Browsing by Author "Herber, Daniel, committee member"
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Item Open Access A modeling toolkit for comparing AC vs. DC electrical distribution efficiency in buildings(Colorado State University. Libraries, 2021) Othee, Avpreet, author; Cale, James, advisor; Young, Peter, committee member; Herber, Daniel, committee member; Jia, Gaofeng, committee memberAn increasing proportion of electrical devices in residential and commercial buildings operate from direct current (DC) power sources. In addition, distributed power generation systems such as solar photovoltaic (PV) and energy storage natively produce DC power. However, traditional power distribution is based on an alternating current (AC) model. Performing the necessary conversions between AC and DC power to make DC devices compatible with AC distribution results in energy losses. For these reasons, DC distribution may offer energy efficiency advantages in comparison to AC distribution. However, reasonably fast computation and comparison of electrical efficiencies of AC-only, DC-only, and hybrid AC/DC distributions systems is challenging because DC devices are typically (nonlinear) power-electronic converters that produce harmonic content. While detailed time-domain modeling can be used to simulate these harmonics, it is not computationally efficient or practical for many building designers. To address this need, this research describes a toolkit for computation of harmonic spectra and energy efficiency in mixed AC and DC electrical distribution systems, using a Harmonic Power Flow (HPF) methodology. The toolkit includes a library of two-port linear and nonlinear device models which can be used to construct and simulate an electrical distribution system. This dissertation includes a description of the mathematical theory and framework underlying the toolkit, development and fitting of linear and nonlinear device models, software implementation in Modelica, verification of the toolkit with laboratory measurements, and discussion of ongoing and future work to employ the toolkit to a variety of building designs.Item Open Access An enterprise system engineering analysis of KC-46A maintenance program decision-making(Colorado State University. Libraries, 2023) Blond, Kyle E., author; Bradley, Thomas, advisor; Ender, Tommer, committee member; Conrad, Steven, committee member; Herber, Daniel, committee member; Ozbek, Mehmet, committee memberThe KC-46A Pegasus is a United States Air Force (USAF) tanker, transport, and medical evacuation commercial derivative aircraft based on the Boeing 767. It is a top acquisition priority to modernize the USAF's refueling capabilities and is governed by a lifecycle sustainment strategy directed by USAF commercial variant policies aligned to Federal Aviation Administration (FAA) policy. While this strategy provides robust mechanisms to manage the KC-46A's performance during its operations and support phase, opportunity exists for the KC-46A sustainment enterprise to better achieve reliability, availability, maintainability, and cost (RAM C) objectives through enhancing KC-46A maintenance program decision making in the context of USAF and FAA policies. This research characterizes the KC-46A maintenance program as an industrial enterprise system governing the maintenance, repair, overhaul, and modification of KC-46A aircraft. Upon this basis, enterprise systems engineering (ESE) characterizes the KC-46A maintenance program and identifies decision making improvement opportunities in its management. Canonical ESE viewpoints are tailored to abstract the organizations, processes, and information composing KC-46A maintenance program decision making and model how decision support methods can better achieve KC-46A sustainment enterprise objectives. A decision making framework then evaluates the RAM C performance of KC-46A maintenance tasks as part of the KC-46A Continued Analysis and Surveillance System (CASS) program. The framework's heuristics classify the compliance, effectiveness, and optimality of a maintenance task to prescribe KC-46A CASS responses. A rule based expert system applies this framework and serves as the knowledge engine for the KC-46A CASS decision support system referred to as the "Pegasus Fleet Management Tool." A focus group of KC-46A sustainment experts evaluated the framework and produced consensus that it advances the state of the art in KC-46A maintenance program decision making. A business case analysis roadmaps the programmatic and technical activities required to implement the framework in PFMT and improve KC-46A sustainment.Item Open Access Big Data decision support system(Colorado State University. Libraries, 2022) Ma, Tian J., author; Chong, Edwin, advisor; Simske, Steve, committee member; Herber, Daniel, committee member; Pezeshki, Ali, committee memberEach day, the amount of data produced by sensors, social and digital media, and Internet of Things is rapidly increasing. The volume of digital data is expected to be doubled within the next three years. At some point, it might not be financially feasible to store all the data that is received. Hence, if data is not analyzed as it is received, the information collected could be lost forever. Actionable Intelligence is the next level of Big Data analysis where data is being used for decision making. This thesis document describes my scientific contribution to Big Data Actionable Intelligence generations. Chapter 