| 1. |
|
|
| 2. |
- Nair, A. S., et al.
(author)
-
CAMP : a hierarchical cache architecture for multi-core mixed criticality processors
- 2024
-
In: International Journal of Parallel, Emergent and Distributed Systems. - : Taylor and Francis Ltd.. - 1744-5760 .- 1744-5779.
-
Journal article (peer-reviewed)abstract
- CAMP proposes a hierarchical cache subsystem for multi-core mixed criticality processors, focusing on ensuring worst-case execution time (WCET) predictability in automotive applications. It incorporates criticality-aware locked L1 and L2 caches, reconfigurable at mode change intervals, along with criticality-aware last level cache partitioning. Evaluation using CACOSIM, Moola Multicore simulator, and CACTI simulation tools confirms the suitability of CAMP for keeping high-criticality jobs within timing budgets. A practical case study involving an automotive wake-up controller using the sniper v7.2 architecture simulator further validates its usability in real-world mixed criticality applications. CAMP presents a promising cache architecture for optimized multi-core mixed criticality systems.
|
|
| 3. |
- Nair, A. S., et al.
(author)
-
CLAMP : Criticality Aware Coherency Protocol for Locked Multi-level Caches in Multi-core Processors
- 2023
-
In: Lect. Notes Networks Syst.. - : Springer Science and Business Media Deutschland GmbH. - 9789819904822 ; , s. 371-381
-
Conference paper (peer-reviewed)abstract
- Cyber-physical systems that combine sensing, computing, control and networking with physical items and infrastructure, such as automotive, avionics and robotics, are rapidly becoming mixed criticality systems (MCS). The increasing expectations for computing ability and predictable temporal behaviour of these systems necessitate substantial enhancements in their memory subsystem architecture. The use of locked caches to have predictable execution time is one such optimization. There is no comprehensive method in order to manage coherency in locked caches in any of the current cache coherence protocols like MOESI. CLAMP—A criticality aware coherency protocol for locked multi-level caches in multi-core processors is an updated variant of MOESI and as an extension of MOESIL, to improve the data consistency of locked caches. The work CLAMP proposes an improvised locked cache coherence protocol for multiple levels of cache in multi-core MCS, whereas MOESIL is restricted to two-level cache architecture. Experiments using real-time benchmark programs on CACOSIM reveal an average cache miss rate reduction of 18% for high-criticality jobs.
|
|
| 4. |
- Sasikumar, A., et al.
(author)
-
A virtual testing based search for optimum compression after impact strength in thin laminates using ply-thickness hybridization and unsymmetrical designs
- 2020
-
In: Composites Science and Technology. - : Elsevier BV. - 0266-3538. ; 196
-
Journal article (peer-reviewed)abstract
- In the quest to improve the compression after impact (CAI) strength of thin laminates, ply-hybrid laminates (where plies of different thicknesses are mixed) have been used in a previous study to mitigate the fibre failure and, consequently, improve the CAI strength. In the same study, hybrid laminates were proposed following qualitative design rules. In this paper, we systematically look for hybrid stacking sequences with improved damage tolerance by virtually testing all the laminates in a defined design space. While the laminates in the design space are made of intermediate and thick ply grades, the baseline laminate has only intermediate grade plies. Using an in-house numerical model, we virtually tested, (impact and CAI at two impact energies), all the candidate stacking sequences. The best hybrid laminates considerably improved the CAI strength over the baseline (31% and 40% improvement for the symmetric and unsymmetrical hybrid laminates, respectively). One of the best hybrid laminates was then manufactured and tested experimentally to validate the approach. Through virtual testing, this study demonstrates the benefits of using ply thickness hybrid laminates and the feasibility of optimizing the stacking sequence for impact damage tolerance.
|
|
| 5. |
- Ali, Nazakat, et al.
