Hasil untuk "Maps"

Hanne Stensola, Tor Stensola, T. Solstad et al.

Jens Behley, C. Stachniss

—Accurate and reliable localization and mapping is a fundamental building block for most autonomous robots. For this purpose, we propose a novel, dense approach to laser- based mapping that operates on three-dimensional point clouds obtained from rotating laser sensors. We construct a surfel-based map and estimate the changes in the robot’s pose by exploiting the projective data association between the current scan and a rendered model view from that surfel map. For detection and verification of a loop closure, we leverage the map representation to compose a virtual view of the map before a potential loop closure, which enables a more robust detection even with low overlap between the scan and the already mapped areas. Our approach is efficient and enables real-time capable registration. At the same time, it is able to detect loop closures and to perform map updates in an online fashion. Our experiments show that we are able to estimate globally consistent maps in large scale environments solely based on point cloud data.

D. Wald, T. Allen

Yicheng Liu, Yue Wang, Yilun Wang et al.

Autonomous driving systems require High-Definition (HD) semantic maps to navigate around urban roads. Existing solutions approach the semantic mapping problem by offline manual annotation, which suffers from serious scalability issues. Recent learning-based methods produce dense rasterized segmentation predictions to construct maps. However, these predictions do not include instance information of individual map elements and require heuristic post-processing to obtain vectorized maps. To tackle these challenges, we introduce an end-to-end vectorized HD map learning pipeline, termed VectorMapNet. VectorMapNet takes onboard sensor observations and predicts a sparse set of polylines in the bird's-eye view. This pipeline can explicitly model the spatial relation between map elements and generate vectorized maps that are friendly to downstream autonomous driving tasks. Extensive experiments show that VectorMapNet achieve strong map learning performance on both nuScenes and Argoverse2 dataset, surpassing previous state-of-the-art methods by 14.2 mAP and 14.6mAP. Qualitatively, VectorMapNet is capable of generating comprehensive maps and capturing fine-grained details of road geometry. To the best of our knowledge, VectorMapNet is the first work designed towards end-to-end vectorized map learning from onboard observations. Our project website is available at \url{https://tsinghua-mars-lab.github.io/vectormapnet/}.

Júlia Resende Oliveira Silva, Décio Karam, Kassio Ferreira Mendes

Knowledge of weed community structure in agricultural systems is important for sustainable management, especially for evaluating the effects of different herbicides on soybean–corn succession crops. This study evaluated, over two crop seasons, weed community structure in response to chemical weed management strategies for soybean–corn succession in Brazil’s Triângulo Mineiro region. Phytosociological surveys of the weed community were conducted during harvest periods throughout the experimental phase, with referenced data for generating spatial distribution maps of biomass and density of the main present species. The survey identified 33 weed species, predominantly from the Poaceae and Asteraceae families. Regardless of the management system, the total weed biomass was lower in corn crops compared to soybean crops. In management systems using six different herbicides, the IVI of <i>Commelina benghalensis</i> was the lowest due to greater diversification of herbicide mechanisms of action. The results demonstrate that chemical weed management strategies strongly influence weed community structure, with significant effects on weed community structure and evenness in intensive agricultural regions. These changes also have implications for resistance management.

Abboudeh Georges, Hennebelle Patrick, Soler Juan D. et al.

Context. Turbulence plays an important role in shaping the interstellar medium, and it strongly influences star formation. Aims. We aim to identify the physical processes capable of sustaining H I turbulence in the solar neighborhood. Methods. We compare recent H I line-of-sight velocity observations within a volume of radius 70–500 pc centered on the Sun with a suite of 1 kpc numerical simulations that include two distinct turbulent drivers: (i) supernova (SN) feedback and (ii) imposed large-scale turbulent forcing. For each simulation, we constructed synthetic sky maps that closely mimic the observational one, allowing for a consistent comparison between the simulations and the observational data. Results. The H I observations show a median velocity dispersion of 11.1 km s−1 in the solar neighborhood. The SN-driven simulations systematically underpredict this value, yielding dispersions in the range 4.9–6.7 km s−1. We find that the simulations with strong enough large-scale forcing can reproduce not only the median observed velocity dispersion but also the observed velocity distribution.

