Relative Position Research Articles

Cross-Platform Partisan Positioning in Congressional Speech

Legislative activity—whether votes or communications—is often represented in a single partisan or ideological dimension. But as lawmakers communicate in various venues (e.g., traditional, direct, or social media), the extent to which these estimates are interchangeable—reflecting a common underlying dimension—is unclear. We estimate a partisan dimension in members’ tweets, Facebook posts, e-newsletters, press releases, and one-minute House floor speeches for the 116th U.S. Congress and test the extent to which representations remain consistent across different venues. We find that while Democrats are consistently separable from Republicans, members’ relative intra-party positions frequently shift between venues. This is likely driven by differences in the affordances and audiences present in each venue, as venues with more nationalized audiences (such as social media) show higher levels of rhetorical polarization than venues with more local audiences (e-newsletters). These results suggest that the level of polarization we observe depends on where we look, and that the scholars of congressional communication should explicitly consider the input they use to measure partisanship.

FPGA-Based Real-Time Synchronous Parallel System for Underwater Acoustic Positioning and Navigation

With the development of autonomous underwater vehicles, the research of underwater acoustic positioning and navigation technology is becoming increasingly important. However, most underwater positioning systems use the traditional acoustic response synchronization method, which leads to insufficient positioning real-time performance and refresh rate. To solve this problem, this paper proposes a real-time global synchronization mechanism with high-precision atomic clocks, which can realize one positioning through one-way propagation, so that the positioning efficiency is at least doubled. To further improve the positioning accuracy, an M-sequence-based phase offset modulation method is proposed to facilitate beacon identification. Consequently, a normalized signal matching capture algorithm against Doppler effect is designed, and the positioning solution is fused with the real-time sound ray bending compensation mechanism. Based on the above content, we developed an FPGA-based real-time synchronous parallel underwater positioning and navigation (RSPUPN) system, which uses FPGA+MCU architecture to accelerate signal processing operations in a low-power and parallel way. The test results in the South China Sea show that the operating range of the system can reach 8 km, the positioning refresh rate can reach 0.2 Hz, and the relative average position error is 0.25%, confirming the effectiveness of the designed system in industrial applications.

Biostratigraphy of the Eocene shallow-water succession of the south Sabzevar area (Central Iran) based on larger benthic foraminifera and calcareous nannofossils

A rich larger foraminifera assemblage from the Eocene carbonates of the south Sabzevar region (Now-Deh section) in central Iran indicates a late Ypresian to early Lutetian age. Nine species of Alveolina d’Orbigny are studied for systematics and biostratigraphy. The assemblage includes A. minuta, A. decastroi, A. cremae, A. cremae elongata, A. decipiens ayrancensis, A. celali, A. rugosa, A. cuspidata, A. frumentiformis. We have also found nummulitids (genus Nummulites and Assilina) and orthophragmines identified as N. campesinus, N. praediscorbinus, A. placentula, A. praespira, A. reicheli, A. ex. intrec. laxispira-maior and Discocyclina archiaci bartholomei. The recovery of Alveolina cremae elongata, A. decipiens ayrancensis, A. celali, A. rugosa, A. cuspidata and Assilina praespira has permitted for the first time to extend their geographical distribution outside of the classical peri-Mediterranean area to the central Tethys regions. The obtained biostratigraphy points to the Shallow Benthic Zones SBZ11 to SBZ13, indicating the occurrence of a Lower–Middle Eocene carbonate system. Part of the age model is supported by the calcareous nannofossil biostratigraphy that belong to the NP14b and CNE8 biozones, recorded from the central portion of the studied section. Issues regarding the application of the SBZ into the Middle East domains are discussed in terms of relative stratigraphic position and biogeographic dispersal of some significant Alveolina species.

