bluuebunny/crossref_metadata_2025_split huggingface dataset:
The motion of twisted particles in a stellar gravitational field
Authors: Lian Dan-Dan , Zhang Peng-Ming 
Published: August 2024

Abstract
In this work, we explore the motion of a twisted particle possessing intrinsic orbital angular momentum (OAM) as it traverses a weak stellar gravitational field, which we approximate using a polytropic model. We disregard the spin characteristic of the twisted particle, modeling it as a massless complex twisted scalar wave packet to simplify its interaction with gravitational fields. Building on this simplification, we determine the trajectory of this twisted particle by using the center of its energy density and investigate the gravitational birefringence induced by its OAM. In a weak field approximation, we find the gravitational birefringence-OAM relationship parallels that with spin, as described by the Mathisson-Papapetrou-Dixon equations. This indicates that the gravitational birefringence induced by OAM can potentially exceed that induced by spin by several orders of magnitude, significantly enhancing its detectability. To broaden our analysis, we introduce a nonminimal coupling term,

λ
R

|

ϕ

|
2

, into the Lagrangian, resulting in the modified expression

L

=
−

1
2

∇
ρ

ϕ

∇
ρ

ϕ
∗

−

1
2

λ
R

|

ϕ

|
2

. This adjustment is necessitated by the quantization of the scalar field in curved spacetime. We then explore the effects of this term on the motion of the twisted particle. Our findings show that the trajectory of the twisted particle under nonminimal coupling (λ ≠ 0) differs from that in the minimal coupling scenario (λ = 0). Specifically, for a positive nonminimal coupling constant λ, the trajectory of the twisted particle is expected to deviate away from the stellar center, compared to the minimal coupling scenario.
A new 2+1 coherent spin-foam vertex for quantum gravity
Authors: Simão J D 
Published: August 2024

Abstract
We propose an explicit spin-foam amplitude for Lorentzian gravity in three dimensions, allowing for both space- and time-like boundaries. The model is based on two main requirements: that it should be structurally similar to its well-known Euclidean analog, and that geometricity should be recovered in the semiclassical regime. To this end we introduce new coherent states for space-like boundary edges, derived from the continuous series of unitary

SU

(
1
,
1
)

representations. We show that the relevant objects in the amplitude can be written in terms of the defining representation of the group, just as so happens in the Euclidean case. We derive an expression for the semiclassical amplitude at large spins, showing it relates to the Lorentzian Regge action.
Shadow of rotating black holes surrounded by dark fluid with Chaplygin-like equation of state and constraints from EHT results
Authors: Zahid Muhammad , Sarikulov Furkat , Shen Chao , Ahmedov Saidmuhammad , Rayimbaev Javlon 
Published: August 2024

Abstract
In this work, we mainly focus on testing the spacetime properties around black holes surrounded by a dark fluid, which are potential candidates for dark energy described by the Chaplygin-like equation of state through its shadow. To do this, we first study the black hole’s horizon structure and shadow for the non-rotating case. Then, we obtain a rotating black hole solution in the presence of a dark fluid using the generalized Newman–Janis algorithm and study the effects of the black hole spin and the fluid parameters on the black hole horizons. Also, we obtained the shadow cast of the rotating black hole using celestial coordinates and showed that the presence of the dark fluid causes an increase in shadow size. Moreover, we use the shadow size of supermassive black holes Sagittarius A* and M87* from Event Horizon Telescope observations to obtain constraints on the spin, black hole charge, and dark fluid parameters. Lastly, we investigate the energy emission rate of a charged black hole surrounded by a Chaplygin-like dark fluid, comparing it to both rotating and non-rotating cases.
A perspective on reducing stabilizing pressure for high-temperature superconductivity in hydrides
Authors: Jiang Qiwen , Chen Ling , Du Mingyang , Duan Defang 
Published: August 2024

