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Articles 61 - 90 of 189
Full-Text Articles in Applied Mathematics
Modeling Radiation Effectiveness For Inactivation Of Bacillus Spores, Emily A. Knight
Modeling Radiation Effectiveness For Inactivation Of Bacillus Spores, Emily A. Knight
Theses and Dissertations
This research models and analyzes the inactivation of Bacillus spores following a radiation exposure and the process enacted by the Bacillus spore to repair the resulting damage. Irradiation of a spore and the medium surrounding the spore induces chemical reactions that produce reactive oxygen species (ROS). This research will consider the reaction- diffusion of these ROS throughout the spore. These ROS can react with the spore's DNA and enzymes to degrade them to such an extent that the DNA cannot be repaired or replicated, thus causing spore death. In order to survive a dose of radiation, a spore must repair …
Testing The Adequacy Of A Semi-Markov Process, Richard S. Seymour
Testing The Adequacy Of A Semi-Markov Process, Richard S. Seymour
Theses and Dissertations
Due to the versatility of its structure, the semi-Markov process is a powerful modeling tool used to describe complex systems. Though similar in structure to continuous time Markov chains, semi-Markov processes allow for any transition time distribution which enables these processes to t a wider range of problems than the continuous time Markov chain. While semi-Markov processes have been applied in fields as varied as biostatistics and finance, there does not exist a theoretically-based, systematic method to determine if a semi-Markov process accurately fits the underlying data used to create the model. In fields such as regression and analysis of …
Symmetry Groups For Linear Programming Relaxations Of Orthogonal Array Problems, David M. Arquette
Symmetry Groups For Linear Programming Relaxations Of Orthogonal Array Problems, David M. Arquette
Theses and Dissertations
Integer linear programs arise in many situations, and solving such problems can be computationally demanding. One way to solve them more efficiently is by exploiting the symmetry within their formulation. This paper proves that the symmetry group for the linear programming relaxation of 2-level orthogonal array problems of strength 2 is a particular semidirect product.
Accuracy Of Time Phasing Aircraft Development Using The Continuous Distribution Function, Gregory E. Brown
Accuracy Of Time Phasing Aircraft Development Using The Continuous Distribution Function, Gregory E. Brown
Theses and Dissertations
Early research on time phasing primarily focuses on the theoretical foundation for applying the continuous distribution function, or S-curve, to model the distribution of development expenditures. Minimal methodology is provided for estimating the S-curve's parameter values. Brown, White, and Gallagher (2002) resolve this shortcoming through regression analysis, but their methodology has not been widely adopted by aircraft cost analysts, as it is judged as overly broad and not specific to aircraft. Instead, analysts commonly apply the 60/40 rule of thumb to aircraft development, assuming 60 percent expenditures at 50 percent schedule. It is currently unknown if the 60/40 heuristic accurately …
Examining The Return On Investment Of Test And Evaluation, Nathan C. Smith
Examining The Return On Investment Of Test And Evaluation, Nathan C. Smith
Theses and Dissertations
This research examined the return on investment of Department of Defense test and evaluation. The thesis analyzed the return on investment of the cost avoidance achieved if an issue discovered late in the program had been discovered and corrected during developmental test and evaluation. The methodology utilized two case study examples from the Joint Primary Training Aircraft System to calculate the potential cost avoidance and the potential return on investment if the program had discovered and corrected the issues during developmental test and evaluation. The result of one case was a 9,260% return on investment. The other case results ranged …
Exploring Heuristics For The Vehicle Routing Problem With Split Deliveries And Time Windows, Marcus E. Mcnabb
Exploring Heuristics For The Vehicle Routing Problem With Split Deliveries And Time Windows, Marcus E. Mcnabb
Theses and Dissertations
This dissertation investigates the Vehicle Routing Problem with Split Deliveries and Time Windows. This problem assumes a depot of homogeneous vehicles and set of customers with deterministic demands requiring delivery. Split deliveries allow multiple visits to a customer and time windows restrict the time during which a delivery can be made. Several construction and local search heuristics are tested to determine their relative usefulness in generating solutions for this problem. This research shows a particular subset of the local search operators is particularly influential on solution quality and run time. Conversely, the construction heuristics tested do not significantly impact either. …
Different Formulations Of The Orthogonal Array Problem And Their Symmetries, Andrew J. Geyer
Different Formulations Of The Orthogonal Array Problem And Their Symmetries, Andrew J. Geyer