1 consists of my colleagues and I's contribution in Big Data Actionable Intelligence Architecture. The proven architecture has demonstrated to support real-time actionable intelligence generation using disparate data sources (e.g., social media, satellite, newsfeeds). This work has been published in the Journal of Big Data. Chapter 2 shows my original method to perform real-time detection of moving targets using Remote Sensing Big Data. This work has also been published in the Journal of Big Data and it has received an issuance of a U.S. patent. As the Field-of-View (FOV) in remote sensing continues to expand, the number of targets observed by each sensor continues to increase. The ability to track large quantities of targets in real-time poses a significant challenge. Chapter 3 describes my colleague and I's contribution to the multi-target tracking domain. We have demonstrated that we can overcome real-time tracking challenges when there are large number of targets. Our work was published in the Journal of Sensors.Item Open Access Human systems integration of agricultural machinery in developing economy countries: Sudan as a case study(Colorado State University. Libraries, 2022) Ahmed, Hamza, author; Miller, Erika, advisor; Owiny, James, committee member; Simske, Steve, committee member; Jablonski, Becca, committee member; Herber, Daniel, committee memberWidespread adoption of agricultural machinery for developing economy countries is commonly regarded as a fundamental component of pro-poor growth and sustainable intensification. Mechanized farming can also improve perceptions of farming and mitigate rural-out migration. However, many traditional farmers do not have access to machinery and/or the machinery is cost prohibitive. This study applies the systems engineering approach to identify human-systems integration (HSI) solutions in agricultural practices to more effectively adapt technologies to satisfy traditional farmers' needs. A treatment control study was conducted on 36 farms in Sudan, Africa, over three farming seasons: 2019 (baseline), 2020, and 2021. The treatment group farmers (N = 6) were provided with agricultural machinery (i.e., tractor, cultivator, planter, and harvester), fuel for the machinery, and training to use the machinery. Farmers were interviewed at the beginning of the study and then after each planting and harvesting season during the study. Findings show that the most significant barriers for technology adoption were culture, security, and maintenance costs. However, they also reported that the most significant challenges in their nonmechanized farming practices were related to labor, safety, and profit margins, all of which could be addressed with machinery. Moreover, the results show that all farmers had similar net profits in 2019, when farming without machinery, while mechanized farming yielded significantly higher net profits ($16.61 per acre more in 2020 and $27.10 per acre more in 2021). Farmers also provided needs and rationales of various design options in tractors and attachments. The findings of this dissertation suggest that, despite the initial resistance to using agricultural machinery, the farmers were pleased by their experience after using farming machinery and expressed an even more accepting attitude from their children towards this new farming process. These results demonstrate the importance of developing effective solutions for integrating farming technology into rural farming practices in developing economy countries. More broadly, this study can be used as an HSI framework for identifying design needs and integrating technology into users' lifestyle. The results presented in this dissertation provide a quantified difference between farming with and without machinery, which can provide a financial basis for purchasing and borrowing models, machinery design requirements, and educational value to farmers. Further, the financial values and design requirements can help inform farmers regarding expected costs, returns, and payoffs from tractor adoption. Manufacturers and policymakers can utilize this to promote technology adoption more effectively to farmers in developing economy countries.Item Open Access Integrated optimization of composite structures(Colorado State University. Libraries, 2022) Lang, Daniel, author; Radford, Donald, advisor; Herber, Daniel, committee member; Chong, Edwin, committee member; Heyliger, Paul, committee memberMany industries are exploring the application of composite materials to structural designs to reduce weight. A common issue that is encountered by these industries, however, is difficulty in developing structural geometries best suited for the materials. Research efforts have begun to develop optimization methodology to help develop structural shapes but have thus far only partially addressed optimization of the geometry. This dissertation provides a literature review of past efforts to develop optimization methodologies. Through that review it is identified that the subprocesses required to fully optimize a composite structure are mold shape optimization, ply draping analysis, kinematic partitioning, connection and joint definition, ply topology optimization and manufacturing simulations. To date, however, these subprocesses have primarily been applied individually and have not been integrated to develop fully optimized designs. In this research, a methodology is proposed to integrate established composite design