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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

PDL with Intersection and Converse is Decidable

Lutz, Carsten 31 May 2022 (has links)
In its many guises and variations, propositional dynamic logic (PDL) plays an important role in various areas of computer science such as databases, artificial intelligence, and computer linguistics. One relevant and powerful variation is ICPDL, the extension of PDL with intersection and converse. Although ICPDL has several interesting applications, its computational properties have never been investigated. In this paper, we prove that ICPDL is decidable by developing a translation to the monadic second order logic of infinite trees. Our result has applications in information logic, description logic, and epistemic logic. In particular, we solve a long-standing open problem in information logic. Another virtue of our approach is that it provides a decidability proof that is more transparent than existing ones for PDL with intersection (but without converse).
272

Stability of building structures using NLFEA including second order effects : Applications with the software ATENA-GiD

Petkoglou, Alexandros January 2021 (has links)
In Sweden, prefabrication in the construction industry is a very common system. In prefabricated structures, there are various kinds of connections and generally many hinged connections. Therefore, it is of high interest to study the behavior of the prefabricated buildings in relation to the connections. Two main theories that can be used to evaluate our structures are the non-linear finite element analysis (NLFEA) and the second order effects. These two theories help to study the real behavior of the structures. Software that can apply these two theories is the ATENA-GiD. Therefore, it was very interesting to explore this software and find out how it can be used for prefabricated buildings. For this reason, a simplified ten-storey building was studied which had been also used in Lindwall’s and Wester’s (2016) master thesis. Various cases were chosen for this building. The building was studied either with monolithic walls or with vertical slip connection between the prefabricated walls. Also, the hollow core (HC) slabs were modelled in two ways and the supports of the columns were modelled in three ways. Even when each slab was modelled with two materials (solid concrete for the upper and lower layer with smeared reinforcement for the lower layer and modified concrete in order to compensate for the voids), the increase in the time for analysis was not important. Also, the cracking was not extensive thanks to the relatively low wind load. The slip joint between the walls didn’t lead to the different displacement between the walls. It was found that the hinged support in the columns was modelled by using the upwind line of the base. In non-linear analysis cases, the model of the structure gave 20% larger displacements than in linear analysis cases which means that the cracking had an important influence on the second order effects despite that the cracking was not extensive. The reduction of the stiffness of the walls to 40% accounting for cracked sections in additional linear analyses to according to the Eurocode 2 was a conservative choice for this building. The most remarkable result was that when the supports of the columns were modelled with hinges there was smaller displacement than when the supports were fixed. The reason for this was the negative displacements due to the buckling of the columns of the first storey. Moreover, for the linear cases, there was a much smaller displacement (5mm) than Lindwall and Wester (2016) (17mm) and this was possibly due to the way that the hinges were modelled in my building. It is interesting to investigate other ways to model the hinges in ATENA-GiD as well as other ways to model the connections between the HC slabs and the perimetric beams. Also, the effect of creep through the modulus of elasticity could be analyzed. Finally, it would be interesting to include foundations in the model to study the possible need for anchorages.
273

