Generalized Hidden Filter Markov Models Applied to Speaker Recognition

Classification of time series has wide Air Force, DoD and commercial interest, from automatic target recognition systems on munitions to recognition of speakers in diverse environments. The ability to effectively model the temporal information contained in a sequence is of paramount importance. Toward this goal, this research develops theoretical extensions to a class of stochastic models and demonstrates their effectiveness on the problem of text-independent (language constrained) speaker recognition. Specifically within the hidden Markov model architecture, additional constraints are implemented which better incorporate observation correlations and context, where standard approaches fail. Two methods of modeling correlations are developed, and their mathematical properties of convergence and reestimation are analyzed. These differ in modeling correlation present in the time samples and those present in the processed features, such as Mel frequency cepstral coefficients. The system models speaker dependent phonemes, making use of word dictionary grammars, and recognition is based on normalized log-likelihood Viterbi decoding. Both closed set identification and speaker verification using cohorts are performed on the YOHO database. YOHO is the only large scale, multiple-session, high-quality speech database for speaker authentication and contains over one hundred speakers stating combination locks. Equal error rates of 0.21% for males and 0.31% for females are demonstrated. A critical error analysis using a hypothesis test formulation provides the maximum number of errors observable while still meeting the goal error rates of 1% False Reject and 0.1% False Accept. Our system achieves this goal

Rapid Development: A Content Analysis Comparison of Literature and Purposive Sampling of Rapid Reaction Projects

In the current environment of military operations requesting short development timelines to counter insurgent tactics, the engineering team often searches for ways to deliver the “80% solution”, typically in 6-12 months. These are labeled rapid development projects. A content analysis of best practices in commercial product development literature, where time to market is often a driving factor, was accomplished showing varying emphasis of systems engineering (SE) technical and technical management processes. This analysis confirms a preconceived notion of “plan upfront and early” by emphasizing Stakeholder Requirements Definition, Architecture Design and Technical Planning. A purposive sampling of Air Force Research Laboratory rapid development project managers and engineers was conducted to identify important SE processes and then compared to the literature content analysis. The results of this sampling did not strongly emphasize one process over another, however Architecture Design and Implementation scored higher among Technical Processes. Decision Analysis, Technical Planning, Technical Assessment and Data Management scored slightly higher among Technical Management Processes. Anecdotal evidence also emphasized iterating prototype designs based on early customer feedback, focusing mostly on managing critical risks and holding frequent early reviews until trust is built in the team

A Proposed Methodology to Characterize the Accuracy of Life Cycle Cost Estimates for DoD Programs

For decades, the DoD has employed numerous reporting and monitoring tools for characterizing the acquisition cost of its major programs. These tools have resulted in dozens of studies thoroughly documenting the magnitude and extent of DoD acquisition cost growth. Curiously, though, there have been extremely few studies regarding the behavior of the other cost component of a system\u27s life cycle: Operating and Support (O&S) costs. This is particularly strange considering that O&S costs tend to dominate the total life cycle cost (LCC) of a program, and that LCCs are widely regarded as the preferred metric for assessing actual program value. The upshot for not examining such costs is that the DoD has little knowledge of how LCC estimates behave over time, and virtually no insights regarding their accuracy. In recent years, however, enough quality LCC data has amassed to conduct a study to address these deficiencies. This paper describes a method for conducting such a study, and represents (to the authors’ knowledge) the first broad-based attempt to do so. The results not only promise insights into the nature of current LCC estimates, but also suggest the possibility of improving the accuracy of DoD LCC estimates via a stochastically-based model

Human-Centered Design Using System Modeling Language

The human user is important to consider during system design. However, common system design models, such as the system modeling language, typically represent human users and operators as external actors, rather than as internal to the system. This research presents a method for integrating human considerations into system models through human-centered design. A specific system is selected to serve as the case study for demonstrating the methodology. The sample system is analyzed to identify the task and information flow. Then, both system- and human-centered diagrams are separately created to represent different viewpoints of the system. These diagrams are compared and analyzed, and new diagrams are created that incorporate both system and human considerations into one concordant representation of the system model. These new views allow systems engineers and human factors engineers to effectively communicate the role of the user during early system design trades