and subprocesses to develop optimized composite structures. The proposed methodology sequentially and iteratively improves the design through mold shape optimization, ply draping analysis, kinematic partitioning, connection and joint definition, ply topology optimization and manufacturing simulations. Throughout the proposed methodology, checks are also integrated to ensure that the developed design meets design objectives and constraints. To test the methodology a case study is conducted to develop composite rail vehicle structures. As part of this case study, it is hypothesized that a composite structure designed through a fully integrated methodology will demonstrate reduced costs, mass and improved manufacturability compared to a structure where functions have only been partially integrated. When the proposed fully integrated methodology is applied to create a case study design, the hypothesis is validated. The design generated by the fully integrated optimization methodology has a 37% lower mass and a 56% lower cost to manufacture than a design that is developed through a partially integrated methodology. The case study also demonstrates that structures developed through the proposed methodology have improved manufacturability.Item Open Access Managing risk in commercial-off-the-shelf based space hardware systems(Colorado State University. Libraries, 2024) Herbert, Eric W., author; Bradley, Thomas, advisor; Sega, Ronald, advisor; Herber, Daniel, committee member; Shahroudi, Kamran, committee member; Wise, Daniel, committee memberThe space industry is experiencing a dynamic renaissance. From 2005 to 2021, the industry has exhibited a 265% increase in commercial and government investment [1]. The demand is forecasted to continue its upward trajectory by an added 55% by 2026 [1]. So, the aerospace industry continually seeks innovative space hardware solutions to reduce cost and to shorten orbit insertion schedules. Using Commercial-Off-the-Shelf (COTS) components to build space-grade hardware is one method that has been proposed to meet these goals. However, using non-space-grade COTS components requires designers to identify and manage risks differently early in the development stages. Once the risks are identified, then sound and robust risk management efforts can be applied. The methods used must verify that the COTS are reliable, resilient, safe, and able to survive rigorous and damaging launch and space environments for the mission's required longevity or that appropriate mitigation measures can be taken. This type of risk management practice must take into consideration form-fit-function requirements, mission objectives, size-weight-and-performance (SWaP) constraints, how the COTS will perform outside of its native applications, manufacturing variability, and lifetime expectations, albeit using a different lens than those traditionally used. To address these uncertainties associated with COTS the space industry can employ a variety of techniques like performing in-depth component selections, optimizing designs, instituting robust stress screening, incorporating protective and preventative measures, or subjecting the hardware to various forms of testing to characterize the hardware's capabilities and limitations. However, industrial accepted guidance to accomplish this does not reside in any standard or guide despite space program policies encouraging COTS use. One reason is because companies do not wish to reveal their proprietary methods used to evaluate COTS which, if broadcast, could benefit their market competition. Another is that high value spacecraft sponsors still cling to low-risk time consuming and expensive techniques that require the use of space hardware built with parts that have historical performance pedigrees. Keeping this data hidden does not help the space industry, especially when there is a push to field space systems that are built with modern technologies at a faster rate. This is causing a change in basic assumptions as stakeholders begin to embrace using parts from other industries such as the automotive, aviation, medical, and the like on a more frequent basis. No longer are COTS relegated to use in CubeSats or research and development spacecraft that have singular and limited missions that are expected to function for a brief period. This is because COTS that are produced for terrestrial markets are equally as dependable because of the optimized manufacturing and quality control techniques that reduce product variability. This increases the use of COTS parts in space hardware designs where until recently space programs had dared not to tread. But using COTS does come with a unique set of uncertainties and risks that still need to be identified and mitigated. Despite legacy risk management tools being mature and regularly practiced across a diverse industrial field, there is not a consensus on which risk management tools are best to use when evaluating COTS for space hardware applications. However, contained within technical literature amassed over the last twenty-plus years there exists significant systems engineering controls and enablers that can be used to develop robust COTS-use risk management frameworks. The controls and enablers become the basis to identify where aleatory and epistemic uncertainties exist within a COTS-based space system hardware design. With these statements in mind, unique activities can be defined to analyze, evaluate, and mitigate the