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Urban road network information is an important part of modern spatial information infrastructure and is crucial for high-precision navigation map production and unmanned driving. Synthetic aperture radar (SAR) is a widely used remote-sensing data source, but the complex structure of road networks and the noises in images make it very difficult to extract road information through SAR images. We developed a new method of extracting road network information from SAR images by considering angular (A) and texture (T) features in the sliding windows and points of interest (POIs, or P), and we named this method ATP-ROAD. ATP-ROAD is a sliding window-based semi-automatic approach that uses the grayscale mean, grayscale variance, and binary segmentation information of SAR images as texture features in each sliding window. Since POIs have much-duplicated information, this study also eliminates duplicated POIs considering distance and then selects a combination of POI linkages by discerning the direction of these POIs to initially determine the road direction. The ATP-ROAD method was applied to three experimental areas in Shanghai to extract the road network using China’s Gaofen-3 imagery. The experimental results show that the extracted road network information is relatively complete and matches the actual road conditions, and the result accuracy is high in the three different regions, i.e., 89.57% for Area-I, 96.88% for Area-II, and 92.65% for Area-III. Our method together with our extraction software can be applied to extract information about road networks from SAR images, providing an alternative for enriching the variety of road information.

In light of the increasing availability of commercial high-resolution imaging sensors, automatic interpretation tools are needed to extractroad features. Currently, many approaches for road extraction are available, but it is acknowledged that there is no single method that would be successful in extracting all types of roads from any remotely sensed imagery. In this paper, a novel classification of roads is proposed, based on both the roads’ geometrical, radiometric properties and the characteristics of the sensors. Subsequently, a general road tracking framework is proposed, and one or more suitable road trackers are designed or combined for each type of roads. Extensive experiments are performed to extract roads from aerial/satellite imagery, and the results show that a combination strategy can automatically extract more than 60% of the total roads from very high resolution imagery such as QuickBird and DMC images, with a time-saving of approximately 20%, and acceptable spatial accuracy. It is proven that a combination of multiple algorithms is more reliable, more efficient and more robust for extracting road networks from multiple-source remotely sensed imagery than the individual algorithms.

Photonic spin texture (PST), the spatial distribution of the spin angular momentum of light, is connected to unique properties of light, such as optical skyrmions and topological optical N-invariants. There has been recent progress on the generation and manipulation of PST using various methodologies. However, a challenge remains for the sub-wavelength characterization of PST. Here, we demonstrate nitrogen–vacancy (NV) centers in diamond as nanoscale quantum sensors for imaging the PST of a beam with orbital angular momentum. Leveraging the coherent interaction between photon spin and NV center electron spin at cryogenic temperature (77 K), and using the Hahn-echo magnetometry technique, we experimentally demonstrate the imprinting of the PST on the quantum phase shift of NV centers. Our work can lead to the development of a quantum imaging platform capable of characterization of the spin texture of light at sub-wavelength scales.

Topological aspects of the geometry of DNA and similar chiral molecules have received a lot of attention, but the topology of their electronic structure is less explored. Previous experiments revealed that DNA can efficiently filter spin-polarized electrons between metal contacts, a process called chiral-induced spin selectivity. However, the underlying correlation between chiral structure and electronic spin remains elusive. In this work, we reveal an orbital texture in the band structure, a topological characteristic induced by the chirality. We found that this orbital texture enables the chiral molecule to polarize the quantum orbital. This orbital polarization effect (OPE) induces spin polarization assisted by the spin–orbit interaction of a metal contact and leads to magnetoresistance and chiral separation. The orbital angular momentum of photoelectrons also plays an essential role in related photoemission experiments. Beyond chiral-induced spin selectivity, we predict that the orbital polarization effect could induce spin-selective phenomena even in achiral but inversion-breaking materials. An orbital polarization effect is proposed to understand chiral-induced spin selectivity.

The Rashba effect is spin degeneracy lift originated from spin–orbit coupling under inversion symmetry breaking and has been intensively studied for spintronics applications. However, easily implementable methods and corresponding materials for directional controls of Rashba splitting are still lacking. Here, we propose organic–inorganic hybrid metal halide perovskites as 3D Rashba systems driven by bulk ferroelectricity. In these materials, it is shown that the helical direction of the angular momentum texture in the Rashba band can be controlled by external electric fields via ferroelectric switching. Our tight-binding analysis and first-principles calculations indicate that [Formula] and [Formula] Rashba bands directly coupled to ferroelectric polarization emerge at the valence and conduction band edges, respectively. The coexistence of two contrasting Rashba bands having different compositions of the spin and orbital angular momentum is a distinctive feature of these materials. With recent experimental evidence for the ferroelectric response, the halide perovskites will be, to our knowledge, the first practical realization of the ferroelectric-coupled Rashba effect, suggesting novel applications to spintronic devices.