Theses and Dissertations
Modern statistical experiments routinely feature a large number of input variables that can each be set to a variety of different levels. In these experiments, output response changes as a result of changes in the individual factor level settings. Often, an individual experimental run can be costly in time, money or both. Therefore, experimenters generally want to gain the desired information on factor effects from the smallest possible number of experimental runs. Orthogonal arrays provide the most desirable designs. However, finding orthogonal arrays is a very challenging problem. There are numerous integer linear programming formulations (ILP) in the literature whose …
An Analysis Of The Impact Of Variation In Mean Time Between Demand On Air Force Fleet Level Aircraft Parts Inventories, Andrew J. Berger, Caleb S. Murphy
An Analysis Of The Impact Of Variation In Mean Time Between Demand On Air Force Fleet Level Aircraft Parts Inventories, Andrew J. Berger, Caleb S. Murphy
Theses and Dissertations
This thesis researched the accuracy of demand forecasting and impact of demand variation on requirements definition for Air Force aircraft secondary items. Specifically, this thesis sought to answer three questions: How does the Air Force calculate item requirements? , How accurate is the current system at predicting future item requirements? , and How do variations in predicted demand change item requirements? The literature review described the Air Force supply system for aircraft secondary items. Analysis into current demand forecast accuracy found that the level of error between actual and predicted historic demand was as high as 92% for the items …
Investr: An R Package For Inverse Estimation, Brandon M. Greenwell, Christine M. Schubert Kabban
Investr: An R Package For Inverse Estimation, Brandon M. Greenwell, Christine M. Schubert Kabban
Faculty Publications
Inverse estimation is a classical and well-known problem in regression. In simple terms, it involves the use of an observed value of the response to make inference on the corresponding unknown value of the explanatory variable. To our knowledge, however, statistical software is somewhat lacking the capabilities for analyzing these types of problems. In this paper, we introduce investr (which stands for inverse estimation in R), a package for solving inverse estimation problems in both linear and nonlinear regression models.
Adverse Impacts Of Furlough Programs On Employee Work Rate And Organizational Productivity, Adedeji B. Badiru
Adverse Impacts Of Furlough Programs On Employee Work Rate And Organizational Productivity, Adedeji B. Badiru
Faculty Publications
This article is primarily a research-provoking exposition against the management approach used in the 2013 government furlough program. It is intended to prompt potentially productive research investigations on the impact of personnel furloughs, particularly on defense acquisition programs. Defense acquisition programs are time-sensitive and systems oriented. What appears as a minor delay in one unit of an acquisition life cycle can lead to long-term encumbrances within the entire defense system, resulting in enormous cost escalation. Pertinent analytical techniques/methodologies are provided to illustrate potential pathways for further research studies of furloughs and how they adversely impact organizational productivity. The author’s intent …
Airborne Wireless Communication Modeling And Analysis With Matlab, Matthew J. Vincie
Airborne Wireless Communication Modeling And Analysis With Matlab, Matthew J. Vincie
Theses and Dissertations
Over the past decade, there has been a dramatic increase in the use of unmanned aerial vehicles (UAV) for military, commercial, and private applications. Critical to maintaining control and a use for these systems is the development of wireless networking systems [1]. Computer simulation has increasingly become a key player in airborne networking developments though the accuracy and credibility of network simulations has become a topic of increasing scrutiny [2-5]. Much of the inaccuracies seen in simulation are due to inaccurate modeling of the physical layer of the communication system. This research develops a physical layer model that combines antenna …
Model Uncertainty And Test Of A Segmented Mirror Telescope, Luke C. Dras
Model Uncertainty And Test Of A Segmented Mirror Telescope, Luke C. Dras
Theses and Dissertations
The future of large aperture telescopes relies heavily on the development of segmented array designs. Today's monolithic mirror technology has reached a barrier, particularly for space-based telescopes. These large diameter, dense mirrors allow stable high-resolution imaging but are incompatible with optimized space launch. Segmented mirror telescopes are designed to balance lightweight with compact stowage. The structure necessary to support the flexible mirror array often combines isogrid geometry and complex actuation hardware. High-fidelity finite element models are commonly used to economically predict how the optics will perform under different environmental conditions. The research detailed herein integrates superelement partitioning and complexity simplifying …