uncertainties and the inherent risks to an acceptable level or to determine if a COTS-based design is not appropriate. These concepts were explored and developed in this research. Specifically, a series of COTS centric risk management frameworks were developed that can be used as a roadmap when considering integrating COTS into space hardware designs. From these frameworks unique risk evaluation processes were developed that identified the unique activities needed to effectively evaluate the non-space grade parts being considered. The activities defined in these risk evaluation processes were tailored to uncover as much uncertainty as possible so that appropriate risk mitigation techniques could be applied, design decisions could be quickly made from an informed perspective, and spacecraft fielding could be accomplished at an accelerated rate. Instead of taking five to ten years to field a spacecraft, it can now take less than one to three years. Thus, if effectively used, COTS integration can be a force multiplier throughout the space industry. But first, the best practices learned over the last few decades must be collected, synthesized, documented, and applied. To validate the risk frameworks discussed, a COTS-based space-grade secondary lithium-ion battery was chosen to demonstrate that the concepts could work. Unique risk evaluation activities were developed that took into consideration the spacecraft's mission, environment, application, and lifetime (MEAL) [2] attributes to characterize the battery's COTS cells, printed circuit board, electrical design, and electrical-electronic-electromechanical (EEE) performance, strengths, and weaknesses. The activities defined and executed included risk evaluation activities that included a variety of modeling, analyses, non-destructive examinations, destructive physical assessments, environmental testing, worst case scenario testing, and manufacturing assessments. These activities were developed based on the enablers and controls extracted from the data that was resident in the literature that was reviewed. The techniques employed proved quite successful in uncovering and mitigating numerous aleatory and epistemic uncertainties. The mitigation of these uncertainties significantly improved the battery's design and improved the battery's performance. As a result, the COTS-based battery was successfully built, qualified, and flown on a fleet of launch vehicles and payloads. The information that follows documents how the risk management frameworks were created, what influenced its architecture, and how these were successfully validated. Validating the COTS centric risk management framework was important because it demonstrated the risk management frameworks' utility to uncover uncertainty. It also proved that methods exist that can be readily employed that are not typically within the scope of traditional space hardware design and qualification techniques. This is important because it provides the industry a new set of systems engineering tools that can be employed to limit the impact of supply chain constraints, reduce reliance on expensive low-yield hardware procurement practices, and minimize the amount of obsolete hardware in designs which tend to constrain the space system hardware's performance. As a result, the techniques developed in this research start to fill a gap that exists in the space industry's systems engineering toolbox.Item Open Access MBSAP application to UAV-based wildfire detection and communication(Colorado State University. Libraries, 2023) Crawford, Setrige W., author; Eftekhari Shahroudi, Kamran, advisor; Borky, Mike, committee member; Kreidenweis-Dandy, Sonia, committee member; Bradley, Thomas, committee member; Herber, Daniel, committee memberBy applying the concepts of the Model Based Systems Architecture Process [90] we were able to link stakeholder needs and operational scenarios (Use Cases) to the preliminary design validation of an autonomous hybrid electric/ gas turbine UAV (H-UAV) intended for wildfire detection and communication. The salient stakeholder requirements were captured, operational scenarios identified, trade study was completed, competing architectures were interlinked to a design exploration (DSE) and preliminary airframe sizing, where a user could probe the bounds of design variables in a probabilistic manner to reveal all necessary sensitives and confirm system behaviors were consistent with stakeholder requirements (spiral verification and validation). This thesis takes the reader through this method and the development of each viewpoint, using Cameo Systems Modeler, starting with the Operational Viewpoint, then refinement to the Logical viewpoint and finally development of the Physical Viewpoint. Emphasized, is the use of a coupled architecture model (digital twin – virtual prototype) to confirm system behaviors against requirements and to graphically display system sensitivities. The deeper details of the DSE method and the trade study were previously published [119]. This paper focuses more on the MBSAP approach, the MBSE artifacts and reflects on the benefits of an interlinked model.