1,721,078 research outputs found
Multi-requirement Parametric Falsification
Full text linkFalsification is a popular simulation-based testing method for Cyber- Physical Systems to find inputs that violate a formal requirement. However, detecting violations considering multiple probabilistic requirements simultaneously with a dense space of changing factors in the execution scenario is an open problem. We address this problem by proposing a novel approach that combines parametric model checking and many-objective optimization. Results of a preliminary empirical evaluation show the effectiveness of the approach compared to selected baseline methods
Automated test-based learning and verification of performance models for microservices systems
Full text linkEffective and automated verification techniques able to provide assurances of performance and scalability are highly demanded in the context of microservices systems. In this paper, we introduce a methodology that applies specification-driven load testing to learn the behavior of the target microservices system under multiple deployment configurations. Testing is driven by realistic workload conditions sampled in production. The sampling produces a formal description of the users' behavior through a Discrete Time Markov Chain. This model drives multiple load testing sessions that query the system under test and feed a Bayesian inference process which incrementally refines the initial model to obtain a complete specification from run-time evidence as a Continuous Time Markov Chain. The complete specification is then used to conduct automated verification by using probabilistic model checking and to compute a configuration score that evaluates alternative deployment options. This paper introduces the methodology, its theoretical foundation, and the toolchain we developed to automate it. Our empirical evaluation shows its applicability, benefits, and costs on a representative microservices system benchmark. We show that the methodology detects performance issues, traces them back to system-level requirements, and, thanks to the configuration score, provides engineers with insights on deployment options. The comparison between our approach and a selected state-of-the-art baseline shows that we are able to reduce the cost up to 73% in terms of number of tests. The verification stage requires negligible execution time and memory consumption. We observed that the verification of 360 system-level requirements took ~1 minute by consuming at most 34 KB. The computation of the score involved the verification of ~7k (automatically generated) properties verified in ~72 seconds using at most ~50 KB. (C)& nbsp;2022 The Author(s). Published by Elsevier Inc.& nbsp
Runtime Equilibrium Verification for Resilient Cyber-Physical Systems
No full textCyber-Physical Systems are the basis of more and more activities in our modern society. Therefore, providing comprehensive, ideally provable, evidence that they continuously exhibit acceptable behavior even in case of unexpected events represents a major challenge that is not completely addressed by existing verification approaches. To this end, in this paper we exploit the notion of equilibrium, i.e., the ability of the system to maintain an acceptable behavior within its multidimensional viability zone and we propose RUNE (RUNtime Equilibrium verification), an approach able to verify at runtime if the system satisfies the equilibrium condition. RUNE includes (i) a system specification that takes into account the uncertainties related to partial knowledge and possible changes by adopting parametric Markov decision processes; (ii) the computation of the equilibrium condition to define the boundaries of the viability zone; and (iii) a runtime equilibrium verification method that leverages on Bayesian inference to reduce the uncertainty under the required level and quantitatively reason about the ability of the system to remain inside the boundaries of the viability zone. We demonstrate the benefits of the proposed approach on a running example from the robotics domain
Using the Distribution of Eye Fixations to Assess Pilots' Mental Workload
No full textBased on previous research showing the usefulness of spatial statistics in detecting randomness in the distribution of eye fixations, this study investigated the ocular behavior of professional pilots engaged in a simulated flight. The distribution of eye fixations is here used an index of mental workload. Eye movements were recorded during the different phases (departure to landing) of a simulated flight, and were analyzed using spatial statistics algorithms. Results showed sensitivity of spatial dispersion indices to variations in mental workload: higher during departure and landing, lower during the other phases. This result provides additional evidence of the utility of fixations distribution as a real-time measure of mental workload and, consequently, as a trigger for adaptive automation
Valutazione delle Caratteristiche di Sedimentabilità del Fango Attivo Attraverso la Misura dell'Indice di Volume del Fango Diluito
No full textViene illustrata la possibilità di correlare i parametri del modello della legge esponenziale, impiegata per simulare i processi di sedimentazione di massa, con l’indice di volume del fango diluito (DSVI). A tal fine vengono illustrati i risultati delle indagini sperimentali condotte per il calcolo delle costanti di sedimentazione e dei corrispondenti valori del DSVI, con riferimento ai fanghi prodotti da tre impianti di depurazione per reflui civili, a ciclo tradizionale. Le espressioni ricavate vengono confrontate con altre presenti in letteratura, mostrandone la buona attendibilità e la pratica possibilità di utilizzo
Psychophysiological Correlates of Shifting Between Levels of Automation
No full textThe main aim of this study was to investigate the effects on performance and workload of the shifting between levels of automation: from manual to automatic (forward shift) and from automatic to manual (backward shift). Three levels of difficulty of the Tetris game were implemented as task load conditions. Two versions of the game were also implemented: automated and manual. The automated version provided the participants a projection of the falling block on the lowest layer for making its placement easier. Results showed that the commonsense consideration that only shifts toward a lower level of automation should reflect poor performance and higher workload is unsupported. Forward shifts may affect performance as well, particularly when workload is moderate
WeakSATD: Detecting Weak Self-admitted Technical Debt
Full text linkSpeeding up development may produce technical debt, i.e., not-quite-right code for which the effort to make it right increases with time as a sort of interest. Developers may be aware of the debt as they admit it in their code comments. Literature reports that such a self-admitted technical debt survives for a long time in a program, but it is not yet clear its impact on the quality of the code in the long term. We argue that self-admitted technical debt contains a number of different weaknesses that may affect the security of a program. Therefore, the longer a debt is not paid back the higher is the risk that the weaknesses can be exploited. To discuss our claim and rise the developers' awareness of the vulnerability of the self-admitted technical debt that is not paid back, we explore the self-admitted technical debt in the Chromium C-code to detect any known weaknesses. In this preliminary study, we first mine the Common Weakness Enumeration repository to define heuristics for the automatic detection and fix of weak code. Then, we parse the C-code to find self-admitted technical debt and the code block it refers to. Finally, we use the heuristics to find weak code snippets associated to self-admitted technical debt and recommend their potential mitigation to developers. Such knowledge can be used to prioritize self-admitted technical debt for repair. A prototype has been developed and applied to the Chromium code. Initial findings report that 55% of self-admitted technical debt code contains weak code of 14 different types
Valutazione delle Caratteristiche di Sedimentabilità del Fango Attivo Attraverso la Misura dell'Indice di Volume del Fango Diluito
No full textViene illustrata la possibilità di correlare i parametri del modello della legge esponenziale, impiegata per simulare i processi di sedimentazione di massa, con l’indice di volume del fango diluito (DSVI). A tal fine vengono illustrati i risultati delle indagini sperimentali condotte per il calcolo delle costanti di sedimentazione e dei corrispondenti valori del DSVI, con riferimento ai fanghi prodotti da tre impianti di depurazione per reflui civili, a ciclo tradizionale. Le espressioni ricavate vengono confrontate con altre presenti in letteratura, mostrandone la buona attendibilità e la pratica possibilità di utilizzo
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