31 research outputs found
Fault-based analysis of cyber physical systems
No full textCyber-physical systems (CPS) consist of computational networked and distributed components monitoring and controlling the physical environment. They are nowadays ubiquitous in many safety-critical applications including autonomous vehicles or smart medical devices. Therefore ensuring the correctness of CPS before their deployment is essential. The complexity and heterogeneity of CPS also makes them vulnerable to faults that are challenging to detect, understand and correct. These faults can propagate in time and space, producing observable misbehavior that is hard to trace to its origin because it is typically a result of complex combination of events. In this thesis, we develop methods for failure analysis of a CPS that help exposing and explaining faults. We develop theoretical, methodological and practical solutions to achieve this goal by focusing on the following topics: (1) methods to localize and explain failures, and (2) testing procedures that facilitate fault analysis. The scientific outcomes of this were implemented as prototypes and tools. The solutions developed in this thesis have been evaluated on publicly available benchmarks and industrial use cases from several domains to demonstrate the applicability of our research
An experimental investigation of interaction of crossflow instability with forward facing steps
No full textExperimental measurements are performed on a 45 degree swept flat plate model at the low speed laboratory (LSL) at the Delft University of Technology, in a low turbulence environment to stimulate the development of stationary crossflow. The swept flat plate model is equipped with two linear manual stages to create forward and backward facing steps. Preliminary measurements characterize the pressure gradient over the swept flat plate model under study. In the preliminary study , hot-wire anemometry (HWA) measurements characterize the flow over the swept plate without steps over a large chordwise domain with and without forcing by discrete roughness elements (DREs). The DREs are spaced at a spanwise wavelength corresponding to the overall maximum N factors from LST. The mean velocity contours and N factor trends presented in these measurements reinforced the need for DREs to control flow. Spectral content is monitored and the frequency bands associated with probe vibration and travelling crossflow interaction were delineated. Infrared thermography was employed to observe the movement of transition front with varying step heights and initial crossflow amplitudes. When the DRE height increases, the transition front moves upstream consistently for all step heights. Furthermore, when the DRE height is kept a constant , but the array is moved upstream and downstream of the neutral point, the transition front moves upstream for all step heights. In order to observe the flow in the vicinity of the step, HWA was once again used to quantify the interaction of crossflow with FFS. The clean, short FFS and supercritical step height configurations identified from the IR study, are studied for two initial amplitudes. For the supercritical step configuration, bandpass filtered fluctuations are found to align with a high wall normal and spanwise shear region which has been identified in previous work. It is postulated to be associated with a vortex shedding mechanism, for which frequency bands are delineated. Estimates of the range of recirculation bubble length were made and a flapping frequency range was also demarcated. In this study, a vortex shedding scenario is used to explain the presence of these near wall fluctuations. To conclude the report, recommendations are made for extending the present study for future work.Aerospace Engineering | Aerodynamic
Nutraceutical Properties of Wellness Rice Flour.
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Isolation and Characterisation of Carotenogenic Bacteria from Marine Environment
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Beyond the 3 R’s ‘Reduce, Reuse, Recycle’: a matterphorical eco-pedagogy project with a picturebook author, illustrator, teacher educator and a London primary school
No full textThis article describes a picturebook arts-based happening that came about spontaneously through an academic meeting the author of the picturebook Ammu’s Bottle Boat and the classteacher eco-lead of a Primary school linked with her university, and finding both to be inspiring champions of eco-pedagogy. Classteacher Andromachi, picturebook author Niveditha, illustrator Aindri and teacher educator Victoria then all met on zoom and planned sessions with the group of children who represent environmental matters for their class as school eco-ambassadors, reading and discussing the book, then making artwork in response to it. Bringing these perspectives together is not only highly unusual but significant in terms of a shared happening where a picturebook enacts this ecocritical nature, or nature-culture. Following Donna Haraway’s inseparability of nature-culture into ‘Natureculture’ (where collective eco-relationships are recognised as both biophysically and socially formed and thus closely associated) the author, illustrator, teacher, teacher-educator and children co-create in response to a picturebook’s ecocritical value. For Haraway, language and matter are also intertwined in ‘matterphorical’ ways, connecting physical, material and language elements together. For Gandorfer and Ayub, matterphorical practice is ‘an aesth-ethics of thought’ which ‘calls for an ethics of both sense-making and sensing in the making’. In this context, the art of the picturebook ‘shapes’ the associated practices of authorship, illustration, environmental education and teaching with ecopedagogies; combining sense-making and sensory learning as they interplay. The article will first set the context for eco-conscious education and various ways in which environmental research and ‘zero carbon’ schools have come together, introduce and explore the picturebook that features here by both its author and illustrator, and conclude with a teacher’s perspective of Green school practice using this picturebook in her primary school
Automatic Failure Explanation in CPS Models
No full textDebugging Cyber-Physical System (CPS) models can be extremely complex. Indeed, only detection of a failure is insufficient to know how to correct a faulty model. Faults can propagate in time and in space producing observable misbehaviours in locations completely different from the location of the fault. Understanding the reason of an observed failure is typically a challenging and laborious task left to the experience and domain knowledge of the designers.