Current Barriers To Successful Implementation Of Fist Principles, Brandon Keller, Joseph R. Wirthlin
Current Barriers To Successful Implementation Of Fist Principles, Brandon Keller, Joseph R. Wirthlin
Faculty Publications
The Fast, Inexpensive, Simple, and Tiny (FIST) framework proposes a broad set of organizational values, but provides limited guidance on practical implementation. Implementing FIST principles requires clarifying the definitions of “fast,” “inexpensive,” and “simple,” recognizing where FIST does and does not apply. Additionally, a subset of the FIST heuristics was expanded upon to increase their usefulness for practitioners. The primary research findings are that FIST principles are less conducive for highly complex or novel systems, immature technologies, future needs, acquisitions in early development phases, or when performance is the foremost value. FIST principles were also found to be constrained by …
Distributional Monte Carlo Methods For The Boltzmann Equation, Christopher R. Schrock
Distributional Monte Carlo Methods For The Boltzmann Equation, Christopher R. Schrock
Theses and Dissertations
Stochastic particle methods (SPMs) for the Boltzmann equation, such as the Direct Simulation Monte Carlo (DSMC) technique, have gained popularity for the prediction of flows in which the assumptions behind the continuum equations of fluid mechanics break down; however, there are still a number of issues that make SPMs computationally challenging for practical use. In traditional SPMs, simulated particles may possess only a single velocity vector, even though they may represent an extremely large collection of actual particles. This limits the method to converge only in law to the Boltzmann solution. This document details the development of new SPMs that …
Quantifying Performance Bias In Label Fusion, Alexander M. Venzin
Quantifying Performance Bias In Label Fusion, Alexander M. Venzin
Theses and Dissertations
Classification systems are employed to remotely assess whether an element of interest falls into a target class or non-target class. These systems have uses in fields as far ranging as biostatistics to search engine keyword analysis. The performance of the system is often summarized as a trade-off between the proportions of elements correctly labeled as target plotted against the number of elements incorrectly labeled as target. These are empirical estimates of the true positive and false positive rates. These rates are often plotted to create a receiver operating characteristic (ROC) curve that acts as a visual tool to assess classification …
Half-Life Learning Curves In The Defense Acquisition Life Cycle, Adedeji B. Badiru
Half-Life Learning Curves In The Defense Acquisition Life Cycle, Adedeji B. Badiru
Faculty Publications
Learning curves are useful for assessing performance improvement due to the positive impact of learning. In recent years, the deleterious effects of forgetting have also been recognized. Workers experience forgetting or decline in performance over time. Consequently, contemporary learning curves have attempted to incorporate forgetting components into learning curves. An area of increasing interest is the study of how fast and how far the forgetting impact can influence overall performance. This article introduces the concept of half-life analysis of learning curves using the concept of growth and decay, with particular emphasis on applications in the defense acquisition process. The computational …
Determining Angular Frequency From A Video With A Generalized Fast Fourier Transform, Lindsay N. Smith
Determining Angular Frequency From A Video With A Generalized Fast Fourier Transform, Lindsay N. Smith
Theses and Dissertations
Suppose we are given a video of a rotating object and suppose we want to determine the rate of rotation solely from the video itself and its known frame rate. In this thesis, we present a new mathematical operator called the Geometric Sum Transform (GST) that can help one determine the angular frequency of the object in question. The GST is a generalization of the discrete Fourier transform (DFT) and as such, the two transforms have much in common. However, whereas the DFT is applied to a sequence of scalars, the GST can be applied to a sequence of vectors. …
Local Histograms For Per-Pixel Classification, Melody L. Massar
Local Histograms For Per-Pixel Classification, Melody L. Massar
Theses and Dissertations
We introduce a rigorous mathematical theory for the analysis of local histograms, and study how they interact with textures that can be modeled as occlusions of simpler components. We first show how local histograms can be computed as a system of convolutions and discuss some basic local histogram properties. We then introduce a probabilistic, occlusion-based model for textures and formally demonstrate that local histogram transforms are natural tools for analyzing the textures produced by our model. Next, we characterize all nonlinear transforms which satisfy the three key properties of local histograms and consider the appropriateness of local histogram features in …
