Local Description Research Articles

Establishment and extension of a compact and robust binary feature descriptor for UAV image matching

Abstract Local feature description is a crucial challenge in unmanned aerial vehicle (UAV) images matching. Although scholars have explored a variety of methods for defining local feature descriptions, improving the matching accuracy of UAV images and reducing the memory consumption of descriptor remain worthwhile research issues. A compact and robust binary feature descriptor for UAV image matching is proposed. To achieve rotational invariance of the descriptor, a sampling pattern based on the region overlap error is employed to assign the dominant direction of the feature points. Additionally, a rotation invariant gradient computation method is proposed to reduce the dominant direction assignment errors. Then, the region around the feature point is divided into grids based on the region overlap error, and gradient orientation histogram and average intensity histogram are constructed. Finally, these histograms are binarized to generate a 30-byte binary descriptor. Results from the Oxford dataset, the Iguazu dataset, and a high-resolution UAV image dataset indicate that the proposed descriptor is compact and achieves the highest matching accuracy compared to nine commonly used feature descriptors, including scale-invariant feature transform, speeded up robust feature, binary robust invariant scalable keypoints, KAZE, oriented fast and rotated brief, fast retina keypoint, local intensity order pattern, boosted efficient binary local image descriptor, and triplet-based efficient binary local image descriptor. Notably, on the high-resolution UAV images with translational transformations, scale variations, salt-and-pepper noise, and Gaussian white noise, the accuracies of the proposed descriptor were 87.09%, 80.83%, 92.46%, and 87.42%, respectively. The improvements ranged from 6.95% to 53.20%, 9.32% to 55.90%, 10.39% to 44.29%, and 6.54% to 58.24%.

Percolation for 2D Classical Heisenberg Model and Exit Sets of Vector Valued GFF

Our motivation in this paper is twofold. First, we study the geometry of a class of exploration sets, called exit sets, which are naturally associated with a 2D vector-valued Gaussian Free Field : ϕ:Z2→RN,N≥1. We prove that, somewhat surprisingly, these sets are a.s. degenerate as long as N≥2, while they are conjectured to be macroscopic and fractal when N=1. This analysis allows us, when N≥2, to understand the percolation properties of the level sets of {‖ϕ(x)‖2,x∈Z2} and leads us to our second main motivation in this work: if one projects a spin O(N+1) model (the case N=2 corresponds to the classical Heisenberg model) down to a spin O(N) model, we end up with a spin O(N) in a quenched disorder given by random conductances on Z2. Using the exit sets of the N-vector-valued GFF, we obtain a local and geometric description of this random disorder in the limit β→∞. This allows us in particular to revisit a series of celebrated works by Patrascioiu and Seiler (J Stat Phys 69(3):573–595, 1992, Nucl Phys B Proc Suppl 30:184–191, 1993, J Stat Phys 106(3):811–826, 2002) which argued against Polyakov’s prediction that spin O(N+1) model is massive at all temperatures as long as N≥2 (Polyakov in Phys Lett B 59(1):79–81, 1975). We make part of their arguments rigorous and more importantly we provide the following counter-example: we build ergodic environments of (arbitrary) high conductances with (arbitrary) small and disconnected regions of low conductances in which, despite the predominance of high conductances, the XY model remains massive. Of independent interest, we prove that at high β, the fluctuations of a classical Heisenberg model near a north pointing spin are given by a N=2 vectorial GFF. This is implicit for example in Polyakov (1975) but we give here the first (non-trivial) rigorous proof. Also, independently of the recent work Dubédat and Falconet (Random clusters in the villain and xy models, arXiv preprint arXiv:2210.03620, 2022), we show that two-point correlation functions of the spin O(N) model can be given in terms of certain percolation events in the cable graph for any N≥1.

Decoherence of quantum superpositions by Reissner-Nordström black holes

Recently, it was shown by Danielson (DSW) that, for the massive or charged body in a quantum spatial separated superposition state, the presence of a black hole can decohere the superposition inevitably toward capturing the radiation of soft photons or gravitons [D. L. Danielson , Black holes decohere quantum superpositions, ; D. L. Danielson , Killing horizons decohere quantum superpositions, ; D. L. Danielson , Local description of decoherence of quantum superpositions by black holes and other bodies, ]. In this work, we study the DSW decoherence effect for the static charged body in the Reissner-Nordström black holes. By calculating the decohering rate for this case, it is shown that the superposition is decohered by the low-frequency photons that propagate through the black hole horizon. For the extremal Reissner-Nordström black hole, the decoherence of quantum superposition is completely suppressed due to the black hole Meissner effect. It is also found that the decoherence effect caused by the Reissner-Nordström black hole is equivalent to that of an ordinary matter system with the same size and charge. Published by the American Physical Society 2025