Abstract
The theoretical predictions and experimental syntheses of hydrogen sulfide (H3S) have ignited a surge of research interest in hydride superconductors. Over the past two decades, extensive investigations have been conducted on hydrides with the ultimate goal of achieving room-temperature superconductivity under ambient conditions. In this review, we present a comprehensive summary of the current strategies and progress towards this goal in hydride materials. We conclude their electronic characteristics, hydrogen atom aggregation forms, stability mechanisms, and more. While providing a real-time snapshot of the research landscape, our aim is to offer deeper insights into reducing the stabilizing pressure for high-temperature superconductors in hydrides. This involves defining key long-term theoretical and experimental opportunities and challenges. Although achieving high critical temperatures for hydrogen-based superconductors still requires high pressure, we remain confident in the potential of hydrides as candidates for room-temperature superconductors at ambient pressure.
Use of real-time electronic extremity dosimeters for monitoring and optimisation of radiopharmacy technique
Authors: Cournane S , McCavana J , Maguire D , Tutty L , Harris L , Lucey J , Kenneally C 
Published: August 2024

Abstract
Radiopharmacy staff members are subject to extremity radiation doses, particularly to the fingertips. Dosemeters, such as, thermoluminescent detectors (TLDs) are currently used for monitoring fingertip doses. This study aimed to use real-time dosemeters to monitor radiopharmacy extremity doses to identify specific procedural steps associated with higher fingertip doses and, subsequently, reduce dose through promotion of optimised radiation protection practises. Five radiopharmacy operators were monitored using an ED3 active extremity dosemeter with a detector attached to each tip of the index fingers. Dose rate and accumulated dose data were matched to the handled radioactivity data, of 99mTc-labelled radiopharmaceuticals only, with the dose per activity (μSv MBq−1) calculated for each step. Once baseline dose data was established, an educational session identified technique adjustments toward improved radiation protection. A subsequent monitored session was undertaken with the dose data compared to quantify changes in operator doses. Radiopharmacy steps which significantly contributed to extremity doses were identified. The average accumulated dose per activity across all procedural steps for the 99mTc-labelled radiopharmaceuticals for all operators before the educational session was 0.042 ± 0.045 μSv MBq−1 and 0.042 ± 0.041 μSv MBq−1 (n = 89) for non-dominant and dominant index fingertips, respectively, and 0.030 ± 0.044 μSv MBq−1 and 0.031 ± 0.032 μSv MBq−1 (n = 97), respectively, afterwards. Overall, there was an average 40.7% reduction in the total extremity dose received after the educational session. Real-time electronic extremity dosemeters for monitoring radiopharmacy extremity dose presented as a useful tool for incorporation into radiation protection education and training, towards optimised radiopharmacy technique.
Multi-scale receptive field grouped and split attention network for real-time detection of hazardous chemical gas leaks in infrared images
Authors: Chen Yan , Wang Kehong , Wang Xiaofeng , Huai Shibao , Xu Lixiang , Zhang Chen , Wang Mingtao 
Published: August 2024

Abstract
The petrochemical industry faces frequent hazardous gas leaks, which demand precise and timely detection to avert severe consequences. Existing computer vision approaches encounter challenges due to limitations in gas characteristics and scene features. To address these issues, we propose a multiscale receptive field grouped and split attention network, GAS-YOLO, that integrates infrared imaging technology. Within GAS-YOLO, we design a novel module, multi-scale receptive field grouped convolution (MRFGConv), to preserve fine-grained information, preventing detail loss and addressing spatial attention feature-sharing issues. An innovative split convolution attention (SCA) mechanism in the C2f module effectively couples multi-scale features, balancing performance and efficiency. Additionally, the asymptotic feature pyramid network (AFPN) facilitates the mutual interaction of information between non-adjacent levels, enabling advanced feature fusion. Using benchmark InfraGasLeakDataset, GAS-YOLO surpasses YOLOv8-n by 5.8% mAP50, with SCA outperforming state-of-the-art attention models. Experiment results validate the effectiveness and feasibility of our proposed approaches, providing valuable insights into hazardous chemical gas leak detection.
LDVI-SLAM: a lightweight monocular visual-inertial SLAM system for dynamic environments based on motion constraints
Authors: Wang Fenghua , Zhao Lengrui , Xu Zhicheng , Liang Hong , Zhang Qian 
Published: August 2024

