Mark-Oliver Stehr

We are exploring a new paradigm for design of high-assurance Networked Cyber-Physical Systems based on the notion of software fractionation with distributed control and optimization aiming at the effective use of resources. The idea of software fractionation is inspired by and complementary to hardware fractionation, which has been proposed for mission-critical space systems. In our approach, software is fractionated by design even beyond the distributed nature of underlying system, with distributed knowledge sharing as the underlying model. In this report we summarize our research on a Stochastic Task Execution Model (STEM) designed to gain insight into design parameters of local decision processes to robustly meet system goals. We also report on our ongoing work on building an NCPS test bed at SRI based on quadricopter hardware.

In this paper, we address the role of middleware in enabling robust and resilient cyber-physical systems (CPSs) of the future. In particular, we will focus on how adaptation services can be used to improve dependability in instrumented cyber-physical systems based on the principles of “computational reflection.” CPS environments incorporate a variety of sensing and actuation devices in a distributed architecture; such a deployment is used to create a digital representation of the evolving physical world and its processes for use by a broad range of applications. CPS applications, in particular, mission critical tasks, must execute dependably despite disruptions caused by failures and limitations in sensing, communications, and computation. This paper discusses a range of applications, their reliability needs, and potential dependability holes that can cause performance degradation and application failures. In particular, we distinguish between the notion of infrastructure and information dependability and illustrate the need to formally model and reason about a range of CPS applications and their dependability needs. Formal methods based tools can help us design meaningful cross-layer adaptation techniques at different system layers of the CPS environment and thereby achieve end-to-end dependability at both the infrastructure and information levels.

Adaptive resource management is critical to ensuring the quality of real-time distributed applications, particularly for energy-constrained mobile handheld devices. In this context, an optimization that simultaneously considers multiple layers (e.g., application, middleware, operating system) needs to be developed for continuous adaptation of system parameters. The tuning of system parameters greatly affects the system's ability to meet QoS requirements, and also directly affects the energy consumption and system robustness. We present a novel approach to developing cross-layer optimization for resource limited real-time distributed systems, based on a constraint refinement technique combined with formal specification and feedback from system implementation. Our approach tunes the parameters in a compositional manner allowing coordinated interaction among sub-layer optimizers that enables holistic cross-layer optimization. We present experiments on a realistic multimedia application which demonstrate that constraint refinement enables us to generate robust and near optimal parameter settings. The constraint language can be used as an interface for composition by encapsulating the details of local optimization algorithms.

This report is the second by the Combating Terrorism Center at West Point to assess the demographics, procedures, finances, and leadership of al-Qa'ida's foreign fighters, especially those currently fighting in Iraq. This report analyzes al-Qa'ida in Iraq's (AQI) operations from spring 2006 to summer 2007 and is being issued with a trove of AQI documents captured by coalition forces near Sinjar, Iraq. The documents include almost 600 AQI personnel records for foreign fighters crossing into Iraq, AQI contracts for suicide bombers, AQI contracts for fighters leaving Iraq, narratives written by al-Qa'ida's Syrian smugglers, and AQI financial records. The CTC also acquired demographic information on all Third Country Nationals (TCNs) in detention at Camp Bucca, Iraq. Most of this data has not previously been released to the public.