Abstract This thesis presents several novel improvements to video coding algorithms, including block-based motion estimation, quantization selection, and video filtering. Most of the presented improvements are fully compatible with the standards in general use, including MPEG-1, MPEG-2, MPEG-4, H.261, H.263, and H.264. For quantization selection, new methods are developed based on the rate-distortion theory. The first method obtains locally optimal frame-level quantization parameter considering frame-wise dependencies. The method is applicable to generic optimization problems, including also motion estimation. The second method, aimed at real-time performance, heuristically modulates the quantization parameter in sequential frames improving significantly the rate-distortion performance. It also utilizes multiple reference frames when available, as in H.264. Finally, coding efficiency is improved by introducing a new matching criterion for motion estimation which can estimate the bit rate after transform coding more accurately, leading to better motion vectors. For fast motion estimation, several improvements on prior methods are proposed. First, fast matching, based on filtering and subsampling, is combined with a state-of-the-art search strategy to create a very quick and high-quality motion estimation method. The successive elimination algorithm (SEA) is also applied to the method and its performance is improved by deriving a new tighter lower bound and increasing it with a small constant, which eliminates a larger part of the candidate motion vectors, degrading quality only insignificantly. As an alternative, the multilevel SEA (MSEA) is applied to the H.264-compatible motion estimation utilizing efficiently the various available block sizes in the standard. Then, a new method is developed for refining the motion vector obtained from any fast and suboptimal motion estimation method. The resulting algorithm can be easily adjusted to have the desired tradeoff between computational complexity and rate-distortion performance. For refining integer motion vectors into half-pixel resolution, a new very quick but accurate method is developed based on the mathematical properties of bilinear interpolation. Finally, novel number theoretic transforms are developed which are best suited for two-dimensional image filtering, including image restoration and enhancement, but methods are developed with a view to the use of the transforms also for very reliable motion estimation.

京都大学 / 0048 / 新制・論文博士 / 博士(理学) / 乙第12910号 / 論理博第1546号 / 新制||理||1590(附属図書館) / 32120 / ソウル大学大学院数学科 / (主査)教授 中島 啓, 教授 小野 薫, 教授 向井 茂 / 学位規則第4条第2項該当 / Doctor of Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(経済学) / 甲第21530号 / 経博第598号 / 新制||経||289(附属図書館) / 京都大学大学院経済学研究科経済学専攻 / (主査)教授 江上 雅彦, 教授 西山 慶彦, 准教授 砂川 伸幸 / 学位規則第4条第1項該当 / Doctor of Economics / Kyoto University / DGAM

The purpose of the study is to investigate how school educators adapt teaching to meet students in theoretical difficulties. The aim is also to get an insight into the educators' experiences about these students and how they talk about these children in conversation with colleagues, parents and school management. This in order to compare and analyze if the language is different from the conversation with parents, colleagues and school management. To answer my purpose, I have used four questions. These questions have been used in interviews of educators who meet and teach students in theoretical difficulties every day in elementary school. These six educators, four women and two men have a long experience in working with children and young people. My study of the experiences of these six educators shows that educators adapt teaching based on the needs of each student. Sometimes the special education teacher/special pedagogue is also in the process of selecting the right adjustments. The adjustments are tested a number of weeks before they are followed up. The most common customizations are compensational tools such as computer, speech synthesis, spell checking, image support, clear instructions, limited tasks, custom material, and understanding. There is no diagnosis for students in theoretical difficulties, which is not required by the educators. This makes it difficult to talk with parents, colleagues and school leaders because the term "student in theoretical difficulties" is not used. The students are named based on their strengths and difficulties. This is done because the educators find it hard to speak of a low talent. From a special pedagogical perspective based on the results, educators need to be responsive to the student's feelings, thoughts and opinions about the school situation. Successful educators support students increase motivation for school work. Educators need to focus on the learning environment and regularly reflect on the students' school situation. They need to let students be active about decisions concerning the pupil's school day. Students lack understanding in their knowledge learning because they have difficulty analyzing, comparing and reflecting. This means that educators must work to make the knowledge understandable to the student.Working actively with relationships between student-student and student-educator gives positive results for student development. Educators need to try different solutions and stick to them so that it is possible to evaluate the actions. Based on the results of the evaluation, students' difficulties may decrease when the measures have worked. Pupils with learning difficulties can have motor difficulties. If the students receive continuous motor training, learning is affected positively. Their concentration and motor skills are increasing as more physical training. These positive effects affect rough, fine motor skills, reading, writing ability, speech, room’s perception and thinking skills.

