91 |
Conjunction monism : Humean scientific explanation explainedMagnusson, Love January 2024 (has links)
Humeans say that laws depend on their instances. Another way of saying this is that the instances explain the laws. However, laws are often used in science to help explain these same instances. If this is true it appears as though the instances help explain themselves, which would be a serious problem for the Humeans (Miller, 2015, pp. 1314-1317). In this essay I expand on a solution proposed by Miller (2015, pp. 1328-1331) that the laws are not explained by their instances but rather grounded by a set of global facts. I develop this into a new framework in which it would be expected for the laws to not be grounded by their instances. I call this framework conjunction monism since the core idea is a that conjunctions ground their conjuncts. I finish with a discussion about the compatibility of conjunction monism and Humeanism.
|
92 |
What Does Theism Add to Ethical Naturalism?Burkette, Jerry W. Jr. 23 March 2018 (has links)
Recent literature seems to have opened up space for naturalistic theistic metaethics in a contemporary context, as proponents of divine command theories have tended to be restricted to either supernatural or theistic non-natural theories within existing taxonomies of normative theory. While perhaps encouraging for theists, would theism add anything substantive to theories of ethical naturalism? In this paper, I examine this question. I argue that theistic naturalism appears to incur certain objections as well as provide a plausible and explanatory constraint on content for theories of ethical naturalism. As a result, a corresponding challenge to non-theistic variants is raised. / Master of Arts / Realists, roughly summarized, are those metaethicists who believe that some moral propositions have truth values, that some (or at least one) of those propositions turn out to be true, and that if rational agents disagree on the truth value of a particular moral proposition, only one of them has the possibility of being correct. Broadly construed, moral realists tend to fall under one of two “tents”, preferring either naturalism (for which moral properties turn out to be wholly natural in constitution) or non-naturalism (which posits that at least some moral properties have, even if only partly, non-natural constituents as part of their make-up.
Theists, who base their theories of morality on some facet of the nature or essence (or commands) of God, have tended to either be relegated in philosophical debate to a characterization of “supernaturalism” or to some seldom visited corner of the non-natural “tent” of moral realism. The former tends to limit theistic engagement in contemporary metaethical dialogue such that it can seem (at times) as if theists and non-theists are talking about two different subjects entirely. On the other hand, a non-naturalistic theory of theistic moral realism saddles the view with some fairly difficult metaphysical and epistemological baggage in the form of powerful objections levied against non-naturalistic theories in general.
This paper explores another option for theism in light of very recent work by Gideon Rosen, namely his article examining the metaphysical implications of varieties of moral realism, particularly naturalistic ones. This article has already garnered a general characterization (within metaethical research, writ large) as being a “taxonomy” of naturalistic (and non-naturalistic, for that matter) theories. Specifically for my purposes here, Rosen suggests that divine command theory (and theistic metaethics in general) should be understood as being naturalistic in formulation.
This would seem to be advantageous to theists, in that their metaethical theories might avoid either the bounded characterization of supernaturalism or the difficult challenges of non-naturalism. However, the theist, should she avail herself of naturalism in this regard, will need to tread carefully. Given that Rosen has couched his 'taxonomy' in terms of metaphysical grounding, I examine some resultant challenges for naturalistic theistic metaethics, concluding they can be overcome, as well as a related objection to non-theistic naturalism that arise as a result of the same grounding discussion coupled with the resources theists can leverage in a naturalistic context.
