Smartness of technical systems relies also on appropriate actuators and sensors. Different to the prevalent definition of smartness to be embedded machine intelligence, in this paper elegance and simplicity of solutions is postulated be a more uniform and useful characterization. This is discussed in view of the current trends towards cyber physical systems and the role of components and subsystems, as well as of models for their effective realization. Current research on actuators and sensing in the fluid power area has some emphasis on simplicity and elegance of solution concepts and sophisticated modeling. This is demonstrated by examples from sensorless positioning, valve actuation, and compact hydraulic power supply.

Doctor of Philosophy / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / Caterina Scoglio / Many physical and engineered systems (e.g., smart grid, transportation and biomedical systems) are increasingly being monitored and controlled over a communication network. These systems where sensing, communication, computation and real time control are closely integrated are referred to as cyber physical systems (CPS). Cyber physical systems present a plethora of challenges related to their design, analysis, optimization and control. In this dissertation, we present some fundamental methodologies to analyze the optimization of physical systems over a communication network. Specifically, we consider a medium voltage DC shipboard smart grid (SSG) reconfiguration problem as a test case to demonstrate our approach. The main goal of SSG reconfiguration is to change the topology of the physical power system by switching circuit breakers, switches, and other devices in the system in order to route power effectively to loads especially in the event of faults/failures. A majority of the prior work has focused on centralized approaches to optimize the switch configuration to maximize specific objectives. These methods are prohibitively complex and not suited for agile reconfiguration in mission critical situations. Decentralized solutions proposed do reduce complexity and implementation time at the cost of optimality. Unfortunately, none of the prior efforts in this arena address the cyber physical aspects of an SSG. This dissertation aims to bridge this gap by proposing a suite of methods to analyze both centralized and decentralized SSG reconfigurations that incorporate the effect of the underlying cyber infrastructure. The SSG reconfiguration problem is a mixed integer non convex optimization problem for which branch and bound based solutions have been proposed earlier. Here, optimal reconfiguration strategies prioritize the power delivered to vital loads over semi-vital and non vital loads. In this work, we propose a convex approximation to the original non convex problem that significantly reduces complexity of the SSG reconfiguration. Tradeoff between power delivered and number of switching operations after reconfiguration is discussed at steady state. Second, the distribution of end-to-end delay associated with fault diagnosis and reconfiguration in SSG is investigated from a cyber-physical system perspective. Specifically, a cross-layer total (end-to-end) delay analysis framework is introduced for SSG reconfiguration. The proposed framework stochastically models the heterogeneity of actions of various sub-systems viz., the reconfiguration of power systems, generation of fault information by sensor nodes associated to the power system, processing actions at control center to resolve fault locations and reconfiguration, and information flow through communication network to:(1) analyze the distribution of total delay in SSG reconfiguration after the occurrence of faults; and (2) propose design options for real-time reconfiguration solutions for shipboard CPS, that meet total delay requirements. Finally, the dissertation focuses on the quality of SSG reconfiguration solution with incomplete knowledge of the overall system state, and communication costs that may affect the quality (optimality) of the resulting reconfiguration. A dual decomposition based decentralized optimization in which the shipboard system is decomposed into multiple separable subsystems with agents is proposed. Specifically, agents monitoring each subsystem solve a local concave dual function of the original objective while neighboring agents share information over a communication network to obtain a global solution. The convergence of the proposed approach under varying network delays and quantization noise is analyzed and comparisons with centralized approaches are presented. Results demonstrate the effectiveness as well as tradeoffs involved in centralized and decentralized SSG reconfiguration approaches.

This dissertation treats a variety of topics in the computer security domain which have direct impact on everyday life. The first extends false data injection attacks against state estimation in electric power grids and then provides a novel power flow model camouflage method to hamper these attacks. The second deals with automotive theft response, detailing a method for a car to intelligently identify when it has been stolen, based on collected behavioral traits of its driver. The third demonstrates a new attack against the content integrity of the PDF file format, caus- ing humans and computers to see different information within the same PDF documents. This dissertation lastly describes some future work efforts, identifying some potential vulnerabilities in the automated enforcement of copyright protection for audio (particularly music) in online systems such as YouTube.

