Ann Miller

Modeling Cyber-Physical Systems with Semantic Agents

The development of accurate models for cyber-physical systems (CPSs) is hampered by the complexity of these systems, fundamental differences in the operation of cyber and physical components, and significant interdependencies among these components. Agent-based modeling shows promise in overcoming these challenges, due to the flexibility of software agents as autonomous and intelligent decision-making components. Semantic agent systems are even more capable, as the structure they provide facilitates the extraction of meaningful content from the data provided to the software agents. In this paper, we present a multi-agent model for a CPS, where the semantic capabilities are underpinned by sensor networks that provide information about the physical operation to the cyber infrastructure. This model is used to represent the static structure and dynamic behavior of an intelligent water distribution network as a CPS case study.

A General Framework for Quantitative Modeling of Dependability in Cyber-Physical Systems: A Proposal for Doctoral Research

The overarching objective of the proposed doctoral researches to build a qualitative and quantitative understanding of dependability in cyber physical systems (CPS).The existing body of knowledge includes frameworks and techniques for assessment, modeling, and simulation of the physical and cyber infrastructures, respectively, but such isolated analysis is incapable of fully capturing the interdependencies between these infrastructures. Understanding these interdependencies is a critical precursor to accurate representation and modeling of the CPS as a whole, especially with respect to dependability.The physical water distribution infrastructure, coupled with the hardware and software that support intelligent water allocation, comprise the model CPS that will be used as a case study for the proposed research. A preliminary literature review has been carried out on dependability modeling for CPS, with very sparse results. Allocation algorithms for water distribution have also been investigated,with game theory appearing to hold the most promise.An agent-based approach is suggested for linking the cyber and physical layers, where the agents retrieve information from sensors monitoring the physical components and provide this information to the cyber components. Fault injection will be used to investigate the propagation of failures between the cyber and physical layers. Markovian models will be used to capture the manifestation of cyber and/or physical faults as failures in water allocation, or containment of contaminants.

A Semantic Agent Framework for Cyber-Physical Systems

The development of accurate models for cyber-physical systems (CPSs) is hampered by the complexity of these systems, fundamental differences in the operation of cyber and physical components, and significant interdependencies among these components. Agent-based modeling shows promise in overcoming these challenges, due to the flexibility of software agents as autonomous and intelligent decision-making components. Semantic agent systems are even more capable, as the structure they provide facilitates the extraction of meaningful content from the data provided to the software agents. In this book chapter, we present a multi-agent model for a CPS, where the semantic capabilities are underpinned by sensor networks that provide information about the physical operation to the cyber infrastructure. As a specific example of the semantic interpretation of raw sensor data streams, we present a failure detection ontology for an intelligent water distribution network as a model CPS. The ontology represents physical entities in the CPS, as well as the information extraction, analysis and processing that takes place in relation to these entities. The chapter concludes with introduction of a semantic agent framework for CPS, and presentation of a sample implementation of the framework using C++.

Managing Large Software Projects

Thirty years ago, as the software industry was first gathering steam, most software projects were run by people with no software experience. Today this is no longer true. Our industry is characterized by managers who have spent most or all of their professional lives in software development. Yet few would argue that the quality of software project management has improved in the same period. While software efforts in general do not seem to be better managed, there are increasing numbers of successes among our largest projects. The Boeing 777 and Lockheed F-16 projects, for example (each covered in this special issue), were successful despite a magnitude that would have daunted software managers even a few years ago.

Selecting software subcontractors

Large-scale software projects place special demands on the developing organization and can require much greater participation by outside companies. The authors describe their methods for selecting subcontractors for a large project in which outside companies are supplying 90 percent of the code.

Symbolic Reduction for High-Speed Power System Simulation

High-speed simulations of power transmission systems, which often rely on solving nonlinear systems of equations, are an increasingly important tool for training, testing equipment, on-line control and situational awareness. Such simulations, however, suffer from two major problems: (1) they can be too computationally demanding to simulate large, complex systems within appropriate time constraints; and (2) they are difficult to develop and debug. Prior work has shown how symbolic computation can be used to help reduce both problems. In this paper, we: (1) review common concepts in power system simulations; (2) summarize prior use of symbolic computation in power system simulation; (3) explore the advantages and disadvantages achieved via symbolic techniques; (4) extend the techniques to solve linear systems via a priori symbolic LU decomposition; and (5) demonstrate the advantages of symbolic techniques on a transient event simulation of the IEEE 118-bus test power system, which runs in one-tenth the time of an equivalent traditional (sparse matrix) approach.

Assurance Cases for Security: The Metrics Challenge

For critical systems it is important to know whether the system is trustworthy and to be able to communicate, review and debate the level of trust achieved. In the safety domain, explicit Safety Cases are increasingly required by law, regulations and standards. Yet the need to understand risks is not just a safety issue and the type of argumentation used for safety cases is not specific to safety alone. Prior workshops, beginning with one held at DSN 2004, have identified a number of technical, policy and research challenges. The focus of this workshop is on one of these challenges: metrics for assurance cases for security.

A Game-Theoretic Approach to Decision Support for Intelligent Water Distribution

Cyber-physical systems, and the intelligent decision support systems that they enable, carry the promise of greater efficacy in environmental management. The complexity of the physical infrastructure subject to decisions by environmental management systems is often an impediment to this efficacy. Other challenges include fundamental differences in the operation of cyber and physical components, and significant interdependency among the cyber components that facilitate decision support and the physical components they control. The agent-based computing paradigm is proposed for surmounting these challenges, due to the flexibility of software agents as autonomous and intelligent decision-making components. In this paper, we utilize an agent-based system to illustrate the application of game theory to decision support for environmental management, in the context of intelligent water distribution. Simulation results are presented to validate the model proposed, and to investigate the effect of various model parameters on water allocation.

System Evaluation and Description Using Abstract Relation Types (ART)

Two abstract relation types (ART) are developed to represent, describe and establish a computational framework for a system. An abstract relation type is closely related to and builds upon two fundamental ideas. The first idea is the binary relation and structural modeling techniques developed by John N. Warfield. The second idea is the concept of abstract data types. These two ideas are combined to create an abstract relation type that provides a structured representation and computational method for systems and system components. The complete system description approach is based on six abstract relation types: context, concept, functions, requirements, architecture, and test (CCFRAT). When combined with digraphs and other graphical representations of the matrix form, ART provides a powerful tool for the communication of complex system interactions to large system design teams.

Software engineering as a business

Increasingly, system functional-ity is implemented in software. Where we used to split hardware from software, the business case entirely determines such boundaries now—what we best package at which level in which component , be it software or silicon. For example, a TV set in the 1970s had no software, whereas today its competitive advantages and the majority of engineering efforts are software-driven. The software business, however , has manifold challenges, ranging from the creation process and its inherent risks to direct balance sheet impacts. For example, the Standish Group found in its survey (2000 edition of the Chaos Report) that only 26 percent of the projects finished on time and within budget and a staggering 28 percent were canceled before deN o matter what business you are in, you are also part of the software business. Software makes the world go round—at ever increasing speeds. Computer-based, software-driven systems pervade todays society. From avionics flight control to the ubiquitous computers in personal digital assistants and cellular phones, to automotive and consumer electronics , software provides features and functions in daily use.