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University of Twente Publications (57.695 recursos)

University of Twente Repository provides publications of UT scientific staff, in many cases full text and publicly available.

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Mostrando recursos 1 - 20 de 25.039

  1. Technical Report on Raster field test at a Water Board

    Vriezekolk, Eelco
    Risk assessment of unavailability of telecommunication services is an important part of an organisation’s business continuity management. We developed the Raster method to enable organisations to assess their telecommunication service unavailability risks. To validate Raster in practice we conducted two field tests in which the Raster method was applied at a typical target organisation. This document reports on the second field test, at a Water Board in the Netherlands. This report describes the research goals, method, and results of this field test, and compares the results to those of the first field test. This field test reconfirms the usefulness of...

  2. Vertical hybrid inorganic-organic nanoelectronic devices

    Wilbers, Janine Gabriele Elisabeth

  3. Quality of equilibria in resource allocation games

    Jong, Jasper de
    In situations where multiple parties are involved, local or selfish decisions result in outcomes that rarely align with what is best for society. In order to evaluate the quality of the resulting outcomes, we first need to predict which outcomes can occur. Game theory offers answers to this question, the Nash equilibrium being the most prominent example: it is an outcome where no party can improve by unilateral deviations. In that sense Nash equilibria are a good description of a stable outcome, but do not ask how that outcome was actually obtained. Implicitly, Nash equilibria make the assumption that parties...

  4. Reconciling food security and bioenergy: priorities for action

    Kline, Keith L.; Msangi, Siwa; Dale, Virginia H.; Woods, Jeremy; Souza, Glaucia M.; Osseweijer, Patricia; Clancy, Joy S.; Hilbert, Jorge A.; Johnson, Francis X.; McDonnell, Patrick C.; Mugera, Harriet K.
    Understanding the complex interactions among food security, bioenergy sustainability, and resource management requires a focus on specific contextual problems and opportunities. The United Nations’ 2030 Sustainable Development Goals place a high priority on food and energy security; bioenergy plays an important role in achieving both goals. Effective food security programs begin by clearly defining the problem and asking, ‘What can be done to assist people at high risk?’ Simplistic global analyses, headlines, and cartoons that blame biofuels for food insecurity may reflect good intentions but mislead the public and policymakers because they obscure the main drivers of local food insecurity...

  5. Modeling of tailor hardened boron steel for crash simulation

    Eller, Tom Karl
    The automotive industry is continuously working on the weight reduction of their vehicles, while maintaining or even improving the crashworthiness in accordance with increasing safety demands. This has favored the development of innovative materials and production processes. The hot stamping process, in which heated blanks are simultaneously formed and quenched in cooled dies, is one of these recent innovations. Due to the high cooling rates during quenching, an ultra high material strength of up to 1500 MPa can be obtained. By locally reducing the cooling rate during quenching, e.g. by using partially heated dies, regions of lower strength with increased...

  6. Hermite-based communications: a time-frequency perspective

    Korevaar, Cornelis Willem

  7. On the modeling, design, and control of compliant robotic manipulators

    Groothuis, Stefan Sebastiaan
    In the future of the aging society it becomes increasingly difficult to provide personal care to people who are in need of help due to physical impairments caused by various diseases or disorders. The number of caregivers is limited and the cost of individual personal care will increase. Although personal care is desired, the downside is that people in need of care become dependent on caregivers for accomplishing their activities of daily living. This dependence has a big influence on one’s quality of life and self esteem. A solution to this situation is the deployment of assistive robotic aids like multifunctional...

  8. Deep web content monitoring

    Khelghati, Mohammadreza
    In this thesis, we investigate the path towards a focused web harvesting approach which can automatically and efficiently query websites, navigate through results, download data, store it and track data changes over time. Such an approach can also facilitate users to access a complete collection of relevant data to their topics of interest and monitor it over time. To realize such a harvester, we focus on the following obstacles. First, we try to find methods that can achieve the best coverage in harvesting data for a topic. Although using a fully automatic general harvester facilitates accessing web data, it is...

  9. Auditing organizational communication: evaluating the methodological strengths and weaknesses of the critical incident technique, network analysis, and the communication satisfaction questionnaire

    Zwijze-Koning, Karen Heleen
    This dissertation focuses on the methodology of communication audits. In the context of three Dutch high schools, we evaluated several audit instruments. The first study in this dissertation focuses on the question whether the rationale of the critical incident technique (CIT) still applies when it is used to evaluate internal communication practices. The results confirm that the CIT is capable of providing more structural insights in the strengths and weaknesses of an organizations communication system and that it is an extremely useful inductive approach to study organizational communication from employees’ perspective. In the second study we evaluated several validity issues...

  10. Assessing loss event frequencies of smart grid cyber threats: Encoding flexibility into FAIR using Bayesian network approach

    Le, Anhtuan; Chen, Yue; Chai, Kok Keong; Vasenev, Alexandr; Montoya, Lorena
    Assessing loss event frequencies (LEF) of smart grid cyber threats is essential for planning cost-effective countermeasures. Factor Analysis of Information Risk (FAIR) is a well-known framework that can be applied to consider threats in a structured manner by using look-up tables related to a taxonomy of threat parameters. This paper proposes a method for constructing a Bayesian network that extends FAIR, for obtaining quantitative LEF results of high granularity, by means of a traceable and repeatable process, even for fuzzy input. Moreover, the proposed encoding enables sensitivity analysis to show how changes in fuzzy input contribute to the LEF. Finally,...

