Wasserstein distributionally robust risk-constrained iterative MPC for motion planning: computationally efficient approximations

This paper considers a risk-constrained motion planning problem and aims to find the solution combining the concepts of iterative model predictive control (MPC) and data-driven distributionally robust (DR) risk-constrained optimization. In the iterative MPC, at each iteration, safe states visited and stored in the previous iterations are imposed as terminal constraints. Furthermore, samples collected during the iteration are used in the subsequent iterations to tune the ambiguity set of the DR constraints employed in the MPC. In this method, the MPC problem becomes computationally burdensome when the iteration number goes high. To overcome this challenge, the emphasis of this paper is to reduce the real-time computational effort using two approximations. First one involves clustering of data at the beginning of each iteration and modifying the ambiguity set for the MPC scheme so that safety guarantees still holds. The second approximation considers determining DR-safe regions at the start of iteration and constraining the state in the MPC scheme to such safe sets. We analyze the computational tractability of these approximations and present a simulation example that considers path planning in the presence of randomly moving obstacle.Comment: 8 pages, 6 figures, Proceedings of the IEEE Conference on Decision and Control, Singapore, 202

Data-driven distributionally robust iterative risk-constrained model predictive control

This paper considers a risk-constrained infinite-horizon optimal control problem and proposes to solve it in an iterative manner. Each iteration of the algorithm generates a trajectory from the starting point to the target equilibrium state by implementing a distributionally robust risk-constrained model predictive control (MPC) scheme. At each iteration, a set of safe states (that satisfy the risk-constraint with high probability) and a certain number of independent and identically distributed samples of the uncertainty governing the risk constraint are available. These states and samples are accumulated in previous iterations. The safe states are used as terminal constraint in the MPC scheme and samples are used to construct a set of distributions, termed ambiguity set, such that it contains the underlying distribution of the uncertainty with high probability. The risk-constraint in each iteration is required to hold for all distributions in the ambiguity set. We establish that the trajectories generated by our iterative procedure are feasible, safe, and converge asymptotically to the equilibrium. Simulation example illustrates our results for the case of finding a risk-constrained path for a mobile robot in the presence of an uncertain obstacle.Comment: 8 pages, 5 figures, Submitted to ECC 202

SCADA System Testbed for Cybersecurity Research Using Machine Learning Approach

This paper presents the development of a Supervisory Control and Data Acquisition (SCADA) system testbed used for cybersecurity research. The testbed consists of a water storage tank's control system, which is a stage in the process of water treatment and distribution. Sophisticated cyber-attacks were conducted against the testbed. During the attacks, the network traffic was captured, and features were extracted from the traffic to build a dataset for training and testing different machine learning algorithms. Five traditional machine learning algorithms were trained to detect the attacks: Random Forest, Decision Tree, Logistic Regression, Naive Bayes and KNN. Then, the trained machine learning models were built and deployed in the network, where new tests were made using online network traffic. The performance obtained during the training and testing of the machine learning models was compared to the performance obtained during the online deployment of these models in the network. The results show the efficiency of the machine learning models in detecting the attacks in real time. The testbed provides a good understanding of the effects and consequences of attacks on real SCADA environmentsComment: E-Preprin

Study of magnetic properties and characterization of Ni/Cu multi-layer structures using in-situ high-temperature X-Ray diffraction (HT-XRD)

In this paper, the results of magnetic and structural measurements of Ni/Cu multi-layers with different thicknesses of Cu and Ni grown on Si (100) substrate are presented. The Ni/Cu multi-layers nanostructure is analyzed using X-ray diffraction (XRD) diagram at room temperature and X-ray diffraction in a vacuum at high temperature (HT-XRD). The periodic peaks in the XRD spectrum, the multilayer structure and thus, the superlattice structure of the films are confirmed. But the in-situ XRD spectrums at high temperature reveal that the increase of temperature and annealing time is associated with the decrease or disappearance of intensity of the multilayer peaks and periodic peaks. It means the increase of these two parameters is accompanied with the weakening of interface sharpness between the layers, and the samples' multilayer structures are inclined toward the alloy structure

Study of magnetic properties and characterization of Ni/Cu multi-layer structures using in-situ high-temperature X-Ray diffraction (HT-XRD)

In this paper, the results of magnetic and structural measurements of Ni/Cu multi-layers with different thicknesses of Cu and Ni grown on Si (100) substrate are presented. The Ni/Cu multi-layers nanostructure is analyzed using X-ray diffraction (XRD) diagram at room temperature and X-ray diffraction in a vacuum at high temperature (HT-XRD). The periodic peaks in the XRD spectrum, the multilayer structure and thus, the superlattice structure of the films are confirmed. But the in-situ XRD spectrums at high temperature reveal that the increase of temperature and annealing time is associated with the decrease or disappearance of intensity of the multilayer peaks and periodic peaks. It means the increase of these two parameters is accompanied with the weakening of interface sharpness between the layers, and the samples' multilayer structures are inclined toward the alloy structure