Analysis Of Transient Electromagnetic Scattering From An Overfilled Cavity Embedded In An Impedance Ground Plane, Robert S. Callihan
Analysis Of Transient Electromagnetic Scattering From An Overfilled Cavity Embedded In An Impedance Ground Plane, Robert S. Callihan
Theses and Dissertations
We consider the transient, or time-domain, scattering problem of a two-dimensional overfilled cavity embedded in an impedance ground plane. This problem is a significant advancement from previous work where more simplified boundary conditions were used, which can limit the number of applications. This research supports a wide range of military applications such as the study of cavity-like structures on aircraft and vehicles. More importantly, this research helps detect the biggest threat on today's battlefield: improvised explosive devices. An important step in solving the problem is introducing an artificial boundary condition on a semicircle enclosing the cavity; this couples the fields …
Modeling Of Bacillus Spores: Inactivation And Outgrowth, Alexis X. Hurst
Modeling Of Bacillus Spores: Inactivation And Outgrowth, Alexis X. Hurst
Theses and Dissertations
This research models and analyzes the thermochemical damage produced in Bacillus spores by short, high-temperature exposures as well the repair process within damaged Bacillus spores. Thermochemical damage in spores is significantly due to reaction with water, hydrolysis reactions. Applying heat to the spore causes absorbed and chemically bound water molecules become mobile within the spore. These mobile water molecules react by hydrolysis reactions to degrade DNA and enzyme molecules in the spore. In order to survive the thermal inactivation, the spore must repair the damaged DNA during spore germination. The DNA repair process, as well as other germination functions, is …
Validation Of A Novel Approach To Solving Multibody Systems Using Hamilton's Weak Principle, Ashton D. Hainge
Validation Of A Novel Approach To Solving Multibody Systems Using Hamilton's Weak Principle, Ashton D. Hainge
Theses and Dissertations
A novel approach for formulating and solving for the dynamic response of multibody systems has been developed using Hamilton’s Law of Varying Action as its unifying principle. In order to assure that the associated computer program is sufficiently robust when applied across a wide range of dynamic systems, the program must be verified and validated. The purpose of the research was to perform the verification and validation of the program. Results from the program were compared with closed-form and numerical solutions of simple systems, such as a simple pendulum and a rotating pendulum. The accuracy of the program for complex …
Maximizing Strike Planning Efficiency For A Given Class Of Targets, Necip Dirik
Maximizing Strike Planning Efficiency For A Given Class Of Targets, Necip Dirik
Theses and Dissertations
Strike planning is one of the fundamental tasks of the Turkish Air Force and involves assignment of strike aircraft to targets with a maximum level of efficiency. Therefore, planning an optimal strike plan based on the preferences of the decision maker is crucial. The efficiency of the strike plan in this research implies attacking the maximum number of targets while considering target priority and the desired level of damage on each target. Another objective is to minimize the cost of the plan. This research develops an exact model that maximizes the efficiency of the strike plan using LINGO with Excel …
The Uav Continuous Coverage Problem, Taegyun Ha
The Uav Continuous Coverage Problem, Taegyun Ha
Theses and Dissertations
The purpose of this research is to develop a method to find an optimal UAV cyclic schedule to provide maximum coverage over a target area to support an ISR mission. The goal is to reach continuous coverage. UAV continuous coverage of a target area is crucial for the success of an ISR mission. Even the smallest coverage gap may jeopardize the success of the mission. Ideally it is desirable to obtain continuous coverage of a target area but the stochastic nature of the problem makes continuous coverage without gaps unlikely. However, it is still possible to obtain a high coverage …
A Multi-Objective Approach To A Bipartite Assignment Matching Problem Using Weighted Values From Multiple Contraints, Greg S. Jeong
A Multi-Objective Approach To A Bipartite Assignment Matching Problem Using Weighted Values From Multiple Contraints, Greg S. Jeong
Theses and Dissertations
US Air Force recruiters routinely assign new recruits to available jobs every month. The goal is to find the best assignments in an efficient manner. Although this problem is modeled as a bipartite assignment matching problem, it is not new to the field of Operations Research. This research presents a new approach to solve assignment matching problems given multiple side constraints. Using two multi-criteria optimization techniques, lexicographic optimization and the elastic constraint method, the assignment matching algorithm efficiently produces an optimal solution in a fraction of the time currently spent. This approach is demonstrated in assigning new USAF recruits to …
Screening And Sufficiency In Multiobjective Decision Problems With Large Alternative Sets, Michael D. Cote
