Predição do sequestro do carbono em área reflorestada utilizando redes neurais artificiais

Pós-graduação em Engenharia Mecânica - FEIS

Análise dinâmica de contingências de sistemas de energia elétrica por redes neurais baseadas na teoria da ressonância adaptativa

Pós-graduação em Engenharia Elétrica - FEIS

Integração conceptual na descrição de fenômenos gramaticais do português

Functional grammar currently has a great acceptance in linguistics, mainly because it can enlighten grammatical facts' motivation in the structure of a text. From its emergence, the tradition of studying grammar by grammar has come to an end. Demonstrative pronouns, for instance, have begun to be viewed as efficient tools of text cohesion, used to resume terms from previous clauses. This task, however, ends up leaving an endless trail of black boxes. How is it possible to explain the origin of demonstratives' anaphoric functioning if they are originally used to indicate things or people relative to the interlocutors' spatial position? This work aims at showing that Cognitive Linguistics arises just as an option for opening those black boxes. This article focuses on one of its themes - the conceptual blending theory - to support this possibility. Firstly, it was necessary to integrate the cognitive model into the complexity theory, according to Bybee (2010) and Castilho (2009), who understand language as a complex adaptive system. After that, a brief updated description on the conceptual blending theory is made and its application in some grammatical facts of the Brazilian Portuguese language is suggested under the morphological and syntactic levels.

Desenvolvimento de um sistema inteligente para o diagnóstico e prognóstico de falhas em sistemas de distribuição de energia elétrica

Pós-graduação em Engenharia Elétrica - FEIS

Fadiga cíclica flexural de instrumentos Hyflex CM e TF Adaptive em diferentes situações experimentais

O presente estudo teve como objetivo avaliar a resistência à fadiga cíclica flexural dos instrumentos de níquel- titânio, Hyflex CM (Coltène, EUA) e TF Adaptive (SybronEndo, EUA) em diferentes situações experimentais. Todas as limas que foram selecionadas possuíam conicidade 0,04 e diâmetro de ponta 35. Utilizou-se um dispositivo desenvolvido especificamente para realizar o ensaio flexural dinâmico. Os instrumentos TF Adaptive foram divididos em 3 grupos de acordo com o ângulo de curvatura do ensaio: 45º, 60º e 90º e cada grupo subdividido em 2 subgrupos de acordo com o tipo de movimento: rotação contínua e Adaptive. Cada subgrupo era composto por 15 instrumentos TF Adaptive, totalizando 90 instrumentos. Quinze instrumentos Hyflex CM formavam o grupo 4, no ensaio com ângulo de curvatura 90 graus e rotação contínua. A simulação foi realizada em canais artificiais de aço com ângulo de 45, 60, 90 graus e raio 5m m. O número de ciclos e o tempo em segundos até a fratura foram tabulados e analisados. Entretanto, a fadiga cíclica flexural foi significante maior nos três grupos em movimento Adaptive. E as limas TF Adaptive em seu próprio movimento tiveram maior número de ciclos e tempo até a fratura quando comparadas as Hyflex CM no ensaio de 90 graus. Portanto, conclui-se que o sistema Adaptive (limas TF Adaptive + movimento Adaptive) foi mais seguro à resistência á fadiga flexural, e no ensaio de 90 graus o sistema Adaptive foi mais resistente quando comparado com as limas Hyflex CM no movimento de rotação contínua.

Why is economics not a complex systems science?

The article argues that economics will have to become a complex systems science before economists can comfortably incorporate institutionalist and evolutionary economics into mainstream theory. The article compares the complex adaptive system of John Foster with that of standard economic theory and illustrates the difference through an examination of familiar production function. The place of neoclassical, Keynesian economics in complex systems is considered. The article concludes that convincing, multiple models have been made possible by the increase in widely available computing power available.

The co-evolutionary dynamics of IS engagement

In this paper we consider the co-evolutionary dynamics of IS engagement where episodic change of implementation increasingly occurs within the context of linkages and interdependencies between systems and processes within and across organisations. Although there are many theories that interpret the various motors of change be it lifecycle, teleological, dialectic or evolutionary, our paper attempts to move towards a unifying view of change by studying co-evolutionary dynamics from a complex systems perspective. To understand how systems and organisations co-evolve in practice and how order emerges, or fails to emerge, we adopt complex adaptive systems theory to incorporate evolutionary and teleological motors, and actor-network theory to incorporate dialectic motors. We illustrate this through the analysis of the implementation of a novel academic scheduling system at a large research-intensive Australian university.

