Polytechnic of Zagreb

Zagreb, Croatia

Polytechnic of Zagreb

Zagreb, Croatia

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Perkov T.,Polytechnic of Zagreb
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Known results on global definability in basic modal logic are generalized in the following sense. A class of Kripke models is usually called modally definable if there is a set of modal formulas such that a class consists exactly of models on which every formula of that set is globally true, i. e. universally quantified standard translations of these formulas to the corresponding first order language are true. Here, the notion of definability is extended to existentially quantified translations of modal formulas - a class is called modally ∃-definable if there is a set of modal formulas such that a class consists exactly of models in which every formula of that set is satisfiable. A characterization result is given in usual form, in terms of closure conditions on such classes of models. © 2012 Springer-Verlag.


Pavlovic T.,Energy Control Systems Engineering | Bjazi T.,Polytechnic of Zagreb | Ban Z.,Energy Control Systems Engineering
IEEE Transactions on Power Electronics | Year: 2013

This paper presents simplified nonlinear averaged large-signal and linear small-signal models of the three basic dc-dc converter topologies, boost, buck, and noninverting buck-boost, respectively, operating in peak current-mode control. Models have been derived for the continuous and discontinuous conduction mode. The modeling methodology used is the equivalent current injected method. The derived models have been compared to the existing full-order large-signal nonlinear models and have been found to exhibit simulation time reduction by a few magnitudes in complex distributed power systems, such as today's popular microgrids. The models developed have been experimentally verified on a custom-built 120-W boost converter prototype, showing great accuracy in steady state and in dynamical behavior in all operating points, as determined by the output resistance. © 1986-2012 IEEE.


Perkov T.,Polytechnic of Zagreb
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

A class of Kripke frames is called modally definable if there is a set of modal formulas such that the class consists exactly of frames on which every formula from that set is valid, i.e. globally true under any valuation. Here, existential definability of Kripke frame classes is defined analogously, by demanding that each formula from a defining set is satisfiable under any valuation. The notion of modal definability is then generalized by combining these two. Model theoretic characterizations of these types of definability are given. © 2014 Springer-Verlag Berlin Heidelberg.


This paper presents the works of the Italian architects Luccichenti and Monaco between 1941 and 1943 in Croatia. The selected buildings in Zadar (Case minime, Genio Civile) and Trogir (Case minime) as well as other projects in Zadar (I.N.A. palace, financial police building, fishmarket) and on Korèula island (hospital building) underline the need for an evaluation and protection of the architectural works as historic and cultural monuments built under various political regimes.


Poljak M.,University of California at Los Angeles | Poljak M.,University of Zagreb | Jovanovic V.,Technical University of Delft | Grgec D.,Polytechnic of Zagreb | Suligoj T.,University of Zagreb
IEEE Transactions on Electron Devices | Year: 2012

We have investigated the electron mobility in ultrathin-body InGaAs-on-insulator devices using physics-based modeling that self-consistently accounts for quantum confinement and covers band-structure effects in ultrathin III-V layers. Scattering by nonpolar and polar acoustic and optical phonons, surface roughness, and thickness fluctuations, Coulomb and alloy disorder have been included in the calculations. The modeling, calibrated and verified on experimental data from the literature, has revealed a strong influence of thickness fluctuations caused by the light effective mass of Γ valley electrons. Our results indicate that InGaAs-on-insulator MOSFETs are more influenced by interface properties compared with silicon-on-insulator devices and outperform them only above certain body thickness that depends on interface quality. © 1963-2012 IEEE.


Frude N.,University of Cardiff | Jandric P.,Polytechnic of Zagreb
E-Learning and Digital Media | Year: 2015

This conversation focuses on a book published in 1983 that examined ‘animism’, the tendency to regard non-living entities as living and sentient. The Intimate Machine suggested that animism will be fully exploited by artificial intelligence (AI) and robotics, generating artefacts that will engage the user in ‘social’ interactions so that eventually people will form close and beneficial social relationships with artificial ‘companion systems’. The author of the book, clinical psychologist Neil Frude, is asked to reflect on his book and, although he admits that his techno-optimism in the 1980s was exaggerated, it is clear that he still holds to his major thesis. He considers ‘virtual pets’, such as Tamagotchi, Furby and Sony’s Aibo, and considers why they did not evolve into more sophisticated social artefacts. Frude identifies three vital elements needed for a successful artificial companion – animism, artistry and AI – and acknowledges that the last of these has been the weak link. However, even simple AI programs can make an impressive impact when skilfully implemented. He emphasizes the relevance of characterization, pointing to examples in recent computer- generated animations. In the context of interactive technology, the addition of character and artificial personality will generate companion machines that are highly engaging and exceptionally appealing. Insights into the likely nature and roles of artificial companions, and how people will relate to them, are available in the science fiction corpus, and this literature has also examined relevant ethical and social issues. Finally, he considers some of the possible clinical applications of such systems in both physical health and mental health and he also reflects on some of the potential dangers of the kind of artefact that he is envisioning. © The Author(s) 2015.


