This study is a result of trying to grasp what teachers look at when they assess writing. The motive is to better understand what goes on inside a teacher’s mind when correcting a written piece of work and to raise the level of awareness of what teachers actually do. Background information as to what the teachers support their assessment on and how they acquired their “correcting skills” is also treated. The study brings up both what teachers say and what teachers do. It is an exploratory and open ended investigation. To perform this exploration a qualitative method is used. Interviews with open questions and observations of the assessment situation with think aloud protocols are performed. Examples of the teachers’ real life marking in students written texts are also considered. The findings show that teachers possess an intuition based on knowledge which has been constructed by themselves and that they cannot depict easily. Their own awareness of what they do seems to be mixed with what they would like to do at occasions. Linguistic topics such as morphology, grammar, syntax, vocabulary, spelling and idiomaticity are considered by both teachers showing that surface errors are of importance. Coherence and thematic treatment are also taken into consideration when teachers assess but the way they value these aspects together with views on what writing is, what communication is together with other possible choices shows that correction and assessing is highly subjective. In addition, this study points at the possibility that a teacher progresses from analytic to holistic with time and that writing as a process is more valid when a teacher becomes more experienced.

Verifying the power grid requires checking if the voltage drops on all the nodes do not exceed the threshold. We aim to correct an RC model of the grid when some voltage drops violate the threshold condition, by making minor changes to the original design. We first propose an accurate approach to correct the grid which turns out to be too slow. We therefore propose another approach, more suitable for large grids and which can be summarized as follows. The voltage drop is estimated as a function of the metal widths on the grid. A non-linear optimization problem is then formulated and the required metal line width changes that reduce the voltage drops by a sufficient amount are determined. There is a tradeoff between accuracy and speed of the algorithm. However the results show that the gain in speed achieved by the second method, outweighs greatly the loss in accuracy.

Verifying the power grid requires checking if the voltage drops on all the nodes do not exceed the threshold. We aim to correct an RC model of the grid when some voltage drops violate the threshold condition, by making minor changes to the original design. We first propose an accurate approach to correct the grid which turns out to be too slow. We therefore propose another approach, more suitable for large grids and which can be summarized as follows. The voltage drop is estimated as a function of the metal widths on the grid. A non-linear optimization problem is then formulated and the required metal line width changes that reduce the voltage drops by a sufficient amount are determined. There is a tradeoff between accuracy and speed of the algorithm. However the results show that the gain in speed achieved by the second method, outweighs greatly the loss in accuracy.

Les progrès technologiques ont permis le développement d’applications de capteurs sans fil. Ces capteurs sont généralement déployés avec des ressources énergétiques réduites où le remplacement d’une batte rie peut être coûteux. L’efficacité énergétique est une contrainte importante pour assurer une grande autonomie. La tendance actuelle vers des applications à haut débit demande non seulement une grande efficacité spectrale mais aussi une consommation réduite de l’énergie. Étudier le compromis entre l’efficacité spectrale et l’efficacité énergétique pour les réseaux de capteurs sans fil (RCSFs) est donc primordial. Nous nous concentrons dans cette thèse sur l’étude des techniques adoptées au niveau de la couche physique. D’abord, les différents aspects caractérisant les RCSFs sont introduits. Puis les approches courantes pour réduire l’énergie dans ces réseaux sont rappe- lés tout en soulignant le lien entre la consommation d’énergie et l’amélioration de l’efficacité spectrale. Des modèles courants de consommation d’énergie sont introduits et classés afin d’étudier l’évolution de l’énergie consommée en fonction de l’efficacité spectrale. En second lieu, nous nous sommes focalisés sur le choix de la modulation du point de vue énergétique et spectrale afin de trouver le schéma de modulation optimal qui minimise l’énergie. Nous avons étudié ensuite le com- promis entre l’efficacité énergétique et spectrale en tenant compte des contraintes imposées par le système. Enfin, nous nous sommes intéressés à l’intégration du codage et du protocole de contrôle d’erreurs dont nous avons étudié l’impact sur le compromis efficacité énergétique et efficacité spectrale. / Technological advances have led to the develop- ment of wireless sensor applications. These sensors are generally deployed with reduced energy resources where replacing a battery can be costly. Energy ef ficiency is an important constraint to ensure a high level of autonomy. The current trend towards high- throughput applications requires not only high spectral efficiency but also reduced energy consumption. It is therefore essential to study the trade-off between spec tral efficiency and energy efficiency for wireless sensor networks (WSNs). In this thesis we concentrate on the different techniques adopted at the level of the phys- ical layer. At first, the various aspects characterizing the WSNs are introduced. Then, the efforts made to optimize the conservation of energy in these networks are summarized while highlighting the link between the energy consumption and the spectral efficiency. Then, different energy models are introduced and classified in order to study the evolution of the consumed energy as a function of the spectral efficiency. Secondly, we focus on the choice of modulation in order to find the optimal scheme that minimizes energy. We then studied the tradeoff between energy and spectral efficiency, taking into account the constraints imposed by the sys- tem. Finally, we are interested in coding strategy and error control protocol to study their impact on the energy efficiency and spectral efficiency tradeoff.

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"The MCNP6 radiation transport code was used to quantify changes in the absorbed dose tissue conversion factors for LiF, Al2O3, and silicon-based electronic dosimeters. While normally calibrated in-air and applied to all general geometric measurements, tissue conversion factors for each dosimeter were obtained at various depths in a simulated water phantom and compared against the standard in-air calibration method. In these experiments, a mono-energetic photon source was modeled at energies between 30 keV and 300 keV for a point-source placed at the center of a water phantom, a point-source placed at the surface of the phantom, and for a 10-cm radial field geometry. Again, mono-energetic photon source was modeled up to 1300 keV for a disk-source placed at the surface of the phantom and dosimetric calculations were obtained for water, LiF, Al2O3, and silicon at depths of 1 mm to 35 cm from the source. The dosimeter’s absorbed dose conversion factor was calculated as a ratio of the absorbed dose to water to that of the dosimeter measured at a specified phantom depth. The dosimeter’s calibration value also was obtained for both mono and polyenergetic source and the calibration value from poly-energetic source was compared with the intensity weighted average calibration value from mono-energetic photon. The calculated changes in the tissue conversion factors are significant because the American Association of Physicists in Medicine (AAPM) recommend that measurements of a brachytherapy or diagnostic source be made with an overall uncertainity of 5% or better. Yet, based on results, the absorbed dose tissue conversion factor for a LiF dosimeter was found to deviate from its calibration value by up to 9%, an Al2O3 dosimeter by 43%, and a silicon dosimeter by 61%. These uncertainties are in addition to the normal measurement uncertainties. By applying these tissue correction factors, these data may be used to meet the AAPM measurement requirements for mono-energetic and poly-energetic sources at measurement depths up to 35 cm under the irradiation geometries investigated herein. "

This thesis mainly studies the active power factor correction circuit using a new AC/DC Single Ended Primary Inductance Converter (SEPIC). For power factor correction, inductor current is operated in the continuous conduction mode. First of all, the converter is analyzed by state space averaging method. Furthermore, the operational principle of PFC circuit with PI control law is analyzed. A good power factor system is then developed by time-domain and frequency-domain analysis. A classical PFC circuit with PI control law has low power factor when light load. In order to overcome problem, the thesis proposes a SEPIC circuit with robust performance. Compared with circuits using classical PI controller and PFC IC, the proposed system obtains higher power factor under the condition of the same light load.