Abstract
Traditional simultaneous localization and mapping (SLAM) systems are typically based on the assumption of a static environment. However, in practical applications, the presence of moving objects significantly reduces localization accuracy, limiting the system’s versatility. To address the challenges of SLAM systems in dynamic environments, the academic community often employs computationally intensive methods such as deep learning, and some algorithms rely on expensive sensors (e.g. LiDAR or RGB-D cameras) to obtain depth information. These factors increase computational complexity or hardware costs, complicating practical deployment. To improve localization accuracy and adaptability of SLAM systems in dynamic scenarios while maintaining low deployment costs, this paper proposes a dynamic environment robust monocular inertial SLAM system named LDVI-SLAM. The system uses more cost-effective sensors—monocular cameras and inertial measurement unit (IMU)—along with lightweight computational methods. In LDVI-SLAM, first, the reliability of IMU data is verified. Then, using the ego-motion information provided by the IMU, along with epipolar constraint and an improved rotation-aware flow vector bound (R-FVB) constraint, dynamic feature points are eliminated. Additionally, this paper proposes a continuous tracking across interval frames method to enhance the distinction between static and dynamic feature points. Experimental results demonstrate that LDVI-SLAM performs effectively in dynamic environments and is easy to deploy. On the Visual-Inertial Odometry in Dynamic Environments dataset, experimental results show that compared to the deep learning-based DynaSLAM, this method reduces the root mean square error of absolute trajectory error by 10.3%. Moreover, in terms of speed, under the same computing power, the single-frame processing speed of this method is comparable to ORB-SLAM3 and is two orders of magnitude faster than DynaSLAM, significantly outperforming deep learning-based SLAM algorithms. Experiments on the Oxford Multimotion Dataset further prove that this method effectively avoids the risk of semantic classification errors, demonstrating better robustness and generality.
Experiment and industrial application of dust concentration measurement method using image transmittance characteristic
Authors: Ye Fangping , Wang Daibing , Xu Xianjin , Fang Chaoyang , Nie Lei 
Published: August 2024

Abstract
To prevent the harm of respirable dust and dust explosions, it is necessary to detect the concentration of dust generated in the process of bulk materials to help dust suppression. In this investigation, a dust concentration measurement method is proposed based on the eigenvalue calculation of image transmittance. The method is combined with the dark channel prior theory into the computer system and calibrated in the laboratory to calculate the transmittance of dust images. Furthermore, a dust concentration online measurement experimental platform is established to verify the correctness and reliability. Moreover, the industrial application is also carried out. The average relative error of dust concentration is 4.53%, and the relative error is less than 10% of the dust concentration measured by online measurement experimental platforms and industrial applications, which satisfied the measurement requirements. It is concluded that the measurement method has high applicability and can be practically applied to dust concentration measurements.
Research on a semi-supervised soft sensor modelling method for complex chemical processes based on INGO-VMD-ESN
Authors: Wang Qinghong , Li Longhao , Li Naiqing , Sun Fengpeng , Liu Xuefeng , Wang Shuang 
Published: August 2024

Abstract
The dynamic and non-linear nature of complex chemical processes often leads to low prediction accuracy of key quality variables by traditional soft sensors, thus affecting the overall system control accuracy and operational efficiency. Therefore, this paper proposes a semi-supervised soft sensor modelling method based on improved the northern goshawk optimization (INGO)-variable mode decomposition (VMD)-echo state network (ESN). Firstly, a new semi-supervised fusion method is proposed to address the problem of model training difficulty due to the scarcity of labelled samples and process dynamics, which reconstructs the sample dataset by fusing labelled and unlabelled samples into more representative new samples, improving the model’s generalization ability. Secondly, for the noise interference present in the reconstructed data, the input data is denoised using the VMD method to improve the quality of data. Then, a soft sensor model is built based on ESN. Additionally, the denoising and prediction performance of VMD and ESN is significantly affected by parameters, therefore the paper utilizes the INGO algorithm to achieve parameter rectification for VMD and ESN. Finally, the method is validated based on actual sulphur recovery data from a refinery. The results demonstrate that the method effectively mitigates the impact of dynamics and nonlinearity in the complex chemical process which enhances prediction accuracy.
Refining penalty parameter selection in whole-body PET image reconstruction for lung cancer patients using the cross-validation log-likelihood method
Authors: Wang Qian , Abdelhafez Yasser G , Nalbant Hande , Spencer Benjamin A , Bayerlein Reimund , Qi Jinyi , Cherry Simon R , Nardo Lorenzo , Badawi Ramsey D 
Published: August 2024