|
93 |
Grounding na análise Bioenergética: Uma proposta de atualização. / Grounding in Bioenergetic Analysis. An update.Weigand, Odila Quartim Barbosa 19 May 2005 (has links)
Made available in DSpace on 2016-04-28T20:39:27Z (GMT). No. of bitstreams: 1
Dissertacao Odila Weigand.pdf: 1845061 bytes, checksum: ec8f3a6a9ad23bd2662db8fa5b42b0e2 (MD5)
Previous issue date: 2005-05-19 / The purpose of this study was to deepen and update the concept of grounding in Bioenergetic Analysis. This approach combines fundamental principles of psychoanalysis with direct work on the organism, seen from the viewpoint of its emotional, energetic and relational development. Both paradigms of psychoanalysis, pulsion and object-relations, were studied within the context of the historical development of Bioenergetics Analysis, in terms of their influence on the theory as well as on the practice. Brazilian Bioenergetic Analysis therapists have been building their own identity over the last 25 years. This should not be seen as a split from Alexander Lowen's ideas, as it actually means a differentiation born out of those therapists maturity. The integration of the object-relations paradigm, indicates the pathway for a model of psychotherapy which associates the construction of functional and integrative internal organizations with the phase, in psychotherapy, of dismantling repressive and defensive structures. In this study, a group of third-age women participated in Bioenergetics exercise classes for a period of four months. This research may be considered a social project with the objective of demonstrating an application of Bioenergetic Analysis that would preserve its healing potential, at the same time respecting the principles of intersubjectivity, of social inclusion, citizenship and ethics, and also that would be compatible with Brazilian social reality. The work with the group was conducted intending to create resources that might make possible for chronic primary defenses gradually to become unnecessary. Body work and level of excitation were adequated to the developmental level and physical possibilities of the participants. The changes observed in the group were verified by the subjective observation of the coordinators, as well as by verbal manifestations of participants, and by the analysis of the HTP test. In short, those verified changes were: improvement in vitality and flexibility, self-perception, social contact, increased maturity and ego strength, along with possible emergence of unconscious pulsional and traumatic contents. / O objetivo deste trabalho foi aprofundar e atualizar o conceito do grounding na Análise Bioenergética. Esta abordagem combina os princípios fundamentais da psicanálise com o trabalho direto no organismo visto do ponto de vista do seu desenvolvimento energético, emocional e relacional. Os dois paradigmas da psicanálise, pulsional e objetal, foram discutidos no contexto da evolução histórica da Análise Bioenergética, em termos de suas influências na teoria e na prática. Os terapeutas brasileiros vêm criando uma identidade própria ao longo dos últimos 25 anos. Não se trata de uma cisão em relação às idéias de Alexander Lowen, mas de uma diferenciação resultante do amadurecimento dos mesmos. A introdução do paradigma objetal indica o caminho para um modelo de psicoterapia no qual se agregam a construção de organizações internas funcionais e integradoras e a fase de desmonte das estruturas repressivas e defensivas. Neste estudo, mulheres da terceira idade participaram de um grupo de exercícios de Análise Bioenergética por um período de quatro meses. A pesquisa pode ser considerada um projeto social, com o objetivo de demonstrar uma aplicação da Análise Bioenergética que preservasse seu potencial curativo, ao mesmo tempo respeitando princípios de intersubjetividade, inclusão social, cidadania e ética, e também fosse compatível com a realidade social brasileira. O trabalho com este grupo foi conduzido com a intenção de criar recursos para que as defesas primitivas crônicas pudessem tornar-se gradualmente desnecessárias. Trabalhou-se corporalmente com níveis de excitação e técnicas adequadas ao estágio de desenvolvimento e capacidade física das participantes. As mudanças ocorridas no grupo foram constatadas por observação subjetiva das coordenadoras, por manifestações verbalizadas pelas participantes e pela análise do teste HTP. Em síntese caracterizam-se essas mudanças como: melhora na vitalidade e flexibilidade, na auto-percepção, no contato social, maior maturidade, fortalecimento do ego e possibilidade de emergência de conteúdos pulsionais e traumáticos inconscientes.
|
94 |
Μελέτη μη συμβατικών γειώσεωνΠουντουρέλη, Άρτεμις 30 December 2014 (has links)
Οι γειώσεις διαδραματίζουν πρωτεύοντα ρόλο στην προστασία οποιασδήποτε εγκατάστασης, είτε πρόκειται για ηλεκτρικές εγκαταστάσεις ισχύος, είτε για τηλεπικοινωνίες, είτε για αντικεραυνική προστασία.
Σκοπός του συστήματος γείωσης είναι η ταχεία διάχυση του κεραυνικού ρεύματος ή γενικότερα του ρεύματος σφάλματος μέσα στη γη, χωρίς να δημιουργούνται επικίνδυνες υπερτάσεις στον περιβάλλοντα χώρο, τόσο για τους ανθρώπους όσο και για τον ηλεκτρολογικό και ηλεκτρονικό εξοπλισμό.
