(E)-Isopentyl 3-(3,4-dihy­droxy­phen­yl)­acrylate

The title compound, C14H18O4, a derivative of caffeic acid, has an E configuration about the C=C bond. The benzene ring is almost coplanar with the C=C—C(O)—O—C linker [maximum deviation = 0.050 (2) Å], making a dihedral angle of only 4.53 (2)°. In the mol­ecule, the adjacent hy­droxy groups form an O—H⋯O inter­action. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds, generating a chain propagating in the [110] direction

Application of the disk instability model to all Quasi-Periodic Eruptions

After the first quasi-periodic eruptions (QPEs, GSN069) was reported in 2019, four other sources have been identified as QPEs or its candidate. However, the physics behind QPEs is still unclear so far, though several models have been proposed. Pan et al. (2022) proposed an instability model for the accretion disk with magnetically driven outflows in the first QPEs GSN 069, which is able to reproduce both the light curve and the evolution of spectrum fairly well. In this work, we exploit this model to all the QPEs. We imporve the calculations of the spectrum of disk by introducing a hardening factor, which is caused by the deviation of opacity from the blackbody. We find that the light curves and evolution of the spectra of the four QPEs or candidate can all be well reproduced by our model calculations.Comment: 8 pages, 7 figures, accepted for publication in Ap

Improved alpha shape-based continuum method for long-term density propagation

This paper presents an improved alpha shape-based linear interpolation method, and an improved binning method within the continuum method framework for accurate and efficient planar phase space long-term density propagation. The density evolution equation is formulated for the continuum density propagation under the influence of the solar radiation pressure and Earth’s oblateness using semi-analytical equations. The concept of the alpha shape is included to get accurate interpolated density within the non-convex hull enclosing all the samples for the highly deformed and elongated density distribution. The improved binning method increases the density accuracy by considering the variant nonlinearity of the density within each alpha shape triangulation, which calculates the joint and marginal density as the weighted sum of density weights per bin area and per bin width, respectively. The suitable sample number for the continuum method and the suitable grid number for performing the linear interpolation are selected by trading off the density accuracy and the computational effort. The superiority of the improved alpha shape-based continuum method is demonstrated for accurate and efficient density propagation in the context of the high-altitude and high area-to-mass ratio satellite long-term propagation

A multi-segment alpha shape-based continuum method for long-term density propagation with bifurcation

This paper studies the bifurcation case for the planar phase space long-term density propagation problem, and presents an improved multi-segment continuum method for accurate and efficient long-term density propagation, by introducing the multi-segment method to the alpha shape triangulation-based linear interpolation method. The density evolution equation is formulated for the continuum density propagation under the influence of the solar radiation pressure and Earth’s oblateness using semi-analytical equations. For the overall highly deformed and elongated density distribution for the bifurcation case, the multi-segment method is introduced to the alpha shape-based linear interpolation method to get accurate interpolated density, by dividing the overall density distribution into multiple segments and performing the linear interpolation within the actual non-convex hull of the sample distribution for each segment. Four segments are divided for the overall density distribution considering the Hamiltonian dynamic constraints on the solar angle domain. The superiority of the improved multi-segment alpha shape-based continuum method is demonstrated for accurate and efficient density propagation for the bifurcation case in the context of the high-altitude and high area-to-mass ratio satellite long-term propagation

FlattenQuant: Breaking Through the Inference Compute-bound for Large Language Models with Per-tensor Quantization

Large language models (LLMs) have demonstrated state-of-the-art performance across various tasks. However, the latency of inference and the large GPU memory consumption of LLMs restrict their deployment performance. Recently, there have been some efficient attempts to quantize LLMs, yet inference with large batch size or long sequence still has the issue of being compute-bound. Fine-grained quantization methods have showcased their proficiency in achieving low-bit quantization for LLMs, while requiring FP16 data type for linear layer computations, which is time-consuming when dealing with large batch size or long sequence. In this paper, we introduce a method called FlattenQuant, which significantly reduces the maximum value of the tensor by flattening the large channels in the tensor, to achieve low bit per-tensor quantization with minimal accuracy loss. Our experiments show that FlattenQuant can directly use 4 bits to achieve 48.29% of the linear layer calculation in LLMs, with the remaining layers using 8 bits. The 4-bit matrix multiplication introduced in the FlattenQuant method can effectively address the compute-bound caused by large matrix calculation. Our work achieves up to 2$\times$ speedup and 2.3$\times$ memory reduction for LLMs with negligible loss in accuracy

Highly sensitive magnetic properties and large linear magnetoresistance in antiferromagnetic CrxSe(0.875\lex\le1)single crystals

CrxSe (x\le1) is a class of quasi-layered binary compounds with potential applications in spintronics due to its intriguing antiferromagnetic properties. In this work, CrxSe single crystals with high Cr content (x=0.87, 0.91 and 0.95) were grown, and their magnetic and transport properties were investigated in detail. It is found that with small increase of Cr content, the N\'eel temperature (TN) of the samples can dramatically increase from 147 K to 257 K, accompanied with obvious changes in the magnetic anisotropy and hysteresis. The phenomena of field-induced spin-flop transitions were unveiled in these alloys, indicating their comparatively low anisotropy. The magnetoresistance (MR) of the three compounds showed positive dependence at low temperatures and particularly, non-saturated linear positive MR was observed in Cr0.91Se and Cr0.95Se, with a large value of 16.2% achieved in Cr0.91Se (10K, 9T). The calculated Fermi surface and MR showed that the quasi-linear MR is a product of carrier compensation. Our work revealed highly sensitive magnetic and transport properties in the Cr-Se compounds, which can lay foundation when constructing further antiferromagnetic spintronic devices based on them