703 research outputs found
A Kind of Nanofluid Consisting of Surface-Functionalized Nanoparticles
A method of surface functionalization of silica nanoparticles was used to prepare a kind of stable nanofluid. The functionalization was achieved by grafting silanes directly to the surface of silica nanoparticles in silica solutions (both a commercial solution and a self-made silica solution were used). The functionalized nanoparticles were used to make nanofluids, in which well-dispersed nanoparticles can keep good stability. One of the unique characteristics of the nanofluids is that no deposition layer forms on the heated surface after a pool boiling process. The nanofluids have applicable prospect in thermal engineering fields with the phase-change heat transfer
Binary Stars in the New Millennium
Binary stars are as common as single stars. Binary stars are of immense
importance to astrophysicists because that they allow us to determine the
masses of the stars independent of their distances. They are the cornerstone of
the understanding of stellar evolutionary theory and play an essential role in
cosmic distance measurement, galactic evolution, nucleosynthesis and the
formation of important objects such as cataclysmic variable stars, X-ray
binaries, Type Ia supernovae, and gravitational wave-producing double compact
objects. In this article, we review the significant theoretical and
observational progresses in addressing binary stars in the new millennium.
Increasing large survey projects have led to the discovery of enormous numbers
of binary stars, which enables us to conduct statistical studies of binary
populations, and therefore provide unprecedented insight into the stellar and
binary evolution physics. Meanwhile, the rapid development of theoretical
concepts and numerical approaches for binary evolution have made a substantial
progress on the alleviation of some long-standing binary-related problems such
as the stability of mass transfer and common envelope evolution. Nevertheless,
it remains a challenge to have a full understanding of fundamental problems of
stellar and binary astrophysics. The upcoming massive survey projects and
increasingly sophisticated computational methods will lead to future progress.Comment: An invited review published in Progress in Particle and Nuclear
Physics; An open access to the published version, see
https://doi.org/10.1016/j.ppnp.2023.10408
Enhancing Topic Extraction in Recommender Systems with Entropy Regularization
In recent years, many recommender systems have utilized textual data for
topic extraction to enhance interpretability. However, our findings reveal a
noticeable deficiency in the coherence of keywords within topics, resulting in
low explainability of the model. This paper introduces a novel approach called
entropy regularization to address the issue, leading to more interpretable
topics extracted from recommender systems, while ensuring that the performance
of the primary task stays competitively strong. The effectiveness of the
strategy is validated through experiments on a variation of the probabilistic
matrix factorization model that utilizes textual data to extract item
embeddings. The experiment results show a significant improvement in topic
coherence, which is quantified by cosine similarity on word embeddings
Characterization and Correction of the Scattering Background Produced by Dust on the Objective Lens of the Lijiang 10-cm Coronagraph
Scattered light from the objective lens, directly exposed to the intense
sunlight, is a dominant source of stray light in internally occulted
coronagraphs. The variable stray light, such as the scatter from dust on the
objective lens, can produce varying scattering backgrounds in coronal images,
significantly impacting image quality and data analysis. Using data acquired by
the Lijiang 10-cm Coronagraph, the quantitative relationship between the
distribution of dust on the objective lens and the resulting scattering
backgrounds background is analyzed. Two empirical models for the scattering
background are derived, and used to correct the raw coronal data. The second
model, which depends on three parameters and performs better, shows that the
scattering-background distribution varies with angle, weakens with increasing
height, and enhances with increasing dust level on the objective lens.
Moreover, we find that the dust on the center of the objective lens can
contribute more significantly to the scattering background than on the edge.
This study not only quantitatively confirms the significant impact of the stray
light produced by dust on the objective lens of the coronagraph, but also
corrects the coronal data with this stray light for the first time. Correcting
for dust-scattered light is crucial for the high-precision calibration of
ground-based coronagraph data, enabling a more accurate analysis of coronal
structures. Furthermore, our model is envisioned to support the provision of
reliable observational data for future routine coronal magnetic-field
measurements using ground-based coronagraphs.Comment: 18 pages, 14 figrue
Perspective: Ferromagnetic Liquids
Mechanical jamming of nanoparticles at liquid–liquid interfaces has evolved into a versatile approach to structure liquids with solid-state properties. Ferromagnetic liquids obtain their physical and magnetic properties, including a remanent magnetization that distinguishes them from ferrofluids, from the jamming of magnetic nanoparticles assembled at the interface between two distinct liquids to minimize surface tension. This perspective provides an overview of recent progress and discusses future directions, challenges and potential applications of jamming magnetic nanoparticles with regard to 3D nano-magnetism. We address the formation and characterization of curved magnetic geometries, and spin frustration between dipole-coupled nanostructures, and advance our understanding of particle jamming at liquid–liquid interfaces
A study on compressive anisotropy and nonassociated flow plasticity of the AZ31 Magnesium Alloy in hot rolling
Effect of anisotropy in compression is studied on hot rolling of AZ31 magnesium alloy with a three-dimensional constitutive model based on the quadratic Hill48 yield criterion and nonassociated flow rule (non-AFR). The constitutive model is characterized by compressive tests of AZ31 billets since plastic deformations of materials are mostly caused by compression during rolling processes. The characterized plasticity model is implemented into ABAQUS/Explicit as a user-defined material subroutine (VUMAT) based on semi-implicit backward Euler\u27s method. The subroutine is employed to simulate square-bar rolling processes. The simulation results are compared with rolled specimens and those predicted by the von Mises and the Hill48 yield function under AFR. Moreover, strip rolling is also simulated for AZ31 with the Hill48 yield function under non-AFR. The strip rolling simulation demonstrates that the lateral spread generated by the non-AFR model is in good agreement with experimental data. These comparisons between simulation and experiments validate that the proposed Hill48 yield function under non-AFR provides satisfactory description of plastic deformation behavior in hot rolling for AZ31 alloys in case that the anisotropic parameters in the Hill48 yield function and the non-associated flow rule are calibrated by the compressive experimental results
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