Nested Lattice Codes for Gaussian Relay Networks with Interference

In this paper, a class of relay networks is considered. We assume that, at a node, outgoing channels to its neighbors are orthogonal, while incoming signals from neighbors can interfere with each other. We are interested in the multicast capacity of these networks. As a subclass, we first focus on Gaussian relay networks with interference and find an achievable rate using a lattice coding scheme. It is shown that there is a constant gap between our achievable rate and the information theoretic cut-set bound. This is similar to the recent result by Avestimehr, Diggavi, and Tse, who showed such an approximate characterization of the capacity of general Gaussian relay networks. However, our achievability uses a structured code instead of a random one. Using the same idea used in the Gaussian case, we also consider linear finite-field symmetric networks with interference and characterize the capacity using a linear coding scheme.Comment: 23 pages, 5 figures, submitted to IEEE Transactions on Information Theor

Improving Sample Quality of Diffusion Models Using Self-Attention Guidance

Following generative adversarial networks (GANs), a de facto standard model for image generation, denoising diffusion models (DDMs) have been actively researched and attracted strong attention due to their capability to generate images with high quality and diversity. However, the way the internal self-attention mechanism works inside the UNet of DDMs is under-explored. To unveil them, in this paper, we first investigate the self-attention operations within the black-boxed diffusion models and build hypotheses. Next, we verify the hypotheses about the self-attention map by conducting frequency analysis and testing the relationships with the generated objects. In consequence, we find out that the attention map is closely related to the quality of generated images. On the other hand, diffusion guidance methods based on additional information such as labels are proposed to improve the quality of generated images. Inspired by these methods, we present label-free guidance based on the intermediate self-attention map that can guide existing pretrained diffusion models to generate images with higher fidelity. In addition to the enhanced sample quality when used alone, we show that the results are further improved by combining our method with classifier guidance on ImageNet 128x128.Comment: Project Page: https://ku-cvlab.github.io/Self-Attention-Guidanc

DVC analysis of a polymer material subjected to tensile loading with synchrotron radiation tomography

Subsurface deformation behavior of a polymeric material is studied through the digital volume correlation (DVC) technique. Fundamental principles of the DVC technique are presented and the supplemental state-of-the-art algorithmic schemes to improve the efficiency and accuracy of the DVC analysis are also introduced. Tensile tests on an epoxy material are performed in conjunction with synchrotron radiation tomography. In order to create randomly distributed grayscale values in the tomograms for the following image analysis, microscale high-density particles are embedded when the epoxy specimens are fabricated. 3D tomographic images taken at multiple loading steps are utilized for the DVC analysis. The performance of the present DVC analysis is evaluated with the experimental data

Service-led Catch-Up in the Indian Economy: Alternative Hypotheses on Tertiarization and the Leapfrogging Thesis

The experience of India in economic catch-up is unique when compared to other countries. First, the catch-up process of India was not only service-led, but also accompanied by a decoupling between manufacturing and services. Second, productivity performance in the service sector was higher than in the manufacturing sector in terms of the level as well as growth rate. Finally, exports in IT services led the tertiarization of the Indian economy. From this perspective, the trajectory of the Indian catch-up can be characterized as path-creating. Existing hypotheses on tertiarization do not fully account for such aspects of the uniqueness of the Indian experience. The leapfrogging argument in Neo-Schumpeterian economics provides a more plausible explanation of the Indian experience. The ICT revolution and the shift from hardware systems to client-server systems have created new markets for the global services trade. This paradigm shift lowered the costs of entry, including fixed investments, for Indian IT service firms and helped close the experience and skill gaps quickly. The industry-specific characteristics of the IT services industry and the country-specific advantages of India further lowered the costs of entry. With steady strategic and organizational innovations, Indian IT service firms succeeded in securing competitive advantages in the global market

Mesoscopic Stacking Reconfigurations in Stacked van der Waals Film

Mesoscopic-scale stacking reconfigurations are investigated when van der Waals films are stacked. We have developed a method to visualize complicated stacking structures and mechanical distortions simultaneously in stacked atom-thick films using Raman spectroscopy. In the rigid limit, we found that the distortions originate from the transfer process, which can be understood through thin film mechanics with a large elastic property mismatch. In contrast, with atomic corrugations, the in-plane strain fields are more closely correlated with the stacking configuration, highlighting the impact of atomic reconstructions on the mesoscopic scale. We discovered that the grain boundaries don`t have a significant effect while the cracks are causing inhomogeneous strain in stacked polycrystalline films. This result contributes to understanding the local variation of emerging properties from moir\'e structures and advancing the reliability of stacked vdW material fabrication.Comment: 38 pages, 23 figure

Non-linear dynamic analysis of reinforced concrete bridge columns under vehicle impact loadings

A 3D nonlinear impact analysis was performed for reinforced concrete bridge columns under truck impact loadings. Three different boundary conditions were considered to investigate the effect of superstructures on the integral column during impact. Fixed bottom conditions and restraints in the loading direction at the top of the column (Model I) showed the largest damaged area. The dominant failure mode of the column was shear. However, Model II, which is equivalent to Model I with the top released, showed less damage, and the dominant failure modes were flexure rather than shear. In Model III, in which the effect of featured the superstructure was considered, the shear and flexural damage to the column were reduced due to the movement of the superstructures