Strategic development process and complex adaptive systems

The two areas of theory upon which this research was based were „strategy development process?(SDP) and „complex adaptive systems? (CAS), as part of complexity theory, focused on human social organisations. The literature reviewed showed that there is a paucity of empirical work and theory in the overlap of the two areas, providing an opportunity for contributions to knowledge in each area of theory, and for practitioners. An inductive approach was adopted for this research, in an effort to discover new insights to the focus area of study. It was undertaken from within an interpretivist paradigm, and based on a novel conceptual framework. The organisationally intimate nature of the research topic, and the researcher?s circumstances required a research design that was both in-depth and long term. The result was a single, exploratory, case study, which included use of data from 44 in-depth, semi-structured interviews, from 36 people, involving all the top management team members and significant other staff members; observations, rumour and grapevine (ORG) data; and archive data, over a 5½ year period (2005 – 2010). Findings confirm the validity of the conceptual framework, and that complex adaptive systems theory has potential to extend strategy development process theory. It has shown how and why the strategy process developed in the case study organisation by providing deeper insights to the behaviour of the people, their backgrounds, and interactions. Broad predictions of the „latent strategy development? process and some elements of the strategy content are also possible. Based on this research, it is possible to extend the utility of the SDP model by including peoples? behavioural characteristics within the organisation, via complex adaptive systems theory. Further research is recommended to test limits of the application of the conceptual framework and improve its efficacy with more organisations across a variety of sectors.

Classrooms as complex adaptive systems:a relational model

In this article, we describe and model the language classroom as a complex adaptive system (see Logan & Schumann, 2005). We argue that linear, categorical descriptions of classroom processes and interactions do not sufficiently explain the complex nature of classrooms, and cannot account for how classroom change occurs (or does not occur), over time. A relational model of classrooms is proposed which focuses on the relations between different elements (physical, environmental, cognitive, social) in the classroom and on how their interaction is crucial in understanding and describing classroom action.

Self-explanation in adaptive systems

The behaviour of self adaptive systems can be emergent. The difficulty in predicting the system's behaviour means that there is scope for the system to surprise its customers and its developers. Because its behaviour is emergent, a self-adaptive system needs to garner confidence in its customers and it needs to resolve any surprise on the part of the developer during testing and mainteinance. We believe that these two functions can only be achieved if a self-adaptive system is also capable of self-explanation. We argue a self-adaptive system's behaviour needs to be explained in terms of satisfaction of its requirements. Since self-adaptive system requirements may themselves be emergent, a means needs to be found to explain the current behaviour of the system and the reasons that brought that behaviour about. We propose the use of goal-based models during runtime to offer self-explanation of how a system is meeting its requirements, and why the means of meeting these were chosen. We discuss the results of early experiments in self-explanation, and set out future work. © 2012 C.E.S.A.M.E.S.

Self-explanation in adaptive systems based on runtime goal-based models

The behaviour of self adaptive systems can be emergent, which means that the system’s behaviour may be seen as unexpected by its customers and its developers. Therefore, a self-adaptive system needs to garner confidence in its customers and it also needs to resolve any surprise on the part of the developer during testing and maintenance. We believe that these two functions can only be achieved if a self-adaptive system is also capable of self-explanation. We argue a self-adaptive system’s behaviour needs to be explained in terms of satisfaction of its requirements. Since self-adaptive system requirements may themselves be emergent, we propose the use of goal-based requirements models at runtime to offer self-explanation of how a system is meeting its requirements. We demonstrate the analysis of run-time requirements models to yield a self-explanation codified in a domain specific language, and discuss possible future work.

A kapitalizmus néhány rendszerspecifikus vonása (Some system-specific features of capitalism)