(author)
-
Modeling and safety analysis for collaborative safety-critical systems using hierarchical colored Petri nets
- 2024
-
In: Journal of Systems and Software. - : Elsevier Inc.. - 0164-1212 .- 1873-1228. ; 210
-
Journal article (peer-reviewed)abstract
- Context: Collaborative systems enable multiple independent systems to work together towards a common goal. These systems can include both human-system and system-system interactions and can be found in a variety of settings, including smart manufacturing, smart transportation, and healthcare. Safety is an important consideration for collaborative systems because one system's failure can significantly impact the overall system performance and adversely affect other systems, humans or the environment. Goal: Fail-safe mechanisms for safety-critical systems are designed to bring the system to a safe state in case of a failure in the sensors or actuators. However, a collaborative safety-critical system must do better and be safe-operational, for e.g., a failure of one of the members in a platoon of vehicles in the middle of a highway is not acceptable. Thus, failures must be compensated, and compliance with safety constraints must be ensured even under faults or failures of constituent systems. Method: In this paper, we model and analyze safety for collaborative safety-critical systems using hierarchical Coloured Petri nets (CPN). We used an automated Human Rescue Robot System (HRRS) as a case study, modeled it using hierarchical CPN, and injected some specified failures to check and confirm the safe behavior in case of unexpected scenarios. Results: The system behavior was observed after injecting three types of failures in constituent systems, and then safety mechanisms were applied to mitigate the effect of these failures. After applying safety mechanisms, the HRRS system's overall behavior was again observed both in terms of verification and validation, and the simulated results show that all the identified failures were mitigated and HRRS completed its mission. Conclusion: It was found that the approach based on formal methods (CPN modeling) can be used for the safety analysis, modeling, validation, and verification of collaborative safety-critical systems like HRRS. The hierarchical CPN provides a rigorous way of modeling to implement complex collaborative systems.
|
|
| 6. |
- Colaco, L., et al.
(author)
-
mcDVFS : cycle conserving DVFS scheduler for multi-core mixed criticality systems
- 2023
-
In: International Journal of Parallel, Emergent and Distributed Systems. - : Taylor and Francis Ltd.. - 1744-5760 .- 1744-5779.
-
Journal article (peer-reviewed)abstract
- Multi-core architectures have grown to be a popular choice for deploying Mixed Criticality Systems (MCS). The focus of research in MCS has been to provide timing assurances for jobs with different criticality levels. Due to their significant processing demands and energy-aware/constrained nature, energy conservation in these systems is becoming mandatory. This article presents, mcDVFS, an energy management technique based on Dynamic-Voltage-and-Frequency-Scaling for multi-core MCS. mcDVFS achieves significant energy reduction while maintaining timing guarantees. It also prioritizes quality of service whenever feasible. Extensive experimental simulations show energy savings of ≈ 52% and 34% when compared to EDF-VD and EDF-VD with QoS.
|
|
| 7. |
- Colaco, L., et al.
(author)
-
pmcEDF : An Energy Efficient Procrastination Scheduler for Multi-core Mixed Criticality Systems
- 2022
-
In: IEEE Int. Conf. High Perform. Comput. Commun., Int. Conf. Data Sci. Syst., Int. Conf. Smart City Int. Conf. Dependability Sensor, Cloud Big Data Syst. Applications, HPCC-DSS-SmartCity-DependSys. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665494571 ; , s. 727-732
-
Conference paper (peer-reviewed)abstract
- The ever increasing computational demands with size, weight, energy, power and time guidelines necessitates innovative energy efficient techniques in multi-core mixed criticality applications. Energy efficient design considerations include energy optimization techniques such as dynamic-voltage-and-frequency-scaling (DVFS) and dynamic-power-management (DPM). DPM techniques of procrastination and power shutdown reduce static and dynamic energy consumption efficiently. This work presents pmcEDF, a procrastination technique that extends the Earliest Deadline First with Virtual Deadlines (EDF-VD) scheduler to support both non-shutdown and shutdown cores. pmcEDF aims to reduce static and dynamic energy consumption by ensuring high criticality job deadlines without hampering quality of service by accommodating feasible low criticality jobs. Experimental evaluation shows that the proposed algorithm provides a total energy saving of 3.61%, 4.76% and 39.16% over existing EDF/EDF-VD based techniques.
|
|
| 8. |
- Colaco, L., et al.