Abstract

Objective. Penalty parameters in penalized likelihood positron emission tomography (PET) reconstruction are typically determined empirically. The cross-validation log-likelihood (CVLL) method has been introduced to optimize these parameters by maximizing a CVLL function, which assesses the likelihood of reconstructed images using one subset of a list-mode dataset based on another subset. This study aims to validate the efficacy of the CVLL method in whole-body imaging for cancer patients using a conventional clinical PET scanner. Approach. Fifteen lung cancer patients were injected with 243.7 ± 23.8 MBq of [18F]FDG and underwent a 22 min PET scan on a Biograph mCT PET/CT scanner, starting at 60 ± 5 min post-injection. The PET list-mode data were partitioned by subsampling without replacement, with 20 minutes of data for image reconstruction using an in-house ordered subset expectation maximization algorithm and the remaining 2 minutes of data for cross-validation. Two penalty parameters, penalty strength β and Fair penalty function parameter δ, were subjected to optimization. Whole-body images were reconstructed, and CVLL values were computed across various penalty parameter combinations. The optimal image corresponding to the maximum CVLL value was selected by a grid search for each patient. Main results. The δ value required to maximize the CVLL value was notably small (⩽10−6 in this study). The influences of voxel size and scan duration on image optimization were investigated. A correlation analysis revealed a significant inverse relationship between optimal β and scan count level, with a correlation coefficient of −0.68 (p-value = 3.5 × 10−5). The optimal images selected by the CVLL method were compared with those chosen by two radiologists based on their diagnostic preferences. Differences were observed in the selection of optimal images. Significance. This study demonstrates the feasibility of incorporating the CVLL method into routine imaging protocols, potentially allowing for a wide range of combinations of injected radioactivity amounts and scan durations in modern PET imaging.
SBL-LCGL: sparse Bayesian learning based on Laplace distribution for robust cone-beam x-ray luminescence computed tomography
Authors: Wang Yifan , Wang Haoyu , Zhu Qiuquan , Chen Yi , Su Linzhi , Yi Huangjian , Gao Chengyi , Cao Xin 
Published: August 2024

Abstract

Objective. To address the quality and accuracy issues in the distribution of nanophosphors (NPs) using Cone-beam x-ray luminescence computed tomography (CB-XLCT) by proposing a novel reconstruction strategy. Approach. This paper introduces a sparse Bayesian learning reconstruction method termed SBL-LCGL, which is grounded in the Lipschitz continuous gradient condition and the Laplace prior to overcome the ill-posed inverse problem inherent in CB-XLCT. Main results. The SBL-LCGL method has demonstrated its effectiveness in capturing the sparse features of NPs and mitigating the computational complexity associated with matrix inversion. Both numerical simulation and in vivo experiments confirm that the method yields satisfactory imaging results regarding the position and shape of the targets. Significance. The advancements presented in this work are expected to enhance the clinical applicability of CB-XLCT, contributing to its broader adoption in medical imaging and diagnostics.
A sectional nonlinear wideband piezoelectric-magnetic coupled energy collector for collecting multi-directional vibrational energy
Authors: Zhu Yuancheng , Zhu Yongqiang , Zou Longhua , Chi Han , Zhuang Huyue , Zhang Pingxia 
Published: August 2024