A szerző korábban a szocialista rendszer és a posztszocialista átmenet elemzésére használta azt a szemléletet és módszertant, amelyet rendszerparadigmának nevezett el. A jelen tanulmány a kapitalizmus néhány általános vonásának vizsgálatára alkalmazza ezt a megközelítést. A cikk - fogalmi tisztázás után - példákat sorol fel a kapitalizmus néhány rendszerspecifikus vonására, majd kettővel részletesebben foglalkozik. Az egyik: a rendszer dinamizmusa. Az elmúlt évszázad nagy újításai, amelyek mélyrehatóan átalakították nemcsak a termelés technológiáját, hanem az emberek mindennapi életét is, a kapitalista rendszer és annak főszereplője, a vállalkozó vezette be és terjesztette el. Csak a kapitalizmusban tud kialakulni a vállalkozás és újítás mechanizmusa, az ehhez szükséges erőteljes ösztönzés és rugalmas tőkepiac. A másik példa: a kapitalista rendszer immanens tulajdonsága a munkaerőpiacon jelentkező tartós többlet, szemben a szocialista rendszerrel, amelynek kifejlett formájában tartós munkaerőhiány mutatkozik. Elméletileg és tapasztalatilag is igazolható, hogy minél dinamikusabb a kapitalista gazdaság állandó átalakulása, annál inkább keletkezik strukturális munkanélküliség. A hatékony bér elmélete megmagyarázza, miért érdeke a munkaadónak, hogy a piactisztító bérnél magasabb bért fizessen, és ezzel munkanélküliséget idézzen elő. A kapitalizmus reformálható rendszer. Ám ügyelni kell arra, hogy a részreformok között milyen a kapcsolat. Szerencsés esetben kiegészítik egymást. Ám ennél sokkal gyakoribb, hogy miközben szembeszállunk a rendszer egyik kedvezőtlen hajlamával, utat engedünk egy másik kedvezőtlen hajlam megerősödésének. ___________________ The author previously applied the outlook and methodology he named the system paradigm to analysing the socialist system and post-socialist transition. This study takes the same approach to some general attributes of capitalism. After clarifying some concepts, the author presents examples of some system-specific features of capitalism, before ad-dressing two of them in detail. One is the dynamism of the system. The great innovations of the last century that radically altered both the technology of production and people s daily lives were all introduced and disseminated by the capitalist system and its protago-nist, the entrepreneur. Only under capitalism can the mechanism of entrepreneurship and innovation emerge, with the strong incentives and flexible capital market they require. The other immanent feature is a chronic surplus on the labour market that contrasts sharply with the chronic labour shortage prevalent under the mature socialist system. Theory and experience confirm that the faster the ongoing transformation of a capitalist economy proceeds, the greater the propensity for structural unemployment to appear. It is explained by the efficiency pay hypothesis how an employer has an incentive to pay more than a market-clearing wage, thereby introducing unemployment. Capitalism is a system that can be reformed, but attention needs paying to relations between reforms of different parts of the system. In fortunate cases they complement each other, but it is commoner to find that tackling one unfavourable tendency only allows another such tendency to increase.

The University as a Genre and Activity System

The author explores the challenges graduate students face preparing for a dissertation through university events. Autoethnography using notes, observation, and journal writing and framed by genre and activity system theory highlight university system conflicts with the culture of the student.

Den offentliga sektorns komplexa adaptiva system : En kvalitativ studie om medarbetarpolicys i praktiken

Intresset för hur HR och ledning kan påverka medarbetarnas beteendemönster och den sociala strukturen inom organisationer har gett upphov till denna undersökning. Med utgångspunkt i teorier om komplexa adaptiva system som perspektiv har jag försökt fånga medarbetarnas förutsättningar att nå organisationers vision och därmed förverkliga medarbetarpolicyn i praktiken. Tillsammans med kontaktpersoner från den undersökta kommunen har jag gjort en djupdykning i en offentlig organisation i syfte att förklara byråkratins inverkan på beteendemönstret hos medarbetarna och hur de tillsammans skapar en social struktur vilken speglar organisationens vision. Syftet med studien är att undersöka hur det adaptiva systemet fungerar i en byråkratisk organisation och vad det betyder för medarbetarnas möjligheter att förverkliga organisationens vision och medarbetarpolicy. Undersökningen har genomförts på en socialförvaltning i en kommun i mellan Sverige och med en kvalitativ metod och semistrukturerade intervjuer har sex respondenter deltagit i undersökningen. Samtliga respondenter har olika befattningar inom organisationen och bidrar därmed med olika perspektiv på samma fenomen. Undersökningens resultat visar att den offentliga verksamhetens byråkratiska organisationsstruktur bidrar till att det bildas olika adaptiva system inom organisationen, där medarbetarnas beteendemönster bildar en social struktur som leder till att visionen och medarbetarpolicyn inte förverkligas. Undersökningen visar även att de adaptiva systemen inom organisationen inte påverkar varandra, då de inte interagerar med varandra inom organisationen. Det som ligger till grund för hur medarbetarnas beteendemönster etableras inom organisationen är kraven från omvärlden, hög arbetsbelastning och avsaknaden av stabilitet i den organisatoriska och sociala arbetsmiljön och inte vad tidigare forskning visat; att det skulle vara hög regelstyrning som ligger till grund för beteendemönstret inom den offentliga sektorn. Slutsatsen är att för att medarbetarna ska kunna förverkliga organisationens vision och medarbetarpolicy kräver det att HR, ledning och medarbetare alla ingår i samma adaptiva system. För att det ska vara möjligt behöver HR upprätta strategier för hur samtliga inom organisationen ska interagera med varandra i det dagliga arbetet. Ledningen och medarbetarna behöver även ha goda möjligheter att kommunicera med varandra regelbundet i en större omfattning än vad de gör idag. Konkreta åtgärder för hur det lämpligen bör genomföras presenteras under diskussionen.