Data-Fitted Generic Second Order Macroscopic Traffic Flow Models

Fan, Shimao January 2013 (has links)
The Aw-Rascle-Zhang (ARZ) model has become a favorable ``second order" macroscopic traffic model, which corrects several shortcomings of the Payne-Whitham (PW) model. The ARZ model possesses a family of flow rate versus density (FD) curves, rather than a single one as in the ``first order" Lighthill-Whitham-Richards (LWR) model. This is more realistic especially during congested traffic state, where the historic fundamental diagram data points are observed to be set-valued. However, the ARZ model also possesses some obvious shortcomings, e.g., it assumes multiple maximum traffic densities which should be a ``property" of road. Instead, we propose a Generalized ARZ (GARZ) model under the generic framework of ``second order" macroscopic models to overcome the drawbacks of the ARZ model. A systematic approach is presented to design generic ``second order" models from historic data, e.g., we construct a family of flow rate curves by fitting with data. Based on the GARZ model, we then propose a phase-transition-like model that allows the flow rate curves to coincide in the free flow regime. The resulting model is called Collapsed GARZ (CGARZ) model. The CGARZ model keeps the flavor of phase transition models in the sense that it assume a single FD function in the free-flow phase. However, one should note that there is no real phase transition in the CGARZ model. To investigate to which extent the new generic ``second order" models (GARZ, CGARZ) improve the prediction accuracy of macroscopic models, we perform a comparison of the proposed models with two types of LWR models and their ``second order" generalizations, given by the ARZ model, via a three-detector problem test. In this test framework, the initial and boundary conditions are derived from real traffic data. In terms of using historic traffic data, a statistical technique, the so-called kernel density estimation, is applied to obtain density and velocity distributions from trajectory data, and a cubic interpolation is employed to formulate boundary condition from single-loop sensor data. Moreover, a relaxation term is added to the momentum equation of selected ``second order" models to address further unrealistic aspects of homogeneous models. Using these inhomogeneous ``second order" models, we study which choices of the relaxation term &tau are realistic. / Mathematics
274

[en] CELLULOSE NANOFIBERS AS A REACTIVE TEMPLATE FOR SYNTHESIS OF ADVANCED NANOMATERIALS / [pt] NANOFIBRAS DE CELULOSE COMO UM TEMPLATE REATIVO NA SÍNTESE DE NANOMATERIAIS AVANÇADOS

LUCAS TONETTI TEIXEIRA 11 March 2024 (has links)
[pt] Devido a grande poluição do meio ambiente, diferentes estratégias devem ser tomadas para remediação ambiental. Dentre as diversas estratégias, é possível citar adsorção de cátions metálicos de soluções aquosas, adsorção de fármacos, utilização e armazanamento de energia verde. Dito isso, o presente estudo relata a utilização das estratégias mencionadas. Portanto, foi utilizada nanofibras de celulose oxidada via TEMPO (2,2,6,6-tetrametil-piperidinil-N-oxil), TCNF, para a remoção de cátions de ferro, zinco e cobalto. Sua capacidade adsortiva para a remoção de ferro e zinco puros apresentou valores de 5902 e 5633 Miligrama por grama−1 , respectivamente. Quando ferro e zinco removidos de uma mesma solução, a capacidade adsortiva de TCNF foi de 5852 e 5622 Miligrama por grama−1 . Para a adsorção de cobalto, sua concentração reduziu de 50 grama por litro−1 para 8,3 grama por litro−1 . Posteriormente, as amostras de TCNF impregnadas com metais foram levadas para calcinação, com objetivo de produção de óxidos nanoestruturados. Em temperaturas a partir de 300 graus C, fases de hematita são identificadas e a partir de 400 graus C fases de zincita e franklinita são identificadas por ajustes de Rietveld nos difratogramas obtidos. Adicionalmente, quando calcinadas em atmosfera inerte, é possível observar o surgimento de óxidos. Além disso, todas as morfologias foram analisadas via MET e MEV, e podem ser comparadas a um nanocoral com espessuras entre 20 e 30 nm. Então, as amotras de ferrita de zinco foram aplicadas em adsorção de tetraciclina, com capacidade adsortiva de 18 miligrama por grama−1 e também como capacitor, atingindo um valor de capacitância de 2031 Farad por grama−1 . A amostra contendo ferrita de cobalto foi utilizada como catalisador para extração de H2 de borohidreto e a quantidade de gás hidrogênio extraída girou em torno de 476,4 Litros de hidrogênio produzido por grama de borohidreto de sódio por grama de catalisador. A energia de ativação para a reação foi calculada em torno de 57 Quilojoules por mol−1 . Portanto, a inovadora rota de síntese de óxidos nanoetruturados aparenta ser promissora. / [en] Due to significant environmental pollution, different strategies require to be implemented for environmental remediation. Among the different approaches, it is possible to cite the adsorption of metallic cations from aqueous solutions, adsorption of pharmaceuticals, and the use and storage of green energy. With this in mind, the present study reports the use of the mentioned strategies. Thus, oxidized cellulose nanofibers, produced via TEMPO (2,2,6,6-tetramethyl-piperidinyl-N-oxyl), TCNF, were used for the removal of iron, zinc, and cobalt cations from aqueous solution. Their adsorptive capacity for the removal of pure iron and zinc was 5902 and 5633 Milligram per gram−1 , respectively. When iron and zinc were removed from the same solution, the adsorptive capacity of TCNF was 5852 and 5622 Milligram per gram−1 , respectively. For cobalt adsorption, its concentration decreased from 50 gram per liter−1 to 8.3 gram per liter−1 . Subsequently, the TCNF samples impregnated with metals were subjected to calcination to produce nanostructured oxides. At temperatures above 300 C degrees, hematite phases were identified, and at 400 C degrees, zincite and franklinite phases were identified through Rietveld refinements of the obtained diffractograms. Additionally, when calcined in an inert atmosphere, the appearance of oxides was observed. Moreover, all morphologies were analyzed via TEM and SEM, resembling a nanocoral with thicknesses between 20 and 30 nm. The zinc ferrite samples were applied to tetracycline adsorption with an adsorptive capacity of 18 miligram per gram−1 and also as a capacitor, achieving a capacitance value of 2031 Farad per gram−1 . The cobalt ferrite sample was used as a catalyst for hydrogen extraction from borohydride, and the amount of extracted H2 was around 476.4 liters of hydrogen produced per gram of sodium borohydride per gram of catalyst. The activation energy for the reaction was calculated to be approximately 57 Kilojoules per mole−1 . Therefore, the innovative route for the synthesis of nanostructured oxides appears to be promising.
275

