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CPS Theory

Computer Sciences

Departmental Papers (CIS)

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Full-Text Articles in Engineering

Holistic Resource Allocation For Multicore Real-Time Systems, Meng Xu, Linh T.X. Phan, Hyon-Young Choi, Yuhan Lin, Haoran Li, Chenyang Lu, Insup Lee Apr 2019

Holistic Resource Allocation For Multicore Real-Time Systems, Meng Xu, Linh T.X. Phan, Hyon-Young Choi, Yuhan Lin, Haoran Li, Chenyang Lu, Insup Lee

Departmental Papers (CIS)

This paper presents CaM, a holistic cache and memory bandwidth resource allocation strategy for multicore real-time systems. CaM is designed for partitioned scheduling, where tasks are mapped onto cores, and the shared cache and memory bandwidth resources are partitioned among cores to reduce resource interferences due to concurrent accesses. Based on our extension of LITMUSRT with Intel’s Cache Allocation Technology and MemGuard, we present an experimental evaluation of the relationship between the allocation of cache and memory bandwidth resources and a task’s WCET. Our resource allocation strategy exploits this relationship to map tasks onto cores, and to ...


Parameter Invariant Monitoring For Signal Temporal Logic, Nima Roohi, Ramneet Kaur, James Weimer, Oleg Sokolsky, Insup Lee Apr 2018

Parameter Invariant Monitoring For Signal Temporal Logic, Nima Roohi, Ramneet Kaur, James Weimer, Oleg Sokolsky, Insup Lee

Departmental Papers (CIS)

Signal Temporal Logic (STL) is a prominent specification formalism for real-time systems, and monitoring these specifications, specially when (for different reasons such as learning) behavior of systems can change over time, is quite important. There are three main challenges in this area: (1) full observation of system state is not possible due to noise or nuisance parameters, (2) the whole execution is not available during the monitoring, and (3) computational complexity of monitoring continuous time signals is very high. Although, each of these challenges has been addressed by different works, to the best of our knowledge, no one has addressed ...


Parameter-Invariant Monitor Design For Cyber Physical Systems, James Weimer, Radoslav Ivanov, Sanjian Chen, Alexander Roederer, Oleg Sokolsky, Insup Lee Jan 2018

Parameter-Invariant Monitor Design For Cyber Physical Systems, James Weimer, Radoslav Ivanov, Sanjian Chen, Alexander Roederer, Oleg Sokolsky, Insup Lee

Departmental Papers (CIS)

The tight interaction between information technology and the physical world inherent in Cyber-Physical Systems (CPS) can challenge traditional approaches for monitoring safety and security. Data collected for robust CPS monitoring is often sparse and may lack rich training data describing critical events/attacks. Moreover, CPS often operate in diverse environments that can have significant inter/intra-system variability. Furthermore, CPS monitors that are not robust to data sparsity and inter/intra-system variability may result in inconsistent performance and may not be trusted for monitoring safety and security. Towards overcoming these challenges, this paper presents recent work on the design of parameter-invariant ...


Resilient Linear Classification: An Approach To Deal With Attacks On Training Data, Sangdon Park, James Weimer, Insup Lee Apr 2017

Resilient Linear Classification: An Approach To Deal With Attacks On Training Data, Sangdon Park, James Weimer, Insup Lee

Departmental Papers (CIS)

Data-driven techniques are used in cyber-physical systems (CPS) for controlling autonomous vehicles, handling demand responses for energy management, and modeling human physiology for medical devices. These data-driven techniques extract models from training data, where their performance is often analyzed with respect to random errors in the training data. However, if the training data is maliciously altered by attackers, the effect of these attacks on the learning algorithms underpinning data-driven CPS have yet to be considered. In this paper, we analyze the resilience of classification algorithms to training data attacks. Specifically, a generic metric is proposed that is tailored to measure ...


Representation Of Confidence In Assurance Cases Using The Beta Distribution, Lian Duan, Sanjai Rayadurgam, Mats Heimdahl, Oleg Sokolsky, Insup Lee Jan 2016

Representation Of Confidence In Assurance Cases Using The Beta Distribution, Lian Duan, Sanjai Rayadurgam, Mats Heimdahl, Oleg Sokolsky, Insup Lee

Departmental Papers (CIS)

Assurance cases are used to document an argument that a system—such as a critical software system—satisfies some desirable property (e.g., safety, security, or reliability). Demonstrating high confidence that the claims made based on an assurance case can be trusted is crucial to the success of the case. Researchers have proposed quantification of confidence as a Baconian probability ratio of eliminated concerns about the assurance case to the total number of identified concerns. In this paper, we extend their work by mapping this discrete ratio to a continuous probability distribution—a beta distribution— enabling different visualizations of the ...


Expressiveness Of Streaming String Transducers, Rajeev Alur Jan 2010

Expressiveness Of Streaming String Transducers, Rajeev Alur

Departmental Papers (CIS)

Streaming string transducers define (partial) functions from input strings to output strings. A streaming string transducer makes a single pass through the input string and uses a finite set of variables that range over strings from the output alphabet. At every step, the transducer processes an input symbol, and updates all the variables in parallel using assignments whose right-hand-sides are concatenations of output symbols and variables with the restriction that a variable can be used at most once in a right-hand-side expression. It has been shown that streaming string transducers operating on strings over infinite data domains are of interest ...


On-The-Fly Reachability And Cycle Detection For Recursive State Machines, Rajeev Alur, Swarat Chaudhuri, Kousha Etessami, P. Madhusudan Apr 2005

On-The-Fly Reachability And Cycle Detection For Recursive State Machines, Rajeev Alur, Swarat Chaudhuri, Kousha Etessami, P. Madhusudan

Departmental Papers (CIS)

Searching the state space of a system using enumerative and on-the-fly depth-first traversal is an established technique for model checking finite-state systems. In this paper, we propose algorithms for on-the-fly exploration of recursive state machines, or equivalently pushdown systems, which are suited for modeling the behavior of procedural programs. We present algorithms for reachability (is a bad state reachable?) as well as for fair cycle detection (is there a reachable cycle with progress?). We also report on an implementation of these algorithms to check safety and liveness properties of recursive boolean programs, and its performance on existing benchmarks.