[7] The method developed affords the researcher a set of tools to efficiently converge on an affordable system solution which meets stakeholder needs and operational requirements for a locally owned and operated wildfire detection and communication system. Further, the MBSAP method is systems agnostic in that. the approach, yields equally effective results whether applied to more software intensive systems, or more mechanical aerospace system (H-UAV) instantiations.Item Open Access Measuring disagreement in segments of the cybersecurity profession as a means of identifying vulnerabilities(Colorado State University. Libraries, 2022) Scalco, Aleksandra, author; Simske, Steven J., advisor; Cale, James, committee member; Herber, Daniel, committee member; Dik, Bryan J., committee memberDisagreement exists among different groups of professionals about remediation of control system vulnerability due to discrepancies in engineering practice, paradigms, processes, and culture. Quantification of agreement among professionals is needed to increase understanding of areas where divergence arises. This need to quantify agreement is particularly among control system Operational Technology (OT) and business enterprise Information Technology (IT) professions. The control system OT workforce does not fully understand the relative vulnerability of each element of its system. Likewise, the business enterprise IT workforce does not widely understand control system assets that control critical infrastructure to achieve cybersecurity assurance. This disagreement among professionals leads to misalignment, which results in vulnerability. Similarly, known vulnerability can inform alignment and bring about agreement among professionals. The exposure induced by misalignment may be greater than innate system design vulnerability. This research introduces an analytical model and methodology for measuring multi-concern assurance among different groups of professions through the statistical uncertainty analysis of Likert and semantic differential scales used for interpreting the scores to identify specific areas of vulnerability.Item Open Access On the integration of materials characterization into the product development lifecycle(Colorado State University. Libraries, 2024) Dare, Matthew S., author; Simske, Steve, advisor; Yourdkhani, Mostafa, committee member; Herber, Daniel, committee member; Radford, Donald W., committee memberThe document is broken down into four sections whereby a more complete integration of materials characterization into the product development lifecycle, when compared to traditional approaches, is researched and considered. The driving purpose behind this research is to demonstrate that an application of systems engineering principles to the characterization sciences mechanism within materials engineering and development will produce a more efficient and comprehensive understanding of complex material systems. This will allow for the mitigation of risk, enhancement of relevant data, and planning of characterization procedures proactively. The first section proposes a methodology for Characterization Systems Engineering (CSE) as an aid in the development life cycle of complex, material systems by combining activities traditionally associated with materials characterization, quality engineering, and systems engineering into an effective hybrid approach. The proposed benefits of CSE include shortened product development phases, faster and more complete problem solving throughout the full system life cycle, and a more adequate mechanism for integrating and accommodating novel materials into already complex systems. CSE also provides a platform for the organization and prioritization of comprehensive testing and targeted test planning strategies. Opportunities to further develop and apply the methodology are discussed. The second section focuses on the need for and design of a characterizability system attribute to assist in the development of systems that involve material components. While materials characterization efforts are typically treated as an afterthought during project planning, the argument is made here that leveraging the data generated via complete characterization efforts can enhance manufacturability, seed research efforts and intellectual property for next-generation projects, and generate more realistic and representative models. A characterizability metric is evaluated against a test scenario, within the domain of electromagnetic interference shielding, to demonstrate the utility and distinction of this system attribute. Follow-on research steps to improve the depth of the attribute application are proposed. In the third section, a test and evaluation planning protocol is developed with the specific intention of increasing the effectiveness of materials characterization within the system development lifecycle. Materials characterization is frequently not accounted for in the test planning phases of system developments, and a more proactive approach to streamlined verification and validation activities can be applied. By applying test engineering methods to materials characterization, systems engineers can produce more complete datasets and more adequately execute testing cycles. A process workflow is introduced to manage the complexity inherent to material systems development and their associated characterization sciences objectives. An example using queuing theory is used to demonstrate the potential efficacy of the technique. Topics for further test and evaluation planning for materials engineering applications are discussed. In the fourth section, a workflow is proposed to more appropriately address the risk generated by materials characterization activities within the development of complex material systems when