Defense Notices

The desire to hide communications has been around for a very long time. This includes hiding the existence of the transmission and the location of the sender. The existence of wireless networks offers another medium for these covert communications. 
With many devices and networks competing for the limited spectrum, new technologies and methods are constantly sought after to increase spectral efficiency and broaden use to more devices and their bandwidth hungry applications. Orthogonal Frequency Division Multiplexing (OFDM) increases spectral efficiency when compared to Frequency Division Multiplexing (FDM). Adaptive modulation and coding (AMC), hybrid auto-repeat-request (HARQ), and opportunistic scheduling allows the system the ability to adapt to the changing environment and maintain performance. These technologies are utilized in fourth generation (4G) wireless networks such as Long Term Evolution Advanced (LITE-Advanced) and WiMAX. 
This research proposes to hide a covert communications network within the RF environment of these packet based networks. We anticipate the existence of the aforementioned technologies to allow the non-covert network to adjust to the existence of the covert network. In other words, the wireless networks will view the covert network as a minor change in the RF environment. This research will also seek to measure the effect of the covert networks on the non-covert networks performance.

Web-based applications have become predominant in commercial software for all businesses, such as e-commerce, health care, government, and academia. There is a critical demand for effective and inexpensive functional testing methodologies for such applications to ensure their quality and reliability. The existing testing methodologies are insufficient to address the testing challenges raised by the increasing complexity of Web applications, including the use of multi-tier architectures, heterogeneous execution environments, dynamic contents, and frequent requirement changes. This research aims to address the above challenges by developing an extensible gray-box model-based testing (GMT) approach. 

The GMT defines a set of models that capture the dependencies of testing artifacts from a multi-tier architectural perspective. The models include Web conceptual model (WCM), Web object relation model (WORM), Web data to logic integration model (WDLIM), Web presentation to logic integration model (WPLIM), and Web system integration model (WSIM). The WORM, in the form of object relation diagrams, is used for the test case generation in intra-tier unit testing. The WLDIM and WPLIM are employed for gray-box integration testing across tiers. The WSIM, in the forms of system dependency graphs or UML sequence diagrams, is constructed for test path selection in black-box system testing phase. 

The GMT is capable of incorporating architectural styles beyond the traditional 3-tier Web applications. Extensions are developed to capture the component dependencies in elementary Web services, composite workflows, and Ajax-based rich Internet applications. A comprehensive empirical study is conducted to validate the GMT. Sixteen medium-scale projects from industrial context are selected as the subject applications. For each subject, 173 measurable attributes are collected. Formal analysis on the experiment data is performed and GMT is empirically evaluated against a well-known benchmark method to compare testing coverage effectiveness and testing performance. 

This research makes several important contributions to the software testing research community and demonstrates that the GMT effectively addresses the difficulty of analyzing multi-tier Web applications. The empirical results verify that the GMT is highly suitable in detecting functional defects in Web applications, particularly those from inter-tier integration. The fault seeding database and its experimental data establish a baseline for future empirical studies.

A hallmark of functional programming languages is their support for the algebraic manipulation of programs. While such techniques lend themselves to mechanization, they are usually employed by hand, requiring considerable expertise, but offering a high assurance of the correctness of the result. Library writers are especially likely to use these techniques in order to implement optimizations which are either deemed too narrowly applicable to be worth implementing in a general language compiler, or may only represent an optimization in certain specific contexts. Such domain-specific optimizations can be incredibly effective however, offering complexity-changing improvement. In many instances, they are accomplished by changing the data structures over which the computation operates. 

We propose a framework for mechanizing the worker/wrapper transformation, which can express a large number of these domain-specific optimizations that depend on changing data structures. As a significant case study, we propose to recast the Stream Fusion transformation as an instance of worker/wrapper, using it to motivate the capabilities of our framework. We also propose extensions to Stream Fusion to allow it to optimize higher-order stream combinators. The resulting framework should lower the effort required to mechanize such transformations, leading to increased correctness and reuse. Additionally, the extended Stream Fusion transformation will offer practical performance improvements to a wide range of programs.

This work presents the design and development of a genetic algorithm to generate long range transmit codes with low autocorrelation side lobes for radar. The genetic algorithm described in this work has a parallel processing design and has been used to generate codes with multiple constellations for various code lengths with low estimated error of a target profile.

As the World Wide Web continues to evolve as the preferred choice for information access it is critical that its utility to the user remains. Latency as a result of network congestion, bandwidth availability, server processing delays, embedded objects, and transmission delays and errors can impact the utility of the web browser application. To improve the overall user experience the application needs to not only provide feedback to the end user about the latency of links that are available but to also provide them decision controls in the retrieval of the web content. This thesis presents a background and related work relating to latency and web optimization techniques to reduce this latency and then introduce an improvement to the "latency aware" Mozilla Firefox extension which was originally developed by Sterbenz et. al., in 2002. This these describes the architecture and prototype implementation, followed with an analysis of its effectiveness to predict latency and future work.

Radar systems can fulfill a wide range of remote sensing missions, from aircraft tracking, to rainfall rate measurements, to automobile cruise control assist. The history of radar is full of innovation and a drive to "get the most" out of a system. History, however, is also full of simplifying assumptions made along the way to make certain problems tractable. In some sense, engineers have historically traded performance for tractability. Antenna arrays and their accompanying electromagnetics is one such area that is ripe to have its simplifying assumptions pealed back in an effort to extract even more performance. This can be demonstrated by developing high fidelity electromagnetic (EM) models of a radar array and showing that existing array processing algorithms based on simplified models are operating at a degraded performance level. These high fidelity EM models can then serve as a basis to enhance the performance of these algorithms. This work will specifically examine integrating a blind calibration process into the Re-Iterative Super Resolution (RISR) Direction of Arrival (DoA) algorithm to improve RISRs performance, show that the misapplication of the reciprocity theorem is holding back radar array processing algorithms, and investigate the possibility of leveraging recent results showing non-linearities in off-boresight emissions to improve clutter mitigation.

Many applications use a variety of components both at the middleware and OS as part of their execution and systems are designed to provide these applications with high availability and specific qualities of service intended for specific application semantics. To provide these features, systems must be developed that exercise precise control over computation 
behaviour. This thesis proposes a mechanism where the structure of the computation and its behaviour can be discovered by tracing the system calls that an application makes during the period of its execution in real time using Data Streams and Computation Component Set Manager frameworks. This thesis also demonstrates the integration of computation behaviour information with Hierarchical Group Scheduling framework to achieve precise control over the execution of the application through arbitrary scheduling semantics.