In this paper, we propose CPSDebug, a novel approach that combines testing, specification mining, and failure analysis, to automatically explain failures in Simulink/Stateflow models. We evaluate CPSDebug on two case studies, involving two use scenarios and several classes of faults, demonstrating the potential value of our approach
Localizing Faults in Simulink/Stateflow Models with STL
No full textFault-localization is considered to be a very tedious and time-consuming activity in the design of complex Cyber-Physical Systems (CPS). This laborious task essentially requires expert knowledge of the system in order to discover the cause of the fault. In this context, we propose a new procedure that AIDS designers in debugging Simulink/Stateflow hybrid system models, guided by Signal Temporal Logic (STL) specifications. The proposed method relies on three main ingredients: (1) a monitoring and a trace diagnostics procedure that checks whether a tested behavior satisfies or violates an STL specification, localizes time segments and interfaces variables contributing to the property violations; (2) a slicing procedure that maps these observable behavior segments to the internal states and transitions of the Simulink model; and (3) a spectrum-based fault-localization method that combines the previous analysis from multiple tests to identify the internal states and/or transitions that are the most likely to explain the fault. We demonstrate the applicability of our approach on two Simulink models from the automotive and the avionics domain
Isolation of Proteins from Aged Garlic Extract (AGE) and their Effect on Lymphocytes and Macrophages
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Adaptive Testing for Specification Coverage in CPS Models
No full textEnsuring correctness of cyber-physical systems (CPS) is an extremely challenging task that is in practice often addressed with simulation-based testing. Formal specification languages, such as Signal Temporal Logic (STL), are used to mathematically express CPS requirements and thus render the simulation activity more systematic and principled. We propose a novel method for adaptive generation of tests with specification coverage for STL. To achieve this goal, we devise cooperative reachability games that we combine with numerical optimization to create tests that explore the system in a way that exercise various parts of the specification. To the best of our knowledge, our approach is the first adaptive testing approach that can be applied directly to MATLAB Simulink/Stafeflow models. We implemented our approach in a prototype tool and evaluated it on several illustrating examples and a case study from the avionics domain, demonstrating the effectiveness of adaptive testing to (1) incrementally build a test case that reaches a test objective, (2) generate a test suite that increases the specification coverage, and (3) infer what part of the specification is actually implemented
Ferrock: A Carbon Negative Sustainable Concrete
No full textIn this fast-growing world, people are focusing on the infrastructural development, where construction sector plays an important role. Cement is the most prominent material being used in construction that emits approximately 6-8% of the total carbon dioxide in the world during its production which is the major constituent of global warming. Thus, focusing on the carbon emission reduction and also utilization of the waste products for a better environment, a product named Ferrock was constituted. This paper is a review over a product that is stepping towards carbon negativity and waste management. It shows the best usage of iron ore waste powder obtained during the mining process that is just dumped away from the mines, causing air pollution, health hazards and also consuming larger area. The product indirectly reduces the carbon dioxide released by its unique strength gaining mechanism, which is in contrary with that of the cement and thus stands out among many other supplements of cement. Ferrock involves a curing process with carbonation and air curing in varied number of days for better strength in terms of compression, tensile strengths and achieving desirable properties. Ferrock is thus a more promising eco friendlier binding material in terms of its carbon negativity and in best usage of the waste
