On the Application of Beam on Elastic Foundation Theory to the Analysis of Stiffened Plate Strips

The main objective of this thesis is to show that plate strips subjected to transverse line loads can be analysed by using the beam on elastic foundation (BEF) approach. It is shown that the elastic behaviour of both the centre line section of a semi infinite plate supported along two edges, and the free edge of a cantilever plate strip can be accurately predicted by calculations based on the two parameter BEF theory. The transverse bending stiffness of the plate strip forms the foundation. The foundation modulus is shown, mathematically and physically, to be the zero order term of the fourth order differential equation governing the behaviour of BEF, whereas the torsion rigidity of the plate acts like pre tension in the second order term. Direct equivalence is obtained for harmonic line loading by comparing the differential equations of Levy's method (a simply supported plate) with the BEF method. By equating the second and zero order terms of the semi infinite BEF model for each harmonic component, two parameters are obtained for a simply supported plate of width B: the characteristic length, 1/ λ, and the normalized sum, n, being the effect of axial loading and stiffening resulting from the torsion stiffness, nlin. This procedure gives the following result for the first mode when a uniaxial stress field was assumed (ν = 0): 1/λ = √2B/π and nlin = 1. For constant line loading, which is the superimposition of harmonic components, slightly differing foundation parameters are obtained when the maximum deflection and bending moment values of the theoretical plate, with v = 0, and BEF analysis solutions are equated: 1 /λ= 1.47B/π and nlin. = 0.59 for a simply supported plate; and 1/λ = 0.99B/π and nlin = 0.25 for a fixed plate. The BEF parameters of the plate strip with a free edge are determined based solely on finite element analysis (FEA) results: 1/λ = 1.29B/π and nlin. = 0.65, where B is the double width of the cantilever plate strip. The stress biaxial, v > 0, is shown not to affect the values of the BEF parameters significantly the result of the geometric nonlinearity caused by in plane, axial and biaxial loading is studied theoretically by comparing the differential equations of Levy's method with the BEF approach. The BEF model is generalised to take into account the elastic rotation stiffness of the longitudinal edges. Finally, formulae are presented that take into account the effect of Poisson's ratio, and geometric non linearity, on bending behaviour resulting from axial and transverse inplane loading. It is also shown that the BEF parameters of the semi infinite model are valid for linear elastic analysis of a plate strip of finite length. The BEF model was verified by applying it to the analysis of bending stresses caused by misalignments in a laboratory test panel. In summary, it can be concluded that the advantages of the BEF theory are that it is a simple tool, and that it is accurate enough for specific stress analysis of semi infinite and finite plate bending problems.

Retrieval of kinetic rates in reactions with semi batch liquid phase using ill-posed inverse problem theory

A neural network procedure to solve inverse chemical kinetic problems is discussed in this work. Rate constants are calculated from the product concentration of an irreversible consecutive reaction: the hydrogenation of Citral molecule, a process with industrial interest. Simulated and experimental data are considered. Errors in the simulated data, up to 7% in the concentrations, were assumed to investigate the robustness of the inverse procedure. Also, the proposed method is compared with two common methods in nonlinear analysis; the Simplex and Levenberg-Marquardt approaches. In all situations investigated, the neural network approach was numerically stable and robust with respect to deviations in the initial conditions or experimental noises.

A brief introduction to molecular orbital theory of simple polyatomic molecules for undergraduate chemistry students

A simple, four-step method for better introducing undergraduate students to the fundamentals of molecular orbital (MO) theory of the polyatomic molecules H2O, NH3, BH3 and SiH4 using group theory is reported. These molecules serve to illustrate the concept of ligand group orbitals (LGOs) and subsequent construction of MO energy diagrams on the basis of molecular symmetry requirements.

Evaluation of group electronegativities and hardness (softness) of group 14 elements and containing functional groups through density functional theory and correlation with NMR spectra data

Quantum Chemical calculations for group 14 elements of Periodic Table (C, Si, Ge, Sn, Pb) and their functional groups have been carried out using Density Functional Theory (DFT) based reactivity descriptors such as group electronegativities, hardness and softness. DFT calculations were performed for a large series of tetracoordinated Sn compounds of the CH3SnRR'X type, where X is a halogen and R and R' are alkyl, halogenated alkyl, alkoxy, or alkyl thio groups. The results were interpreted in terms of calculated electronegativity and hardness of the SnRR'X groups, applying a methodology previously developed by Geerlings and coworkers (J. Phys. Chem. 1993, 97, 1826). These calculations allowed to see the regularities concerning the influence of the nature of organic groups RR' and inorganic group X on electronegativities and hardness of the SnRR'X groups; in this case, it was found a very good correlation between the electronegativity of the fragment and experimental 119Sn chemical shifts, a property that sensitively reflects the change in the valence electronic structure of molecules. This work was complemented with the study of some compounds of the EX and ER types, where E= C, Si, Ge, Sn and R= CH3, H, which was performed to study the influence that the central atom has on the electronegativity and hardness of molecules, or whether these properties are mainly affected for the type of ligand bound to the central atom. All these calculations were performed using the B3PW91 functional together with the 6-311++G** basis set level for H, C, Si, Ge, F, Cl and Br atoms and the 3-21G for Sn and I atoms.

