1,721,250 research outputs found
Cyber-Physical Attack Detection for Networked Control Systems
No full textUntil 1960s, control systems consisted mainly of mechanical or analog electronic devices exchanging information among system components, i.e., sensors, controllers, and actuators, via wired communication. However, recent advancement in computer and communication industries have led to the growing use of Internet, embedded systems, wireless and digital communication technologies in many industrial control systems and transformed them into Networked Control Systems (NCSs).
A defining feature of an NCS is that it consists of a number of devices implemented distributively so that system information is exchanged through a shared communication network. In light of many distinct advantages of NCSs including flexible architectures and less installation and maintenance costs, the development and application of NCSs have been recently boosted in a wide range of practical areas and critical infrastructures including transportation systems, electrical power systems and smart grids, remote surgery, industrial and manufacturing systems.
Owing to heterogeneous IT components and open network connections among controllers, sensors, actuators, and other networked components, the Confidentiality, Integrity, and Availability (CIA) of exchanged data in an NCS may suffer from vulnerability to malicious cyber attacks. Undoubtedly, this kind of threat is mainly launched by an adversary in either the physical world or the cyber-space with the aim of substantial economic benefits or disrupting human life. Therefore, it is imperative to properly address security issues of NCSs so as to ensure their reliable and safe performance.
In securing NCSs, reliable attack detection is of utmost importance. Generally speaking, when cyber attacks are detected and located in a timely fashion, the damage to overall systems can be controlled within a tolerable limit. Motivated by security concerns of NCSs, the first major contribution of this thesis is the development of a novel centralized detection method based on set-membership filtering technique so as to detect cyber attacks in an NCS subject to Unknown-But-Bounded (UBB) process noise and UBB measurement noise. In response to it, a set-membership filter is designed so as to construct two ellipsoidal sets: 1) a prediction set and 2) an estimation set. The estimation ellipsoidal set is calculated through updating the prediction ellipsoidal set with the current sensor measurement data. Whether the filter can detect the occurrence of such an attack is determined by the existence of intersection between these two sets.
The developed centralized detection method may not be straightforwardly applicable for a large-scale NCS because it requires full knowledge of the entire network information. Furthermore, the computational overhead for this detection method is quite high and hence, it may make the use of the detection system unrealistic. Therefore, the second major contribution of this thesis is the development of a distributed attack detection method for a vehicular platoon system, which is one of the large-scale NCSs from real engineering world. Moreover, two recovery mechanisms are developed to mitigate the adversarial impacts of attacks on the performance of the vehicle platooning system. With these two recovery mechanisms, the system can be brought back to the normal condition after detection of the attacks.
In some practical situations, it is quite common for a crafty adversary to launch assorted attacks of different models and strategies for comprehensively compromising the sensor measurements and control signals. It has been well acknowledged that different attack strategies are generally stealthy to any detection method. Motivated by this observation, the property of system’s resiliency is of utmost significance. In this study, the focus lies on resilient remote tracking control through a shared communication network. Thus, the third major contribution of this thesis is the analysis of the joint problem of resilient tracking control and resilient estimation in NCSs subject to the presence of various cyber attacks that are modeled in a unified framework which leads the NCS to be operated and controlled via some digital and unprotected communication networks.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Eng & Built EnvScience, Environment, Engineering and TechnologyFull Tex
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Message from the chairs
No full text"Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public."Intelligent Electrical Power Grid
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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