HPNet: High precision point cloud registration using feature pyramid and hybrid position encoding

Point cloud registration precision degrades when the scene contains symmetric structures or repeated patches. Also, the common operation of continuous downsampling in existing registration methods causes the loss of detailed information and leads to further registration precision degradation. In this paper, we propose a high precision point cloud registration network (HPNet) to learn discriminative features by considering both multi-scale information and position information. We first propose a multi-scale feature extraction module similar to the feature pyramid that allows the extracted features to contain multi-scale information. Then, an information interaction is performed on the features to learn global contextual information by using Transformer with a hybrid position encoding, which takes into account both absolute and relative positions of points. Finally, the features obtained from the information interaction module are directly used to predict the point correspondences. Comprehensive experiments on 3DMatch, 3DLoMatch, ModelNet, and ModelLoNet datasets demonstrate the state-of-the-art performance of the proposed method and the implementation of HPNet in SLAM shows its effectiveness in real application.

Active stabilization of an open-access optical microcavity for low-noise operation in a standard closed-cycle cryostat

Open-access optical microcavities are Fabry–Perot type cavities consisting of two micrometer-size mirrors, separated by an air (or vacuum) gap typically of a few micrometers. Compared to integrated microcavities, this configuration is more flexible as the relative position of the two mirrors can be tuned, allowing for easy changes in parameters such as cavity length and mode volume and the selection of specific transverse cavity modes. These advantages come at the expense of the mechanical stability of the cavity itself, which is particularly relevant in noisy closed-cycle cryostats. Here, we show an open-access optical microcavity based on scanning-probe microscope design principles. When operated at 4 K in a tabletop optical closed-cycle cryostat without any dedicated mechanical low-pass filter, we obtain stabilities of 5.7 and 10.6 pm rms in the quiet and full periods of the cryocooler cycle, respectively. Our device has free-space optical access, essential, for instance, for full polarization control.

Perfect chirality constructed by position-dependent backscattering in a whispering gallery mode microresonator

Unidirectional propagation of photons originated from perfect chirality meets the critical requirement for building a high-performance quantum network. However, it not only requires that the circular dipole emitter is precisely located at points of circularly polarized electric fields, which leads to non-reciprocal interactions for photons with opposite propagation directions, but also the light-emitter interaction strength should be strong enough to guarantee a π phase shift. Unfortunately, these perfect chirality points are scarce and accessible points with elliptically polarized fields result in non-ideal photon-emitter chiral interactions and emitters radiating photons bidirectionally. Meanwhile, reflection properties, phase shifts, and non-reciprocal interactions are sensitive to frequency detunings and dissipations. Here, without engineering the dipole and optimizing the distribution of the field, a scatter such as a nanotip placed at the evanescent field of a whispering gallery mode resonator (WGMR) is adopted to control the transporting properties of single photons under non-ideal chiral interactions. By properly adjusting the relative position between the nanotip and the atom or the overlap between the nanotip and the mode volume of the WGMR, amplitudes of reflected photons in different pathways are changed. Consequently, complete destructive interference appears and thus no photons are reflected. The corresponding phase shifts of π and non-reciprocal interactions are guaranteed simultaneously. Significantly, the perfect chirality reconstructed here is robust against frequency detunings and dissipations. Therefore, the atom-WGMR-nanotip structure can be regarded as a compound chiral atom with radiating photons in only one direction.

Robust Collision-Avoidance Formation Navigation of Velocity and Input-Constrained Multirobot Systems.

In this work, we consider the safe deployment problem of multiple robots in an obstacle-rich complex environment. When a team of velocity and input-constrained robots is required to move from one area to another, a robust collision-avoidance formation navigation method is needed to achieve safe transferring. The constrained dynamics and the external disturbances make the safe formation navigation a challenging problem. A novel robust control barrier function-based method is proposed which enables collision avoidance under globally bounded control input. First, a nominal velocity and input-constrained formation navigation controller is designed which uses only the relative position information based on a predefined-time convergent observer. Then, new robust safety barrier conditions are derived for collision avoidance. Finally, a local quadratic optimization problem-based safe formation navigation controller is proposed for each robot. Simulation examples and comparison with existing results are provided to demonstrate the effectiveness of the proposed controller.

