Computer Engineering Commons^™

Parametric Reliability Of Space-Based Field Programmable Gate Arrays, Joseph C. Pomager

Theses and Dissertations

The high cost of failure for microelectronic devices operating in the space environment has led to a need for an accurate characterization of a device's reliability prior to being deployed. In addition, significant cost savings can be achieved by determining this reliability prior to fabrication. With the increased performance needs required for many missions, designers are seeking to utilize devices that have smaller and smaller feature sizes. Specifically, feature sizes as small as 130, 90, and 65 nm. A characterization of the space environment is constructed specifically to address the extreme conditions that can affect the performance and functionality of …

Hardware Virtualization Applied To Rootkit Defense, Douglas P. Medley

Theses and Dissertations

This research effort examines the idea of applying virtualization hardware to enhance operating system security against rootkits. Rootkits are sets of tools used to hide code and/or functionality from the user and operating system. Rootkits can accomplish this feat through using access to one part of an operating system to change another part that resides at the same privilege level. Hardware assisted virtualization (HAV) provides an opportunity to defeat this tactic through the introduction of a new operating mode. Created to aid operating system virtualization, HAV provides hardware support for managing and saving multiple states of the processor. This hardware …

Implementation And Optimization Of The Advanced Encryption Standard Algorithm On An 8-Bit Field Programmable Gate Array Hardware Platform, Ryan J. Silva

Theses and Dissertations

The contribution of this research is three-fold. The first is a method of converting the area occupied by a circuit implemented on a Field Programmable Gate Array (FPGA) to an equivalent as a measure of total gate count. This allows direct comparison between two FPGA implementations independent of the manufacturer or chip family. The second contribution improves the performance of the Advanced Encryption Standard (AES) on an 8-bit computing platform. This research develops an AES design that occupies less than three quarters of the area reported by the smallest design in current literature as well as significantly increases area efficiency. …

Using Concept Maps To More Efficiently Create Intelligence Information Models, Christopher E. Coryell

Theses and Dissertations

Information models are a critical tool that enables intelligence customers to quickly and accurately comprehend U.S. intelligence agency products. The Knowledge Pre-positioning System (KPS) is the standard repository for information models at the National Air and Space Intelligence Center (NASIC). The current approach used by NASIC to build a KPS information model is laborious and costly. Intelligence analysts design an information model using a manual, butcher-paper-based process. The output of their work is then entered into KPS by either a single NASIC KPS "database modeler" or a contractor (at a cost of roughly $100K to the organization). This thesis proposes …

Exploring Hardware Based Primitives To Enhance Parallel Security Monitoring In A Novel Computing Architecture, Stephen D. Mott

Theses and Dissertations

This research explores how hardware-based primitives can be implemented to perform security-related monitoring in real-time, offer better security, and increase performance compared to software-based approaches. In doing this, we propose a novel computing architecture, derived from a contemporary shared memory architecture, that facilitates efficient security-related monitoring in real-time, while keeping the monitoring hardware itself safe from attack. This architecture is flexible, allowing security to be tailored based on the needs of the system. We have developed a number of hardware-based primitives that fit into this architecture to provide a wide array of monitoring capabilities. A number of these primitives provide …

A Study Of Rootkit Stealth Techniques And Associated Detection Methods, Daniel D. Nerenberg

Theses and Dissertations

In today's world of advanced computing power at the fingertips of any user, we must constantly think of computer security. Information is power and this power is had within our computer systems. If we cannot trust the information within our computer systems then we cannot properly wield the power that comes from such information. Rootkits are software programs that are designed to develop and maintain an environment in which malware may hide on a computer system after successful compromise of that computer system. Rootkits cut at the very foundation of the trust that we put in our information and subsequent …

Distributed Fault-Tolerant Quality Of Service Routing In Hybrid Directional Wireless Networks, Larry C. Llewellyn Ii

Theses and Dissertations

This thesis presents a distributed fault-tolerant routing protocol (EFDCB) for QoS supporting hybrid mobile ad hoc networks with the aim of mitigating QoS disruption time when network failures occur. The experimental design presented in this thesis describes 22 experiments aimed at illustrating EFDCB's ability to handle fault-tolerance. The interpreted results show that EFDCB excels over a global rerouting protocol at this challenge which is the goal of this work.