compared to conventional engineering approaches. Quality engineering, risk mitigation efforts, and emergency response protocols are discussed with the intention of reshaping post-development phase activities to address in-service material failures. While root cause investigations are a critical component to stewardship of the full system lifecycle during a product's development, deployment and operation, a more tailored and proactive response to system defects and failures is required to meet the increasingly stringent technical performance requirements associated with modern, material-intensive systems. The analysis includes a Bayesian approach to risk assessment of materials characterization efforts through which uncertainty regarding scheduling and cost can be quantified.Item Open Access Rotor position synchronization control methods in central-converter multi-machine architectures with application to aerospace electrification(Colorado State University. Libraries, 2024) Lima, Cláudio de Andrade, author; Cale, James, advisor; Chong, Edwin, committee member; Herber, Daniel, committee member; Kirby, Michael, committee memberWith the continuous advancement of the aerospace industry, there has been a significant shift towards More Electric Aircraft (MEA). Some of the advantages of the electrification of some actuation systems in an aircraft include lower weight --- hence, lower fuel consumption, --- robustness, flexibility, ease of integration, and higher availability of sensors to achieve better diagnostics of the system. One cannot ignore the challenges of the electrification process, which encompasses finding appropriate hardware architectures, and control schemes, and obtaining at least the same reliability as traditional drives. The thrust reverser actuation system (TRAS), which acts during landing to reduce the necessary runway for the aircraft to fully decelerate, has a big potential to be replaced by an electromechanical version, the so-called EM-TRAS. Among the different hardware architectures, the central-converter multi-machine (CCMM) stands out for employing a single power converter that drives multiple machines in parallel, saving weight and room usage inside the aircraft. This solution comes with its challenges related to the requirement of ensuring position synchronization among all the machines, even under potentially unbalanced mechanical loads. Since there is only one central converter, all the machines are subject to its common output, limiting the control independence of each machine. Moreover, the lack of position synchronization among the machines can cause harmful stresses to the mechanical structure of the EM-TRAS. This work proposes a solution for position synchronization under CCMM architectures, for aerospace applications. The proposed method utilizes three-phase external and variable resistors connected in series with each of the machines, which increases the degrees of freedom (DOF) to control independently each machine under different demands. Mathematical modeling for the different components of the system is presented, from which the proposed solution is derived. Numerical simulations are used to show the working capabilities of the external resistor method. The performance of the position synchronization is enhanced via H-infinity control design methods. Hardware experiments are also presented, obtained from an experimental testbed that was partially designed and constructed during this work. Both numerical and experimental results are in agreement. Initial findings show that the method is promising and works well under some operating conditions. However, some limitations of the method are presented, such as the unstable operation under negative loads. An alternative position synchronization method for CCMM systems is proposed at the end of this work. The method is based on independently controlled induced voltages on each machine's power cables through low-power auxiliary converters and three-phase compact transformers, resulting in independent terminal voltages applied to each machine. This work describes the method and validates it through numerical simulations. Initial findings show that the method overcomes some of the limitations of the external resistors method, while keeping -- and, in some cases, improving -- the overall performance in terms of convergence time and peak position error.Item Open Access Situational strategic awareness monitoring surveillance system (SSAMSS)(Colorado State University. Libraries, 2023) Maldonado, Kenly R., author; Simske, Steven J., advisor; Miller, Erika, committee member; Herber, Daniel, committee member; Dandy, David, committee memberThis dissertation takes a Systems Engineering approach for the development of a cost-effective, deployable remote sensing materials safeguarding system. This co-called system-of-systems undergoes the major portions of the Systems Engineering development process to assure with confidence that a Situational Strategic Awareness Monitoring Surveillance System (SSAMSS) is a competitive product considered for actual development. The overall assessment takes a strategic approach by using selective tools to create, confirm and consider whether SSAMSS as a product idea ultimately should be developed into an actual prototypical Model (Engineering Model). Although the dissertation explores whether a prototype should be considerate with confidence and risk consideration it does not actually dive into the physical