The influence of the geographic positioning system error on the quality of ship magnetic signature reproduction based on measurements in sea conditions

In previous studies, the authors performed the magnetic signature reconstruction of the marine ship Zodiak as part of the measurement campaign focused on recording magnetic data and the relative position of a ship during its passage over a magnetometer immersed on the testing ground. A high degree of representation of the magnetic signature was obtained. However, the recorded measurement data revealed new patterns of the multi-dipole model behavior that were not observed in the synthetic data based analyzes. It was assumed that the main factor influencing the abovementioned behavior of the model is the error in determining the geographical position of the ship in relation to the magnetometer. Therefore, another research was carried out to determine the relative position of the ship and the measurement device in sea conditions, in the area of the test site used in the previous study. For this purpose, two different classes of GPS receivers were used. The first receiver was the same as that used to determine the position of Zodiak in the previous measurement campaign, while the second receiver, treated as a reference, was a top-class geodetic receiver. The difference in indications between these two receivers gave a picture of the scale of errors in the data recorded during the previous measurement campaign. These errors are used in the article to analyze the effect of inaccuracies in determining the ship position on the quality of magnetic signature reproduction. Two types of signature reproduction error were introduced – the error based only on the data collected from the ship’s paths, and the error in the entire area of magnetic anomaly. The model of Zodiak was used to determine the value of the magnetic flux outside the paths. Profiles of differences in indications of GPS receivers at sea which were obtained from actual measurements were used to analyze the errors in determining the ship position. A measurable result of the work reported in the article is the map of the loss of quality of magnetic signature reproduction as a function of the ship position determination error, which can indicate the range of applicability of the model and the described method.

A B3LYP-D3 computational study of electronic, structural and torsional dynamic properties of mono-substituted naphthalenes: the effect of the nature and position of substituent.

The effects of selectedsubstituent groups (-CH3, -Br, -CO2CH3, -COOH, and -NH2) and their relative positions on the electronic and structural properties of mono-substituted naphthalenes were investigated theoretically. In order to elucidate the suitability of the studied substituents in different fields including chemistry, spectroscopy, and materials sciences, accurate DFT calculations were performed at the dispersion-corrected B3LYP level of theory (B3LYP-D3/6-311 + + G(d,p)), and the obtained results were then validated by extensive comparisons with available experimental data. Among the studied substituents, the -NH2group causes the maximum reduction of the HOMO-LUMO energy gap. This result revealed clearly the suitability of the -NH2group, compared to other studied substituents, in the chemical synthesis of future organic-semiconductors having small energy gaps. In addition, the level of theory adopted in this study allowed the fine discrimination between the chemical reactivity parameters of the studied congeners, which is very difficult to perform experimentally. On the other hand, the rotational barriers of the studied non-halogen substituent groups were predicted. The greater sensitivity of the rotational barrier heights to the local environments, arising from intra-molecular interactions, was attributed to the -CH3 group. The torsional frequencies, calculated within the harmonic approximation, were also employed to relatively explore the differences between the environments of the same substituent at two different positions. The usefulness of these results can be manifested in the vibrational spectroscopy field, especially, for the IR/ Raman spectral analysis of polycyclic-aromatic congeners. All calculations were conducted within the Density functional theory (DFT) using the so-called dispersion-corrected B3LYP functional (B3LYP-D3) with the carefully selected 6-311 + + G(d,p) basis set. The B3LYP-D3/6-311 + + G(d,p) calculations were performed using the Gaussian 09 program, and the obtained results were visualized by employing the GaussView 6.0.16 program.

The Role of Geological and Geotechnical Factors in Shale Slope Instability: Case of Landslides on Road Embankments, Tizi Ouadrene Sector - Rif Extern, Morocco

Constructing roads in geologically unstable regions such as northern Morocco poses a major challenge. The Tizi Ouadrene sector, located in the Rif External Nappe of the Rif Belt, exemplifies a significant complexity in this issue, with a risk of landslides threatening the road embankments in this area. This study aims to characterize the frequent Cretaceous shales in the study area and analyze the landslides that have occurred on the road embankments cut into these shales. It examines the role of lithology, geometry, tectonics, human activity, and water in these landslides. The geological structure of slopes and their geometric configuration are crucial factors in determining the occurrence, distribution, and other characteristics of these landslides. Defects are controlled by the relative position of sedimentary and tectonic discontinuities, as well as the relative abundance of indurated shales compared to crushed ones. Crushed shales are susceptible to rotational slides, while the indurated ones are prone to planar and wedge sliding. The latter are mainly associated with bedding planes, particularly those oriented N65-80 with slopes facing south and SSE, as well as NW-SE and NE-SW-trending fractures. Hydrological, tectonic, and anthropogenic factors also contribute to the instability.