Perkov T.,Polytechnic of Zagreb
CEUR Workshop Proceedings | Year: 2013

A class of Kripke frames is called modally definable if there is a set of modal formulas such that the class consists exactly of frames on which every formula from that set is valid, i. e. globally true under any valuation. Here, existential definability of Kripke frame classes is defined analogously, by demanding that each formula from a defining set is satisfiable under any valuation. This is equivalent to the definability by the existential fragment of modal language enriched with the universal modality. A model theoretic characterization of this type of definability is given.


Tenenbaum J.,Boston University | Horvatic D.,University of Zagreb | Bajic S.C.,Polytechnic of Zagreb | Pehlivanovic B.,University of Bihac | And 2 more authors.
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

In developed economies, the sign of the price increment influences the volatility in an asymmetric fashion-negative increments tend to result in larger volatility (increments with larger magnitudes), while positive increments result in smaller volatility. We explore whether this asymmetry extends from developed economies to European transition economies and, if so, how such asymmetry changes over time as these transition economies develop and mature. We analyze eleven European transition economies and compare the results with those obtained by analyzing U.S. market indices. Specifically, we calculate parameters that quantify both the volatility asymmetry and the strength of its dependence on prior increments. We find that, like their developed economy counterparts, almost all transition economy indices exhibit a significant volatility asymmetry, and the parameter γ characterizing asymmetry fluctuates more over time for transition economies. We also investigate how the association between volatility and volatility asymmetry varies by type of market. We test the hypothesis of a negative correlation between volatility and volatility asymmetry. We find that, for developed economies, γ experiences local minima during (i) "Black Monday" on October 19, 1987, (ii) the dot-com bubble crash in 2002, and (iii) the 2007-2009 global crisis while for transition economies, γ experiences local maxima during times of economic crisis. © 2010 The American Physical Society.


Perkov T.,Polytechnic of Zagreb
Journal of Logic, Language and Information | Year: 2016

We can formalize judgments as (consistent sets of) logical formulas. Judgment aggregation deals with judgments of several agents, which need to be aggregated to a collective judgment. There are several logical formalizations of judgment aggregation. This paper focuses on a modal formalization which nicely expresses classical properties of judgment aggregation rules and famous results of social choice theory, like Arrow’s impossibility theorem. A natural deduction system for modal logic of judgment aggregation is presented in this paper. The system is sound and complete. As an example of derivation, a formal proof of Arrow’s impossibility theorem is given. © 2016 Springer Science+Business Media Dordrecht


Cuban L.,Stanford University | Jandric P.,Polytechnic of Zagreb
E-Learning and Digital Media | Year: 2015

In this article, Larry Cuban discusses his ideas about the topic of this Special Issue of E-learning and Digital Media ‘Networked Realms and Hoped-For Futures: A trans-generational dialogue’ with one of its co-editors, Petar Jandrić. The conversation explores the historical relationships between education and information and communication technologies and draws lessons for present and future. The first part of the conversation explores methodological issues pertaining to historical thinking about schools and computers in the network society. It identifies a continued need to recognize historical patterns, including those in thought experiments, and shows that Rogers’ theory of diffusion of innovations should be supplemented by more nuanced approaches to the historical relationships between schools and computers. The second part of the conversation presents an attempt to explain historical patterns using the ancient notion of magical thinking. It explores why teachers use computers in their private lives much more than in their professional lives, and ‘school anarchy’ caused by student usage of personally owned devices in classrooms. It creates a baseline for comparison between desktop / laptop computers and various hand-held devices, and dismantles the quest for deschooling as another example of magical thinking. The third part of the conversation examines the ideological role of information and communication technologies in contemporary school reform and explores their potential for democracy. It analyses the contemporary transformations of traditional publishing formats such as books, journals and newspapers, and their reflections in the world of academia. It examines the changing role of teachers as public intellectuals, and the role of information and communication technologies in their public exposure. The last part of the conversation analyses the process of ‘educationalizing’ various social and economic problems, and links it to contemporary technologies. It revisits Larry Cuban’s predictions from Teachers and Machines: Classroom Use of Technology Since 1920 (1986), and reminds us that accurate predictions are rare, while inaccurate ones are not only common but often memorable. Finally, it examines why it is so hard to balance education with information and communication technologies. © The Author(s) 2015.

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