The growing connectivity of cyber-physical systems (CPSes) has led to an increased concern over the ability of cyber-attacks to inflict physical damage. Current cybersecurity measures focus on preventing attacks from penetrating control supervisory networks. These reactive techniques, however, are often plagued with vulnerabilities and zero-day exploits. Embedded processors in CPS field devices often possess little security of their own, and are easily exploited once the network is penetrated. In response, researchers at Georgia Tech and Virginia Tech have proposed a Trustworthy Autonomic Interface Guardian Architecture (TAIGA), which monitors communication between the embedded controller and physical process. This autonomic architecture provides the physical process with a last line of defense against cyber-attacks by switching process control to a trusted backup controller if an attack causes a system specification violation. This thesis focuses on classifying the effects of cyberattacks on embedded controllers, evaluating TAIGA’s resilience against these attacks, and determining the applicability of TAIGA to other CPSes. This thesis identifies four possible outcomes of a cyber-attack on a CPS embedded processor. We then evaluate TAIGA’s mechanisms to defend against those attack outcomes, and verify TAIGA satisfies the listed trust requirements. Next, we discuss an implementation and the experimental results of TAIGA on a hazardous cargo transportation robot. Then, by making various modifications to the setup configuration, we are able to explore TAIGA’s ability to provide security and process protection to other CPSes with varying levels of autonomy or distributed components.

abstract: Cyber Physical Systems (CPSs) are systems comprising of computational systems that interact with the physical world to perform sensing, communication, computation and actuation. Common examples of these systems include Body Area Networks (BANs), Autonomous Vehicles (AVs), Power Distribution Systems etc. The close coupling between cyber and physical worlds in a CPS manifests in two types of interactions between computing systems and the physical world: intentional and unintentional. Unintentional interactions result from the physical characteristics of the computing systems and often cause harm to the physical world, if the computing nodes are close to each other, these interactions may overlap thereby increasing the chances of causing a Safety hazard. Similarly, due to mobile nature of computing nodes in a CPS planned and unplanned interactions with the physical world occur. These interactions represent the behavior of a computing node while it is following a planned path and during faulty operations. Both of these interactions change over time due to the dynamics (motion) of the computing node and may overlap thereby causing harm to the physical world. Lack of proper modeling and analysis frameworks for these systems causes system designers to use ad-hoc techniques thereby further increasing their design and development time. The thesis addresses these problems by taking a holistic approach to model Computational, Physical and Cyber Physical Interactions (CPIs) aspects of a CPS and proposes modeling constructs for them. These constructs are analyzed using a safety analysis algorithm developed as part of the thesis. The algorithm computes the intersection of CPIs for both mobile as well as static computing nodes and determines the safety of the physical system. A framework is developed by extending AADL to support these modeling constructs; the safety analysis algorithm is implemented as OSATE plug-in. The applicability of the proposed approach is demonstrated by considering the safety of human tissue during the operations of BAN, and the safety of passengers traveling in an Autonomous Vehicle. / Dissertation/Thesis / M.S. Computer Science 2010

abstract: There has been exciting progress in the area of Unmanned Aerial Vehicles (UAV) in the last decade, especially for quadrotors due to their nature of easy manipulation and simple structure. A lot of research has been done on achieving autonomous and robust control for quadrotors. Recently researchers have been utilizing linear temporal logic as mission specification language for robot motion planning due to its expressiveness and scalability. Several algorithms have been proposed to achieve autonomous temporal logic planning. Also, several frameworks are designed to compose those discrete planners and continuous controllers to make sure the actual trajectory also satisfies the mission specification. However, most of these works use first-order kinematic models which are not accurate when quadrotors fly at high speed and cannot fully utilize the potential of quadrotors. This thesis work describes a new design for a hierarchical hybrid controller that is based on a dynamic model and seeks to achieve better performance in terms of speed and accuracy compared with some previous works. Furthermore, the proposed hierarchical controller is making progress towards guaranteed satisfaction of mission specification expressed in Linear Temporal Logic for dynamic systems. An event-driven receding horizon planner is also utilized that aims at distributed and decentralized planning for large-scale navigation scenarios. The benefits of this approach will be demonstrated using simulations results. / Dissertation/Thesis / Masters Thesis Computer Science 2016

Computational power of mobile devices has been continuously improving in the recent years. One of the benefits which it brings, is feasibility of new kinds of distributed systems, such as Ensemble-Based Component Systems (EBCS). For practical reasons, EBCS systems are usually tested using simulations before being released. However, it can be difficult to interpret the simulation output, as it is usually contained in XML format, which is more suited to be read by machines than by people. We provide a visualizing application, which creates a graphical representation of such a simulation output. Out of the box, it is able to visualize data from applications built on top of the JDEECo component model, but it can be easily modified to accept output from different EBCS applications. It is able to visualize both components and ensembles and provides a scripting interface to modify the graphical output. In addition, it has an extensibility mechanism for adding new functionalities. Our benchmarking shows that the application is expected to run reasonably fast in typical scenarios.

