Estágio realizado na PT Inovação e orientado pelo Eng.º Sérgio Ramalho / Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Major Telecomunicações). Faculdade de Engenharia. Universidade do Porto. 2010

The title of my dissertation is "confirmation theory & confirmation logic", and it consists of five Parts. The motivation of the dissertation was to construct an adequate confirmation theory that could solve "the paradoxes of confirmation" discovered by Carl G. Hempel. In Part One I try mainly to do the three things, (i) introduce the fundamentals of Hempel's theory of qualitative confirmation as the common background for subsequent discussions, (ii) review the major views of the paradoxes of confirmation, (iii) present a new view, which is more radical than other known views, and argue that a solution to the paradoxes of confirmation may require a change of logic. In Part Two I construct a number of promising three-valued logics. I employ these "quasi confirmation logics" as the underlying logics of some new confirmation theories which, I had hoped, would solve the paradoxes of confirmation. I consider three-valued logics instead of any other many-valued logics as the underlying logic for any promising confirmation theory, because I believe that there is some intimate relationship or, even, a one-to-one correspondence between the (controversial) three truth-values of "truth", "falsity" and "neither truth nor falsity" and, respectively, the (non-controversial) three confirmation-statuses of "confirmation", "disconfirmation" and "neutrality". Unfortunately, these theories were found to be semantically inadequate. This became clear after a complete semantics for them had been developed. Thus, one negative result of Part Two is that our syntactical approach to confirmation theory is wrong from the very beginning. However, from this negative result we learn a positive lesson: a semantical approach is more fundamental and decisive than a syntactical one, at least this is so for constructing an adequate theory of confirmation. It is rewarding to note that the three-valued semantics worked out in Part Two is simple, complete and the first of its kind. In fact, the new three-valued semantics is in the spirit of Frege, although the line of thought is much neglected (even by Frege himself). In Part Three I shift the search for a confirmation logic and an adequate theory of confirmation from a syntactical to a semantical approach because of the lesson learned in Part Two. After a systematic search through several promising three-valued logics I come, at last, to a plausible confirmation logic and to a confirmation theory that could solve all known paradoxes of confirmation. The promising three-valued confirmation theory is called "the internal confirmation theory". In Part Four I review and appraise the adequacy conditions laid down by Hempel as the necessary conditions for any adequate confirmation theory. Under the criticisms of Carnap, Goodman and, especially, with the help of Hanen's thorough studies, I come to almost an identical conclusion to Hanen's we should not impose a priori in a theory of qualitative confirmation any adequacy conditions laid down by Hempel except perhaps the Entailment Condition, although the internal confirmation theory also adopts the Equivalence Condition for some intrinsic reasons. In the last Part Five I try to appraise the three most important confirmation theories discussed and/or constructed in this dissertation. They are Hempel's theory of confirmation, Goodman's and Scheffler's theory of selective confirmation and the internal confirmation theory. After some more vigorous criticisms are made and some new paradoxes of confirmation are unexpectedly derived in both the theory of selective confirmation and the internal confirmation theory, I arrive at, perhaps reluctantly, this more reasonable conclusion under the present situation when there is no obvious way to overcome the new difficulties the best thing that we can do is to dissolve (i.e. to live with) all new and old paradoxes of confirmation, for Hempel may be after all right to say that the paradoxes of confirmation are not genuine and to think otherwise is to have psychological illusions as Hempel says. / Arts, Faculty of / Philosophy, Department of / Graduate

The complexity of radiation therapy delivery has increased over the years due to advancements in computing and technical innovation. A system of dose delivery verification has the potential to catch treatment errors and therefore improve patient safety. The goal of this thesis was to create a portal image-based in vivo dose reconstruction model for volumetric modulated arc therapy (VMAT) deliveries, specifically for stereotactic body radiation therapy (SBRT). This model-based approach should be robust and feasible within a clinical setting. VMAT involves the modulation of dose rate, gantry speed, and aperture shaping while the treatment gantry (i.e., x-ray beam) rotates about the patient. In this work, portal images were acquired using an amorphous silicon electronic portal imaging device (a-Si EPID). A geometrical characterization of the linear accelerator (linac) during VMAT delivery was performed. An angle adjustment method was determined which improves each EPID’s angular accuracy to within ±1° of the true physical angle. SBRT delivers large doses over fewer fractions than conventional radiotherapy, therefore, any error during an SBRT delivery will have a greater impact on the patient. In this work, a robust, model-based SBRT-VMAT dose reconstruction verification system using EPID images was developed. The model was determined to be clinically feasible. The accuracy of a 3D in vivo dose reconstruction, using all the EPID images acquired during treatment, is sensitive to the chosen frame averaging per EPID image: the greater the frame averaging, the larger the reconstruction error. Optimization of the EPID frame averaging number as a function of average linac gantry speed and dose per fraction were determined. The EPID-based in vivo dose reconstruction model for SBRT-VMAT developed here was determined to be robust, accurate, and clinically feasible as long as adjustments were made in order to correct for EPID image geometrical errors and frame-averaging errors. / May 2016

Register file logic verification historically involves comparing two human generated logic sources such as a VHDL code file and a circuit schematic for logic equivalence. This method is valid for most cases, however it does not account for instances when both logic sources are equivalent but incorrect. This report proposes a method to eliminate this problem by testing logic coherency of various sources with a golden logic source. This golden logic source will be generated by a register file simulation program which has been developed to simulate accurate regfile I/O port data. Implementation of this simulation program for logic verification will eliminate the accuracy problem stated above, in addition the logic simulation time for the new method has also been reduced by 36% compared to the former method. / text

Over the past few years, computer scientists have been using formal verification techniques to show the correctness of digital systems. The verification process, however, is complicated and expensive. Even proofs of simple circuits can involve thousands of logical steps. Often it can be extremely difficult to find correct device specifications and it is desirable that one sets off to prove a correct specification from the start, rather than repeatedly backtrack from the verification process to modify the original definitions after discovering they were incorrect or inaccurate. The main idea presented in the thesis is to amalgamate the techniques of simulation and verification, rather than have the latter replace the former. The result is that behavioural definitions can be simulated until one is reasonably sure that the specification is correct. Furthermore, providing the correctness with respect to these simulated specifications avoids the inadequacies of simulation, where it may not be computationally feasible to demonstrate correctness by exhaustive testing. Simulation here has a different purpose: to get specifications correct as early as possible in the verification process. Its purpose is not to demonstrate the correctness of the implementation - this is done in the verification stage when the very same specifications that were simulated are proven correct. The thesis discusses the implementation of an executable subset of the HOL logic, the version of Higher Order Logic embedded in the HOL theorem prover. It is shown that hardware can be effectively described using both relations and functions; relations being suitable for abstract specification, and functions being suitable for execution. The differences between relational and functional specifications are discussed and illustrated by the verification of an <i>n</i>-bit adder. Techniques for executing functional specifications are presented and various optimisation stratagies are shown which make the execution of the logic efficient. It is further shown that the process of generating optimised functional definitions from relational definitions can be automated. Example simulations of three hardware devices (a factorial machine, a small computer and a communications chip) are presented.

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