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1. Simulation integration platforms for cyber-physical systems

   https://doi.org/10.1145/3313151.3313169  

   Neema, Himanshu; Sztipanovits, Janos; Steinbrink, Cornelius; Raub, Thomas; Cornelsen, Bastian; Lehnhoff, Sebastian (January 2019, Proceedings of the Workshop on Design Automation for CPS and IoT)

   Simulation-based analysis is essential in the model-based design process of Cyber-Physical Systems (CPS). Since heterogeneity is inherent to CPS, virtual prototyping of CPS designs and the simulation of their behavior in various environments typically involve a number of physical and computation/communication domains interacting with each other. Affordability of the model-based design process makes the use of existing domain-specific modeling and simulation tools all but mandatory. However, this pressure establishes the requirement for integrating the domain-specific models and simulators into a semantically consistent and efficient system-of-system simulation. The focus of the paper is the interoperability of popular integration platforms supporting heterogeneous multi-model simulations. We examine the relationship among three existing platforms: the High-Level Architecture (HLA)-based CPS Wind Tunnel (CPSWT), MOSAIK, and the Functional Mockup Unit (FMU). We discuss approaches to establish interoperability and present results of ongoing work in the context of an example. 

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2. Secure and Timely GPU Execution in Cyber-physical Systems

   https://doi.org/10.1145/3576915.3623197  

   Wang, Jinwen; Wang, Yujie; Zhang, Ning (November 2023, ACM Conference on Computer and Communications Security)

   Graphics Processing Units (GPU) are increasingly deployed on Cyber-physical Systems (CPSs), frequently used to perform real-time safety-critical functions, such as object detection on autonomous vehicles. As a result, availability is important for GPU tasks in CPS platforms. However, existing Trusted Execution Environments (TEE) solutions with availability guarantees focus only on CPU computing.To bridge this gap, we propose AvaGPU, a TEE that guarantees real-time availability for CPU tasks involving GPU execution under compromised OS. There are three technical challenges. First, to prevent malicious resource contention due to separate scheduling of CPU and GPU tasks, we proposed a CPU-GPU co-scheduling framework that couples the priority of CPU and GPU tasks. Second, we propose software-based secure preemption on GPU tasks to bound the degree of priority inversion on GPU. Third, we propose a new split design of GPU driver with minimized Trusted Computing Base (TCB) to achieve secure and efficient GPU management for CPS. We implement a prototype of AvaGPU on the Jetson AGX Orin platform. The system is evaluated on benchmark, synthetic tasks, and real-world applications with 15.87% runtime overhead on average. 

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3. Understanding the Roles of Low-fidelity Prototypes in Engineering Design Activity

   Ali, Hadi; Lande, Micah (June 2019, ASEE Annual Conference proceedings)

   Practical ingenuity is demonstrated in engineering design through many ways. Students and practitioners alike create many iterations of prototypes in solving problems and design challenges. While focus is on the end product and/or the process employed along the way, this study combines these interests to better understand the product and process through the roles of initial prototyping through the creation of such things as alpha prototypes, conceptual mock-ups, and other rapid prototypes. We explore the purposes and affordances of these low-fidelity prototypes in engineering design activity through both synthesis of different perspectives from literature to compose an integrated framework to characterize prototypes that are developed as part of ideation in designing, as well as historic and student examples and case studies. Studying prototyping (activity) and prototypes (artifacts) is a way to studying design thinking and how students and practitioners learn and apply a problem solving process to their work. Prototyping can make readily evident and explicit (through act of creating and the creations themselves) some of the thinking and insights of the engineering designer into the design problem. Initial, low-fidelity prototypes are characterized as prototypes that are not always elaborate depictions containing all the fine details of the design. In fact, features in a prototype do not always appear in the final design. The underpinning of this work is that prototyping, as a process, is an act of externalizing design thinking, embodying it through physical objects. While several prescriptive frameworks have been developed to describe what prototypes prototype and the role of prototype, the role of low-fidelity prototypes, specifically, lacks sufficient attention. We will present prototyping rather as an holistic mindset that can be a means to approach problem solving in a more accessible manner. It can be helpful to apply this sort of mindset approach from these initial problem understanding through functional decomposition to quickly communicate and learn by trial and building in learning loops to oneself, with an engineering design team, and to potential stakeholders outside the team. 

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4. Interactive Application to Control and Rapid-prototype in a Collaborative Immersive Environment

   Chabot, Samuel; Braasch, Jonas (October 2021, Audio Engineering Society Convention 151)

   Human-scale immersive environments offer rich, often interactive, experiences and their potential has been demonstrated across areas of research, teaching, and art. The variety of these spaces and their bespoke configurations leads to a requirement for content highly-tailored to individual environments and/or interfaces requiring complicated installations. These introduce hurdles which burden users with tedious and difficult learning curves, leaving less time for project development and rapid prototyping. This project demonstrates an interactive application to control and rapid-prototype within the Collaborative-Research Augmented Immersive Virtual Environment Laboratory, or CRAIVE-Lab. Application Programming Interfaces (APIs) render complex functions of the immersive environment, such as audio spatialization, accessible via the Internet. A front-end interface configured to communicate with these APIs gives users simple and intuitive control over these functions from their personal devices (e.g. laptops, smartphones). While bespoke systems will often require bespoke solutions, this interface allows users to create content on day one, from their own devices, without set up, content-tailoring, or training. Three examples utilizing some or all of these functions are discussed. 

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5. ARI: attestation of real-time mission execution integrity

   Wang, Jinwen; Wang, Yujie; Li, Ao; Xiao, Yang; Zhang, Ruide; Lou, Wenjing; Hou, Y. Thomas; Zhang, Ning (August 2023, Proceedings of the 32nd USENIX Conference on Security Symposium)

   With the proliferation of autonomous safety-critical cyber-physical systems (CPS) in our daily life, their security is becoming ever more important. Remote attestation is a powerful mechanism to enable remote verification of system integrity. While recent developments have made it possible to efficiently attest IoT operations, autonomous systems that are built on top of real-time cyber-physical control loops and execute missions independently present new unique challenges. In this paper, we formulate a new security property, Realtime Mission Execution Integrity (RMEI) to provide proof of correct and timely execution of the missions. While it is an attractive property, measuring it can incur prohibitive overhead for the real-time autonomous system. To tackle this challenge, we propose policy-based attestation of compartments to enable a trade-off between the level of details in measurement and runtime overhead. To further minimize the impact on real-time responsiveness, multiple techniques were developed to improve the performance, including customized software instrumentation and timing recovery through re-execution. We implemented a prototype of ARI and evaluated its performance on five CPS platforms. A user study involving 21 developers with different skill sets was conducted to understand the usability of our solution. 

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