(author)
-
Task models for mixed criticality systems – a review
- 2023
-
In: International Journal of Critical Computer-Based Systems. - : Inderscience Publishers. - 1757-8779 .- 1757-8787. ; 10:4, s. 287-329
-
Journal article (peer-reviewed)abstract
- The past decade has seen tremendous interest in mixed criticality systems research due to its exponential growth with inherent challenges of effective resource utilisation and isolation. The pervasiveness of these systems along with their certification needs, prompt for suitable task models to perform the required analysis. Extensive usage scenarios and strict certification requirements have spawned a broad spectrum of research and evolved into several task models. In this work, a thematic survey of task models for both uni-core and multi-core mixed criticality systems is carried out. The work categorises task models based on attributes such as resources, quality of service, operating system overheads, energy, fault tolerance and parallel processing. After synthesising the state-of-the-art, the work summarises task models by providing a visual aid and a ready reckoner with traceability to mixed criticality challenges. This work serves as a quintessential reference manual for researchers and academicians in the mixed criticality domain.
|
|
| 9. |
- Daelman, Bo, et al.
(author)
-
Frailty and cognitive function in middle-aged and older adults with congenital heart disease
- 2024
-
In: Journal of the American College of Cardiology. - : Elsevier. - 0735-1097 .- 1558-3597. ; 83:12, s. 1149-1159
-
Journal article (peer-reviewed)abstract
- Background: Life expectancy of patients with congenital heart disease (CHD) has increased rapidly, resulting in a growing and aging population. Recent studies have shown that older people with CHD have higher morbidity, health care use, and mortality. To maintain longevity and quality of life, understanding their evolving medical and psychosocial challenges is essential.Objectives: The authors describe the frailty and cognitive profile of middle-aged and older adults with CHD to identify predictor variables and to explore the relationship with hospital admissions and outpatient visits.Methods: Using a cross-sectional, multicentric design, we included 814 patients aged ≥40 years from 11 countries. Frailty phenotype was determined using the Fried method. Cognitive function was assessed by the Montreal Cognitive Assessment.Results: In this sample, 52.3% of patients were assessed as robust, 41.9% as prefrail, and 5.8% as frail; 38.8% had cognitive dysfunction. Multinomial regression showed that frailty was associated with older age, female sex, higher physiologic class, and comorbidities. Counterintuitively, patients with mild heart defects were more likely than those with complex lesions to be prefrail. Patients from middle-income countries displayed more prefrailty than those from higher-income countries. Logistic regression demonstrated that cognitive dysfunction was related to older age, comorbidities, and lower country-level income.Conclusions: Approximately one-half of included patients were (pre-)frail, and more than one-third experienced cognitive impairment. Frailty and cognitive dysfunction were identified in patients with mild CHD, indicating that these concerns extend beyond severe CHD. Assessing frailty and cognition routinely could offer valuable insights into this aging population.
|
|
| 10. |
- Dimov, Aleksandar, et al.
(author)
-
Mutation testing framework for software reliability model analysis and reliability estimation
- 2010
-
In: Central and Eastern European Software Engineering Conference (CEE-SECR). - 9781457706066 ; , s. 163-169
-
Conference paper (peer-reviewed)abstract
- After several years of research, even today estimation of software reliability is extremely challenging. The undeterministic nature of the factors that contribute to the reliability estimation has led to the development of numerous statistical models for this purpose. One of the important factors that contribute to software reliability is testing. The aim of this paper is to use mutation testing for estimating the „true” reliability of a system and provide a framework for estimation of uncertainty bounds associated with testing and a measure for factors such as test coverage, time between failures and code coverage that contribute to the estimation of reliability and use mutation testing as a tool to create a software failure dataset. The approach is experimented with an open source search tool.
|
|