Numerical Investigations on Phase Cancelation of Interaction Noise for Counter-Rotating Propellers

The large interaction tonal noise of counter-rotating propellers significantly restricts their application in civil aviation. A pair of counter-rotating propellers was simulated by the lattice Boltzmann method, and the far-field noise was predicted by the Ffowcs Williams and Hawkings analogy. Dynamic mode decomposition was introduced to analyze the surface pressure contribution to far-field noise and to provide insights on the cancellation mechanism of the noise source distribution for the interaction tone. It was found that the cancellation effect is closely related to the relative position between the front blade wake and rear blade element. By adjusting the rear blade sweep and, hence, changing the relative position, the interaction tone can be reduced effectively.

Properties, age, and origin of a huge meteor cluster observed over Scandinavia on 30 October 2022

Context. A meteor outburst consisting of at least 22 meteors above the Baltic sea and southern Scandinavia that occurred on 30 October 2022 was recorded using multiple cameras. A bright fireball was followed by fainter meteors over a 10 second period. All the meteors were travelling on parallel trajectories. Aims. The goal of this study is to determine the atmospheric trajectories and photometric masses of meteors and to use these data to determine the specifics of the progenitor meteoroid break-up and cluster formation. Methods. Double and triple-station observations using video cameras were used for the calculation of the atmospheric trajectories and photometric masses of the meteors. Their relative positions and mass distribution were then used to determine the time and cause of the meteoroid fragmentation. Results. The relative position of the cluster particles in the atmosphere and the distribution of their masses best correspond to the separation of the smaller fragments from the mass-dominant fragment 10.6 ± 1.7 days before the collision with Earth, assuming a meteoroid bulk density of 1000 kg m−3. The ejection velocities are in the range 0.16–0.61 ms−1. The directions of the ejection velocities are bounded by a cone with an apex angle of 43°. The axis of this cone has ecliptic coordinates of l = 154° and b = 26° and is 66° away from the direction to the Sun. Thermal stresses appear to be the most likely cause of such meteor cluster formation.

The anisotropy of MODIS LST in urban areas: A perspective from different time scales using model simulations

Remote sensing is one of the effective means to obtain urban land surface temperature (LST), but the observed temperature varies with sensor viewing angle due to urban thermal anisotropy (UTA) and biased sensor viewing angle. The anisotropy of satellite-based LST products (e.g., MODIS LST) varies at different time scales. Previous researches focus on the anisotropy of MODIS LST at the seasonal scale or at other time scales (e.g., hourly) but only for individual cities. The characteristics of anisotropy at different time scales and for cities at different latitudes are still unknown. In this study, we focus on analyzing the characteristics of anisotropy at hourly, daily, seasonal, and annual time scales separately for 80 global cities using the simulation data. The simulation data were generated by coupling a microscale urban surface temperature model and a thermal remote sensing model. In addition, the impact factors (i.e., sensor factor, meteorological factor, and surface factor) at different time scales are discussed and validated using satellite observations. The results show that the daytime instantaneous anisotropy varies from −4.2 K to 1.1 K at the hourly scale. For each city, the smaller anisotropy is captured at the local time 12:00 more easily for both Terra and Aqua overpass during daytime. This is because the magnitude of urban thermal anisotropy is more influenced by the sensor factor (i.e., sensor zenith angle), which varies with the overpass time and the relative position of the city in the track. However, if the seasonally or yearly aggregated MODIS LST is utilized to study mean surface temperature, the intensity of angular effect is much smaller with the value ranging from 0.1 K to 3.3 K at the seasonal scale (from 0.2 K to 2.1 K at the yearly scale) because the variation of sensor zenith angle is smoothed. At seasonal and yearly scales, the strength of the angular effect is greater in the morning during daytime, in summer among all seasons, and in the cities with lower latitudes, which is due to larger solar radiation. Among all meteorological factors, wind speed also has a larger impact on the magnitude of surface thermal anisotropy besides the downward surface shortwave radiation. Our study provides a reference for the correction of the angular effect in the MODIS LST products.