Allocation of Communications to Reduce Mental Workload

As the United States Department of Defense continues to increase the number of Remotely Piloted Aircraft (RPA) operations overseas, improved Human Systems Integration becomes increasingly important. Manpower limitations have motivated the investigation of Multiple Aircraft Control (MAC) configurations where a single pilot controls multiple RPAs simultaneously. Previous research has indicated that frequent, unpredictable, and oftentimes overwhelming, volumes of communication events can produce unmanageable levels of system induced workload for MAC pilots. Existing human computer interface design includes both visual information with typed responses, which conflict with numerous other visual tasks the pilot performs, and auditory information that is provided through multiple audio devices with speech response. This paper extends previous discrete event workload models of pilot activities flying multiple aircraft. Specifically, we examine statically reallocating communication modality with the goal to reduce and minimize the overall pilot cognitive workload. The analysis investigates the impact of various communication reallocations on predicted pilot workload, measured by the percent of time workload is over a saturation threshold

Confidence Investigation of Discovering Organizational Network Structures Using Transfer Entropy

Transfer entropy has long been used to discover network structures and relationships based on the behavior of nodes in the system, especially for complex adaptive systems. Using the fact that organizations often behave as complex adaptive systems, transfer entropy can be applied to discover the relationships and structure within an organizational network. The organizational structures are built using a model developed by Dodd, Watts, et al, and a simulation method for complex adaptive supply networks is used to create node behavior data. The false positive rate and true positive rates are established for various organizational structures and compared to a basic tree. This study provides a baseline understanding for the accuracy that can be expected when discovering organizational networks using these techniques. It also highlights conditions in which it may be more difficult to successfully discover a network structure using transfer entropy and bounds confidence levels for practitioners of such methods

Observations on Expedited Systems Engineering Practices in Military Rapid Development Projects

This research, conducted in the Systems Engineering Research Center (SERC), examined systems engineering and engineering management practices for military rapid capability and urgent needs programs. Lifecycle of urgent needs programs is driven by “time to market” as opposed to complete satisfaction of static requirements, with delivery expected in months versus years/decades. The processes and practices applied to urgent needs must add value and not require an excessive bureaucratic oversight to implement, while at the same time address, understand, and manage risk such that programs can understand better where to include, truncate, eliminate, tailor, or scale systems engineering practices and processes. Focusing on aspects of the product, process, and people of military rapid organizations, the analysis showed that these organizations have the right team, develop innovative conceptual solutions, quickly prune the design space, and identify appropriate designs that can deliver warfighting capability expeditiously. While these observations may not seem new, they provide the foundation for a broader framework of rapid development, which is the subject of ongoing research

Observations on Expedited Systems Engineering Practices in Military Rapid Development Projects

This research, conducted in the Systems Engineering Research Center (SERC), examined systems engineering and engineering management practices for military rapid capability and urgent needs programs. Lifecycle of urgent needs programs is driven by “time to market” as opposed to complete satisfaction of static requirements, with delivery expected in months versus years/decades. The processes and practices applied to urgent needs must add value and not require an excessive bureaucratic oversight to implement, while at the same time address, understand, and manage risk such that programs can understand better where to include, truncate, eliminate, tailor, or scale systems engineering practices and processes. Focusing on aspects of the product, process, and people of military rapid organizations, the analysis showed that these organizations have the right team, develop innovative conceptual solutions, quickly prune the design space, and identify appropriate designs that can deliver warfighting capability expeditiously. While these observations may not seem new, they provide the foundation for a broader framework of rapid development, which is the subject of ongoing research

Using Information-theoretic Principles to Analyze and Evaluate Complex Adaptive Supply Network Architectures

Information-theoretic principles can be applied to the study of complex adaptive supply networks (CASN). Previous modeling efforts of CASN were impeded by the complex, dynamic nature of the systems. However, information theory provides a model-free approach to the problem removing many of those barriers. Understanding how principles such as transfer entropy, excess entropy/predictive information, information storage, and separable information apply in the context of supply networks opens up new ways of studying these complex systems. Additionally, these principles provide the potential for new business analytics which give managers of CASN new insights into the system\u27s health, behavior, and eventual control strategies

Confidence Investigation of Discovering Organizational Network Structures Using Transfer Entropy

Transfer entropy has long been used to discover network structures and relationships based on the behavior of nodes in the system, especially for complex adaptive systems. Using the fact that organizations often behave as complex adaptive systems, transfer entropy can be applied to discover the relationships and structure within an organizational network. The organizational structures are built using a model developed by Dodd, Watts, et al, and a simulation method for complex adaptive supply networks is used to create node behavior data. The false positive rate and true positive rates are established for various organizational structures and compared to a basic tree. This study provides a baseline understanding for the accuracy that can be expected when discovering organizational networks using these techniques. It also highlights conditions in which it may be more difficult to successfully discover a network structure using transfer entropy and bounds confidence levels for practitioners of such methods