Leibniz's theory of bodies: monadic aggregates, phenomena, or both?

Leibniz's conception of bodies seems to be a puzzling theory. Bodies are seen as aggregates of monads and as wellfounded phenomena. This has initiated controversy and unending discussions. The paper attempts to resolve the apparent inconsistencies by a new and formally spirited reconstruction of Leibniz's theory of monads and perception, on the one hand, and a (re-)formulation and precisation of his concept of preestablished harmony, on the other hand. Preestablished harmony is modelled basically as a covariation between the monadic and the ideal realm.

Benjamin's conception of language and Adorno's aesthetic theory

According to the theory of language of the young Benjamin, the primary task of language isn't the communication of contents, but to express itself as a "spiritual essence" in which also men take part. That conception according to which language would be a medium to signification of something outside it leads to a necessary decrease of its original strength and is thus denominated by Benjamin bürgerlich. The names of human language are remainders of an archaic state, in which things weren't yet mute and had their own language. Benjamin suggests also that all the arts remind the original language of things, as they make objects "speak" in form of sounds, colors, shapes etc. That relationship between arts as reminders of the "language of things" and the possible reconciliation of mankind with itself and with nature has been developed by Theodor Adorno in several of his writings, specially in the Aesthetic Theory, where the artwork is ultimately conceived as a construct pervaded by "language" in the widest meaning - not in the "bourgeois" sense.

THE FORMAL AND THE FORMALIZED: THE CASES OF SYLLOGISTIC AND SUPPOSITION THEORY

As a discipline, logic is arguably constituted of two main sub-projects: formal theories of argument validity on the basis of a small number of patterns, and theories of how to reduce the multiplicity of arguments in non-logical, informal contexts to the small number of patterns whose validity is systematically studied (i.e. theories of formalization). Regrettably, we now tend to view logic 'proper' exclusively as what falls under the first sub-project, to the neglect of the second, equally important sub-project. In this paper, I discuss two historical theories of argument formalization: Aristotle's syllogistic theory as presented in the "Prior Analytics", and medieval theories of supposition. They both illustrate this two-fold nature of logic, containing in particular illuminating reflections on how to formalize arguments (i.e. the second sub-project). In both cases, the formal methods employed differ from the usual modern technique of translating an argument in ordinary language into a specially designed symbolism, a formal language. The upshot is thus a plea for a broader conceptualization of what it means to formalize.

Rebuilding Defenses: Explorations in Norman Fairclough’s Theory of Critical Discourse Analysis

Tutkielmassa eritellään Norman Faircloughin kriittisen diskurssianalyysin teoriaa ja siihen kohdistettua kritiikkiä. Pyrkimyksenä on sovittaa näitä erilaisia näkemyksiä keskenään ja tarjota ratkaisuja yhteen kiriittisen diskurssianalyysin keskeiseen ongelmaan eli emansipaation (sosiaalisten epäkohtien tunnistamisen ja ratkaisemisen) puutteellisuuteen. Teoriaosuudesta esiin nousevia mahdollisuuksia sovelletaan tekstianalyysiin. Tutkimuksen kohteena on teksti Rebuilding America’s Defenses: Strategy, Forces and Resources For a New Century ja jossain määrin sen tuottanut järjestö Project for the New American Century. Näitä tarkastellaan ennen kaikkea sosiaalisina ilmiöinä ja suhteessa toisiinsa. Faircloughin mallin suurimmiksi ongelmiksi muodostuvat perinteinen käsitys kielestä, jonka mukaan kielen järjestelmän abstraktit ja sisäiset suhteet ovat tärkeimpiä, sekä ideologinen vastakkainasettelu kritiikin lähtökohtana. Ensimmäinen johtaa kielellisten tutkimustulosten epätyydyttävään kykyyn selittää sosiaalisia havaintoja ja jälkimmäinen poliittiseen tai maailmankatsomukselliseen väittelyyn, joka ei mahdollista uusia näkemyksiä. Tutkielman lopputulema on, että keskittymällä asiasisältöön kielen rakenteen sijasta ja ymmärtämällä tekstin tuottaja yksittäisenä, rajattuna sosiaalisena toimijana voidaan analyysiin saada avoimuutta ja täsmällisyyttä. Kriittiinen diskurssianalyysi kaipaa tällaista näkemystä kielellisten analyysien tueksi ja uudenlaisen relevanssin löytääkseen.