development of the model due to limited time and actual funding. Through the Systems Engineering V-Model, SSAMSS as a product and enterprise is vetted from the customer needs analyses through unit testing (the bottom of the V-model). This is the point where an actual customer would decide to continue the to incorporate SSAMSS into integration and testing, prototype to operations, maintenance, and retirement. Through simulations, assessment, and analysis it has been determined that SSAMSS as a product and enterprise is a viable option to supersede current material safeguarding systems that are competitive in the marketplace today.Item Open Access Techniques in reactive to proactive obsolescence management for C5ISR systems(Colorado State University. Libraries, 2023) Chellin, Matthew D., author; Miller, Erika, advisor; Daily, Jeremy, committee member; Herber, Daniel, committee member; Simske, Steven, committee member; Prawel, David, committee memberObsolescence is a significant challenge for the Command, Control, Communications, Computers, Cyber, Intelligence, Surveillance and Reconnaissance (C5ISR) community. Obsolescence can negatively affect a C5ISR system's cost, schedule, performance, and readiness. This research examines the challenge of obsolescence for C5ISR systems by focusing on the U.S. Army at Aberdeen Proving Ground, Maryland and their industry partners. The objective of this research is to synthesize insights from the experiences of government and industry practitioners that mitigate diminishing manufacturing sources and material shortages (DMSMS) challenges into mitigation techniques. The obsolescence mitigation areas described in this research include proactive and reactive obsolescence mitigation, obsolescence mitigation methods, and the importance of DMSMS contracting language. This research also offers approaches grounded in practitioner experiences to mitigate obsolescence through a proactive obsolescence management model, risk mitigation framework, metrics, modeling & simulation, and systems thinking methods. The combination of the models, methods, and approaches discussed from this research have the potential to achieve greater system readiness, more availability, better maintainability, and lower costs for C5ISR systems.Item Open Access The application of model-based systems engineering to understand security of systems using SAE J1939(Colorado State University. Libraries, 2024) Salinger, Gabe, author; Daily, Jeremy, advisor; Herber, Daniel, committee member; Windom, Bret, committee memberThe Engineering community is adopting a Digital Engineering approach enabled by Model-Based Systems Engineering (MBSE) as an effective tool for designing complex systems. As technology continues to rapidly advance, security risk mitigation and requirements engineering is becoming a prominent and important factor in the cybersecurity domain. As a result, engineering methods and frameworks must constantly be improved and updated to implement the successful realization of cyber-physical systems (CPS). With the inherent connectivity, accessibility, and lack of security making CPSs attractive targets for cyber attacks, integrating security considerations into system development is crucial. With 'security by design' being a fundamental pillar of system development, MBSE plays a pivotal role in shaping secure system architectures. In this thesis, I explore the application of MBSE to the system security domain, focusing on secure system development and the incorporation of security by design throughout the system development phase. This is accomplished by investigating the utility of MBSE in understanding the vulnerabilities of a Medium to Heavy Duty (MHD) vehicle, improving its security posture, and providing recommendations on how to improve the process. This is achieved by first exploring the utility of simulation using model-based tools to better understand complex systems, and bridge the gap between bottom-up and top-down approaches. Next, an established method, MBSEsec, is applied to the system of interest (SOI) to develop security controls for the vehicle's transport protocol. Additionally, recommendations are provided for improving the method's effectiveness in documenting vulnerabilities, and risk. MBSEsec is a security-focused MBSE method using SysML to develop a system architecture that highlights security design considerations. The method's structured workflow facilitates the elicitation of security requirements and controls using specific systems modeling activities. The primary focus is on the heavy vehicle network transport protocol, J1939, serving as the SOI. The discovery and validation of new exploits that take advantage of vulnerabilities in the data-link layer of the protocol highlights the need to elicit better security requirements for cyber-physical systems (CPS). Using the J1939 network as the SOI for this work allows the models to be supported by and validated with on-vehicle testing. This work contributes a survey of modeling approaches for secure system design. Lastly, this thesis details the development of a novel approach for system-level mission-focused security goal elicitation. EGRESS: Eliciting Goals for Requirement Engineering of Secure Systems, incorporates best practices from security requirement engineering works, and utilizes Model-Based Systems Engineering to formulate security goals for cyber-physical systems, aiming to create more comprehensive security requirements.