Για να είναι ένα σύστημα γείωσης αποδοτικό, θα πρέπει η αντίσταση γείωσής του να έχει πολύ χαμηλή τιμή ούτως ώστε να διασφαλίζεται η απρόσκοπτη διέλευση του ρεύματος προς τη γη. Για να επιτευχθεί μια τέτοια χαμηλή τιμή, λαμβάνοντας υπόψη ότι δεν είναι δυνατόν να επιλέγουμε πάντα το μέρος όπου θα εγκατασταθεί το σύστημα γείωσης με γνώμονα τη χαμηλή ειδική αντίστασή του, μπορούμε να προβούμε σε αύξηση των διαστάσεων του ηλεκτροδίου γείωσης (μήκος και διάμετρος), σε εγκατάσταση περισσοτέρων του ενός ηλεκτροδίων και τέλος σε προσθήκη βελτιωτικού υλικού (μη συμβατική γείωση) το οποίο μειώνει την ειδική αντίσταση του εδάφους γύρω απ’ το ηλεκτρόδιο. Η τελευταία επιλογή είναι ιδιαίτερα δημοφιλής σε εδάφη με πολύ υψηλές τιμές ειδικής αντίστασης ή και με αυξημένο κίνδυνο διάβρωσης του ηλεκτροδίου.
Στα πλαίσια της παρούσας διπλωματικής εργασίας, προσομοιώθηκαν διάφορα συστήματα γείωσης, συμβατικά και μη, με διαφορετικά μήκη και αριθμούς ηλεκτροδίων, σε ομοιογενή και πολυστρωματικά εδάφη με διαφορετικές ειδικές αντιστάσεις, διαφορετικές εγχύσεις ρεύματος και με ή χωρίς χρήση βελτιωτικού, με σκοπό τη μελέτη της επίδρασης κάθε παράγοντα στην τελική διαμόρφωση της αντίστασης γείωσης και των αναπτυσσόμενων τάσεων/ηλεκτρικών πεδίων. Ιδιαίτερη έμφαση δόθηκε στα μη συμβατικά συστήματα και στη σύγκριση της απόδοσής τους με την απόδοση των αντίστοιχων συμβατικών. Όλες οι προσομοιώσεις πραγματοποιήθηκαν στο πρόγραμμα Opera-3d που χρησιμοποιεί τη Μέθοδο Πεπερασμένων Στοιχείων για τον υπολογισμό των ηλεκτρομαγνητικών πεδίων και ακολούθως, των λοιπών σχετικών μεγεθών.
Ακολουθεί μια σύντομη περιγραφή των θεμάτων που πραγματεύεται το κάθε κεφάλαιο.
Στο Κεφάλαιο 1 γίνεται εισαγωγή στην έννοια των γειώσεων, αναφέρονται τα είδη και οι μέθοδοι γείωσης καθώς επίσης και οι διάφοροι τύποι των ηλεκτροδίων γείωσης και οι διατάξεις τοποθέτησής των.
Στο Κεφάλαιο 2 παρουσιάζονται ορισμένα χαρακτηριστικά μεγέθη των συστημάτων γείωσης: η αντίσταση γείωσης, που αποτελεί μέτρο της απόδοσής τους και η ειδική αντίσταση του εδάφους που τα περιβάλλει. Γίνεται αναφορά τόσο στο θεωρητικό υπολογισμό όσο και στην πειραματική τους μέτρηση.
Στο Κεφάλαιο 3 γίνεται αναφορά στα βελτιωτικά υλικά γειώσεων και στα διάφορα υλικά που έχουν χρησιμοποιηθεί κατά καιρούς γι’ αυτό το σκοπό.
Στο Κεφάλαιο 4 γίνεται αναφορά στις διάφορες μεθόδους υπολογισμού πεδιακών μεγεθών. Ιδιαίτερη έμφαση δίνεται στη Μέθοδο των Πεπερασμένων Στοιχείων μιας και αυτή χρησιμοποιήθηκε στα πλαίσια της διπλωματικής.