Det pedagogiska övervägandet : en uppmärksamhetsriktande studie i och genom humanvetenskaplig handlingsteori

Det övergripande syftet med avhandlingen är att bidra till en handlingsinriktad diskurs. Ambitionen är att rikta uppmärksamheten mot den pedagogiska övervägande handlingen genom att pröva konkreta exempel från en pedagogisk praktik mot en begreppsapparat inspirerad av den humanvetenskapliga handlingsteorin. Forskningsfrågorna lyder: Vad är en övervägande handling? Hur byggs den upp och vad förutsätter den? Bakgrunden till intresset att belysa den övervägande handlingen är en önskan att överbrygga klyftan mellan teori och praktik och att hitta ett sätt att samtala om ”tyst kunskap” och den konkreta pedagogiska verkligheten så att denna kan utvecklas på ett meningsfullt sätt. Förhållandet mellan intentionalitet och instrumentella handlingar är av särskilt intresse. Den aristoteliska begreppsapparaten som avser att belysa den mänskliga handlingen används i studien som både utgångspunkt och analysredskap. Retoriken ses som den vetenskap som kan beskriva och förklara hur vi skapar mening med hjälp av språket. Fyra fokussamtal med sammanlagt fem studerande på musikanimatörutbildningen genomfördes under vårterminen 2006. Referaten från samtalen bearbetades till en berättelse. I konstruktionen av berättelsen användes dels en fenomenologisk analys, dels narrativ bearbetning. De aristoteliska begreppen poíesis, praxis och theoria tillämpades och prövades på berättelsen varefter en retorisk analys genomfördes. Berättelsen visar två konkurrerande praxis. Utbildningen framstår i berättelsen dels som en horisontell ”alla kan”-utbildning, dels som en vertikal och lärarstyrd verksamhet. Berättelsen ger inte så många exempel på pedagogiska överväganden men tydliggör ändå den övervägande handlingen. Det pedagogiska övervägandet innebär ett väljande utifrån teoretiskt tänkbara och med praxis förenliga handlingsalternativ. Reflektion ingår i övervägandet men är inte detsamma som övervägande. Övervägandet är inte enbart en rationellt kalkylerande aktivitet. Holistiska och intuitiva procedurer är en viktig del i processen. Övervägande förutsätter dessutom ansvar.

Remarks on abstract Galois theory

This paper is a historical companion to a previous one, in which it was studied the so-called abstract Galois theory as formulated by the Portuguese mathematician José Sebastião e Silva (see da Costa, Rodrigues (2007)). Our purpose is to present some applications of abstract Galois theory to higher-order model theory, to discuss Silva's notion of expressibility and to outline a classical Galois theory that can be obtained inside the two versions of the abstract theory, those of Mark Krasner and of Silva. Some comments are made on the universal theory of (set-theoretic) structures.

The relation between the general maxim of causality and the principle of uniformity in hume's theory of knowledge

ABSTRACT When Hume, in the Treatise on Human Nature, began his examination of the relation of cause and effect, in particular, of the idea of necessary connection which is its essential constituent, he identified two preliminary questions that should guide his research: (1) For what reason we pronounce it necessary that every thing whose existence has a beginning should also have a cause and (2) Why we conclude that such particular causes must necessarily have such particular effects? (1.3.2, 14-15) Hume observes that our belief in these principles can result neither from an intuitive grasp of their truth nor from a reasoning that could establish them by demonstrative means. In particular, with respect to the first, Hume examines and rejects some arguments with which Locke, Hobbes and Clarke tried to demonstrate it, and suggests, by exclusion, that the belief that we place on it can only come from experience. Somewhat surprisingly, however, Hume does not proceed to show how that derivation of experience could be made, but proposes instead to move directly to an examination of the second principle, saying that, "perhaps, be found in the end, that the same answer will serve for both questions" (1.3.3, 9). Hume's answer to the second question is well known, but the first question is never answered in the rest of the Treatise, and it is even doubtful that it could be, which would explain why Hume has simply chosen to remove any mention of it when he recompiled his theses on causation in the Enquiry concerning Human Understanding. Given this situation, an interesting question that naturally arises is to investigate the relations of logical or conceptual implication between these two principles. Hume seems to have thought that an answer to (2) would also be sufficient to provide an answer to (1). Henry Allison, in his turn, argued (in Custom and Reason in Hume, p. 94-97) that the two questions are logically independent. My proposal here is to try to show that there is indeed a logical dependency between them, but the implication is, rather, from (1) to (2). If accepted, this result may be particularly interesting for an interpretation of the scope of the so-called "Kant's reply to Hume" in the Second Analogy of Experience, which is structured as a proof of the a priori character of (1), but whose implications for (2) remain controversial.