Local description of decoherence of quantum superpositions by black holes and other bodies

It was previously shown that if an experimenter, Alice, puts a massive or charged body in a quantum spatial superposition, then the presence of a black hole (or more generally any Killing horizon) will eventually decohere the superposition. This decoherence was identified as resulting from the radiation of soft photons/gravitons through the horizon, thus suggesting that the global structure of the spacetime is essential for describing the decoherence. In this paper, we show that the decoherence can alternatively be described in terms of the local two-point function of the quantum field within Alice’s lab, without any direct reference to the horizon. From this point of view, the decoherence of Alice’s superposition in the presence of a black hole arises from the extremely low frequency Hawking quanta present in Alice’s lab. We explicitly calculate the decoherence occurring in Schwarzschild spacetime in the Unruh vacuum from the local viewpoint. We then use this viewpoint to elucidate (i) the differences in decoherence effects that would occur in Schwarzschild spacetime in the Boulware and Hartle-Hawking vacua; (ii) the difference in decoherence effects that would occur in Minkowski spacetime filled with a thermal bath as compared with Schwarzschild spacetime; (iii) the lack of decoherence in the spacetime of a static star even though the vacuum state outside the star is similar in many respects to the Boulware vacuum around a black hole; and (iv) the requirements on the degrees of freedom of a material body needed to produce a decoherence effect that mimics that of a black hole. Published by the American Physical Society 2025

Plagioclase feldspars (Ca1-x Na x )(Al2-x Si2+x )O8: synthesis and characterizations of mechanical weathering relevant to Martian regolith

Abstract Plagioclase feldspars draw intensive research attention in planetary sciences because of their abundance in the Martian regolith. Crystal chemical studies on plagioclase feldspars would be of crucial importance for possible in situ resource utilization for future human settlement on Mars. This study focuses on the synthesis of representative plagioclase feldspars followed by simulation of mechanical weathering using ball milling. A series of (Ca1-x Na x )(Al2-x Si2+x )O8 plagioclase feldspars is synthesized perfoming the solid-state method, where the endmembers are the anorthite (CaAl2Si2O8) and albite (NaAlSi3O8). The bulk chemical composition, particularly the Al/Si ratio, of each member is determined from energy-dispersive X-ray spectroscopy, which is supported by X-ray powder diffraction data Rietveld refinements. Selective plagioclase members (x = 0.0, 0.4 and 1.0) are mechanically weathered using high-energy ball milling, leading to significant changes of microstructural features such as average crystallite size and micro-strain. Total scattering data are collected using in-house X-ray facilities and analyzed by pair distribution function refinements. The vibrational modes of the samples are evaluated by Raman spectroscopy, complementing the local structural description.

INTERPRETING FAULT DYNAMICS IN TERMS OF HYPOCENTER RELOCATION AND FAULT CHARACTERIZATION

Southeast and Central Sulawesi are the areas characterized by high tectonic activity due to the presence of the active Matano fault. The seismicity along this fault is high. However, the initial hypocenter often deviates from the fault’s trend line, thus causing the need for earthquake relocation with an improved local structure description. The double difference method stands out as a precise technique for hypocenter relocation, utilizing the data on relative travel time between hypocenter pairs. After relocation, the selected hypocenter facilitates the derivation of a focal mechanism, crucial in determining fault types. In this research, we relocated the hypocenters of 485 events of January 2009 to December 2016, ranging in magnitude from M2 to M6.1, 427 of which showed a pattern close to the general trend of major and minor faults. Seismic offsets along the Matano fault are predominantly oriented in the southeast or northwest direction. Moreover, most of the earthquake activity recorded at a depth of 10 km before relocation is no longer visible. Based on the statistics, the time residuals from –2.5 to +2.5 ms resulting from the relocation procedure are better close to 0 than those of –4.5 to +4.5 ms for the events before relocation. The focal mechanism solutions of 16 events of final relocation are dominated by strike-slip faulting. The Matano fault is predominantly sinistral-type. The seismicity along this fault zone results from an activity of this fault, which is the main source of earthquakes, and from its interaction with the neighboring Palu-Koro and Sorong faults.

Killing tensors on reducible spaces

We prove that on the product of two Riemannian manifolds one of which is compact, any Killing tensor is reducible, that is, is the sum of products of Killing tensors on the factors. The same is true for the lifts to the universal cover of Killing tensors on a compact manifold with reducible holonomy. We give a local description of Killing tensors on product manifolds and present an example of a complete product manifold whose factors are locally irreducible which admits an irreducible Killing tensor field.

The possible role of coherence in highly diluted and succussed aqueous solutions

The historical problem of potentized (homeopathic, spagiric and other) remedies deals with their chemical-physical plausibility, i.e.: a consistent physical (molecular or electromagnetic) description have not yet been worked out and shared in scientific contexts [1]. I think that this difficulty pertains to the "generally accepted view of condensed matter" (to quote our mourned Giuliano Preparata [2]) and water condensed phases. Until we stay attached to a local, corpuscular and short-ranged description of matter (and of water, mainly) we won't be able to conceive the emergence of complex collective dynamics and their phenomenological outcomes. These are engendered by non-trivial ground states of the aqueous system in consequence both of its intrinsic nature and of the treatments to which it is subjected during dynamization. In this lecture I'll try, through a Quantum Electro-Dynamic (QED) theoretical framework [3,4,5], to sketch out the main features which let us envision liquid water as a two-phase system, where coherence is the basis both for its condensedness and for its ability to maintain long-lasting and far-from-equilibrium states able to non-randomly evolve in time through dissipative dynamics, and to understand the physical nature and properties of potentized remedies. Further comments about a likewise important question will be shared: how and why living matter is able to respond to such a kind of (possibly therapeutic) stimulations? [6,7]

Molecular anatomy of the pressure anisotropy in the interface of one and two component fluids: Local thermodynamic description of the interfacial tension.

Through the decomposition of the pressure into the kinetic and the intermolecular contributions, we show that the pressure anisotropy in the fluid interface, which is the source of the interfacial tension, comes solely from the latter contribution. The pressure anisotropy due to the intermolecular force between the fluid particles in the same or the different fluid components is approximately proportional to the multiplication of the corresponding fluid density gradients, and from the molecular dynamics simulation of the liquid-vapor and liquid-liquid interfaces, we demonstrate that the density gradient theory by van der Waals gives the leading order approximation of the free energy density in inhomogeneous systems, neglecting the Tolman length.

Dielectric Response Using Long-Range Neural Network Potential

Machine learning-based neural network potentials are revolutionizing molecular dynamics simulations enabling large system sizes and longer time scales with ab initio-level accuracy. Conventional neural network potentials, however, rely on a local description of atomic interactions but can not predict system properties where long-range interactions become important. Several methodologies have been developed to embed the long-range interactions in the neural network potentials. Here, we explore the transferability of a recently developed long-range self-consistent field neural network (SCFNN) by modeling the dielectric saturation in water. The SCFNN model was trained only in the linear response region but correctly predicts the dielectric response and saturation of the dielectric constant of water at higher field strengths. We also examine classic theories and quantify the structural underpinnings of dielectric saturation, including electronic polarization effects. Our results highlight that the focus of SCFNN to learn the physics associated with long-range response makes it transferable. We expect that the transferability of the current SCFNN model can be extended further to aqueous electrolytes by including additional local interactions, such as those between water and ions.

Newly found and rediscovered hornworts (Anthocerotophyta) in Poland: Indicators of climate change impact in Central Europe.

In 2023, field research in south-western Poland led to the noteworthy discovery of two hornworts: Notothylasorbicularis, a species previously unrecorded in this country, and the rediscovery of Anthocerosneesii for the Polish bryoflora. These findings are significant as they suggest a response to climate change, which is facilitating the range expansion of hornworts within Central Europe. Detailed descriptions of the new localities for both species are provided, highlighting the specific environmental conditions and habitats where they were found. Distribution maps for Notothylasorbicularis and Anthocerosneesii in Poland are provided, as well as SEM micrographs of spores. Additionally, a key to the identification of Polish hornwort species is also included. Furthermore, a model projecting the potential future spread of these hornworts within Poland and the broader Central European region is presented. This model considers climatic variables and habitat availability, offering insights into possible range shifts. This study contributes to the growing body of evidence that climate change is a driving factor in the redistribution of bryophytes.

Evolution of creases on the event horizon of a black hole merger

A generic black hole merger occurs through a restructuring of creases (sharp edges) on the event horizon. This process is studied for a black hole merger in the limit of infinite mass ratio, for which constructing the event horizon reduces to finding a null hypersurface that asymptotes to a Rindler horizon in the Kerr spacetime. Geometrical properties of the creases on this horizon are determined and the results are compared with the predictions of an exact local description of the event horizon in a generic merger. The crease set is shown to have finite area. A recently proposed expression for the gravitational entropy of a crease is shown to diverge at the instant of merger. Caustics on (and off) the event horizon are determined by exploiting the correspondence with the problem of gravitational lensing by a Kerr black hole. Caustics form an “astroid tube” in spacetime, two edges of which lie on the event horizon of the merger. Perturbative expressions for the location of this tube are presented, extending previous work to much higher perturbative order. Published by the American Physical Society 2024

Georeferencing Sunda pangolin Manis javanica records in Singapore

Abstract In Singapore, the Critically Endangered Sunda pangolin Manis javanica is threatened by habitat loss and fragmentation, and road traffic collisions. To mitigate these threats, an understanding of its spatiotemporal distribution is needed, as identified in the National Conservation Strategy and Action Plan for the species. However, Sunda pangolin occurrence data are held in multiple separate databases, are typically collected using non-standardized methods, and often lack accurate location details. To compile a complete georeferenced database of Sunda pangolin records in Singapore, we consolidated occurrence data from heterogeneous databases and mainstream and social media, and converted locality descriptions into geographical coordinates. We demonstrate the use of this database to analyse data on rescued pangolins and those killed on roads, to aid conservation efforts in Singapore, and describe other potential applications. We georeferenced 482 records of pangolin sightings, rescues and roadkill for 1996–2021, finding an increase in all three over the study period. Roadkill and rescues occurred mostly in central and western Singapore, close to forested areas, and were predominantly of subadults and adult males. The data can be used to inform threat mitigation strategies, post-rescue release plans and further research. The database has already been used in practice, contributing to environmental impact assessments and conservation recommendations. Overall, this georeferenced database demonstrates the value of citizen science and collating wildlife data from multiple sources, and the methods used can be applied to other taxa to aid conservation strategies.

Stages and main tasks of the century-long control theory and system identification development. Part VI. Model predictive control

The article is devoted to one of the relatively new areas in the field of control theory and practice, called model predictive control. The ideas underlying it, the connection with the theory of optimal control and numerical methods for solving optimization problems are described. It should be noted that currently the number of problems solved and control systems developed within the framework of this approach has come out on top in comparison with all others. This is evidenced by numerous publications concerning the theory and practical application of control methods and algorithms using a predictive model. The main distinctive feature of this method is that the control is not synthesized in advance, but is calculated directly during the operation of the system, i.e. at the current time. This made it possible, with such control, to implement original feedback that ensures stabilization of the process when the model is inaccurate and there is uncertainty associated with existing disturbances and measurements. It describes how such feedback is organized based on current measurement data. In this case, there is no need to interpret somehow the nature of the disturbances and errors acting on the system. Much attention in the article is paid to the possibilities that are admitted with this method of control. The model predictive control method seems especially attractive for systems with discrete impulse processes that are well described with using cognitive maps. It is considered an example of cognitive modeling of evolutionary demographic processes in Ukraine and the possibility of control them using a predictive model, when the model contains unstable eigenvalues. When solving problems of predictive control, it is proposed to use trajectory models, which directly follow from the Cauchy formula, in particular for discrete systems, instead of a local description in the state space. This makes it possible to take into account, when solving predictive control problems, how well or poorly controlled, observable or identifiable the system is. Non-standard capabilities of this method with a trajectory description appear during terminal control on a sliding interval with a finite horizon. A number of original formulations of terminal control problems are presented in the article and some of their properties are described.

LatLBP: Spatial-spectral latent local binary pattern for hyperspectral image classification

The rich spatial and spectral information brings great potential for pixel-wise classification of hyperspectral image (HSI). Recently, Local Binary Pattern (LBP) as a prominent texture operator has been introduced for discriminative feature extraction of complex volumetric HSI. However, the popular two-dimensional LBP series can only capture spatial structure features and lack pattern descriptions of the spectral domain. The extended three-dimensional LBP series are capable of local multidimensional descriptions, while the information mining for narrow and continuous bands in the spectral domain is still limited. To tackle these issues, we develop a novel local binary pattern named LatLBP for investigating spatial-spectral latent information, which provides a low-dimensional, fine-grained, high-level representation of dual-domain latent semantic information by exploring the group structure of data. LatLBP consists of representative spatial latent (RSLat) LBP encoding and grouped spectral latent (GSLat) LBP encoding, where RSLat describes the local spatial potential features of each grouped representative band, and GSLat characterizes information about each group of latent spectral factors. Besides, a supporting neighborhood band grouping (NBG) algorithm is also designed to provide a finer group structure. Extensive experiments conducted on four HSI datasets indicate that the optimal classification results, i.e., 86.94% for Pavia University, 88.66% for Indian Pines, 77.75% for HanChuan, and 85.54% for HongHu, are achieved by either the proposed LatLBP or GSLat compared to competitive operators.

AI-Vision: A Three-Layer Accessible Image Exploration System for People with Visual Impairments in China

Accessible image exploration systems are able to help people with visual impairments (PVI) to understand image content by providing different types of interactions. With the development of computer vision technologies, image exploration systems are supporting more fine-grained image content processing, including image segmentation, description and object recognition. However, in developing countries like China, it is still rare for PVI to widely rely on such accessible system. To better understand the usage situation of accessible image exploration system in China and improve the image understanding of PVI in China, we developed AI-Vision, an Android based hierarchical accessible image exploration system supporting the generations of image general description, local object description and metadata information. Our 7-day diary study with 10 PVI verified the usability of AI-Vision and also revealed a series of design implications for improving accessible image exploration systems similar to AI-Vision.

Local Symmetry Deviation from the Average Structure of MnAs Revealed by Pair Distribution Function.

MnAs is an interesting material due to its magnetocaloric properties, which can be utilized in magnetic refrigeration. However, despite major efforts, its magnetic refrigeration performances in the substituted forms could not be improved compared to the parent MnAs phase. Both small and big box modeling of the pair distribution function of MnAs for the local structure description and powder X-ray diffraction for the average structure reveal an inherent local orthorhombic distortion in the hexagonal structure of MnAs. As a result of this distortion, any modification to the hexagonal structure results in an orthorhombic structure and a weaker magnetocaloric performance. This study highlights the importance of studying local distortion in magnetic materials. This is achieved by combining X-ray absorption spectroscopy with total scattering X-ray diffraction.

Decoherence by warm horizons

Recently Danielson, Satishchandran, and Wald (DSW) have shown that quantum superpositions held outside of Killing horizons will decohere at a steady rate. This occurs because of the inevitable radiation of soft photons (gravitons), which imprint a electromagnetic (gravitational) “which-path” memory onto the horizon. Rather than appealing to this global description, an experimenter ought to also have a local description for the cause of decoherence. One might intuitively guess that this is just the bombardment of Hawking/Unruh radiation on the system, however simple calculations challenge this idea—the same superposition held in a finite temperature inertial laboratory does not decohere at the DSW rate. In this work we provide a local description of the decoherence by mapping the DSW setup onto a worldline-localized model resembling an Unruh-DeWitt particle detector. We present an interpretation in terms of random local forces which do not sufficiently self-average over long times. Using the Rindler horizon as a concrete example we clarify the crucial role of temperature, and show that the Unruh effect is the only quantum mechanical effect underlying these random forces. A general lesson is that for an environment which induces Ohmic friction on the central system (as one gets from the classical Abraham-Lorentz-Dirac force, in an accelerating frame) the fluctuation-dissipation theorem implies that when this environment is at finite temperature it will cause steady decoherence on the central system. Our results agree with DSW and provide the complementary local perspective. Published by the American Physical Society 2024

Bridging the small and large in twisted transition metal dichalcogenide homobilayers: A tight binding model capturing orbital interference and topology across a wide range of twist angles

Many of the important phases observed in twisted transition metal dichalcogenide homobilayers are driven by short-range interactions, which should be captured by a local tight binding description since no Wannier obstruction exists for these systems. Yet, published theoretical descriptions have been mutually inconsistent, with honeycomb lattice tight binding models adopted for some twist angles, triangular lattice models adopted for others, and with tight binding models forsaken in favor of band projected continuum models in many numerical simulations. Here, we derive and study a minimal model containing both honeycomb orbitals and a triangular site that represents the band physics across a wide range of twist angles. The model provides a natural basis to study the interplay of interaction and topology in these heterostructures. It elucidates from generic features of the bilayer the sequence of Chern numbers occurring as twist angle is varied, and the microscopic origin of the magic angle at which flat-band physics occurs. At integer filling, the model successfully captures the Chern ferromagnetic and van Hove-driven antiferromagnetic insulators experimentally observed for small and large angles, respectively, and allows a straightforward calculation of the magnetoelectric properties of the system. Published by the American Physical Society 2024

The local representation of incrementally scattering passive nonlinear systems

AbstractWe investigate the local (in time) description of incrementally scattering passive nonlinear systems. We show that these systems can be defined by a differential inclusion and a function that gives the current output in term of the current state and the current input. Our approach uses the theory of maximal monotone operators and Lax–Phillips-type nonlinear semigroups.