Στο Κεφάλαιο 5 παρουσιάζεται το πρόγραμμα Opera-3d, στο οποίο πραγματοποιήθηκαν οι προσομοιώσεις, καθώς και τα ποικίλα πακέτα ανάλυσης που χρησιμοποιεί. Γίνεται επίσης αναφορά στις εξισώσεις και τον αλγόριθμο που χρησιμοποιεί για τον υπολογισμό των ηλεκτρομαγνητικών μεγεθών του εκάστοτε προβλήματος.
Στο Κεφάλαιο 6 περιγράφονται αναλυτικά οι διατάξεις των συστημάτων γείωσης που προσομοιώθηκαν και τα μοντέλα πεπερασμένων στοιχείων που δημιουργήθηκαν. Παράλληλα, παρουσιάζονται τα γραφήματα και τα αποτελέσματα που προέκυψαν σε κάθε περίπτωση. Τέλος, γίνεται αναφορά στη μετεπεξεργασία των αποτελεσμάτων, με σκοπό τον υπολογισμό της αντίστασης γείωσης, αλλά και στο θεωρητικό υπολογισμό της τελευταίας. Δίνεται μάλιστα και μία επέκταση του τύπου του Fagan [16] για την περίπτωση διστρωματικού εδάφους στο οποίο έχει γίνει προσθήκη βελτιωτικού.
Στο Κεφάλαιο 7 γίνεται σχολιασμός των αποτελεσμάτων και καταγραφή διαφόρων χρήσιμων συμπερασμάτων. Τα αποτελέσματα επιδεικνύουν αφενός την τεράστια επίδραση που ασκεί το περιβάλλον έδαφος στην αντίσταση γείωσης ενός συστήματος και αφετέρου τη βελτίωση που επιτυγχάνεται απ’ το διπλασιασμό του μήκους του ηλεκτροδίου (μείωση αντίστασης γείωσης έως και 36,7%), την τοποθέτηση βελτιωτικού γύρω απ’ αυτό (μείωση έως και 68,3%) καθώς και την προσθήκη πλέον του ενός ηλεκτροδίων σε κατάλληλη μεταξύ τους απόσταση (μείωση 29,2% για δύο ηλεκτρόδια σε απόσταση τετραπλάσια του μήκους τους). Επίσης, προκύπτει ότι οι μη συμβατικές γειώσεις με βελτιωτικά προκαλούν πιο ομαλή μείωση του δυναμικού, περιορίζοντας έτσι τις αναπτυσσόμενες βηματικές τάσεις και τάσεις επαφής. Τέλος, προτείνεται ένας θεωρητικός τρόπος υπολογισμού της αντίστασης γείωσης σε περιπτώσεις μη συμβατικών συστημάτων με βελτιωτικά ειδικής αντίστασης ≤1Ωm. / Grounding systems contribute considerably to the protection of constructions (electrical power installations, telecommunications or even lightning protection).
The main objective of a grounding system is to quickly dissipate fault current into the ground, without causing dangerous overvoltages in the surrounding area, both for people and electrical or electronic equipment.
For a grounding system to be effective, its grounding resistance should be low enough so as to make sure that the fault current is dissipated into the earth without any hindrances. To achieve such a low value, taking into account that it is not always possible to install a grounding system in a low resistivity soil, one could increase the electrode dimensions (its length and diameter), add more electrodes and finally enhance the surrounding ground by using various ground enhancing compounds (conductive backfills – nonconventional grounding). In this way, the surrounding soil resistivity decreases and that’s why this option is commonly used in sites where resistivity is very high or where corrosion constitutes a common threat to the electrode life span.
In the context of the present diploma thesis, various grounding systems were simulated, both conventional and nonconventional. The parameters that were modified were: numbers and lengths of electrodes, current injections and homogenous or multilayered soil with different resistivity values and either with or without conductive backfills. The objective was to study the effect of each of the aforementioned parameters on the grounding resistance and the potential/electric field. Special emphasis was given on nonconventional grounding systems and their effectiveness comparing to conventional ones. The simulations were conducted in Opera-3d, a program that calculates electromagnetic fields through the Finite Element Method.
A brief description of the issues that are analyzed in each chapter can be found next.
Chapter 1 constitutes an introduction to the meaning and role of “grounding”. The reader is then acquainted with the grounding types and methods as well as the various types of electrodes and their set-ups.