An Orientation-Aware Attention Network for Person Re-Identification

Humans always identify persons through their characteristics, salient attributes, and these attributes’ locations on the body. Most person re-identification methods focus on global and local features corresponding to the former two discriminations, cropping person images into horizontal strips to obtain coarse locations of body parts. However, discriminative clues corresponding to location differences cannot be discovered, so persons with similar appearances are often confused because of their alike components. To address the above problem, we introduce pixel-wise relative positions for the invariance of their orientations in viewpoint changes. To cope with the scale change of relative position, we combine relative positions with self-attention modules that perform on multi-level features. Moreover, in the data augmentation stage, mirrored images are given new labels due to the conversion of the relative position along a horizontal orientation and change in visual chirality. Extensive experiments on four challenging benchmarks demonstrate that the proposed approach shows its superiority and effectiveness in discovering discriminating features.

Leader–follower UAVs formation control based on a deep Q-network collaborative framework

This study examines a collaborative framework that utilizes an intelligent deep Q-network to regulate the formation of leader–follower Unmanned Aerial Vehicles (UAVs). The aim is to tackle the challenges posed by the highly dynamic and uncertain flight environment of UAVs. In the context of UAVs, we have developed a dynamic model that captures the collective state of the system. This model encompasses variables like as the relative positions, heading angle, rolling angle, and velocity of different nodes in the formation. In the subsequent section, we elucidate the operational procedure of UAVs in a collaborative manner, employing the conceptual framework of Markov Decision Process (MDP). Furthermore, we employ the Reinforcement Learning (RL) to facilitate this process. In light of this premise, a fundamental framework is presented for addressing the control problem of UAVs utilizing the DQN scheme. This framework encompasses a technique for action selection known as ε\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varepsilon$$\\end{document}-imitation, as well as algorithmic specifics. Finally, the efficacy and portability of the DQN-based approach are substantiated by numerical simulation validation. The average reward curve demonstrates a satisfactory level of convergence, and kinematic link between the nodes inside the formation satisfies the essential requirements for the creation of a controller.

Safe and socially compliant robot navigation in crowds with fast-moving pedestrians via deep reinforcement learning

AbstractSafe and socially compliant navigation in a crowded environment is essential for social robots. Numerous research efforts have shown the advantages of deep reinforcement learning techniques in training efficient policies, while most of them ignore fast-moving pedestrians in the crowd. In this paper, we present a novel design of safety measure, named Risk-Area, considering collision theory and motion characteristics of different robots and humans. The geometry of Risk-Area is formed based on the real-time relative positions and velocities of the agents in the environment. Our approach perceives risk in the environment and encourages the robot to take safe and socially compliant navigation behaviors. The proposed method is verified with three existing well-known deep reinforcement learning models in densely populated environments. Experiment results demonstrate that our approach combined with the reinforcement learning techniques can efficiently perceive risk in the environment and navigate the robot with high safety in the crowds with fast-moving pedestrians.

Occluded apples orientation estimator based on deep learning model for robotic harvesting

Apple harvesting robot is in rapid development in the recent years due to the shortage of manual labor. Robotics vision system has been one of the main focus in the development to achieve successful grasping. Information such as the apple orientation is valuable for developing more effective fruit detachment strategies. Occlusions in the orchard environment and the lack of distinct features in an apple has made it challenging to identify the apple orientation. Our study presents a novel approach that aims to estimate the orientation of fruits by projecting 2D information onto a 3D space. This method specifically targets the field of robotic harvesting and leverages multiple well-established and reliable fundamental methods currently available that includes keypoint detection neural network and circle detection based on extracted line segments of occluded apple. Based on the extracted information, a unit vector that represents orientation of the apple can be computed and transformed according to the relative position between the apple and the camera. The proposed method is evaluated using a publicly available 3D point cloud data of 11 apple trees from an orchard farm that was additionally labeled manually with apple orientations. To verify the evaluation results, the proposed method is tested by integrating it into an apple harvesting robot to perform inspection. Results shows that the median angular error in the orchard setting is 17.6° whilst in the lab setting is 14.6°. The experimental results show that the performance of the proposed method is comparable to existing research when under heavy occlusion and thus it is suitable for harvesting robot operating in the orchard farm.