  11. Threat navigator: grouping and ranking malicious external threats to current and future urban smart grids

    Vasenev, Alexandr; Montoya, Lorena; Ceccarelli, Andrea; Le, Anhtuan; Ionita, Dan
    Deriving value judgements about threat rankings for large and entangled systems, such as those of urban smart grids, is a challenging task. Suitable approaches should account for multiple threat events posed by different classes of attackers who target system components. Given the complexity of the task, a suitable level of guidance for ranking more relevant and filtering out the less relevant threats is desirable. This requires a method able to distill the list of all possible threat events in a traceable and repeatable manner, given a set of assumptions about the attackers. The Threat Navigator proposed in this paper tackles...

  12. Opportunistic beacon networks

    Türkes, Okan
    Modern society is surrounded by an ample spectrum of personal mobile devices with short-range wireless communication support. This ubiquity creates an immense potential of new concepts for people-centric ad hoc networks that can be applied to every personal and social dimension of life. The last decade introduced the concept of Opportunistic Networks (OppNets) that facilitates delay-tolerant information sharing between mobile users anytime, anywhere, and every which way possible. OppNets constitute an appealing solution to provide connectivity in those situations where communication is desired, but situated network architectures fail to provide it effectively. This thesis focuses on the design, implementation, and...

  13. Flow Separation and Turbulence in Jet Pumps for Thermoacoustic Applications

    Oosterhuis, Joris P.; Verbeek, Anton A.; Bühler, Simon; Wilcox, Douglas; Meer, Theo H. van der
    The effect of flow separation and turbulence on the performance of a jet pump in oscillatory flows is investigated. A jet pump is a static device whose shape induces asymmetric hydrodynamic end effects when placed in an oscillatory flow. This will result in a time-averaged pressure drop which can be used to suppress acoustic streaming in closed-loop thermoacoustic devices. An experimental setup is used to measure the time-averaged pressure drop as well as the acoustic power dissipation across two different jet pump geometries in a pure oscillatory flow. The results are compared against published numerical results where flow separation was...

  14. Smoothed analysis of belief propagation and minimum-cost flow algorithms

    Cornelissen, Kamiel
    Abstract: Algorithms that have good worst-case performance are not always the ones that perform best in practice. The smoothed analysis framework is a way of analyzing algorithms that usually matches practical performance of these algorithms much better than worst-case analysis. In this thesis we apply smoothed analysis to two classes of algorithms: minimum-cost flow algorithms and belief propagation algorithms. The minimum-cost flow problem is the problem of sending a prescribed amount of flow through a network in the cheapest possible way. It is very well known, and over the last half a century many algorithms have been developed to solve...

  15. Political attitudes in a rapidly changing European landscape: methodological and substantive insights from the ESS-Netherlands panel component

    Turper, Sedef

  16. Topochip: technology for instructing cell fate and morphology via designed surface topography

    Hulshof, Godefridus Fransciscus Bernardus
    The control of biomaterial surface topography is emerging as a tool to influence cells and tissues. Due to a lack a theoretical framework of the underlying molecular mechanisms, high-throughput screening (HTS) technology is valuable to identify and study bioactive surface topographies. To identify the bioactive topographies that can be applied to medical implants and in vitro cell culture systems the TopoChip HTS platform has been developed which contains more than 2000 unique randomly generated surface topography designs. In this thesis we used the state of the art TopoChip HTS platform to investigate bioactive topographies on materials which are similar to...

  17. Tailored ceria nanoparticles for CO2 mediated ethylbenzene dehydrogenation

    Kovacevic, Marijana
    Styrene production via ethylbenzene dehydrogenation (EBDH) is one of the ten most important petrochemical processes. Possessing highly reactive double bond which facilitates self-polymerization and polymerization with other monomers, styrene is the fourth utmost essential bulk monomer at present. Current commercial ethylbenzene dehydrogenation is highly endothermic reaction, thus highly energy demanding. Several alternatives to steam, conventionally used to supply heat have been widely investigated. In this thesis we report on the CO2 mediated EBDH in which CO2 has been used as a mild oxidant instead of stream. Reaction was solely employed as a model reaction to probe inherent surface reactivity of...

  18. Experience with LEDS and NAMA Low Carbon Strategies: The Case of Georgia

    Mdivani, Kakhaberi; Hoppe, Thomas
    Low Emission Development Strategies (LEDS) and National Appropriate Mitigation Actions (NAMAs) have the potential to support developing countries in attaining low carbon goals. In spite of the evident potential, there is a need to learn from practice. This paper explores the case of Georgia. The main research question discussed is: What experience has been gained with the development of LEDS and NAMAs in Georgia? The study reveals that both LEDS and NAMAs are subject to barriers that considerably slow development processes: there is a lack of institutional capacity, little inter-governmental goal alignment and poor coordination of actions, a lack of...

  19. Interviewing Suspects with Avatars: Avatars Are More Effective When Perceived as Human

    Ströfer, Sabine; Ufkes, Elze G.; Bruijnes, Merijn; Giebels, Ellen; Noordzij, Matthijs L.
    It has been consistently demonstrated that deceivers generally can be discriminated from truth tellers by monitoring an increase in their physiological response. But is this still the case when deceivers interact with a virtual avatar? The present research investigated whether the mere "belief" that the virtual avatar is computer or human operated forms a crucial factor for eliciting physiological cues to deception. Participants were interviewed about a transgression they had been seduced to commit, by a human-like virtual avatar. In a between-subject design, participants either deceived or told the truth about this transgression. During the interviews, we measured the physiological...

  20. Nanomachining using gold: creation of gold nanoparticle arrays and nanopores

    Vreede, Lennart Jacobus de

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