Chapter 2 focuses on certain typical quantities of grounding systems: namely, the grounding resistance and the surrounding soil resistivity.
Chapter 3 provides information on the various ground enhancing compounds.
Chapter 4 focuses on the various methods used for the calculation of electromagnetic fields. A more detailed reference to the Finite Element Method is given.
Chapter 5 provides information on the Opera-3d program, which was used for the simulations, as well as the various analysis programs that are included. Information are also provided on the equations and the algorithm used by the program in order to calculate the electromagnetic fields.
Chapter 6 provides an illustration of the various grounding set-ups which were simulated as well as the corresponding finite element models that were designed. Furthermore, the simulation results and graphs are presented. Last but not least, post-processing takes place in order to calculate the grounding resistance. The latter one is also calculated using theoretical formulas. An expansion of Fagan’s formula [16] is also given in the case of two-layered soil which has been enriched by a conductive backfill.
In Chapter 7 the results are discussed and several observations are made. The results demonstrate the great impact the surrounding soil has on the grounding resistance. They also show the improvement which is achieved by doubling the electrode length (decrease of grounding resistance up to 36,7%), adding conductive backfills (decrease up to 68,3%) and installing more than one electrodes at appropriate distances (29,2% decrease in the case of two electrodes at a distance four times their length). Nonconventional grounding systems with conductive backfills are found to cause a smoother potential reduction, thus minimizing the step and touch voltages. Finally, a theoretical way of calculating the grounding resistance in nonconventional grounding systems with backfill resistivity ≤1Ωm is proposed.
|
95 |
Dismissivism in metaphysics : debates about what there is and debates about what grounds whatPorro, Laura Cecilia January 2013 (has links)
In this thesis I focus on dismissivism in metaphysics. Some philosophers argue that at least some metaphysical disputes are not substantial, and as a consequence should be dismissed. In this work I restrict my attention to metaphysics and focus on debates about existence and grounding. In particular I am interested in finding out whether there is a difference between the possible options available for dismissing debates about what there is and the possible options available for dismissing debates about what grounds what. I will delve into this in two different steps. First of all I explore the possibility to dismiss debates about what there is, and as a case study I analyse the debate between three-dimensionalism and four-dimensionalism. Secondly I delve into whether it is possible to dismiss debates about what grounds what, thanks to the discussion of another case study, i.e. the debate between tropes ontologies and universals ontologies. It is worth exploring the nature of dismissivism, because it bears on the future of philosophy. If philosophy has to have a future, we have to make sure that at least some disagreements within it are substantial. My conclusions will be that metaphysical debates about what there is can be dismissed for a variety of reasons (semantic, epistemic, ...). I also argue there is no general formula to find out whether a specific debate should be dismissed. On the other hand I argue that debates about what grounds what should be dismissed. I offer two distinct arguments in favour of my claim. Firstly, I argue that disputants are having a verbal dispute when they talk about what grounds what, and thus their disagreement is non genuine. Secondly, I argue that the notion of grounding is underspecified, because it cannot be properly distinguished from causation.
|
96 |
Aplicação do método de imagens complexas ao cálculo de malhas de aterramento em solos com estratificação horizontal. / Modelling of grounding grids in multilayer soils using complex images.Pereira Filho, Mário Leite 21 May 1999 (has links)
O projeto de malhas de aterramento requer o cálculo da resistência de aterramento e dos potenciais na superfície do solo. Quando o método das imagens é utilizado para este cálculo o modelo típico do solo é uma estratificação horizontal em 2 camadas. A extensão do método das imagens para solos com múltiplas camadas horizontais apresenta problemas numéricos importantes, de forma que a técnica de imagens complexas foi utilizada para permitir este cálculo, porém restringindo a posição dos eletrodos à primeira camada. Este trabalho objetiva a aplicação do método de imagens complexas a eletrodos situados em qualquer camada de solos com estratificação horizontal, deduzindo as funções kernel para posições arbitrárias da fonte e do objeto e determinando os resíduos e pólos das imagens utilizando a decomposição em autovalores e autovetores. Foi desenvolvido um programa que calcula a resistência de aterramento e os potenciais na superfície do solo para solos com até 4 camadas. Foram realizadas comparações com outros trabalhos publicados e os resultados obtidos permitem validar o uso do programa para esta aplicação. / Grounding grid design requires both ground resistance and surface potential. Traditional method of images restricts this calculation to two layer soils. Complex image method allows calculation of both resistance values and potentials at the soil surface, in multilayer soils with horizontal stratification, without grounding grid position limitation. This work presents a complete methodology for calculation of safety aspects of grounding grid design, validating results by comparison with published previous work.