Effective Mobile Routing Through Dynamic Addressing, Heungsoon Park

Theses and Dissertations

Military communications has always been an important factor in military victory and will surely play an important part in future combat. In modern warfare, military units are usually deployed without existing network infrastructure. The IP routing protocol, designed for hierarchical networks cannot easily be applied in military networks due to the dynamic topology expected in military environments. Mobile ad-hoc networks (MANETs) represent an appropriate network for small military networks. But, most ad-hoc routing protocols suffer from the problem of scalability for large networks. Hierarchical routing schemes based on the IP address structure are more scalable than ad-hoc routing but are …

Random Test Data Generation For Java Classes Annotated With Jml Specifications, Yoonsik Cheon, Carlos E. Rubio-Medrano

Departmental Technical Reports (CS)

The hidden states of objects create a barrier to designing and generating test data automatically. For example, the state of an object has to be established indirectly through a sequence of method invocations. For a non-trivial class, however, it is extremely unlikely that a randomly-chosen sequence of method invocations can construct an object successfully, as each invocation has to satisfy the state invariants. Nonetheless, automated random testing can reduce the cost of testing dramatically and has potential for finding errors that are difficult to find in other ways because it eliminates the subjectiveness in constructing test data. We propose a …

Interval Approach To Preserving Privacy In Statistical Databases: Related Challenges And Algorithms Of Computational Statistics, Luc Longpre, Gang Xiang, Vladik Kreinovich, Eric Freudenthal

Departmental Technical Reports (CS)

In many practical situations, it is important to store large amounts of data and to be able to statistically process the data. A large part of the data is confidential, so while we welcome statistical data processing, we do not want to reveal sensitive individual data. If we allow researchers to ask all kinds of statistical queries, this can lead to violation of people's privacy. A sure-proof way to avoid these privacy violations is to store ranges of values (e.g., between 40 and 50 for age) instead of the actual values. This idea solves the privacy problem, but it leads …

Three Prosodic Features That Cue Back-Channel Feedback In Northern Mexican Spanish, Anais G. Rivera, Nigel G. Ward

Departmental Technical Reports (CS)

In order to demonstrate attentiveness during a conversation it is generally necessary for the listener to provide back-channel feedback. To some extent, the times when back-channel feedback is welcome are determined by the speaker and conveyed to the listener with prosodic cues. In this study we sought to identify the cues used for this purpose in Northern Mexican Spanish. Based on quantitative analysis of a corpus of unstructured conversations, we found three cues, of which the most common is a pitch downslope followed by a pitch rise accompanied by a rate reduction on the last syllable and a drop in …

On Decision Making Under Interval Uncertainty: A New Justification Of Hurwicz Optimism-Pessimism Approach And Its Use In Group Decision Making, Van Nam Huynh, Chenyi Hu, Yoshiteru Nakamori, Vladik Kreinovich

Departmental Technical Reports (CS)

If we know the exact consequences of each action, then we can select an action with the largest value of the objective function. In practice, we often only know these values with interval uncertainty. If two intervals intersect, then some people may prefer the alternative corresponding to the first interval, and some prefer the alternative corresponding to the second interval. How can we describe the portion of people who select the first alternative? In this paper, we provide a new theoretical justification for Hurwicz optimism-pessimism approach, and we show how this approach can be used in group decision making.

On-Demand Key Distribution For Mobile Ad-Hoc Networks, Daniel F. Graham

Theses and Dissertations

Mobile ad-hoc networks offer dynamic portable communication with little or no infrastructure. While this has many benefits, there are additional shortcomings specific to wireless communication that must be addressed. This research proposes gossip-based on-demand key distribution as a means to provide data encryption for mobile ad-hoc networks. This technique uses message keys to avoid encrypting and decrypting a message at every node. Other optimizations used include secure channel caching and joint rekey messages. The use of gossip makes the scheme robust to node failure. Experimental results show only a 15% increase in end-to-end delay with a node failure rate of …

Overcoming Tcp Degradation In The Presence Of Multiple Intermittent Link Failures Utilizing Intermediate Buffering, Duane F. Harmon

Theses and Dissertations

It is well documented that assumptions made in the popular Transmission Control Protocol's (TCP) development, while essential in the highly reliable wired environment, are incompatible with today's wireless network realities in what we refer to as a challenged environment. Challenged environments severely degrade the capability of TCP to establish and maintain a communication connection with reasonable throughput. This thesis proposes and implements an intermediate buffering scheme, implemented at the transport layer, which serves as a TCP helper protocol for use in network routing equipment to overcome short and bursty, but regular, link failures. Moreover, the implementation requires no modifications to …

Hardware Realization Of A Transform Domain Communication System, Marshall E. Haker

Theses and Dissertations

The purpose of this research was to implement a Transform Domain Communication System (TDCS) in hardware and compare experimental bit error performance with results published in literature. The intent is to demonstrate the effectiveness or ineffectiveness of a TDCS in communicating binary data across a real channel. In this case, an acoustic channel that is laden with narrowband interference was considered. A TDCS user pair was constructed to validate the proposed design using Matlab™ to control a PC sound card. The proposed TDCS design used the Bartlett method of spectrum estimation, the spectral notching algorithm found in TDCS literature, quadrature …

