Navindran Davendralingam

A Robust Portfolio Optimization Approach to System of System Architectures

The realization of military capability as a System of Systems (SoS), presents significant development challenges across technical, operational and programmatic dimensions. In particular, tools for deciding how to form and evolve SoS which consider performance and risk are lacking. This research leverages tools from financial engineering and operations research perspectives in portfolio optimization to assist decision making in this setting. Our approach facilitates evolutions of SoS architecture through a framework that supports architecture selection at a given decision-epoch of the evolutionary process. The approach models hierarchies of interdependent systems as generic nodes on a network that, subject to connectivity and compatibility constraints, work cohesively to fulfill overarching capability objectives. A robust portfolio algorithm is employed to address inherent real world issues of data uncertainty, inter-nodal performance and developmental risk. A naval warfare scenario illustrates application of the method to find “portfoliosˮ of systems from a candidate list of available systems. Results show how the framework effectively reduces the combinatorial complexity of tradespace exploration (e.g., connectivity rules, feasibility of solutions, optimality of solutions) by allowing the optimization problem to handle the mathematically intensive aspects of the decision-making process. As a result, human decision-makers can focus on choosing the appropriate weights for risk aversion in making final decisions.

A Robust Optimization Framework to Architecting System of Systems

Abstract The architecting of a System-of-Systems (SoS) is greatly challenging due to coupling of managerial independence and highly complex operational interdependence, in achieving desired overarching capabilities. Furthermore, difficulties arise when uncertainties in the performance of individual, interconnected systems, lead to significant risks of cascading modes of failure. Mitigation of these risks through appropriate selection and design of constituent systems is important to ensure resilience of SoS architectures to operational disruptions, whilst preserving resource and cost constraints. Current guidelines and tools for architecting SoS architectures are lacking sufficient capabilities in enabling effective decision-making for SoSE practitioners. This paper presents a novel robust optimization framework to architecting a System-of-Systems (SoS). Hierarchies of operationally interdependent systems are modeled as nodes on a network that work cohesively to fulfill overarching capability objectives. Inter-nodal performance and constraints associated with connectivity under performance uncertainty are addressed. Recent advances in robust optimization methods are employed within the context of a Mixed-Integer Program (MIP) for the developed framework. A simplified case scenario using the Littoral Combat Ship (LCS) platform demonstrates application of the formulation.

An Approach to Facilitate Decision Making on Architecture Evolution Strategies

Abstract The evolution of System of Systems (SoS) architectures is a difficult process due to the complex interactions between entities that exist in an SoS. Adequate tools are thus needed in capturing these interdependencies to support informed decisions on architectural evolutions. In this paper, an approach is introduced to facilitate decision making on architecture evolution strategies. The main purpose of evolving architecture is to satisfy advanced capability and performance objectives through adding new systems, replacing existing systems, changing links, etc. The paper employs Colored Petri Nets (CPN), a powerful discrete event dynamic simulation tool, to model, simulate and evaluate the existing and evolving architectures. However, it is unrealistic to improve performance without considering the cost of architecture evolutions. This paper regards complexity as an indicator of the architecture evolving cost. Compared to other complexity metrics, dynamic complexity is included in the complexity metric in this paper. Eventually, an appropriate evolution choice could be achieved by examining the tradeoff space between complexity and performance. This approach is illustrated with a conceptual SoS problem.

Concurrent Aircraft Design and Airline Network Design Incorporating Passenger Demand Models

Conceptual aircraft design and the network routes that they trave l on are inextricably linked to passenger driven demand. Decisions made in the acquisition and subsequent allocation of aircraft assets to serve chosen links translate to latent passenger observations of ticket pricing and routes served between origin -destination (OD) pairs. It is proposed that such latency gives rise to a reflexive behavior in demand as subsequent operational decisions give rise to reflexive passenger demand conditions. In this paper, a unifying conceptual framework that builds upon previous works is proposed to concurrently design aircraft and the operational network by incorporating established passenger demand models . A conceptual scenario formulated and solved to exhibit the methodology employed and reflexivity of demand.

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.

Robust Approach for Concurrent Aircraft Design and Airline Network Design

Conceptual aircraft design directly impacts the structure of an airline’s route network and ability to service demand for various ticket itineraries between origin and destination city pairs. The decisions made in allocating new aircraft to serve predicted future demand of various ticket itineraries affects an airline’s risk and profit potential. Therefore, choices on the selection of target market travel itineraries to be served and design requirements of new, yet-to-be-introduced aircraft directly govern the tradeoff of risk against potential profit. This paper presents a concurrent engineering strategy for an airline that wishes to investigate the impact that aircraft design choices and target market capture decisions have on tradeoffs between expected profit and risk in serving particular demand itineraries. The approach considers the integrated domains of aircraft design, airline operations, and passenger demand within the context of a mathematical programming problem. More specifically, innovations ...

A mechanism design framework for the acquisition of independently managed systems of systems

This paper applies results from studies of the acquisition process and from algorithmic methods applicable to the mechanism design of agent-based auctions to modeling behaviors and effecting policy interventions that are intended to improve overall programmatic performance when acquiring independently managed systems of systems. Previous models and empirical studies provide an understanding of the behavioral aspects of the acquisition process and are supported by empirical data from surveys. A method inspired by mechanism design is proposed that incorporates the insights and data from these studies to formulate a probabilistic optimization framework for constructing interventions that enhance the probability of meeting cost and schedule goals when acquiring a system of systems.

Scientific Foundations for Systems Engineering: Challenges and Strategies

There is an increasing realization of the need for fundamental research in the science of systems engineering. The International Council on Systems Engineering vision document calls for theoretical foundations for systems architecting, systems design and systems understanding. During a recent NSF workshop, a number of knowledge areas ranging from mathematics, information sciences, physical sciences, systems science to human and social sciences were identified as possible sources from which the scientific foundation of systems engineering can be enhanced. However, the primary challenge facing the community lies in orchestrating the breadth and diversity of the many knowledge areas into a cohesive foundation. This paper briefly surveys systems science-related efforts across multiple application domains. The specific objectives in this paper are to present a classification of initiatives for developing foundations for systems engineering, and to discuss the challenges, and potential strategies forward, associated with systems science research. The classification is discussed using two case examples — the Internet and the air transportation system. Through these examples, some of the key research challenges and strategies are exemplified.Copyright

Robust Optimization of Aircraft Design and Airline Network Design Incorporating Economic Trends

Traditionally, aircraft design seeks an aircraft that can perform a specific design mission(s) at minimum cost and/or weight; these metrics serve as surrogates for airline profitability. Here, an approach to evaluate new aircraft for use along with an existing fleet and the optimal choice of routes to be served subject to risk constraints is presented. The framework simulateously considers aircraft design and airline network (routes) served within an investment portfolio context under conditions of uncertainty. The resulting ‘portfolio’ addresses the amount of projected demand the airline should serve and determines an optimal service network to satisfy this demand at an aggregate level. This approach balances the expected reward from using potential yet-to-be introduced aircraft to serve additional routes and demand against the risk associated with demand volatility on each route. A robust optimization method using semidefinite programming (SDP) addresses tractability.

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.