Cesare Guariniello

Dependency Analysis of System-of-Systems Operational and Development Networks☆

Abstract In this research, a Dependency Network Analysis technique has been adapted to assess operability, reliability, and resilience in both operational and development networks, associated with System of System architectures. The architecture is modeled as a directed network where nodes represent either the component systems or the capabilities to be acquired. Links on the network represent various kinds of dependencies between the constituent systems: functional dependency in an operational network, sequential development dependency in a development network. Each dependency is characterized by strength and criticality. The ultimate goal of the technique seeks to analyze effects of such dependencies -and of their strength and criticality- on operability, and to identify valid operating and developing strategies and architectures. For operational networks, Functional Dependency Network Analysis is used to assess the effect of topology and of possible degraded functioning of one or more systems on the operability of the network. For development networks, Development Dependency Network Analysis is used to assess how development time or capabilities are affected by the network topology and by delays in the development of component systems. Each technique is evaluated with regard to amount and quality of necessary input, completeness and usefulness of results, and applicability to problems of diverse nature.

Communications, Information, and Cyber Security in Systems-of-Systems: Assessing the Impact of Attacks through Interdependency Analysis.

Abstract The analysis of risks associated with communications, and information security for a system-of-systems is a challenging endeavor. This difficulty is due to the complex interdependencies that exist in the communication and operational dimensions of the system-of-systems network, where disruptions on nodes and links can give rise to cascading failure modes. In this paper, we propose the modification of a functional dependency analysis tool, as a means of analyzing system-of-system operational and communication architectures. The goal of this research is to quantify the impact of attacks on communications, and information flows on the operability of the component systems, and to evaluate and compare different architectures with respect to their reliability and robustness under attack. Based on the topology of the network, and on the properties of the dependencies, our method quantifies the operability of each system as a function of the availability and correctness of the required input, and of the operability of the other systems in the network. The model accounts for partial capabilities and partial degradation. Robustness of the system-of-systems is evaluated in terms of its capability to maintain an adequate level of operability following a disruption in communications. Hence, different architectures can be compared based on their sensitivity to attacks, and the method can be used to guide decision both in architecting the system-of-systems and in planning updates and modifications, accounting for the impact of interdependencies on the robustness of the system-of-systems. Synthetic examples show conceptual application of the method.

Maintenance and Recycling in Space: Functional Dependency Analysis of On-Orbit Servicing Satellites Team for Modular Spacecraft

This paper introduces an innovative perspective in the problem of on-orbit servicing and maintenance. A network of modular satellites and servicing satellites is modeled as a two-level System-of-Systems. At the lower level, the architecture of the modular satellites is analyzed in terms of functional interdepencies between the component modules. Analysis of the impact of such interdependencies gives insight into the operability of the satellite, and accounts for partial failures, redundancies, and criticality of the modules. At the higher level, communication, observation, and experimental satellites and constellation are constituents of a System-of-Systems functional network. The other components of this network are servicing satellites, able to perform inspection, refueling, maintenance. At this level, results from the overall functional dependency analysis are used to evaluate and compare different architectures, i.e. different number, capabilities, and location of servicing satellites. We discuss the innovation brought by the proposed approach with respect to the current practice. A hypothetical scenario is considered, featuring satellites with different architectures, whose parts are susceptible to aging and to failures over time, and on-orbit servicing satellites. Results show not only the general applicability of the method in order to perform analysis, but also possible future applications of both the proposed concepts and the analytical tool in space systems architecture and design.

