstract In this dissertation, we present a predictive framework to provide camera nodes with an ability to anticipate the arrival of an object in the …

Automated Failure Explanation Through Execution Comparison, William Nicholas Sumner

Open Access Dissertations

When fixing a bug in software, developers must build an understanding or explanation of the bug and how the bug flows through a program. The effort that developers must put into building this explanation is costly and laborious. Thus, developers need tools that can assist them in explaining the behavior of bugs. Dynamic slicing is one technique that can effectively show how a bug propagates through an execution up to the point where a program fails. However, dynamic slices are large because they do not just explain the bug itself; they include extra information that explains any observed behavior that …

Control-Theoretic Decision Support For Mitigation Of Modeled Software Project Cost Overruns, Scott David Miller

Open Access Dissertations

Despite sixty years of practice, the production of software remains an endeavor that is difficult to manage according to a schedule. Control theory studies the ability to influence the dynamical behavior of systems to achieve desired behaviors or eliminate undesired behaviors. In this work, the management problem of software project schedule adherence is re-cast as a problem in control theory.

Below, a modeling framework is proposed for capturing the constraints and dependencies found in the arbitrary organization specific work-flows underlying software production. Combined with proposed models for productivity, defect introduction, and defect detection, the framework completes a method for producing …

Methods For Increasing Domains Of Convergence In Iterative Linear System Solvers, David Michael Imberti

Open Access Dissertations

In this thesis, we introduce and improve various methods for increasing the domains of convergence for iterative linear system solvers. We rely on the following three approaches: making the iteration adaptive, or nesting an inner iteration inside of a previously determined outer iteration; using deflation and projections to manipulate the spectra inherent to the iteration; and/or focusing on reordering schemes. We will analyze a specific combination of these three strategies. In particular, we propose to examine the influence of nesting a Flexible Generalized Minimum Residual algorithm together with an inner Recursive Projection Method using a banded preconditioner resulting from the …

Ribbons: A Partially Shared Memory Programming Model, Kevin John Hoffman

Open Access Dissertations

The need for programs to execute subcomponents in isolation from each other or with lower privileges is prevalent among today's systems. While modern operating systems provide mechanisms for fine-grained isolation of OS resources, only course-grained mechanisms exist for efficient isolation of heap memory. This dissertation develops a new memory programming model known as ribbons to enable fine-grained isolation of heap memory. Ribbons is a shared memory programming model that allows for more implicit sharing of memory than multiprocessing yet is more restrictive than multithreading. The ribbons model hierarchically structures the heap into protection domains. Privileges between these protection domains are …

Cloud To Cloud Registration For 3d Point Data, Darion Shawn Grant

Open Access Dissertations

The vast potential of digital representation of objects by large collections of 3D points is being recognized on a global scale and has given rise to the popularity of point cloud data (PCD). 3D imaging sensors provide a means for quickly capturing dense and accurate geospatial information that represent the 3D geometry of objects in a digital environment. Due to spatial and temporal constraints, it is quite common that two or more sets of PCD are obtained to provide full 3D analysis. It is therefore quite essential that all the PCD are referenced to a homogeneous coordinate frame of reference. …

Simulating Land Use Land Cover Change Using Data Mining And Machine Learning Algorithms, Amin Tayyebi

Open Access Dissertations

The objectives of this dissertation are to: (1) review the breadth and depth of land use land cover (LUCC) issues that are being addressed by the land change science community by discussing how an existing model, Purdue's Land Transformation Model (LTM), has been used to better understand these very important issues; (2) summarize the current state-of-the-art in LUCC modeling in an attempt to provide a context for the advances in LUCC modeling presented here; (3) use a variety of statistical, data mining and machine learning algorithms to model single LUCC transitions in diverse regions of the world (e.g. United States …

Information Measures For Statistical Orbit Determination, Alinda Kenyana Mashiku

Open Access Dissertations

The current Situational Space Awareness (SSA) is faced with a huge task of tracking the increasing number of space objects. The tracking of space objects requires frequent and accurate monitoring for orbit maintenance and collision avoidance using methods for statistical orbit determination. Statistical orbit determination enables us to obtain estimates of the state and the statistical information of its region of uncertainty given by the probability density function (PDF). As even collision events with very low probability are important, accurate prediction of collisions require the representation of the full PDF of the random orbit state. Through representing the full PDF …