Lightweight Error Correction Coding For System-Level Interconnects, Jason D. Bakos, Donald M. Chiarulli, Steven P. Levitan

Faculty Publications

"Lightweight hierarchical error control coding (LHECC)" is a new class of nonlinear block codes that is designed to increase noise immunity and decrease error rate for high-performance chip-to-chip and on-chip interconnects. LHECC is designed such that its corresponding encoder and decoder logic may be tightly integrated into compact, high-speed, and low-latency I/O interfaces. LHECC operates over a new channel technology called multi-bit differential signaling (MBDS). MBDS channels utilize a physical-layer channel code called "N choose M (nCm)" encoding, where each channel is restricted to a symbol set such that half of the bits in each symbol are set to one. …

Performance Evaluation Of Ad Hoc Routing In A Swarm Of Autonomous Aerial Vehicles, Matthew T. Hyland

Theses and Dissertations

This thesis investigates the performance of three mobile ad hoc routing protocols in the context of a swarm of autonomous unmanned aerial vehicles (UAVs). It is proposed that a wireless network of nodes having an average of 5.1774 log n neighbors, where n is the total number of nodes in the network, has a high probability of having no partitions. By decreasing transmission range while ensuring network connectivity, and implementing multi-hop routing between nodes, spatial multiplexing is exploited whereby multiple pairs of nodes simultaneously transmit on the same channel. The proposal is evaluated using the Greedy Perimeter Stateless Routing (GPSR), …

Analysis Of Routing Worm Infection Rates On An Ipv4 Network, James Gorsuch

Theses and Dissertations

Malicious logic, specifically worms, has caused monetary expenditure problems to network users in the past. Worms, like Slammer and Code Red, have infected thousands of systems and brought the Internet to a standstill. This research examines the ability of the original Slammer worm, the Slammer based routing worm proposed by Zou et al, and a new Single Slash Eight (SSE) routing worm proposed by this research to infect vulnerable systems within a given address space. This research investigates the Slammer worm's ability to generate a uniform random IP addresses in a given address space. Finally, a comparison of the speed …

A Compositional Approach To Asynchronous Design Verification With Automated State Space Reduction, Jared Ahrens

USF Tampa Graduate Theses and Dissertations

Model checking is the most effective means of verifying the correctness of asynchronous designs, and state space exploration is central to model checking. Although model checking can achieve very high verification coverage, the high degree of concurrency in asynchronous designs often leads to state explosion during state space exploration. To inhibit this explosion, our approach builds on the ideas of compositional verification. In our approach, a design modeled in a high level description is partitioned into a set of parallel components. Before state space exploration, each component is paired with an over-approximated environment to decouple it from the rest of …

Performance Evaluation For Hybrid Architectures, Praveen Krishnamurthy

All Computer Science and Engineering Research

In this dissertation we discuss methologies for estimating the performance of applications on hybrid architectures, systems that include various types of computing resources (e.g. traditional general-purpose processors, chip multiprocessors, reconfigurable hardware). A common use of hybrid architectures will be to deploy coarse pipeline stages of application on "suitable" compute units with communication path for transferring data. The first problem we focus on relates to the sizing the data queues between the different processing elements of an hybrid system. Much of the discussion centers on our analytical models that can be used to derive performance metrics of interest such as, throughput …

Russian Peasant Multiplication Algorithm, Rsa Cryptosystem, And A New Explanation Of Half-Orders Of Magnitude, J. Ivan Vargas, Olga Kosheleva

Departmental Technical Reports (CS)

In his papers, J. Hobbs has observed that when people make crude estimates, they usually feel reasonably comfortable choosing between alternatives which differ by a half order of magnitude (HOM). He also provided an explanation for this level of granularity based on the need for the resulting crude estimates to represent both the original data and the result of processing this data. According to this explanation, HOM are optimal -- when we limit ourselves to these first crude estimates.

In many practical situations, we do not stop with the original estimate, we refine it one or more times by using …

Use Of Deterministic Traffic Assignment Algorithms In Stochastic Networks: Analysis Of Equivalent Link Disutility Functions, Ruey L. Cheu, Vladik Kreinovich

Departmental Technical Reports (CS)

At present, in practice, most traffic assignment tasks are performed by using deterministic network (DN) models, which assume that the link travel time is uniquely determined by the link volume and link capacity. In reality, for the same link volume and link capacity, a link may have different travel times. However, the corresponding stochastic network (SN) models are not widely used because they are much more computationally complex than the DN models. In the past research, it was shown that in the important particular case, when the link travel time follows Gamma distribution, the traffic assignment problem for SN can …

Logit Discrete Choice Model: A New Distribution-Free Justification, Ruey L. Cheu, Hung T. Nguyen, Tanja Magoc, Vladik Kreinovich

