Fibra de crital fotônico: fundamentação e aplicações

The main purpose of this dissertation, consists of the study and analysis of the PBG (Photonic Band Gap )..tecnology incorporated in optical fiber structures. So, we'l1 present a complete PBG structure theory, and folowing this, we'l1 present also a chapter for convencional optical fiber, due to the need to construct the base theory of them, and latter a more complete work about photonic crystal fiber. Finaly, we'l1 show the results of the signals , dispersion, and obtained curves under the right dimensions according to the required signals, for convencional optical and photonic crystal fiber. Knowing that PBG crystals with low losses act as perfect mirrors for forbidden frequences and knowing that the persence of structures of PBG as substrates, brings some desirable characteristics such as spontaneous emition supression and superficial waves. We' 11 show according to these characteristics its applications in telecomunication. Therefore, the enphasis of this work is to show that the optical fibers are the only practible thing to integrate the enormous quantity of data and video at intemet' s market, developing, manipulating, changing, and multiplexing the optical fibers chanels in an area where we expect that the photonic crystals has an important hole, since the photonic crystals can be projected and made to avoid losses in the bands of certain wavelength which permits the increase in efficiency ofthe optical components projected with crystals. A sequence of this work would be the utilisation of the PBG structures in the new system of optical network without fiber developed by Bell laboratories of the lucent tecnology, last year using light rays for transmiting information through the air. The new system of optical networks without fiber will permit sending the data of 15 cd-rooms in less then one second, what represents 65 times more information than those transmitted through the actual radio frequences

Crítica ao fundacionismo cartesiano com base no argumento contra a linguagem privada

This assignment ains to prove the pertinency of using the wittgenstein´s argument against private language as a criticism to cartesian fundacionism. Therefore, I want to demonstrate in the first chaper the conceptual viability of facing the cartesian argument of cogito not as a simple silogism but as an exemple of a private experience (process of thinking). At the second chaper, the subordination of the argument against private language give us the idea that rules can only be followed by means of corrections givem by a linguistic community that is external to the private subject, in a way to be unviable the assumption that is possible to name an internal experience without searching external rules of the use of terms. At the chaper 3 the pertinency of the hypothesis raised by A. Kenny, about the overtaking of the argument against private language can be extended to the idea of epistemic and ontologic privacy that would lend validity to the fundacion present at the argument at the cartesian cogito. In oder to become evident the pertinency of use of Wittgenstein´s argument agaist Descartes´ fundation, it´s necessary, at the chaper 3, to demonstrate the impertinency of the objection to the A. Kenny´s hypothesis, based on the experiency of the thought of the brain at the recipient, to make clear the incompatibility existing between the cartesian idea of cogito and Wittgenstein´s notion that language is an activitie followed by rules, wich correction criterion may be external and intersubjective