Autonomous formation flying: unified control and collision avoidance methods for close manoeuvring spacecraft

The idea of spacecraft formations, flying in tight configurations with maximum baselines of a few hundred meters in low-Earth orbits, has generated widespread interest over the last several years. Nevertheless, controlling the movement of spacecraft in formation poses difficulties, such as in-orbit high-computing demand and collision avoidance capabilities, which escalate as the number of units in the formation is increased and complicated nonlinear effects are imposed to the dynamics, together with uncertainty which may arise from the lack of knowledge of system parameters. These requirements have led to the need of reliable linear and nonlinear controllers in terms of relative and absolute dynamics. The objective of this thesis is, therefore, to introduce new control methods to allow spacecraft in formation, with circular/elliptical reference orbits, to efficiently execute safe autonomous manoeuvres. These controllers distinguish from the bulk of literature in that they merge guidance laws never applied before to spacecraft formation flying and collision avoidance capacities into a single control strategy. For this purpose, three control schemes are presented: linear optimal regulation, linear optimal estimation and adaptive nonlinear control. In general terms, the proposed control approaches command the dynamical performance of one or several followers with respect to a leader to asymptotically track a time-varying nominal trajectory (TVNT), while the threat of collision between the followers is reduced by repelling accelerations obtained from the collision avoidance scheme during the periods of closest proximity. Linear optimal regulation is achieved through a Riccati-based tracking controller. Within this control strategy, the controller provides guidance and tracking toward a desired TVNT, optimizing fuel consumption by Riccati procedure using a non-infinite cost function defined in terms of the desired TVNT, while repelling accelerations generated from the CAS will ensure evasive actions between the elements of the formation. The relative dynamics model, suitable for circular and eccentric low-Earth reference orbits, is based on the Tschauner and Hempel equations, and includes a control input and a nonlinear term corresponding to the CAS repelling accelerations. Linear optimal estimation is built on the forward-in-time separation principle. This controller encompasses two stages: regulation and estimation. The first stage requires the design of a full state feedback controller using the state vector reconstructed by means of the estimator. The second stage requires the design of an additional dynamical system, the estimator, to obtain the states which cannot be measured in order to approximately reconstruct the full state vector. Then, the separation principle states that an observer built for a known input can also be used to estimate the state of the system and to generate the control input. This allows the design of the observer and the feedback independently, by exploiting the advantages of linear quadratic regulator theory, in order to estimate the states of a dynamical system with model and sensor uncertainty. The relative dynamics is described with the linear system used in the previous controller, with a control input and nonlinearities entering via the repelling accelerations from the CAS during collision avoidance events. Moreover, sensor uncertainty is added to the control process by considering carrier-phase differential GPS (CDGPS) velocity measurement error. An adaptive control law capable of delivering superior closed-loop performance when compared to the certainty-equivalence (CE) adaptive controllers is finally presented. A novel noncertainty-equivalence controller based on the Immersion and Invariance paradigm for close-manoeuvring spacecraft formation flying in both circular and elliptical low-Earth reference orbits is introduced. The proposed control scheme achieves stabilization by immersing the plant dynamics into a target dynamical system (or manifold) that captures the desired dynamical behaviour. They key feature of this methodology is the addition of a new term to the classical certainty-equivalence control approach that, in conjunction with the parameter update law, is designed to achieve adaptive stabilization. This parameter has the ultimate task of shaping the manifold into which the adaptive system is immersed. The performance of the controller is proven stable via a Lyapunov-based analysis and Barbalat’s lemma. In order to evaluate the design of the controllers, test cases based on the physical and orbital features of the Prototype Research Instruments and Space Mission Technology Advancement (PRISMA) are implemented, extending the number of elements in the formation into scenarios with reconfigurations and on-orbit position switching in elliptical low-Earth reference orbits. An extensive analysis and comparison of the performance of the controllers in terms of total Δv and fuel consumption, with and without the effects of the CAS, is presented. These results show that the three proposed controllers allow the followers to asymptotically track the desired nominal trajectory and, additionally, those simulations including CAS show an effective decrease of collision risk during the performance of the manoeuvre.