Screening And Sufficiency In Multiobjective Decision Problems With Large Alternative Sets, Michael D. Cote
Theses and Dissertations
Portfolio selection problems with combinatorially-large alternative sets can be impossible to evaluate precisely on a reasonable timescale. When portfolios require complex modeling for performance assessment, prohibitive computational processing times can result. Eliminating a small number of alternatives through an intelligent screening process can greatly reduce the number of alternative combinations, thereby decreasing a problem's evaluation time and cost. A methodology was developed for the class of hierarchical portfolio selection problems in which multiple objectives are all judged on the same sub-objectives. First, a novel capability-based alternative screening process was devised to identify and remove poor alternatives, thereby reducing the number …
Determining The Orbit Locations Of Turkish Airborne Early Warning And Control Aircraft Over The Turkish Air Space, Nebi Sarikaya
Determining The Orbit Locations Of Turkish Airborne Early Warning And Control Aircraft Over The Turkish Air Space, Nebi Sarikaya
Theses and Dissertations
The technology improvement affects the military needs of individual countries. The new doctrine of defense for many countries emphasizes detecting threats as far away as you can from your homeland. Today, the military uses both ground RADAR and Airborne Early Warning and Control (AEW&C) Aircraft. AEW&C aircraft has become vital to detect low altitude threats that a ground RADAR cannot detect because of obstacles on the earth. Turkey has ordered four AEW&C aircraft for her air defense system because of the lack of complete coverage by ground RADAR. This research provides optimal orbit locations that can be updated according to …
Quantification Of Mandatory Sustainment Requirements, Joe M. Blackman
Quantification Of Mandatory Sustainment Requirements, Joe M. Blackman
Theses and Dissertations
To emphasize the importance of sustainment, the DoD Joint Requirements Oversight Council addressed sustained Materiel readiness and established a mandatory Key Performance Parameter (KPP) for Materiel Availability; it also established supporting Key System Attributes (KSAs) for Materiel Reliability and Ownership Cost (Chairman of the Joint Chiefs of Staff Manual (CJCSM) 3170.01C, 2007). Current guidance requires two numbers: a threshold value and an objective value (Chairman of the Joint Chiefs of Staff Manual (CJCSM) 3170.01C, 2007). No distinction is made between the approaches in establishing these values for major system acquisitions, versus smaller, modification-focused efforts for existing systems. The Joint Staff …
A Wigner Distribution Analysis Of One Dimensional Scattering, Brent R. Lacy
A Wigner Distribution Analysis Of One Dimensional Scattering, Brent R. Lacy
Theses and Dissertations
We applied the Wigner Distribution Function, a distribution function of time and frequency based on an initial function of either of those variables, to a series of time based correlation functions. These time based correlation functions were the result of a 1-dimensional free particle wave packet, the reactant wave function, which had propagated through a quantum potential well and then had components of the reactant wave function that exited the opposite side of the well auto-correlated in time with a stationary 1-dimensional free particle wave packet, the product wave function. This process was undertaking in order to generate a 3-dimensional …
Characterizing And Detecting Unrevealed Elements Of Network Systems, James A. Leinart
Characterizing And Detecting Unrevealed Elements Of Network Systems, James A. Leinart
Theses and Dissertations
This dissertation addresses the problem of discovering and characterizing unknown elements in network systems. Klir (1985) provides a general definition of a system as “... a set of some things and a relation among the things" (p. 4). A system, where the `things', i.e. nodes, are related through links is a network system (Klir, 1985). The nodes can represent a range of entities such as machines or people (Pearl, 2001; Wasserman & Faust, 1994). Likewise, links can represent abstract relationships such as causal influence or more visible ties such as roads (Pearl, 1988, pp. 50-51; Wasserman & Faust, 1994; Winston, …
Probabilistic Estimation Of Rare Random Collisions In 3-Space, Timothy Holzmann
Probabilistic Estimation Of Rare Random Collisions In 3-Space, Timothy Holzmann
Theses and Dissertations
A study of risk assessment for artillery fire randomly colliding with fixed wing aircraft is presented. The research lends itself to a general study of collision models. Current models of object collisions fall under one of three categories: the historical model, the gas particle model, and the satellite model. These three vary in data requirements and mathematical representation of the impact event. The gas particle model is selected for its flexibility and robust estimation. However, current mathematical development in the literature does not include certain spatial and dynamic components necessary for a general encounter (collision) model. These are derived in …