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32. Supervised Contrastive Learning for 3D Cross-Modal Retrieval.

Author

Choo, Yeon-Seung, Kim, Boeun, Kim, Hyun-Sik, and Park, Yong-Suk

Subjects
SUPERVISED learning, POINT cloud, ASSETS (Accounting)
Abstract

Interoperability between different virtual platforms requires the ability to search and transfer digital assets across platforms. Digital assets in virtual platforms are represented in different forms or modalities, such as images, meshes, and point clouds. The cross-modal retrieval of three-dimensional (3D) object representations is challenging due to data representation diversity, making common feature space discovery difficult. Recent studies have been focused on obtaining feature consistency within the same classes and modalities using cross-modal center loss. However, center features are sensitive to hyperparameter variations, making cross-modal center loss susceptible to performance degradation. This paper proposes a new 3D cross-modal retrieval method that uses cross-modal supervised contrastive learning (CSupCon) and the fixed projection head (FPH) strategy. Contrastive learning mitigates the influence of hyperparameters by maximizing feature distinctiveness. The FPH strategy prevents gradient updates in the projection network, enabling the focused training of the backbone networks. The proposed method shows a mean average precision (mAP) increase of 1.17 and 0.14 in 3D cross-modal object retrieval experiments using ModelNet10 and ModelNet40 datasets compared to state-of-the-art (SOTA) methods. [ABSTRACT FROM AUTHOR]

Published
2024
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50. Transport properties of indium-alloyed and indium telluride nanostructured bismuth telluride.

Author

Kim, Hyun-Sik, Heinz, Nicholas A., Gibbs, Zachary M., Kim, Junsu, and Snyder, G. Jeffrey

Abstract

Nanostructured thermoelectric materials ideally reduce lattice thermal conductivity without harming the electrical properties. Thus, to truly improve the thermoelectric performance, the quality factor, which is proportional to the weighted mobility divided by the lattice thermal conductivity of the material, must be improved. Precipitates of In2Te3 form in the state-of-the-art Bi2Te3 with crystallographic alignment to the Bi2Te3 structure. Like epitaxy in films, this can be called endotaxy in solids. This natural epitaxy in a 3-dimensional solid is ideally situated to scatter phonons but produces minimal electronic scattering and, therefore, maintains high mobility. Here, we study the effects of In-alloying in Bi2Te3 at high In concentrations (about 4 at%), enough to produce the endotaxial microstructure. It is found that such concentrations of indium in Bi2Te3 significantly alter the electronic structure, reducing the effective mass and weighted mobility so significantly as to effectively destroy the thermoelectric properties even though the lattice thermal conductivity is successfully reduced. [ABSTRACT FROM AUTHOR]

Published
2024
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