Uncertainty-wise Test Case Generation and Minimization for Cyber-Physical Systems

Cyber-Physical Systems (CPSs) typically operate in highly indeterminateenvironmental conditions, which require the development of testing methods that must explicitly consider uncertainty in test design, test generation, and test optimization. Towards this direction, we propose a set of uncertainty-wise test case generation and test case minimizationstrategies that rely on test ready models explicitly specifying subjective uncertainty. We propose two test case generation strategies and four test case minimizationstrategies based on the Uncertainty Theory and multi-objectivesearch. These strategies include a novel methodology for designing and introducing indeterminacy sources in the environment during test execution and a novel set of uncertainty-wise test verdicts. We performed an extensive empirical study to select the bestalgorithm out of eight commonly used multi-objective search algorithms, for each of the four minimizationstrategies, with five use cases of two industrial CPS case studies. The minimizedset of test cases obtained with the best algorithm for each minimizationstrategy were executedon the two real CPSs. The results showed that our best test strategy managed to observe 51% more uncertainties due to unknown indeterminate behaviorsof the physical environmentsof the CPSs as compared to the other test strategies. Also, the same test strategy managed to observe 118% more unknown uncertainties as compared to the unique number of known uncertainties.submittedVersio

Cost-effectiveness of a European preventive cardiology programme in primary care: A Markov modelling approach

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license.OBJECTIVE: To investigate the longer-term cost-effectiveness of a nurse-coordinated preventive cardiology programme for primary prevention of cardiovascular disease (CVD) compared to routine practice from a health service perspective. DESIGN: A matched, paired cluster-randomised controlled trial. SETTING: Six pairs of general practices in six countries. PARTICIPANTS: 1019 patients were randomised to the EUROACTION intervention programme and 1005 patients to usual care (UC) and who completed the 1-year follow-up. OUTCOME MEASURES: Evidence on health outcomes and costs was based on patient-level data from the study, which had a 1-year follow-up period. Future risk of CVD events was modelled, using published risk models based on patient characteristics. An individual-level Markov model for each patient was used to extrapolate beyond the end of the trial, which was populated with data from published sources. We used an 11-year time horizon and investigated the impact on the cost-effectiveness of varying the duration of the effect of the intervention beyond the end of the trial. Results are expressed as incremental cost per quality-adjusted life-year gained. RESULTS: Unadjusted results found the intervention to be more costly and also more effective than UC. However, after adjusting for differences in age, gender, country and baseline risk factors, the intervention was dominated by UC, but this analysis was not able to take into account the lifestyle changes in terms of diet and physical activity. CONCLUSIONS: Although the EUROACTION study achieved healthier lifestyle changes and improvements in management of blood pressure and lipids for patients at high risk of CVD, compared to UC, it was not possible to show, using available risk equations which do not incorporate diet and physical activity, that the intervention reduced longer-term cardiovascular risk cost-effectively. Whether or not an intervention such as that offered by EUROACTION is cost-effective requires a longer-term trial with major cardiovascular events as the outcome.This study is sponsored solely by AstraZeneca through the provision of an unconditional educational grant