Dysregulated CXCL12 expression in osteoblasts promotes B-lymphocytes preferentially homing to the bone marrow in MRL/lpr mice

Objective: Todetect the abnormal distribution of B-lymphocytes between peripheral and bone marrow (BM) compartments and explore the mechanism of abnormal chemotaxis of B-lymphocytes in lupus subjects. Methods: The proportions of CXC chemokine receptor (CXCR)4+ B cells and CFDA-labeled MRL/lpr-derived B cells were detected by flow cytometry. The levels of CXC chemokine ligand (CXCL)12in peripheral blood (PB)were measured by ELISA. The migrated B cells to osteoblasts (OBs) was measured by transwell migration assay. The relative spatial position of B cells, OBs and CXCL12 was presented by Immunofluorescence assay. Results: Firstly, we found that the percentage of CXCR4+ B cells was lower in PB and higher in the BM from both MRL/lpr mice and patientswith Systemic lupus erythematosus (SLE). Secondly, OBs from MRL/lpr mice produced more CXCL12 than that from C57BL/6 mice. Besides, MRL/lpr-derived OBs demonstrated more potent chemotactic ability toward B-lymphocytes than control OBs by vitro an vivo. Additionally, more B-lymphocytes were found to co-localize with OBs within the periosteal zone of bone in MRL/lpr mice. Lastly, the percentages of CXCR4+B cells were found to be negatively correlated with serum Immunoglobulin (Ig) G concentration, moreover, BM CXCL12 levels were found to be positively correlated with SLE disease activity index Score and negatively correlated with serum Complement3 (C3) concentration. Conclusions: our results indicated that there is a shifted distribution of B-lymphocytes between BM and peripheral compartments in both SLE patients and MRL/lpr mice. Besides, the up-regulated levels of CXCL12 in OBs was indicated to contribute to the enhanced chemotactic migration and anchorage of B-lymphocytes to OBs.

Modification of Woven Endo-Bridge After Intracranial Aneurysm Treatment: A Methodology for Three-Dimensional Analysis of Shape and Relative Position Changes.

During follow-up of patients treated with WEB devices, shape changes have been observed. The quantitative three-dimensional measurement of the WEB shape modification (WSM) would offer useful information to be studied in association with the anatomical results and try to better understand mechanisms implicated in this modification phenomenon. We present a methodology to quantify the morphology and position of the WEB device in relation to the vascular anatomy. Three-dimensional rotational angiography (3DRA) images of seven aneurysms patients treated with WEBs were used, which also accompanied by a post-treatment 3DRA image and a follow-up 3DRA image. The device was manually segmented, obtaining the 3D models after treatment and at the follow-up. Volume, surface area, height, maximum diameter and WSM ratio of both surfaces were calculated. Position changes were evaluated measuring WEB axis and relative position between post-treatment and follow-up. Changes in WEB volume and surface area were observed with a mean modification of and , respectively. The positional variables also showed differences, mean change of device axis direction was and mean change of distance was . Inter-observer and intra-observer variability analyses did not show differences (ANOVA ). This methodology allows quantifying the morphological and position changes suffered by the WEB device after treatment, offering new information to be studied in relation to the occurrence of WEB shape modification.

AI-assisted deepfake detection using adaptive blind image watermarking

This paper proposes a new adaptive blind watermarking technology for deepfake detection, which can embed deepfake detection information into the image and verify the image's authenticity without requiring additional information. The proposed scheme utilizes mixed modulation combined with partly sign-altered mean value to embed a set of coefficients that enhance robustness against attacks while maintaining high image quality. Additionally, blind adaptive deepfake detection technology with the tamper detection mean value is employed to detect relative positions adaptively, even when face images are slightly modified or deepfaked. To further improve the performance of the proposed scheme, a gray wolf optimizer is introduced to optimize parameters, and a denoising autoencoder is employed to facilitate the identification of extracted watermarks. This technology will adaptively embed watermark information while preserving the original face image, thereby maintaining the authenticity of the face in the image and verifying the owner of the image. The code is available at https://github.com/lyhsu01/AwDD.