Addressing Pragmatic Challenges in Utilizing AI for Security of Industrial IoT

Industrial control systems (ICSs) are an essential part of every nation\u27s critical infrastructure and have been utilized for a long time to supervise industrial machines and processes. Today’s ICSs are substantially different from the information technology (IT) devices a decade ago. The integration of internet of things (IoT) technology has made them more efficient and optimized, improved automation, and increased quality and compliance. Now, they are a sub (and arguably the most critical) part of IoT\u27s domain, called industrial IoT (IIoT). In the past, to secure ICSs from malicious outside attack, these systems were isolated from the outside world. However, recent advances, increased connectivity with corporate networks, and utilization of internet communications to transmit the information more conveniently have introduced the possibility of cyber-attacks against these systems. Due to the sensitive nature of the industrial applications, security is the foremost concern. We discuss why despite the exceptional performance of artificial intelligent (AI) and machine learning (ML), industry leaders still have a hard time utilizing these models in practice as a standalone units. The goal of this dissertation is to address some of these challenges to help pave the way of utilizing smarter and more modern security solutions in these systems. To be specific, here, we focus on data scarcity for the AI, black-box nature of the AI, high computational load of the AI. Industrial companies almost never release their network data, because they are obligated to follow confidentiality laws and user privacy restrictions. Hence, real-world IIoT datasets are not available for security research area, and we face a data scarcity challenge in IIoT security research community. In this domain, the researchers usually have to resort to commercial or public datasets that are not specific to this domain. In our work, we have developed a real-world testbed that resembles an actual industrial plant. We have emulated a popular industrial system in water treatment processes. So, we could collect datasets containing realist traffic to conduct our research. There exists several specific characteristics of IIoT networks that are unique to them. We have provided an extensive study to figure out them and incorporate them in the design. We have gathered information on relevant cyber-attacks in IIoT systems to run them against the system to gather realistic datasets containing both normal and attack traffic analogous to real industrial network traffic. Their particular communication protocols are also their specific to them. We have implemented one of the most popular one in our dataset. Another attribute that distinguishes the security of these systems from others is the imbalanced data. The number of attack samples are significantly lower compared to the enormous number of normal traffic that flows in the system daily. We have made sure we build our datasets compliant with all the specific attributes of an IIoT. Another challenge that we address here is the ``black box nature of learning models that creates hurdles in generating adequate trust in their decisions. Thus, they are seldom utilized as a standalone unit in IIoT high-risk applications. Explainable AI (XAI) has gained an increasing interest in recent years to help with this problem. However, most of the research works that have been done so far focus on image applications or are very slow. For applications such as security of IIoT, we deal with numerical data and low latency is of utmost importance. In this dissertation, we propose a universal XAI model named Transparency Relying Upon Statistical Theory (TRUST). TRUST is model-agnostic, high-performing, and suitable for numerical applications. We prove its superiority compared to another popular XAI model in performance regarding speed and being able to successfully reason the AI\u27s behavior. When dealing with the IoT technology, especially industrial IoT, we deal with a massive amount of data streaming to and from the IoT devices. In addition, the availability and reliability constraints of industrial systems require them to operate at a fast pace and avoid creating any bottleneck in the system. High computational load of complex AI models might cause a burden by having to deal with a large number of data and producing the results not as fast as required. In this dissertation, we utilize distributed computing in the form of edge/cloud structure to address these problems. We propose Anomaly Detection using Distributed AI (ADDAI) that can easily span out geographically to cover a large number of IoT sources. Due to its distributed nature, it guarantees critical IIoT requirements such as high speed, robustness against a single point of failure, low communication overhead, privacy, and scalability. We formulate the communication cost which is minimized and the improvement in performance

Analysis of AeroMACS Data Link for Unmanned Aircraft Vehicles

Aeronautical Mobile Airport Communications System (AeroMACS) is based on the IEEE 802.16e mobile wireless standard commonly known as WiMAX. It is expected to be the main part of the next-generation aviation communication system to support fixed and mobile services for manned and unmanned applications. AeroMACS will be an essential technology helping pave the way toward full integration of Unmanned Aircraft Vehicle (UAV) into the national airspace. A number of practical tests and analyses have been done so far for AeroMACS. The main contribution of this paper is to consider the theoretical concepts behind its features and discuss their suitability for UAV applications. Mathematical analyses of the AeroMACS physical layer framework are provided to show the theoretical trade-offs. We mainly focus on the analysis of the AeroMACS OFDMA structure, which affects the speed limits, coverage cell, channel estimation requirements, and inter-carrier interference

Security Services Using Blockchains: A State of the Art Survey

This article surveys blockchain-based approaches for several security services. These services include authentication, confidentiality, privacy and access control list (ACL), data and resource provenance, and integrity assurance. All these services are critical for the current distributed applications, especially due to the large amount of data being processed over the networks and the use of cloud computing. Authentication ensures that the user is who he/she claims to be. Confidentiality guarantees that data cannot be read by unauthorized users. Privacy provides the users the ability to control who can access their data. Provenance allows an efficient tracking of the data and resources along with their ownership and utilization over the network. Integrity helps in verifying that the data has not been modified or altered. These services are currently managed by centralized controllers, for example, a certificate authority. Therefore, the services are prone to attacks on the centralized controller. On the other hand, blockchain is a secured and distributed ledger that can help resolve many of the problems with centralization. The objectives of this paper are to give insights on the use of security services for current applications, to highlight the state of the art techniques that are currently used to provide these services, to describe their challenges, and to discuss how the blockchain technology can resolve these challenges. Further, several blockchain-based approaches providing such security services are compared thoroughly. Challenges associated with using blockchain-based security services are also discussed to spur further research in this area