Integrated Analysis of Functional and Developmental Interdependencies to Quantify and Trade-off Ilities for System-of-Systems Design, Architecture, and Evolution

Abstract When complex systems and systems-of-systems are involved, the behavior of the whole entity is not only due to that of the individual systems, but also to the interactions and interdependencies between the systems. Classical systems engineering approach is not always suitable to manage such feature, and new tools and methods are required, capable to identify, analyze and quantify properties of the system-of-systems as a whole. This research addresses the need to deal with complex dependencies between systems, in both developmental and functional relationships. We propose a combination of two previously developed methods, to analyze functional and developmental dependencies between systems in a system-of-systems, and to assess the impact of such dependencies on metrics that characterize global prop erties of a system-of-systems over its life span known as ilities. The analysis can be used to drive decisions for system-of- systems design, architecture, and evolution, with respect to the identified metrics of interest. It also accounts for the presence of multiple stakeholders, and external factors that influence the operability and the development of a system-of-systems. The methods support the analysis of trade-offs between competing ilities and facilitates identification of better performing architectures. We show preliminary results of the application of the methods, and how the results can be interpreted to evaluate system-of-system ilities on synthetic problems. We also propose the necessary steps for further improvement of the methods, and for future research.

An Analytic Workbench Perspective to Evolution of System of Systems Architectures

Abstract The development of a large group of interdependently operating systems, or ‘System of Systems (SoS)’, presents significant challenges across technical, operational and programmatic dimensions. Trades between cost, schedule, performance, and associated spectrum of risks, are essential during analysis of alternatives for both individual systems and the SoS architecture as a whole. The large number of decision variables involved, ubiquitous uncertainty and complex interactions that exist between systems creates analysis problems that go well beyond the immediate mental faculties of decision-makers. Often times, the decisions made focus on localized development at the systems level with little consideration for cascading effects on the bigger SoS picture. Hence, the process of evolving SoS architectures requires tools that provides the SoS practitioner with meaningful analytical quantifications of the SoS tradespace. In the defense arena, existing tools for such trades, have been guided by policies set forth in the Defense Acquisitions Guidebook (DAG) (5000 series) and the System Engineering Guide for System of Systems (SoS-SE), but are lacking an analytic perspective towards more informed decision-making. This paper discusses a multidisciplinary effort, funded by the DoDs Systems Engineering research Center (SERC), to establish an analytic workbench of computational tools to facilitate better-informed decision-making on SoS architectures. The work is motivated by the idea that SoS practitioners possess relevant information and archetypal questions that reflect desired outcomes at the SoS level. These archetypal, technically -driven queries are mapped to relevant methods that can provide analytical outputs to directly support SoS acquisition and architectural decisions. The applicability and respective value-added of each method in addressing various archetypal measures are presented.

Modularity research to guide MOSA implementation

The US Department of Defense’s acquisition strategy incorporates directives to encourage the use of open architectures and modular solutions through the Modular Open Systems Approach (MOSA). The ways in which open standards are currently implemented, and programmatic guidance regarding the adoption of modular approaches, are inadequate, however, because of limitations on how modularity is objectively viewed to achieve its perceived benefits. Furthermore, current examples of implementations of modular concepts largely do not consider interdependencies at the enterprise level. This paper reviews ongoing research on modularity and openness, to synthesize best practices, community driven knowledge, and technical and programmatic catalysts that can better shape the appropriate adoption of MOSA. These items will be part of a comprehensive decision-making framework that can provide guidance to program managers in defense acquisition.

A Robust Portfolio Optimization Approach Using Parametric Piecewise Linear Models of System Dependencies

“System of Systems” architecture problems can be very challenging due to the large number of systems involved and complex interdependencies that exist between and among them. The high number of decision variables and interactions presents the need for an appropriate collection of methods, processes, and tools that can help practitioners deal with such complexities and answer key questions that typically arise when evolving an architecture. In this chapter, we build on prior work toward developing a System-of-Systems Analytic Workbench and propose a combined use of two of the workbench tools, namely, the Robust Portfolio Optimization and Systems Operational Dependency Analysis tools. The purpose of the combination is to more explicitly introduce the dependency modeling capabilities of one with the computationally efficient decision-support capabilities of the other. We demonstrate application of the proposed combined approach on a conceptual Naval Warfare Scenario problem.