|
97 |
Grundstötningsolyckor på svenskt farvatten och bland svenskflaggade fartyg / Grounding accidents on Swedish waters and among Swedish flagged shipsLindqvist, Michael, Andersson, Simon January 2019 (has links)
Trots att det finns många tekniska hjälpmedel ombord, vilka har i uppgift att hjälpa navigatören att framföra fartyget på ett säkert sätt, så fortsätter grundstötningar att inträffa. Denna litteraturstudie sammanställer och granskar grundstötningsolyckor som inträffat på svenska fartyg och på utländska fartyg som befunnit sig på svenskt territorialvatten under åren 2011-2016. Studien behandlar frågeställningar om vilka huvudsakliga faktorer som ligger till grund för att grundstötningar inträffar. Studien omfattar såväl inre som yttre faktorer. De inre faktorerna som behandlas är styrmetod, bryggbemanning och vilken typ av sjökort som använts. Våghöjd, vindstyrka, typ av farvatten, sikt- och ljusförhållande ingår i de yttre faktorerna. Både de inre- och yttre faktorerna sammanställs och presenteras för att kunna ge en bild av vad som kan ha föranlett grundstötningarna. Studiens resultatet visar att passagerar- och bulkfartyg av det mindre tonnaget står för majoriteten av olyckorna. I likhet med tidigare studier är antalet olyckor som beror på den mänskliga faktorn hög. / Even though there are plenty of technological aids onboard modern-day merchant vessels, intended to help the Officer on watch to drive his vessel safely, groundings continue to happen. This literature study summarises and reviews data from several groundings that involved Swedish-registered ships and ships within Swedish territory during the period 2011-2016. This study covers questions about the main factors that have caused the groundings. It covers both internal and external factors. Method of steering, bridge manning and type of chart belong to the internal factors. Factors such as wave height, wind force, type of waters, visibility and light conditons are part of the external factors. This data is then discussed and analysed to give a picture of what may have caused the groundings. The results show that the smaller tonnage passenger and bulk carriers account for the majority of the accidents. Like previous studies the number of accidents due to human factors are high.
|
98 |
Contribuições à modelagem de sistemas de aterramento pelo método dos elementos finitos no regime harmônico. / Contributions to grounding systems modelling by the finite element method in the harmonic regime.Lucas Blattner Martinho 18 February 2009 (has links)
Este trabalho tem como objetivo fornecer contribuições ao estudo de sistemas de aterramento submetidos a correntes elétricas no regime permanente senoidal pelo Método dos Elementos Finitos. Nele se discutem as motivações para a utilização deste procedimento numérico em problemas desta categoria, e mais especificamente para o uso da variante deste método com elementos finitos de aresta. O tratamento completo necessário à construção das funções de forma para a aproximação local de grandezas vetoriais com elementos hexaédricos é nele desenvolvido e detalhado. Com estes resultados, uma aplicação computacional capaz de modelar o comportamento de uma haste de aterramento verticalmente enterrada no solo foi desenvolvida, utilizando-se para a discretização do domínio elementos finitos hexaédricos tri-lineares e quadráticos incompletos. Esta aplicação computacional foi utilizada para o estudo da resposta em freqüência da impedância equivalente a aterramentos desta categoria em diferentes condições de solo e com as duas variedades de elemento hexaédrico anteriormente mencionados. Os resultados obtidos são então discutidos, bem como a validade da modelagem adotada para o problema físico aqui considerado. / This work aims to provide contributions to the study of grounding systems subjected to electric currents at the sinusoidal steady state by the Finite Element Method. Motivations for the use of this numerical procedure in problems of this category, and more specifically for the usage of the Edge Finite Element Method variant, are discussed in it. The complete treatment required for building the shape functions for the local approximation of vector physical quantities with hexahedral finite elements is here developed and detailed. With these results a computer application capable of modeling the behavior of vertically buried grounding rods was developed, in which domain discretization is accomplished by the usage of both tri-linear and incomplete quadratic hexahedral finite elements. This computer application was employed in the study of the frequency response of the impedance equivalent to grounding systems of this class at different soil conditions and with both hexahedral element varieties previously mentioned. The results obtained are then discussed, as well as the validity of the modeling adopted for this physical problem.
