89 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
A conceptual framework for the assessment of integrated energy storage resources
No full textConcerns regarding climate change impacts, energy security and sustainability are key drivers of the growing deployment of renewable energy resources. The variability, uncertainty and intermittency associated with the integration of these resources make the operation of the conventional power grid particularly challenging. Energy storage resources (ESRs) are one of the most promising solutions to address these challenges. The unique and versatile nature of storage finds its use in applications over a broad time spectrum. Furthermore, fast acting storage helps smoothen out the variable renewable output, minimize spillage of clean energy and manage the steep ramps associated with renewable energy integration. Storage also finds its use across all three domains of the electrical network, i.e., generation, transmission and distribution.
Cost reductions, technological innovations and regulatory initiatives have invigorated the interest in storage. However, the rapid growth of the storage sector is met by daunting challenges to the implementation of storage in the grid, especially since storage is very different from the conventional grid assets. The nature of storage is unique and its implementation has to be treated as such to fully harness the value it brings to the system it is integrated into. To this end, we outline a framework in this thesis for the integration of energy storage resources into the grid. The framework provides a systematic construct to study the various aspects of ESR integration in a system. The framework is comprehensive as it reflects the physical, information, environmental and financial aspects of storage operations. The thrust of the framework is its flexibility to accommodate the wide range of applications that storage provides on different time-scales. Furthermore, the framework explicitly captures the nature of deployment of storage for a particular application and shows the necessary interactions between ESR and the various players that interact with the ESR.
Case studies to illustrate the implementation of the information, environmental and financial layers of the framework are also presented in the thesis. The studies and their results establish that the framework is an extremely useful construct for the development of tools and models to aid in planning and operational studies and the formulation of policy and incentives and as such, is helpful in bringing the vision of energy storage closer to reality.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-05-01The student, Archana Manjunath, accepted the attached license on 2016-04-09 at 13:31.The student, Archana Manjunath, submitted this Thesis for approval on 2016-04-09 at 13:43.This Thesis was approved for publication on 2016-04-13 at 11:07.DSpace SAF Submission Ingestion Package generated from Vireo submission #9172 on 2016-07-07 at 13:49:01Made available in DSpace on 2016-07-07T20:27:12Z (GMT). No. of bitstreams: 2
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Previous issue date: 2016-04-13Embargo set by: Seth Robbins for item 93095
Lift date: 2018-07-07T20:28:14Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 93095
Lift date: 2018-07-07T20:35:34Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 93095 on 2018-07-08T09:15:20Z
Strategy and Steps for Analytical Method Validation
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
Survey of levels of common toxic metals and pesticides residues in some selected organically grown foods of Indian origin
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
Determination of arsenic and fluoride in borewell water samples collected from in and around Mysore City
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
Insertion and deletion tolerance of point processes
No full textWe develop a theory of insertion and deletion tolerance for point processes. A process is insertion-tolerant if adding a suitably chosen random point results in a point process that is absolutely continuous in law with respect to the original process. This condition and the related notion of deletion-tolerance are extensions of the so-called finite energy condition for discrete random processes. We prove several equivalent formulations of each condition, including versions involving Palm processes. Certain other seemingly natural variants of the conditions turn out not to be equivalent. We illustrate the concepts in the context of a number of examples, including Gaussian zero processes and randomly perturbed lattices, and we provide applications to continuum percolation and stable matching
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
Computational Study of the Dynamics of the Flow-Field Induced by Vortex Generators
No full textVortex Generators (VGs) are one of the most commonly used passive flow control devices. Recent studies have shown that it is beneficial to use sub-boundary layer vortex generators (SBVGs). The height of these generators varies between 10% - 50% of the boundary layer thickness. However, the reduced height causes the induced vortices to be substantially weaker. Therefore, using SBVG is beneficial only when the regions of flow separation are well defined. To better understand and comprehensively predict the effectiveness of these devices for flow control over a range of operating conditions, two different SBVG profile: rectangular vortex generators (RVGs) and triangular vortex generators (TVGs) are analysed when subjected to a laminar boundary layer. The topics of interest are instantaneous flow, mean flow, far-field acoustic properties and influence of the angle of attack on the VG vane. The results emphasise the unsteady nature of the induced vortices for both the VG profiles. For RVGs, mean flow visualisation indicates the presence of local re-circulation zones in between the vanes with an increase in angle of attack. Additionally, secondary vortices are noted for both the VGs. These secondary vortices significantly influence the properties of the primary vortices thereby, suggesting that, effectively managing the secondary vortices using suitable design changes to VG profile could be one of the possible ways to accomplish better flow control.Aerospace Engineerin
Temporal Synchronization of Sensors
No full textAdvanced automotive vehicles are based on the real-time fusion of an increasing number of automotive sensors. For precise fusion of different sensors, measurements need to be synchronized both temporally and spatially. This thesis aims to design a hardware temporal synchronization block as part of the PRISTINE systolic array accelerator project for multi-sensor data fusion. In this process, we study and address several temporal sensor synchronization issues that are characteristic of the considered system as well as any other typical sensor fusion system. First and foremost, we handle the problem of estimating the actual time of sensor measurement by exploring well-known filtering techniques such as Kalman, mean and median filters. A suitable filter is selected for implementation based on the statistical characteristics of the observed sensor cycle times, the complexity of the filters and the quality of obtained estimates. Next, we address the issue of reconstructing incoming sensor data streams according to the estimated sensor measurement times while maintaining minimal latency and synchronization error by employing an adaptive stream buffering technique utilized in distributed multimedia systems. An analysis of the effects of the stream synchronization algorithm's parameters on buffering latency and synchronization error was presented. Finally, the above synchronization solution was efficiently implemented on hardware by making certain modifications and design decisions to the algorithm. A method to evaluate the whole temporal synchronization process is proposed and the obtained results on real sensor data are presented.PRYSTINEElectrical Engineering | Circuits and System
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