Elevers förklaringar i det nationella provet i historia / Students’ explanations in the Swedish national test in history

Westberg, Oskar, Voigt, Johanna January 2024 (has links)
Denna studie undersöker elevers förklaringar i det nationella provet 2014. Provet skall tas i särskilt beaktning och därmed är det viktigt att förstå hur elever förklarar historiska skeenden vid provtillfället. Syftet med studien är att undersöka elevers uttryck av historiska förklaringar när de resonerar om orsaker till Förintelsen, Gulag och slavhandeln över Atlanten. Frågeställningarna utgår från elevers hantering av tankebegrepp och de mönster som återfinns i deras förklaringar. För studien användes en kvalitativ metod där 53 katalogiserade prov som bedömts med A analyserades. Resultatet delades upp i två grupper: Elevers hantering av kausalitet samt elevers hantering av aktör och struktur. Materialet inhämtades från arkivet vid Malmö Universitet, som på uppdrag av Skolverket utvecklar och utvärderar det nationella provet i historia. Resultatet visar att elever uttrycker komplexa förklaringar utifrån kausalitet och ett implicit förklarande av aktör och struktur. Därutöver visade resultatet att elever lägger stor vikt vid aktörers intentioner i sina framställningar av historia. Studien visar också att komplexiteten i förklaringarna skiljer sig mellan de olika frågorna, möjligtvis då de har olika platser i historiekulturen. Därutöver är en av studiens slutsatser att lärare i sin undervisning måste vara medvetna om hur de förklarar historiska skeenden. Studien visar ett behov av mer forskning kring hur lärare undervisar om svårhanterliga historiska skeenden och hur marginaliserade grupper framställs av lärare.
276

Bäst i test eller bara ett modest valmanifest? : - En kvantitativ studie gällande svenska partiers valmanifesti två europaparlamentsval / Best in Test or Just a Modest Election Manifesto? : – A Quantitative Study on Swedish Parties' ElectionManifestos in two European Parliament Elections