|
99 |
Aplicação do método de imagens complexas ao cálculo de malhas de aterramento em solos com estratificação horizontal. / Modelling of grounding grids in multilayer soils using complex images.Mário Leite Pereira Filho 21 May 1999 (has links)
O projeto de malhas de aterramento requer o cálculo da resistência de aterramento e dos potenciais na superfície do solo. Quando o método das imagens é utilizado para este cálculo o modelo típico do solo é uma estratificação horizontal em 2 camadas. A extensão do método das imagens para solos com múltiplas camadas horizontais apresenta problemas numéricos importantes, de forma que a técnica de imagens complexas foi utilizada para permitir este cálculo, porém restringindo a posição dos eletrodos à primeira camada. Este trabalho objetiva a aplicação do método de imagens complexas a eletrodos situados em qualquer camada de solos com estratificação horizontal, deduzindo as funções kernel para posições arbitrárias da fonte e do objeto e determinando os resíduos e pólos das imagens utilizando a decomposição em autovalores e autovetores. Foi desenvolvido um programa que calcula a resistência de aterramento e os potenciais na superfície do solo para solos com até 4 camadas. Foram realizadas comparações com outros trabalhos publicados e os resultados obtidos permitem validar o uso do programa para esta aplicação. / Grounding grid design requires both ground resistance and surface potential. Traditional method of images restricts this calculation to two layer soils. Complex image method allows calculation of both resistance values and potentials at the soil surface, in multilayer soils with horizontal stratification, without grounding grid position limitation. This work presents a complete methodology for calculation of safety aspects of grounding grid design, validating results by comparison with published previous work.
|
100 |
Contribuições à modelagem de sistemas de aterramento pelo método dos elementos finitos no regime harmônico. / Contributions to grounding systems modelling by the finite element method in the harmonic regime.Martinho, Lucas Blattner 18 February 2009 (has links)
Este trabalho tem como objetivo fornecer contribuições ao estudo de sistemas de aterramento submetidos a correntes elétricas no regime permanente senoidal pelo Método dos Elementos Finitos. Nele se discutem as motivações para a utilização deste procedimento numérico em problemas desta categoria, e mais especificamente para o uso da variante deste método com elementos finitos de aresta. O tratamento completo necessário à construção das funções de forma para a aproximação local de grandezas vetoriais com elementos hexaédricos é nele desenvolvido e detalhado. Com estes resultados, uma aplicação computacional capaz de modelar o comportamento de uma haste de aterramento verticalmente enterrada no solo foi desenvolvida, utilizando-se para a discretização do domínio elementos finitos hexaédricos tri-lineares e quadráticos incompletos. Esta aplicação computacional foi utilizada para o estudo da resposta em freqüência da impedância equivalente a aterramentos desta categoria em diferentes condições de solo e com as duas variedades de elemento hexaédrico anteriormente mencionados. Os resultados obtidos são então discutidos, bem como a validade da modelagem adotada para o problema físico aqui considerado. / This work aims to provide contributions to the study of grounding systems subjected to electric currents at the sinusoidal steady state by the Finite Element Method. Motivations for the use of this numerical procedure in problems of this category, and more specifically for the usage of the Edge Finite Element Method variant, are discussed in it. The complete treatment required for building the shape functions for the local approximation of vector physical quantities with hexahedral finite elements is here developed and detailed. With these results a computer application capable of modeling the behavior of vertically buried grounding rods was developed, in which domain discretization is accomplished by the usage of both tri-linear and incomplete quadratic hexahedral finite elements. This computer application was employed in the study of the frequency response of the impedance equivalent to grounding systems of this class at different soil conditions and with both hexahedral element varieties previously mentioned. The results obtained are then discussed, as well as the validity of the modeling adopted for this physical problem.
|
Page generated in 0.0791 seconds