The emerging field of orbitronics aims to generate and control orbital angular momentum for information processing. Chiral crystals are promising orbitronic materials because they have been predicted to host monopole-like orbital textures, where the orbital angular momentum aligns isotropically with the electron’s crystal momentum. However, such monopoles have not yet been directly observed in chiral crystals. Here, we use circular dichroism in angle-resolved photoelectron spectroscopy to image orbital angular momentum monopoles in the chiral topological semimetals PtGa and PdGa. The spectra show a robust polar texture that rotates around the monopole as a function of photon energy. This is a direct consequence of the underlying magnetic orbital texture and can be understood from the interference of local atomic contributions. Moreover, we also demonstrate that the polarity of the monopoles can be controlled through the structural handedness of the host crystal by imaging orbital angular moment monopoles and antimonopoles in the two enantiomers of PdGa, respectively. Our results highlight the potential of chiral crystals for orbitronic device applications, and our methodology could enable the discovery of even more complicated nodal orbital angular momentum textures that could be exploited for orbitronics. Chiral topological materials have been predicted to host orbital angular momentum monopoles, which can be useful for orbitronics applications. Now such monopoles have been imaged in chiral materials.

We explore the spin texture dynamics of a harmonically trapped spin-1 Bose–Einstein condensate with Rashba spin–orbit coupling and ferromagnetic spin-exchange interactions under a sinusoidally varying magnetic field along the x -direction. This interplay yields an intrinsic spin texture in the ground state, forming a linear chain of alternating skyrmions at the saddle points of the magnetic field. Our study analyzes the spin-mixing dynamics for both a freely evolving and a controlled longitudinal magnetization. The spin-1 system exhibits the Einstein–de Haas effect for the first case, for which an exchange between the total orbital angular momentum and the spin angular momentum is observed, resulting in minimal oscillations about the initial position of the skyrmion chain. However, for the fixed magnetization dynamics, the skyrmion chain exhibits ample angular oscillations about the equilibrium position, with the temporary formation of new skyrmions to facilitate the oscillatory motion. For the case of fixed magnetization, this contrast now stems from the exchange between the canonical and spin-dependent contribution to the orbital angular momentum. The variation in canonical angular momentum is linked to the angular oscillations, while the spin-dependent angular momentum accounts for the creation or annihilation of skyrmions. We confirm the presence of scissors mode excitations in the spin texture due to the angular skyrmion oscillations.

This article investigates the atomic thermal diffusion process and microstructure evolution of copper–aluminum bimetallic structures under the route A continuous equal channel angular pressing technology combined with different long-term annealing processes. Scanning electron microscopy, x-ray diffraction, and electron back scattering diffraction were used to observe texture evolution, grain orientation, and atomic diffusion processes. The mechanical properties were characterized using a universal mechanical testing machine. The results show that after 4 passes of extrusion, the bimetallic crystallographic orientation is consistent (111), and the copper grains appear fibrous. An increase in annealing time induces a deepening of the atomic bonding layer, with the thickest reaching 30 μm. Transitioning from {112} R-copper texture to {110} R-Cube texture. Under the process of Route A 4 passes+1 h 450 °C, the mechanical property is significantly improved, with a strength of 270 MPa, a bonding strength of 70 MPa, and a conductivity of 94% International Annealed Copper Standard.

The goal of this article was to analyze the microstructural, texture development, deformation mode, and mechanical properties of a Mg–8.7Gd–4.18Y–0.42Zr (wt%) magnesium alloy that underwent conventional extrusion in conjunction with equal channel angular pressing (EX-ECAP) deformation. The findings indicate that as-extruded alloy reveals a significant basal texture, while the ECAPed GW94K alloy demonstrates basal poles that are inclined ~ 45° from the extrusion direction. After 4p-ECAP process at 370 °C via the Bc path, the microstructure of the alloy exhibits a high level of uniformity, with a fine grain area fraction of 92.7% and an average grain size of 3 μm. The GW94K alloy experiences a significant increase in elongation when the ECAP pass is increased, although the ultimate tensile strength (UTS) decreases remarkably. In particular, the sample subjected to ECAP demonstrates a room-temperature tensile elongation of 36.8% in the extrusion direction. This phenomenon can be ascribed primarily to the evolution of the texture during repeated ECAP processes, leading to the activation of multiple deformation modes in ECAP deformation process of the GW94K alloy. Furthermore, the results suggest that the presence of multiple slip systems, characterized by their high Schmid factor and IGMA analyses, significantly influences the uniform elongation.

Industrial pure titanium was processed through 1–4 passes by equal-channel angular pressing (ECAP), and the processed samples were subsequently short-term annealed for 15 min at 300 °C, to achieve better mechanical properties for industrial applications. The microstructure was analyzed using TEM, EBSD, and XRD observations. The mechanical properties were studied through tensile testing. The TEM and EBSD results showed that the grain size of industrial pure titanium was refined to approximately 420 nm after four passes of ECAP processing, with very little grain growth after annealing. The XRD analysis proved the enhanced basal texture in the subsequent annealed samples. Tensile tests indicated that the strength of the processed sample increased with more ECAP passes and was improved by 39% after four passes compared with the as-received state; in addition, the low-temperature short-term annealing resulted in a further strengthening phenomenon. It was concluded that the strengthening after annealing in industrial pure titanium was likely due to the improved basal texture, resulting in texture strengthening.