The cyber-physical systems (CPS), such as smart grid and intelligent transportation system, permeate into our modern societies recently. The infrastructures in such systems are closely interconnected and related, e.g., the intelligent transportation system is based on the reliable communication system, which requires the stable electricity provided by power grid for the proper function. We call such mutually related systems interdependent networks. This thesis addresses the cascading failure issue in interdependent cyber physical system. We consider CPS as a system that consists of physical-resource and computational-resource networks. The failure in physical-resource network might cause the failures in computational-resource network, and vice versa. This failure may recursively occur and cause a sequence of failures in both networks. In this thesis, we propose two novel interdependence models that better capture the interdependent networks. Then, we study the effect of cascading failures using percolation theory and present the detailed mathematical analysis on failure propagation in the system. By calculating the size of functioning parts in both networks, we analyze the robustness of our models against the random attacks and failures. The cascading failures in smart grid is also investigated, where two types of cascading failures are mixed. We estimate how the node tolerance parameter T (ratio of capacity to initial workload) affect the system performance. This thesis also explores the small clusters. We give insightful views on small cluster in interdependent networks, under different interdependence models and network topologies.

The conceptual evolution of smart cities is highly motivated by the advancement of information and communication technologies (ICTs). The purpose of a smart city is to facilitate the best quality of life to its inhabitants. Its implementation has to be supported by the compliant utilities and networked infrastructures. In the current world, it can only be achieved by applying ICTs in an extensive manner. The move towards the smart city's seamless connectivity widens the scope of cyber security concerns. Smart city infrastructures to face a high risk of targeted attacks due to extended cyber-physical vulnerabilities. This creates many challenging research issues relevant to the design and implementation of cyber security solutions. Networks associated with city infrastructures vary from a small indoor one to a large geographically distributed one. The context of a network is an essential consideration for security solutions. This thesis investigates a set of optimal security placement problems for enhancing monitoring in smart city infrastructures. It develops solutions to such placement problems from a resource management perspective. Economy and quality-of-security service (QoSS) are two major design goals. Such goals are translated into three basic performance metrics: (i) coverage, (ii) tolerance, and (iii) latency. This thesis studies security placement problems pertaining to three different types of networks: (i) wireless sensor network (WSN), (ii) supervisory control and data acquisition (SCADA) backbone, and (iii) advanced metering infrastructure (AMI) wide area network (WAN). In a smart city, WSNs are deployed to support real time monitoring and safety alert (RTMSA) applications. They are highly resource constrained networks. For WSNs, placement problems for an internally configured security monitor named watchdog have been studied. On the other hand, a smart grid is a key driver for smart cities. SCADA and AMI are two major components of a smart grid. They are associated with two different types of geographically distributed networks. For SCADA backbones, placement problems for a specially designed security device named trust system have been studied. For AMI-WANs, placement problems for a cloud-based managed security service have been studied. This thesis proposes a number of promising solution schemes to such placement problems. It includes evaluation results that demonstrate the enhancements of the proposed schemes.

Cyber-Physical Systems (CPS) are physical entities whose operations are monitored, coordinated, and controlled by a computing and communication core. These systems are highly heterogeneous and complex. Their numerous components and cross domain complexity make attacks easy to propagate and security difficult to implement. Consequently, to secure these systems, they need to be built in a systematic and holistic way, where security is an integral part of the development lifecycle and not just an activity after development. These systems present a multitude of implementation details in their component units, so it is fundamental to use abstraction in the analysis and construction of their architecture. In particular, we can apply abstraction through the use of patterns. Pattern-based architectural modeling is a powerful way to describe the system and analyze its security and the other non-functional aspects. Patterns also have the potential to unify the design of their computational, communication, and control aspects. Architectural modeling can be performed through UML diagrams to show the interactions and dependencies between different components and its stakeholders. Also, it can be used to analyze security threats and describe the possible countermeasures to mitigate these threats. An important type of CPS is a maritime container terminal, a facility where cargo containers are transported between ships and land vehicles; for example, trains or trucks, for onward transportation, and vice versa. Every cargo port performs four basic functions: receiving, storing, staging and loading for both, import and export containers. We present here a set of patterns that describe the elements and functions of a cargo port system, and a Reference Architecture (RA) built using these patterns. We analyze and systematically enumerate the possible security threats to a container terminal in a cargo port using activity diagrams derived from selected use cases of the system. We describe these threats using misuse patterns, and from them select security patterns as defenses. The RA provides a framework to determine where to add these security mechanisms to stop or mitigate these threats and build a Security Reference Architecture (SRA) for CPS. An SRA is an abstract architecture describing a conceptual model of security that provides a way to specify security requirements for a wide range of concrete architectures. The analysis and design are given using a cargo port as our example, but the approach can be used in other domains as well. This is the first work we know where patterns and RAs are used to represent cargo ports and analyze their security. / Includes bibliography. / Dissertation (PhD)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection