4,645 research outputs found
First-principles study of spin orbit coupling contribution to anisotropic magnetic interaction
Anisotropic magnetic exchange interactions lead to a surprisingly rich
variety of the magnetic properties. Considering the spin orbit coupling (SOC)
as perturbation, we extract the general expression of a bilinear spin
Hamiltonian, including isotropic exchange interaction, antisymmetric
Dzyaloshinskii-Moriya (DM) interaction and symmetric term. Though it
is commonly believed that the magnitude of the DM and interaction
correspond to the first and second order of SOC strength
respectively, we clarify that the term proportional to also has
contribution to DM interaction. Based on combining magnetic force theorem and
linear-response approach, we have presented the method of calculating
anisotropic magnetic interactions, which now has been implemented in the open
source software WienJ. Furthermore, we introduce another method which could
calculate the first and second order SOC contribution to the DM interaction
separately, and overcome some shortcomings of previous methods. Our methods are
successfully applied to several typical weak ferromagnets for , and
transition metal oxides. We also predict the conditions where the DM
interactions proportional to are symmetrically forbidden while the
DM interactions proportional to are nonzero, and believe that it
is widespread in certain magnetic materials
Open Compound Domain Adaptation with Object Style Compensation for Semantic Segmentation
Many methods of semantic image segmentation have borrowed the success of open
compound domain adaptation. They minimize the style gap between the images of
source and target domains, more easily predicting the accurate pseudo
annotations for target domain's images that train segmentation network. The
existing methods globally adapt the scene style of the images, whereas the
object styles of different categories or instances are adapted improperly. This
paper proposes the Object Style Compensation, where we construct the
Object-Level Discrepancy Memory with multiple sets of discrepancy features. The
discrepancy features in a set capture the style changes of the same category's
object instances adapted from target to source domains. We learn the
discrepancy features from the images of source and target domains, storing the
discrepancy features in memory. With this memory, we select appropriate
discrepancy features for compensating the style information of the object
instances of various categories, adapting the object styles to a unified style
of source domain. Our method enables a more accurate computation of the pseudo
annotations for target domain's images, thus yielding state-of-the-art results
on different datasets.Comment: Accepted by NeurlPS202
Hybrid intelligent deep kernel incremental extreme learning machine based on differential evolution and multiple population grey wolf optimization methods
Focussing on the problem that redundant nodes in the kernel incremental extreme learning machine (KI-ELM) which leads to ineffective iteration increase and reduce the learning efficiency, a novel improved hybrid intelligent deep kernel incremental extreme learning machine (HI-DKIELM) based on a hybrid intelligent algorithms and kernel incremental extreme learning machine is proposed. At first, hybrid intelligent algorithms are proposed based on differential evolution (DE) and multiple population grey wolf optimization (MPGWO) methods which used to optimize the hidden layer neuron parameters and then to determine the effective hidden layer neurons number. The learning efficiency of the algorithm is improved by reducing the network complexity. Then, we bring in the deep network structure to the kernel incremental extreme learning machine to extract the original input data layer by layer gradually. The experiment results show that the HI-DKIELM methods proposed in this paper with more compact network structure have higher prediction accuracy and better ability of generation compared with other ELM methods
Effect of heat input on nanomechanical properties of wire-arc additive manufactured Al 4047 alloys
Heat input is one of the most important process parameters during additive manufacturing (AM). It is of great significance to understand the effect of heat input on the microstructure and nanomechanical properties, as well as the underlying mechanisms. Wire-arc additive manufactured (WAAM-ed) Al 4047 alloys under different heat inputs were produced and studied in this work. The as-manufactured Al alloys showed hypoeutectic microstructure that consisted of primary Al (α-Al) dendrite and ultrafine Al–Si eutectic. The effect of heat input on hardness and strain rate sensitivity (SRS) were investigated through nanoindentation. The nanohardness decreased with the increasing heat input, in accordance with the trend of yield strength and microhardness in the previous studies, in which the mechanism was usually explained by the grain growth model and Hall-Petch relationship. This work suggests a distinct mechanism regarding the effect of heat input on nanohardness, which is the enhanced solid solution strengthening produced by lower heat input. In addition, the heat input had little effect on the SRS and activation volume. It is hoped that this study leads to new insights into the understanding of the relation between heat input and nanomechanical properties, and further benefits to improve the targeted mechanical properties and engineering applications of the AM-ed materials.publishedVersio
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