Departmental Technical Reports (CS)

According to decision making theory, if we know the user's utility Ui=U(si) of all possible alternatives si, then we can uniquely predict the user's preferences. In practice, we often only know approximate values Vi~Ui of the user's utilities. Based on these approximate values, we can only make probabilistic predictions of the user's preferences. It is empirically known that in many real-life situations, the corresponding probabilities are described by a logit model, in which the probability pi of selecting the alternative si is equal to pi=exp(b*Vi)/(exp(b*V1)+...+exp(b*Vn)). There exist many theoretical explanations of this empirical formula, some of these explanations led to …

Towards A General Description Of Physical Invariance In Category Theory, John Symons, Julio C. Urenda, Vladik Kreinovich

Departmental Technical Reports (CS)

Invariance is one of the most important notions in applications of mathematics. It is one of the key concepts in modern physics, is a computational tool that helps in solving complex equations, etc. In view of its importance, it is desirable to come up with a definition of invariance which is as general as possible. In this paper, we describe how to formulate a general notion of invariance in categorial terms.

A Framework For Requirements Engineering Support For Service Providers, Yohana Saad Soliman Nassim

Archived Theses and Dissertations

No abstract provided.

Mining Generalized Associations Of Semantic Relations From Textual Web Content, Tao Jiang, Ah-Hwee Tan, We Wang

Research Collection School Of Computing and Information Systems

Traditional text mining techniques transform free text into flat bags of words representation, which does not preserve sufficient semantics for the purpose of knowledge discovery. In this paper, we present a two-step procedure to mine generalized associations of semantic relations conveyed by the textual content of Web documents. First, RDF (resource description framework) metadata representing semantic relations are extracted from raw text using a myriad of natural language processing techniques. The relation extraction process also creates a term taxonomy in the form of a sense hierarchy inferred from WordNet. Then, a novel generalized association pattern mining algorithm (GP-Close) is applied …

Segmentation Of Overlapping Particles In Automatic Size Analysis Using Multi-Flash Imaging, Tze K Koh, Nicholas Miles, Steve Morgan, Barrie Hayes-Gill

Research Collection College of Integrative Studies

In this paper, we propose a novel hardware approach to image segmentation, specifically in the case of overlapping particles. Our research is based on multi-flash imaging (MFI), originally developed to detect depth discontinuities. Multiple images captured with different illumination conditions provide additional information about a scene compared to conventional segmentation techniques. Shadows are used to identify true object edges and underlying particles. We applied the new approach in automated particle size analysis and evaluated it against the watershed and canny edge detection techniques. Evaluation results confirm that MFI can be applied in image segmentation and reveals the superiority of the …

Speech Signal Enhancement Through Adaptive Wavelet Thresholding, Michael T. Johnson, Xiaolong Yuan, Yao Ren

Electrical and Computer Engineering Faculty Research and Publications

This paper demonstrates the application of the Bionic Wavelet Transform (BWT), an adaptive wavelet transform derived from a non-linear auditory model of the cochlea, to the task of speech signal enhancement. Results, measured objectively by Signal-to-Noise ratio (SNR) and Segmental SNR (SSNR) and subjectively by Mean Opinion Score (MOS), are given for additive white Gaussian noise as well as four different types of realistic noise environments. Enhancement is accomplished through the use of thresholding on the adapted BWT coefficients, and the results are compared to a variety of speech enhancement techniques, including Ephraim Malah filtering, iterative Wiener filtering, and spectral …

Doppler Spread Estimation In Mobile Fading Channels, Hong Zhang

Dissertations

The Doppler spread, or equivalently, the mobile speed, is a measure of the spectral dispersion of a mobile fading channel. Accurate estimation of the mobile speed is important in wireless mobile applications which require such as knowledge of the rate of channel variations. In this dissertation, first the performance of classical crossing- and covariance-based speed estimators is studied. Next, the problem of mobile speed estimation using diversity combining is investigated. Then, a nonparametric estimation technique is proposed that is robust to different channel variations. Finally, cyclostationarity-based speed estimators which can be applied either blindly or with the aid of pilot …

Non-Repudiation Secure File Transfer Protocol (Nrsftp), Jerry Chen

Theses

Non Repudiation Secure File Transfer Protocol (NRSFTP) is designed to resolve three main concerns for today's electronic file transfer methodology. The three main concerns are Non-Repudiation, Secure, and Non-Real Time file transfer. Non-repudiation is to assure the receiver that the sender of the document is not an imposter. Secure document transfer is to assure the sender that only the intended receiver will be able to read the document. Non-real-time file transfer is to provide convenient and low cost transportability of the encrypted data from one party to another. With the above three concerns addressed, the NRSFTP protocol can be widely …