モーション特徴抽出と多変量解析に基づくジェスチャ認識

This Thesis proposes a user-independent gesture recognition system, which operates in real-time under real-world conditions, and as such could be useful as a building block in a more sophisticated human-computer interface. In the proposed system, efficient and robust extraction/representation of motion patterns is achieved by utilizing relative-motion dependent primitive features. This bottom-up approach for primitive feature extraction in the early processing stage of the system is combined with multivariate analysis based top-down learning and Dynamic Buffer Structures for online gesture segmentation. The proposed system exhibits good generalization abilities even if trained with only a few samples. In test experiments conducted on several different data sets it was observed that system’s performance is robust to changes in the background and in the illumination conditions, to subjects’ body size and external appearance, able to cope with the non-uniformity in the performance speed of the gestures, etc., all of which are important conditions for a successful application in human-computer interfaces. Gesture recognition in the present system is not restricted to hand gestures only – larger-scale whole body gestures can be processed simultaneously with relatively smaller-scale hand or head gestures. No manual segmentation of any kind or use of markers, sensors, etc. is necessary. Also, since no domain knowledge is utilized, the system proposed here can be easily adapted and applied to other problems involving motion recognition.Thesis (Ph. D. in Engineering)--University of Tsukuba, (A), no. 2374, 2000.3.24Bibliography: p. 82-87"List of publication": p.88Titlepage,Abstract,Acknowledgments,Contents -- List of Figures -- Chapter 1. Introduction -- Chapter 2. Related Work -- Chapter 3. Primitive features for relative motion dependent feature extraction -- Chapter 4. Multivariate analysis based learning -- Chapter 5. Online gesture segmentation by Dynamic Buffer Structures -- Chapter 6. Experimental results -- Chapter 7. Conclusion and further work -- BIBLIOGRAPHY -- LIST OF PUBLICATION

Nouvelles applications des proazaphosphatranes et molécules apparentées : vers la catalyse en espace confiné et en milieu hétérogène

The work described in this PhD thesis deals with the chemistry of proazaphosphatrane-type superbases, which are highly reactive bicyclic phosphorous systems largely applied in catalysis. The main goal of these investigations was to devise new applications for their use in catalysis. In this way, several strategies were followed, with an emphasis on their molecular confinement and use in interfacial catalytic systems. In the first part, the manuscript describes the synthesis and characterisation of a supramolecular proazaphosphatrane obtained via the enclosing of a proazaphosphatrane moiety in a hemicryptophane-type macrobicyclic cavity. In parallel, the semi-preparative scale resolution of two macrobicyclic intermediates allowed us to assign their absolute configurations. In the second part, the synthesis and characterisation of a new class of superbases supported on mesoporous silica was achieved. The synthesis was followed by their application in base-catalysed organic reactions. The last part reports the use of their conjugate acids, or azaphosphatranes, in phase transfer catalysis. Their usefulness as achiral phase transfer agents in four relevant reactions was thus determined. The thesis ends with an introduction into asymmetric phase transfer catalysis, using enantiopure azaphosphatranes.Le travail qui est décrit dans ce manuscrit de thèse traite de la chimie des superbases de type proazaphosphatranes, systèmes phosphorés bicycliques très utilisés en catalyse. L’objectif des investigations qui ont été menées à été d’ouvrir de nouvelles voies d’applications de ces catalyseurs. Afin de satisfaire cet objectif, plusieurs stratégies ont été envisagées. D’une part par la mise en confinement de la structure proazaphosphatrane et l’étude de l’influence de ce confinement sur la réactivité intrinsèque du proazaphosphatrane, et d’autre part par la catalyse en conditions bi-phasiques, que ce soit à l’interface entre une phase liquide et un solide ou entre deux phases liquides non-miscibles. Les recherches se sont orientées dans un premier temps sur la synthèse et la caractérisation complète d’un proazaphosphatrane supramoléculaire, obtenu par la fonctionnalisation par un proazaphosphatrane de la cavité supramoléculaire d’un récepteur macrobicyclique. Les séparations semi-préparatives des deux énantiomères d’un intermédiaire et de la molécule phosphorée finale ont également été réalisées, séparations qui ont permis de réaliser l’attribution des configurations absolues des deux structures macrobicycliques. La synthèse d’une famille de catalyseurs de type proazaphosphatrane supportés sur silice mésoporeuse a ensuite été réalisée, suivie de sa caractérisation texturale et structurale par les procédés physico-chimiques habituels, et enfin de sa mise en application dans des réactions d’intérêts de la synthèse organique. En dernier lieu, l’exploitation de la forme acide conjuguée des proazaphosphatranes, dite forme azaphosphatrane, dans des réactions de catalyse par transfert de phase a été entreprise. Il a ainsi put être démontré leur activité en tant qu’agent de transfert dans le cadre de quatre réactions significatives de la catalyse par transfert de phase en version racémique. Ce travail de thèse s’est finalement terminé par une ouverture vers la catalyse par transfert de phase en version asymétrique, par le biais de l’utilisation d’azaphosphatranes chiraux énantiopurs

Which visual questions are difficult to answer? Analysis with Entropy of Answer Distributions

We propose a novel approach to identify the difficulty of visual questions for Visual Question Answering (VQA) without direct supervision or annotations to the difficulty. Prior works have considered the diversity of ground-truth answers of human annotators. In contrast, we analyze the difficulty of visual questions based on the behavior of multiple different VQA models. We propose to cluster the entropy values of the predicted answer distributions obtained by three different models: a baseline method that takes as input images and questions, and two variants that take as input images only and questions only. We use a simple k-means to cluster the visual questions of the VQA v2 validation set. Then we use state-of-the-art methods to determine the accuracy and the entropy of the answer distributions for each cluster. A benefit of the proposed method is that no annotation of the difficulty is required, because the accuracy of each cluster reflects the difficulty of visual questions that belong to it. Our approach can identify clusters of difficult visual questions that are not answered correctly by state-of-the-art methods. Detailed analysis on the VQA v2 dataset reveals that 1) all methods show poor performances on the most difficult cluster (about 10% accuracy), 2) as the cluster difficulty increases, the answers predicted by the different methods begin to differ, and 3) the values of cluster entropy are highly correlated with the cluster accuracy. We show that our approach has the advantage of being able to assess the difficulty of visual questions without ground-truth (i.e. the test set of VQA v2) by assigning them to one of the clusters. We expect that this can stimulate the development of novel directions of research and new algorithms. Clustering results are available online at https://github.com/tttamaki/vqd .Comment: accepted by IEEE access available at https://doi.org/10.1109/ACCESS.2020.3022063 as "An Entropy Clustering Approach for Assessing Visual Question Difficulty