<p> A number of questions are examined concerning many body correlations in connection with electron gas at metallic densities (2 < = rs <= 5.7) and the annihilation of a positron in simple metals, by means of a technique involving the two particle correlation Green's function. Estimates are made of low temperature contributions to angular correlation data, which describe the momentum distribution of annihilating electron positron pairs, in the form of smearing at the sharp cutoff corresponding to the Fermi momentum from electron- and positron- photon interactions, and in the form of broad tails beyond the cutoff resulting from the high-momentum components introduced into the electron wave function by the presence of a periodic crystal lattice. </p> <p> Phonon effects are introduced into the perturbation expansion of the two particle Green's function describing an electron positron pair. A calculation of the lowest order phonon contribution seems to indicate that such effects do not explain the smearing at the Fermi momentum. </p> <p> A Green's function calculation of the first-order enhancement of the lattice tails, due to the positron-electron correlation, is made by introducing particle-lattice interactions explicitly in a model based on a simple metal such as sodium. It considers a weak potential and treats as zero the lattice components corresponding to other than nearest-neighbours points in reciprocal lattice space. The enhancement for rs =4, which is almost a constant, is very similar to that for the main part of angular correlation data. This indicates that, for simple metals at least, angular correlation data can be interpreted directly from a free-particle model. </p> <p> Short-range correlations among opposite-spin electrons are examined by field-theoretic techniques as a step to obtaining a fundamental understanding of the correlations among electrons at metallic densities. A calculation of the p.d.f. for opposite-spin electrons is positive over a wide range of metallic densities and seems to account for short-range correlations of the Coulomb hole through the multiple scattering of particle-particle ladders. </p> / Thesis / Doctor of Philosophy (PhD)

<p> In this thesis, we focus on the rationing polices for the hotel room inventory control problems. Our study begins with a brief overview of revenue management in hotel industry, emphasizing the importance of room inventory control in revenue management problems. Mathematical models for controlling the room inventory in the literature are then reviewed along with recently developed game theoretic applications in revenue management. In game theoretic context, we establish three types of models to solve the hotel room inventory control problem in three different situations: 1) two-player two-fare-class static single-period game with complete information; 2) two-player two-fare-class dynamic multiple-period game with complete information; and 3) two-player two-fare-class single-period game with incomplete information.</p> <p> In the first situation, we find the existence of unique Nash equilibrium and Stackelberg equilibrium in the non-cooperative case. We provide the exact forms for these equilibria and corresponding conditions. Next, under the dynamic game settings, we provide the sufficient conditions for the unique Nash equilibrium. In the last situation, we consider the static single-period games with incomplete information and discuss the optimal strategies for the uninformed case, secret information case, private information case and public information case. The unique Bayesian Nash equilibrium in each case is found. We then analyze the values of different types of information and study their relations in different situations. Under each game theoretic setting, we present the managerial implications of our solutions along with the numerical examples. The thesis is concluded by a discussion of how game theory can is useful in hotel industry, and its relationship to other topics in revenue management.</p> / Thesis / Doctor of Philosophy (PhD)

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京都大学 / 新制・課程博士 / 博士(理学) / 甲第23691号 / 理博第4781号 / 新制||理||1684(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 佐々 真一, 准教授 武末 真二, 講師 DECHANT Andreas / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM