<p>This thesis presents an approach for working with low level source code that enables automatic restructuring and raising the abstraction level of the programs. This makes it easier to understand the logic of the program, which in turn reduces the development time.The process in this thesis was designed to be flexible and consists of several independent tools. This makes the process easy to adapt as needed, while at the same time the developed tools can be used for other processes. There are usually two basic steps. First is the translation to WSL language, which has a great number of semantic preserving program transformations. The second step are the transformations of the translated WSL. Two tools were developed for translation: one that works with a subset of x86 assembly, and another that works with MicroJava bytecode. The result of the translation is a low level program in WSL.The primary goal of this thesis was to fully automate the selection of the transformations. This enables users with no domain&nbsp; knowledge to efficiently use this process as needed. At the same time, the flexibility of the process enables experienced users to adapt it as needed or integrate it into other processes. The automation was achieved with a <em>hill climbing </em>algorithm.Experiments that were run on several types of input programs showed that the results can be excellent. The fitness function used was a built-in metric that gives the &ldquo;weight&rdquo; of structures in a program. On input samples that had original high level source codes, the end result metrics of the translated and transformed programs were comparable. On some samples the result was even better than the originals, on some others they were somewhat more complex. When comparing with low level original source code, the end results was always significantly improved.</p> / <p>U okviru ove teze se predstavlja pristup radu sa programima niskog nivoa koji omogućava automatsko restrukturiranje i podizanje na vi&scaron;e nivoe. Samim tim postaje mnogo lak&scaron;e razumeti logiku programa &scaron;to smanjuje vreme razvoja.Proces je dizajniran tako da bude fleksibilan i sastoji se od vi&scaron;e nezavisnih alata. Samim tim je lako menjati proces po potrebi, ali i upotrebiti razvijene alate u drugim procesima. Tipično se mogu razlikovati dva glavna koraka. Prvi je prevođenje u jezik WSL,za koji postoji veliki broj transformacija programa koje očuvavaju semantiku. Drugi su transformacije u samom WSL-u. Za potrebe prevođenja su razvijena dva alata, jedan koji radi sa podskupom x86 asemblera i drugi koji radi sa MikroJava bajtk&ocirc;dom. Rezultat prevođenja je program niskog nivoa u WSL jeziku.Primarni cilj ovog istraživanja je bila potpuna automatizacija odabira transformacija, tako da i korisnici bez iskustva u radu sa sistemom mogu efikasno da primene ovaj proces za svoje potrebe. Sa druge strane zbog fleksibilnosti procesa, iskusni korisnici mogu lakoda ga pro&scaron;ire ili da ga integri&scaron;u u neki drugi već postojeći&nbsp;&nbsp; proces.Automatizacija je&nbsp; postignuta pretraživanjem usponom (eng. hill climbing).Eksperimenti vr&scaron;eni na nekoliko tipova ulaznih programa niskog nivoa su pokazali da rezultati mogu biti&nbsp; izuzetni. Za funkciju pogodnosti je kori&scaron;ćena ugrađena metrika koja daje &ldquo;težinu&rdquo; struktura u programu. Kod ulaza za koje je originalni izvorni k&ocirc;d bio dostupan, krajnje metrike najboljih varijanti prevedenih i transformisanih programa su bile na sličnom nivou. Neki primeri su bolji od originala, dok su drugi bili ne&scaron;to kompleksniji. Rezultati su uvek pokazivali značajna unapređenja u odnosu na originalni k&ocirc;d niskog nivoa.</p>

Ce travail de thèse s’inscrit dans le domaine de l’énergie nucléaire, de l’aval du cycle du combustible et du calcul des incertitudes. Le CEA doit concevoir le prototype ASTRID, réacteur à neutrons rapides refroidi au sodium (RNR), qui est l’un des concepts retenus au sein du forum Génération IV et dont la puissance résiduelle et l’estimation de son incertitude ont un impact important. Ce travail consiste à développer un code de propagation des incertitudes des données nucléaires sur la puissance résiduelle dans les RNR.La démarche s’est déroulée en trois temps.La première étape a permis de limiter le nombre de paramètres intervenant dans le calcul de la puissance résiduelle. Pour cela, un essai de puissance résiduelle sur le réacteur PHENIX (PUIREX 2008) a été interprété de façon à valider expérimentalement le formulaire d’évolution DARWIN pour les RNR et à quantifier les termes sources de la puissance résiduelle.La deuxième étape a eu pour but de développer un code de propagation des incertitudes : CyRUS (Cycle Reactor Uncertainty and Sensitivity). Une méthode de propagation déterministe a été retenue car elle permet des calculs rapides et fiables. Les hypothèses de linéarité et de normalité qu’elle entraîne ont été validées théoriquement. Le code a également été comparé avec succès à un code stochastique sur l’exemple de la fission élémentaire thermique de l’235U.La dernière partie a été une application du code sur des expériences de puissance résiduelle d’un réacteur, de bilan matière d’une aiguille combustible et d’une fission élémentaire de l’235U. Le code a démontré des possibilités de retour d’expériences sur les données nucléaires impactant l’incertitude de cette problématique.Deux résultats principaux ont été mis en évidence. Tout d’abord, les hypothèses simplificatrices des codes déterministes sont compatibles avec un calcul précis de l’incertitude de la puissance résiduelle. Ensuite, la méthode développée est intrusive et permet un retour d’expérience sur les données nucléaires des expériences du cycle. En particulier, ce travail a montré qu’il est déterminant de mesurer précisément les rendements de fission indépendants et de déterminer leurs matrices de covariances afin d’améliorer la précision du calcul de la puissance résiduelle. / This PhD study is in the field of nuclear energy, the back end of nuclear fuel cycle and uncertainty calculations. The CEA must design the prototype ASTRID, a sodium cooled fast reactor (SFR) and one of the selected concepts of the Generation IV forum, for which the calculation of the value and the uncertainty of the decay heat have a significant impact. In this study is developed a code of propagation of uncertainties of nuclear data on the decay heat in SFR.The process took place in three stages.The first step has limited the number of parameters involved in the calculation of the decay heat. For this, an experiment on decay heat on the reactor PHENIX (PUIREX 2008) was studied to validate experimentally the DARWIN package for SFR and quantify the source terms of the decay heat.The second step was aimed to develop a code of propagation of uncertainties : CyRUS (Cycle Reactor Uncertainty and Sensitivity). A deterministic propagation method was chosen because calculations are fast and reliable. Assumptions of linearity and normality have been validated theoretically. The code has also been successfully compared with a stochastic code on the example of the thermal burst fission curve of 235U.The last part was an application of the code on several experiments : decay heat of a reactor, isotopic composition of a fuel pin and the burst fission curve of 235U. The code has demonstrated the possibility of feedback on nuclear data impacting the uncertainty of this problem.Two main results were highlighted. Firstly, the simplifying assumptions of deterministic codes are compatible with a precise calculation of the uncertainty of the decay heat. Secondly, the developed method is intrusive and allows feedback on nuclear data from experiments on the back end of nuclear fuel cycle. In particular, this study showed how important it is to measure precisely independent fission yields along with their covariance matrices in order to improve the accuracy of the calculation of the decay heat.