Anssi Lahtinen

We develop a theory of umkehr maps for twisted generalized homology theories. In this theory, interesting umkehr maps, including generalizations of important classical ones, are induced by cartesian morphisms of a certain category opfibred over the category of spaces and continuous maps, making it possible to access them through universal properties.

Valerii Kidalov, Lukas Hertling, Roman Redko et al.

Silicon carbide films on porous-Si/Si substrates have attracted considerable attention due to their potential use in modern high-power electronic devices. Here, SiC/porous-Si/Si heterostructures fabricated by an atomic substitution method are investigated. Scanning electron microscopy shows the formation of a continuous about 40 nm thick film of SiC, with a sharp interface to the porous Si sublayer. Energy-dispersive x-ray spectroscopy confirmed that Si, C, and O are the only constituents of the SiC film and the porous-Si underlayer. Raman spectroscopy indicated 3C and 6H polytypes in the SiC film. Spectroscopic ellipsometry in the range of 0.6–5.1 eV was performed in order to determine the refractive index (n), extinction coefficient (k), and bandgap (Eg) of the SiC layer. Macro-FTIR transmission spectra showed the expected absorption features of SiC. IR reflectance maps measured with nano-resolution reveal lateral inhomogeneities of the intensity, which we attribute to the morphology of the porous silicon sublayer. Numerical simulations of the local near-field response were performed for regions, where the SiC layer lay directly on silicon and for regions where it is free-standing over pores. The simulation results are in close agreement with the experimental observations obtained by nanoFTIR and confirm that the porous substrate plays a decisive role in determining the local optical and structural properties of the SiC/porous-Si/Si heterostructures.

Hongfa Wan, Shanshan Li, Xinxing Li et al.

High-resolution and high-precision marine gravity reference maps are core prerequisites for the practical application of gravity-assisted inertial navigation algorithms, and their accuracy directly determines the performance of the navigation system. In view of the problems existing in the current geographic rectangular grid gravity reference map, such as severe polar deformation, poor adjacent consistency, and low positioning accuracy in high latitudes, this study introduces a hexagonal grid system to construct a gravity reference map. It systematically analyzes its compatibility and accuracy in navigation applications. A multi-resolution hexagonal grid scheme with a 7-aperture structure is further proposed to meet the characterization requirements of gravitational fields with different complexities. Experimental verification shows that the accuracy of the gravity-assisted inertial navigation algorithm improved by 0.4%, while that of gravity sequence matching improved by 50%. The proposed hybrid resolution grid can achieve a maximum gravity data compression rate of 68% while ensuring navigation accuracy, especially with regard to the computational efficiency and accuracy requirements of gravity-assisted inertial navigation.

Fabian Immel, Jan-Hendrik Pauls, Richard Fehler et al.

Autonomous vehicles rely on detailed and accurate environmental information to operate safely. High definition (HD) maps offer a promising solution, but their high maintenance cost poses a significant barrier to scalable deployment. This challenge is addressed by online HD map construction methods, which generate local HD maps from live sensor data. However, these methods are inherently limited by the short perception range of onboard sensors. To overcome this limitation and improve general performance, recent approaches have explored the use of standard definition (SD) maps as prior, which are significantly easier to maintain. We propose SDTagNet, the first online HD map construction method that fully utilizes the information of widely available SD maps, like OpenStreetMap, to enhance far range detection accuracy. Our approach introduces two key innovations. First, in contrast to previous work, we incorporate not only polyline SD map data with manually selected classes, but additional semantic information in the form of textual annotations. In this way, we enrich SD vector map tokens with NLP-derived features, eliminating the dependency on predefined specifications or exhaustive class taxonomies. Second, we introduce a point-level SD map encoder together with orthogonal element identifiers to uniformly integrate all types of map elements. Experiments on Argoverse 2 and nuScenes show that this boosts map perception performance by up to +5.9 mAP (+45%) w.r.t. map construction without priors and up to +3.2 mAP (+20%) w.r.t. previous approaches that already use SD map priors. Code is available at https://github.com/immel-f/SDTagNet

Reza Rezaeian Farashahi, Mojtaba Fadavi, Soheila Sabbaghian

An addition law for an elliptic curve is complete if it is defined for all possible pairs of input points on the elliptic curve. In Elliptic Curve Cryptography (ECC), a complete addition law provides a natural protection against side-channel attacks which are based on Simple Power Analysis (SPA). Montgomery curves are a specific family of elliptic curves that play a crucial role in ECC because of its well-known Montgomery ladder, particularly in the Elliptic Curve Diffie-Hellman Key Exchange (ECDHKE) protocol and the Elliptic Curve factorization Method (ECM). However, the complete addition law for Montgomery curves, as stated in the literature, has a computational cost of 14M+ 2D, where M,D denote the costs of a field multiplication and a field multiplication by a constant, respectively. The lack of a competitive complete addition law has led implementers towards twisted Edwards curves, which offer a complete addition law at a lower cost of 8M+ 1D for appropriately chosen curve constants. In this paper, we introduce extended Montgomery coordinates as a novel representation for points on Montgomery curves. This coordinate system enables us to define birational multiplication-free maps between the extended twisted Edwards coordinates and extended Montgomery coordinates. Using this map, we can transfer the complete addition laws from twisted Edwards curves to Montgomery curves without incurring additional multiplications or squarings. In addition, we employ a technique known as scaling to refine the addition laws for twisted Edwards curves, which results in having i) Complete addition laws with the costs varying between 8M+1D and 9M+1D for a broader range of twisted Edwards curves, ii) Incomplete addition laws for twisted Edwards curves with the cost of 8M. Consequently, by leveraging our birational multiplication-free maps, we present complete addition laws for Montgomery curves with the cost of 8M+1D. This shows a significant improvement for complete addition law for Montgomery curves by reducing the computational cost by 6M+ 1D. This improvement makes Montgomery curves a more attractive option for applications where an efficient complete addition law is essential.

Ana Belén Avilez

We generalize the notions of $β$- and $λ$-maps to general selections of sublocales, obtaining different classes of localic maps. These new classes of maps are used to characterize almost normality, extremal disconnectedness, $F$-frames, $Oz$-frames, among others types of locales, in a manner akin to the characterization of normal locales via $β$-maps. As a byproduct we obtain a characterization of localic maps that preserve the completely below relation (that is, the right adjoints of assertive frame homomorphisms).

Till Hauser

Mean equicontinity is a well studied notion for actions. We propose a definition of mean equicontinuous factor maps that generalizes mean equicontinuity to the relative context. For this we work in the context of countable amenable groups. We show that a factor map is equicontinuous, if and only if it is mean equicontinuous and distal. Furthermore, we show that a factor map is topo-isomorphic, if and only if it is mean equicontinuous and proximal. We present that the notions of topo-isomorphy and Banach proximality coincide for all factor maps. In the second part of the paper we turn our attention to decomposition and composition properties. It is well known that a mean equicontinuous action is a topo-isomorphic extension of an equicontinuous action. In the context of minimal and the context of weakly mean equicontinuous actions, respectively, we show that any mean equicontinuous factor map can be decomposed into an equicontinuous factor map after a topo-isomorphic factor map. Furthermore, for factor maps between weakly mean equicontinuous actions we show that a factor map is mean equicontinuous, if and only if it is the composition of an equicontinuous factor map after a topo-isomorphic factor map. We will see that this decomposition is always unique up to conjugacy.

István Rebenku, Cameron B. Lloyd, János Szöllősi et al.

Abstract The actual interaction between signaling species in cellular processes is often more important than their expression levels. Förster resonance energy transfer (FRET) is a popular tool for studying molecular interactions, since it is highly sensitive to proximity in the range of 2–10 nm. Spectral spillover-corrected quantitative (3-cube) FRET is a cost effective and versatile approach, which can be applied in flow cytometry and various modalities of fluorescence microscopy, but may be hampered by varying levels of autofluorescence. Here, we have implemented pixel-by-pixel autofluorescence correction in microscopy FRET measurements, exploiting cell-free calibration standards void of autofluorescence that allow the correct determination of all spectral spillover factors. We also present an ImageJ/Fiji plugin for interactive analysis of single images as well as automatic creation of quantitative FRET efficiency maps from large image sets. For validation, we used bead and cell based FRET models covering a range of signal to autofluorescence ratios and FRET efficiencies and compared the approach with conventional average autofluorescence/background correction. Pixel-by-pixel autofluorescence correction proved to be superior in the accuracy of results, particularly for samples with spatially varying autofluorescence and low fluorescence to autofluorescence ratios, the latter often being the case for physiological expression levels.

M. L. Dorofeev

The development of methodology for analyzing efficiency is acute today due to fundamental basis of budget system functioning. The last ten years proved the importance of social policy and the welfare system during periods of uncertainty and economic crises. In 2022 the vector of Russian economy development changed from west to east and the country will face a long-term opposition through unprecedented sanctions and challenges to its economy transformation. The article puts forward a simple ratio method of analyzing efficiency of budget expenses aimed at overcoming poverty in Russian regions, systematizes the most frequently mentioned in academic literature methods of researching efficiency of expenses on social policy, investigates the method of analyzing the utmost efficiency and provides conclusions about its low practical significance. The article proposes to use the author’s approach to ratio analysis supplemented with ranking method, plotting heat maps and estimating basic descriptive statistics. Research findings demonstrate its high theoretic and practical value, especially as a preliminary stage of the research within the frames of a complex analytical approach to assessing efficiency of expenses on social policy allotted from consolidated budgets of Russian Federation entities.

Martin Montagnac, Yoann Brûlé, Aurélien Cuche et al.

Abstract Light emission of europium (Eu3+) ions placed in the vicinity of optically resonant nanoantennas is usually controlled by tailoring the local density of photon states (LDOS). We show that the polarization and shape of the excitation beam can also be used to manipulate light emission, as azimuthally or radially polarized cylindrical vector beam offers to spatially shape the electric and magnetic fields, in addition to the effect of silicon nanorings (Si-NRs) used as nanoantennas. The photoluminescence (PL) mappings of the Eu3+ transitions and the Si phonon mappings are strongly dependent of both the excitation beam and the Si-NR dimensions. The experimental results of Raman scattering and photoluminescence are confirmed by numerical simulations of the near-field intensity in the Si nanoantenna and in the Eu3+-doped film, respectively. The branching ratios obtained from the experimental PL maps also reveal a redistribution of the electric and magnetic emission channels. Our results show that it could be possible to spatially control both electric and magnetic dipolar emission of Eu3+ ions by switching the laser beam polarization, hence the near field at the excitation wavelength, and the electric and magnetic LDOS at the emission wavelength. This paves the way for optimized geometries taking advantage of both excitation and emission processes.

Kiyoung Jo, Emanuele Marino, Jason Lynch et al.

Abstract Strong light-matter interactions in localized nano-emitters placed near metallic mirrors have been widely reported via spectroscopic studies in the optical far-field. Here, we report a near-field nano-spectroscopic study of localized nanoscale emitters on a flat Au substrate. Using quasi 2-dimensional CdSe/CdxZn1-xS nanoplatelets, we observe directional propagation on the Au substrate of surface plasmon polaritons launched from the excitons of the nanoplatelets as wave-like fringe patterns in the near-field photoluminescence maps. These fringe patterns were confirmed via extensive electromagnetic wave simulations to be standing-waves formed between the tip and the edge-up assembled nano-emitters on the substrate plane. We further report that both light confinement and in-plane emission can be engineered by tuning the surrounding dielectric environment of the nanoplatelets. Our results lead to renewed understanding of in-plane, near-field electromagnetic signal transduction from the localized nano-emitters with profound implications in nano and quantum photonics as well as resonant optoelectronics.

Ningping Cao, Maxwell Fitzsimmons, Zachary Mann et al.

For an open quantum system to evolve under CPTP maps, assumptions are made on the initial correlations between the system and the environment. Hermitian-preserving trace-preserving (HPTP) maps are considered as the local dynamic maps beyond CPTP. In this paper, we provide a succinct answer to the question of what physical maps are in the HPTP realm by two approaches. The first is by taking one step out of the CPTP set, which provides us with Semi-Positivity (SP) TP maps. The second way is by examining the physicality of HPTP maps, which leads to Semi-Nonnegative (SN) TP maps. Physical interpretations and geometrical structures are studied for these maps. The non-CP SPTP maps $Ψ$ correspond to the quantum non-Markovian process under the CP-divisibility definition ($Ψ= Ξ\circ Φ^{-1}$, where $Ξ$ and $Φ$ are CPTP). When removing the invertibility assumption on $Φ$, we land in the set of SNTP maps. A by-product of set relations is an answer to the following question -- what kind of dynamics the system will go through when the previous dynamic $Φ$ is non-invertible. In this case, the only locally well-defined maps are in $SN\backslash SP$, they live on the boundary of $SN$. Otherwise, the non-local information will be irreplaceable in the system's dynamic. With the understanding of physical maps beyond CPTP, we prove that the current quantum error correction scheme is still sufficient to correct quantum non-Markovian errors. In some special cases, lack of complete positivity could provide us with more error correction methods with less overhead.

Fatemeh Rezaee, Mohan Swaminathan

Let $X$ be a smooth projective variety. Define a stable map $f:C\to X$ to be "eventually smoothable" if there is an embedding $X\hookrightarrow\mathbb{P}^N$ such that $(C,f)$ occurs as the limit of a $1$-parameter family of stable maps to $\mathbb{P}^N$ with smooth domain curves. Via an explicit deformation-theoretic construction, we produce a large class of stable maps (called "stable maps with model ghosts"), and show that they are eventually smoothable.

Benoit Cosset, Benoit Cosset, Loic Boussel et al.

Objective:The standard treatment for complicated Stanford type B aortic dissection (TBAD) is thoracic endovascular aortic repair (TEVAR). Functional parameters, specifically blood flow, are not measured in the clinical assessment of TEVAR, yet they are of outmost importance in patient outcome. Consequently, we investigated the impact of TEVAR on the flows in the aorta and its branches in TBAD using 4D Phase-Contrast Magnetic Resonance Imaging (4D Flow MRI).MethodsSeven patients with TBAD scheduled for TEVAR underwent pre and post-operative 4D Flow MRI. An experienced reader assessed the presence of helical flow in the false lumen (FL) using streamlines and measured net flow at specific locations. In addition, forward and reverse flows, stasis, helicity, and absolute helicity were computed automatically along the aorta centerline. Average values were then computed in the segmented vessels. Impact of TEVAR on these parameters was assessed with a Wilcoxon signed rank test. Impact of the metallic stent on the velocity quantification was assessed using intra-class correlation coefficient (ICC) between velocities measured intra-stent and in adjacent stent-free regions.ResultsFL helical flow was observed proximally in 6 cases and distally in 2 cases pre-operatively. Helical flow disappeared post-TEVAR proximally, but developed distally for 2 patients. Intra-stent measures were similar to stent-free with a median difference of 0.1 L/min and an ICC equal to 0.967 (p &lt; 0.01). Forward flow increased from 59.9 to 81.6% in the TL and significantly decreased in the FL from 15.9 to 3.3%. Similarly, reverse flow increased in the TL from 4.36 to 10.8% and decreased in the FL from 10.3 to 4.6%. No significant changes were observed in net flow for aortic branches (p &gt; 0.05). A significant increase in FL stasis was observed (p = 0.04).DiscussionTEVAR significantly increased forward flow in the TL and significantly decreased both forward and reverse flows in the FL. Interestingly, reverse flow in the TL increased post-TEVAR, which could be due to increased rigidity of the wall, due to the metallic stent. User independent helicity quantification enabled detection of elevated helicity at the level of secondary entry tears which had been missed by streamline visualization.