Lindström, Johan January 2024 (has links)
This study aims to investigate the policy focus of Swedish parties in the two most recent European Parliament elections through a quantitative content analysis of the parties' election manifestos. The method for this analysis has been inspired by the well-known Comparative Manifesto Project. The information made available through the method has been analyzed within the framework of relevant theories in the field, namely Second-order Election theory and Issue Ownership theory, to examine whether this policy focus aligns with expected outcomes. Descriptive statistics show significant changes between the elections; for example, the length of the election manifestos has more than doubled on average. Theoretically, the statistical results can be said to align with expected outcomes. Each party places a significant emphasis on the issues in which they already have established credibility, which is the expected outcome according to Issue Ownership research. However, one party stands out in this regard: the Liberals. This is likely due to a combination of the fact that education issues are largely not decided within the European Parliament, while the Liberals have ambitious goals to be the most pro-EU party. This combination potentially affects the Liberals' results in the European Parliament elections negatively, given Second-order Election theories that argue the connection to the national arena is crucial for achieving good election results. The issue of the environment and climate stands out in that all parties, except the Sweden Democrats, place a significant emphasis on it, despite many parties not having high credibility in this area. This contradicts both Issue Ownership theory and Second-order Election theory. Potentially, the cross-border nature of the environment and climate issue is starting to change what we think we know about the connection between national and the European election.
277

Beyond cybernetics : connecting the professional and personal selves of the therapist

Marovic, Snezana 11 1900 (has links)
Text in English / This research explores the meaning of the first and second-order therapeutic stances with reference to the therapist's professional and personal development. The dominant positivist paradigm was reflected in the therapist's initial position of expert observer, outside of the observed. The observed phenomena were a group of children suffering from thalassemia major, a terminal genetic disease, and their mothers. The initial idea of short-term intervention and focus on the observed evolved into six-year journey where the observer and the observed became an interconnected unit of observation, understanding and change. A first-order stance led to therapeutic stuckness, where the therapist's confrontation with her therapeutic failure and the limitations of the dominant paradigm provoked a deconstruction of the expert position and promoted a self-reflexive therapeutic stance. The author's self-searching process took her back to her personal self, her family of origin and the ''wounded healer". The researcher moved from an initial disconnection between her professional and personal selves to an awareness of the interface between the two and, ultimately, to a unification of her professional and personal selves. Such development involved an individuation process moving from a narcissistic belief in her objective stance towards a therapeutic stance where she sees herself less as a powerful agent of change and moves to an increasingly higher order of integration of the professional and personal selves (Skovholt & Ronnestad, 1992). The process with the children and mothers shifted from a focus on compliance and medical issues to more personal and emotional stories. The therapist's participation and collaborative stance created a context for change, where greatly improved medical compliance was just one of the many transformations experienced by all the participants. The researcher speculates that development of a second-order stance requires second-order change, which comes "at the end of long, often frustrating mental and emotional labor" (Watzlawick et al., 1974, p. 23), promoting integration between the professional and personal selves of the therapist. The researcher therefore contends that this process has important implications for psychotherapy training, supervision and continuing education. / Psychology / D. Litt. et Phil. (Psychology)
278

Beyond cybernetics : connecting the professional and personal selves of the therapist

Marovic, Snezana 11 1900 (has links)
Text in English / This research explores the meaning of the first and second-order therapeutic stances with reference to the therapist's professional and personal development. The dominant positivist paradigm was reflected in the therapist's initial position of expert observer, outside of the observed. The observed phenomena were a group of children suffering from thalassemia major, a terminal genetic disease, and their mothers. The initial idea of short-term intervention and focus on the observed evolved into six-year journey where the observer and the observed became an interconnected unit of observation, understanding and change. A first-order stance led to therapeutic stuckness, where the therapist's confrontation with her therapeutic failure and the limitations of the dominant paradigm provoked a deconstruction of the expert position and promoted a self-reflexive therapeutic stance. The author's self-searching process took her back to her personal self, her family of origin and the ''wounded healer". The researcher moved from an initial disconnection between her professional and personal selves to an awareness of the interface between the two and, ultimately, to a unification of her professional and personal selves. Such development involved an individuation process moving from a narcissistic belief in her objective stance towards a therapeutic stance where she sees herself less as a powerful agent of change and moves to an increasingly higher order of integration of the professional and personal selves (Skovholt & Ronnestad, 1992). The process with the children and mothers shifted from a focus on compliance and medical issues to more personal and emotional stories. The therapist's participation and collaborative stance created a context for change, where greatly improved medical compliance was just one of the many transformations experienced by all the participants. The researcher speculates that development of a second-order stance requires second-order change, which comes "at the end of long, often frustrating mental and emotional labor" (Watzlawick et al., 1974, p. 23), promoting integration between the professional and personal selves of the therapist. The researcher therefore contends that this process has important implications for psychotherapy training, supervision and continuing education. / Psychology / D. Litt. et Phil. (Psychology)
279

Designing Public Play : Playful Engagement, Constructed Activity, and Player Experience

Back, Jon January 2016 (has links)
This thesis sets out to explore why people engage in, and how to design for, play in a public setting. It does this by separating design for play from design of games, describing play as a socially and mentally understood activity, and a playful approach to engaging in that activity. It emphasises that while play is voluntary, design can help shape the players’ mode of engagement. The thesis uses a qualitative and inductive approach to research, with an understanding of knowledge as being constructed in the individual. The research is grounded in human computer interaction and interaction design, and closely related to game studies and design science. The research question concerns how design can influence the player activity in order to create a desired player experience in public, by harnessing playful engagement. It’s foundation is a theory of play which describes play as a framed, or hedged-off, activity with a fragile border; where knowledge and feelings can leak both in and out of the activity, and affect the play as well as what is around it. The theory of enjoyment of play is discussed, and the problem of treating this as ‘fun’ is addressed, concluding in a presentation of how playful engagement can be harnessed through design. The theory is applied in five design cases: I’m Your Body, a locative storytelling app; Codename Heroes, a pervasive game of personal empowerment; Passing On, a slow-paced game about communication; Busking Studies, which involves observing street performers and their shows; and DigiFys, an architectural design exploration of playgrounds and play paths. Finally, three concepts, or design tools, are presented, which address: 1) a structure for understanding a design through three layers, constructs designed by the designer, inspiring play activity with the player, leading to experience; 2) an approach to designing invitations to play; and finally 3), a four faceted structure for understanding play engagement when players engage in non intended ways.
280

A second-order cybernetic explanation for the existence of network direct selling organisations as self-creating systems

Davis, Corne 18 August 2011 (has links)
Network Direct Selling Organisations (NDSOs) exist in more than 50 countries and have more than 74 million members. The most recent statistical information reveals that the vast majority of members do not earn significant income. Criticism of these organisations revolves around the ethicality of consumption, the commercialisation of personal relationships, and the exploitation of unrealistic expectations. This study aims to explore how communication creates networks that sustain an industry of this kind despite the improbability of its existence. The study commences with a description of NDSOs from historical, operational, tactical, and strategic perspectives. Given the broader context created by the global presence of this industry, cybernetics has been selected as a meta-theoretical perspective for the study of communication. The more recent development of second-order cybernetics and social autopoiesis are introduced to communication theory as a field. Niklas Luhmann‟s new social theory of communication is assessed and applied in relation to existing communication theory. New conceptual models are developed to explore communication as the unity of the synthesis of information, utterance, understanding, and expectations as selections that occur both consciously and unconsciously, intentionally and unintentionally. These models indicate the multiplexity of individual and social operationally closed, yet informationally open systems, and they are used here to provide a systemic and coherent alternative to orthodox communication approaches to the study of organisations. The study adopts a constructivist epistemological stance and propounds throughout the necessity of further interdisciplinary collaboration. The study concludes that individuals are composite unities of self-creating systems, and they co-create social systems by self-creating and co-creating meaning. Meaning is described as the continuous virtualisation and actualisation of potentialities that in turn coordinate individual and social systems‟ actions. A communication process flow model is created to provide a theoretical explanation for the existence of NDSOs as self-creating systems. The study aims to show that communication has arguably become the most pervasive discipline as a result of the globally interactive era. It is shown that second-order cybernetics and social autopoiesis raise several further questions to be explored within communication theory as a field. / Communication, first-order cybernetics, second-order cybernetics, Complexity and complex systems, autopoiesis, self-reference, recursivity, operational closure, system boundaries, Network Direct Selling Organisations / Communication / D. Litt. et Phil. (Communication)

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