Abstract
The classic vibration energy collector has functional restrictions, and it can only collect vibration energy in one or two dimensions. At the same time, it has issues with low output power in the low-frequency vibration region and a limited reaction frequency range. This research proposes a segmented nonlinear broadband piezoelectric–magnetic coupled energy collector capable of collecting vibration energy in different directions. The collector is equivalent to current state-of-the-art research in that it can collect vibration energy in three dimensions while also having a wide collection frequency and a high power density. The collection consists of a hemispherical support structure and four fundamental piezoelectric beam collision components. The rationality of the collision segmentation nonlinear principle is first clarified through theoretical calculation and analysis, and then the collision design is applied between the ends of different cantilever beams to broaden the captured energy frequency band, while parallel piezoelectric beams use a 45° tilt treatment to fully utilize the geometrical properties of the tilted beams for multidirectional energy collection. In addition, the collector introduces a magnetic coupling effect to create a bistable structure via magnetic contact. Comsol 5.6 software is used to model and simulate the planned 45° tilted beam structure, which clarifies the piezoelectric beam’s linear intrinsic frequency characteristics and multi-directional geometric aspects. To further verify the collector’s validity, a physical model is built and a vibration experiment apparatus is created. The experimental results demonstrate that the collector’s effective bandwidth range is up to 6.3 Hz under 1 g acceleration excitation, representing a 125.0% increase in bandwidth when compared to the cantilever beam with a linear array. At 14 Hz frequency, the collector produces a maximum total output power of 19.52 mW and a power density of up to 3211uW cm−3 when excitation is provided in the Z-direction.
Periodicity of bipartite walk on biregular graphs with conditional spectra
Authors: Chen Qiuting 
Published: August 2024

Abstract
In this paper we study a class of discrete quantum walks, known as bipartite walks. These include the well-known Grover’s walks. A discrete quantum walk is given by the powers of a unitary matrix U indexed by arcs or edges of the underlying graph. The walk is periodic if U

k
= I for some positive integer k. Kubota has given a characterization of periodicity of Grover’s walk when the walk is defined on a regular bipartite graph with at most five eigenvalues. We extend Kubota’s results—if a biregular graph G has eigenvalues whose squares are algebraic integers with degree at most two, we characterize periodicity of the bipartite walk over G in terms of its spectrum. We apply periodicity results of bipartite walks to get a characterization of periodicity of Grover’s walk on regular graphs.
Physical interpretation of invariance of vector differential operators in three orthogonal coordinate systems and a case study of wall and globe of death
Authors: Gapale D L , Arote S A , Baviskar P K , Navale S R , Palve B M , Bardapurkar P P , Pathan A S , Dalvi S N 
Published: August 2024

Abstract
In the present study, the effect of operators on fundamental physical quantities in three orthogonal coordinate systems was analyzed using differential equations. The mathematical expression for the position vector and its magnitude, velocity, &acceleration in three orthogonal coordinate systems were obtained from the geometry of the figure and differentiation. The derivations of operation of vector differential operators (curl and diversions) on position vectors were derived, and their physical significance was illustrated. Similarly, the operation of the Laplacian operator on the magnitude of the position vector was also studied. The study highlighted the invariance in the results of all operations in three orthogonal coordinate systems. An investigation has been performed to describe the wall of death and the globe of death problem in appropriate orthogonal coordinate systems. The interpretations in terms of velocity, acceleration, and the net force acting on the vehicle are explained in detail.
Dynamics of cosmic string formation with emission of gravitational waves: a toy model
Authors: Mendoza Hernández Jaime , Bellini Mauricio 
Published: August 2024

Abstract
Starting from an extended theory of general relativity with boundary terms included, we study a toy model to describe the dynamical collapse of an infinite cylinder with positive spatial curvature from which a cosmic string is formed after collapsing, and we examine the production of gravitational waves (GW) emitted during the collapse. The background dynamics of the radial collapse is described by a massive scalar field which departs from the equilibrium when the scalar field climbs through the quadratic potential. During the collapse the radial pressure is considered as null, so that the kinetic and the potential energy densities are equaled. The components of the GW modes +,×and B, for the polarization tensor, are analytically obtained.