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In recent years, the abundance of information in 3D data has made the semantic segmentation of 3D point clouds a topic of great interest. However, current methods often rely solely on the original three-dimensional coordinates of the point cloud as input geometric features, leading to poor generalization performance. Additionally, occlusion of the point cloud data can negatively impact segmentation accuracy when only local information is considered. To address these issues, this paper proposes a network named LGFF-Net. To fully utilize the original information of point clouds, we designed a Local Feature Aggregation (LFA) module that treats geometric and semantic information equally and preserves the original properties while cross-augmenting them. On the other hand, we proposed a simple and effective Global Feature Extraction (GFE) module to extract global features. Finally, we hierarchically fuse local and global features using a U-shaped segmentation structure. Compared to state-of-the-art networks, our method achieves competitive results on several benchmark datasets, including Semantic Topographic Point Labeling-Synthetic 3D, Toronto_3D, Stanford Large 3-D Indoor Space, and ScanNet. We also conduct multiple ablation experiments to validate the efficacy of LGFF-Net.

The ferromagnetic thin-film elements can be prepared to form a "diamond" remanent state that contains two vortices with opposite circulation and with the same or opposite core polarities. The vortex polarity could influence their normal modes through the magnetostatic interactions between two vortices. In this paper, micromagnetic simulations, combined with Fourier techniques, are employed to study the spin-wave (SW) modes excited in a submicron Permalloy ellipse with a vortex pair configuration. After the application of an inplane Gaussian field pulse, it is found that a series of azimuthal SW modes is excited and the high-order harmonics of SW modes are strongly dependent of the core polarities due to the dynamic magnetic interactions between the two vortices. [ABSTRACT FROM AUTHOR]

In magnetic nanostructures, one usually uses a magnetic field to commute between two resistance (R) states. A less common but technologically more interesting alternative to achieve R-switching is to use an electrical current, preferably of low intensity. Such current-induced switching (CIS) was recently observed in thin magnetic tunnel junctions and attributed to electromigration of atoms into/out of the insulator. Here, we study the CIS, electrical resistance, and magnetoresistance (MR) of thin MnIr/CoFe/AlOx/CoFe tunnel junctions. The CIS effect at room temperature amounts to 6.9% R-change between the high and low states and is attributed to nanostructural rearrangements of metallic ions in the electrode/barrier interfaces. After switching to the low R-state, some electromigrated ions return to their initial sites through two different energy channels. A low (high) energy barrier of ~0.13 eV (~0.85 eV) was estimated. Ionic electromigration then occurs through two microscopic processes associated with different types of ions sites/defects. Measurements under an external magnetic field showed an additional intermediate R-state due to the simultaneous conjugation of the MR (magnetic) and CIS (structural) effects [ABSTRACT FROM PUBLISHER]

We present a micromagnetic simulation for detection of magnetic labels modulated by an ac magnetic field. As the sensing element, spin valves with synthetic ferrimagnetic (SF) free and pinned layers are optimized. At lower fields, the sensors with SF free layers show linear transfer curves, demonstrating a coherent switching due to the strong antiferromagnetic coupling inside the SF free layers. The sensor offset field can be reduced by tuning the effective thickness of SF free and pinned layers. Magnetic simulation for the detection of 250-nm magnetic labels with this sensor shows a linear giant magnetoresistive signal dependence on the number of particles. [ABSTRACT FROM AUTHOR]

Spin-transfer-induced spin-wave excitations in spin-valve nanopillars with perpendicular polarizers have been investigated by micromagnetic simulations. Two coexistent steady states with in-plane magnetizations are observed at small current. With the increased current, periodic oscillating spin waves with frequency from several to tens of gigahertz can be tuned by current alone. High-order harmonics with odd times of fundamental frequency only are observed in these periodic oscillations. The fundamental frequency decreases with the increased thickness of the free layer. Large current could excite chaotic spin waves. [ABSTRACT FROM AUTHOR]

A micromagnetic simulation for the detection of magnetic nanobeads by planar Hall sensors is presented. The calculated dipole field created by the polarized nanobeads shows the strong dependence on the distance from beads to the sense plane. In this simulation, nonuniform dipole field, random configuration of beads, and experimental parameters of device were used. Micromagnetic calculation shows the linear signal response to the bead number. This linear behavior is insensitive to the random distribution of beads, but is sensitive to the bead number, indicating the possible application to quantitative biomolecular recognition. [ABSTRACT FROM AUTHOR]