Engineering topics

Li, Yuke

Publications and source records attributed to Li, Yuke.

4 records

DOE OSTI2024

Accelerating Lossy and Lossless Compression on Emerging BlueField DPU Architectures

Data compression has become a crucial technique in addressing performance bottlenecks caused by increasing data volumes in High-Performance Computing (HPC), Big Data, and Deep Learning (DL). Despite its potential to boost system performance, recent studies have identified significant challenges with existing compression methods, mainly due to their high computational demands amidst continuously growing data sizes. Concurrently, the advent of Data Processing Units (DPUs), equipped with programmable System-on-Chip (SoC) and specialized compression accelerators, offers a promising opportunity to alter the landscape of data compression. This paper explores the complexities and potential of leveraging NVIDIA BlueField DPUs to accelerate lossy and lossless compression. Towards this, we introduce PEDAL, an innovative library that leverages the hardware capabilities of DPUs to unify and optimize data compression designs. Moreover, we seamlessly co-design PEDAL with the popular MPICH MPI library, demonstrating up to 101x speedup in compression time and 88x decrease in communication latency. Drawing on these achievements, we share our experience with various research communities about accelerating data compression on DPUs in communication-oriented HPC scenarios.

Li, Yuke↗

DOE OSTI2023

Valence transition and termination-dependent surface states in the topological Kondo semimetal YbPtBi

Here, the Yb-terminated and Bi-terminated (111) surface electronic structure of topological Kondo semimetal YbPtBi is investigated using both density-functional-theory (DFT) -based calculations and angle-resolved photoemission spectroscopy (ARPES). The cleavage plane is found to be between Yb-layers and Bi-layers in both experiment and theory, and the broken inversion symmetry ensures the Yb-terminated surface does not mix with the Bi-terminated surface. The ARPES results at the Bi-terminated surface are similar to those reported for YPtBi or LuPtBi, and they can be well explained using DFT calculations assuming trivalent Yb atoms. In contrast, at the Yb-terminated surface, a trivalent to divalent transition and reduced hybridization with conduction electrons for the topmost Yb atoms are observed, as a result of reduced bonding with Bi-atoms. In addition, the Fermi arc features induced by the triply degenerate-points, which are missing at the Bi-terminated surface, can be identified at the Yb-terminated surface. Our study demonstrates unambiguously the reconstruction of surface electronic structure due to the valence transition of the lanthanide element in a Kondo lattice system.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Anomalous Ferromagnetic Behavior in Orthorhombic Li 3 Co 2 SbO 6

Monoclinic Li 3 Co 2 SbO 6 has been proposed as a Kitaev spin liquid candidate and investigated intensively, whereas the properties of its polymorph, the orthorhombic phase, are less known. In this work, we report the magnetic properties of orthorhombic Li 3 Co 2 SbO 6 as revealed by dc and ac magnetic susceptibility, muon spin relaxation (μSR), and neutron diffraction measurements. Successive magnetic transitions at 115, 89, and 71 K were observed in the low-field dc susceptibility measurements. The transitions below T N (115 K) are suppressed at higher applied fields. However, zero-field ac susceptibility measurements reveal distinct frequency-independent transitions at about 114, 107, 97, 79, and 71 K. A long-range magnetic ordered state was confirmed by specific heat, μSR, and neutron diffraction measurements, all indicating a single transition at about 115 K. The discrepancy between different measurements is attributed to possible stacking faults and/or local disorders of the ferromagnetic zigzag chains, resulting in ferromagnetic boundaries within the overall antiferromagnetic matrix.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Universal Bound to the Amplitude of the Vortex Nernst Signal in Superconductors

A liquid of superconducting vortices generates a transverse thermoelectric response. This Nernst signal has a tail deep in the normal state due to superconducting fluctuations. Here, we present a study of the Nernst effect in two-dimensional heterostructures of Nb-doped strontium titanate (STO) and in amorphous MoGe. Additionally, the Nernst signal generated by ephemeral Cooper pairs above the critical temperature has the magnitude expected by theory in STO. On the other hand, the peak amplitude of the vortex Nernst signal below Tc is comparable in both and in numerous other superconductors despite the large distribution of the critical temperature and the critical magnetic fields. In four superconductors belonging to different families, the maximum Nernst signal corresponds to an entropy per vortex per layer of ≈kBln 2 .

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