bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of the electronic oscillation spectrum in metallic clusters, caused by the presence of a large spatial scale of inhomogeneity
Authors: Kuratov S. E. , Lozovik Yu. E. , Igashov S. Yu.
Published: August 2024

This work presents a theoretical analysis of the oscillations of a system of degenerate electrons in metallic submicron clusters, taking into account the presence of a large-scale spatial inhomogeneity caused by quantum shell effects. The analysis was carried out in a model formulation in which the large-scale effect was taken into account by the presence of an effective external field acting on the electrons. Two approaches to the description of electron dynamics were considered: kinetic and hydrodynamic. The results obtained within these approaches are in good qualitative and quantitative agreement with each other and demonstrate that for certain cluster sizes, a spectrum of oscillations of the electronic system appears with frequencies differing by the value Δω ∼ ω0/R20 and localized in the vicinity of plasmon frequency ω0 (R0, radius of cluster). The impact of the large-scale effect on the processes of light and electron scattering by metal clusters is estimated. It is shown that maxima appear in the absorption spectrum of the electromagnetic waves, and they turn out to be shifted from the plasmon frequency by value Δω ∼ ω0/R20. Within the framework of the Born approximation, it is shown that a maximum at kR0 ∼ 4π appears in the cross section of elastic scattering of electrons on a metal cluster. The results obtained are important from the point of view of interpreting experiments on plasmonic structures, in particular, on metal films.
GaN microdisks with a single porous optical confinement layer for whispering gallery mode lasing
Authors: Li Yuyin , Zhou Jing , Yan Ziwen , Zhang Xianfei , Xie Zili , Xiu Xiangqian , Chen Dunjun , Liu Bin , Zhao Hong , Shi Yi , Zhang Rong , Zheng Youdou , Chen Peng
Published: August 2024

This paper details the fabrication of GaN-based microdisks with a single porous n-GaN layer positioned beneath the multiple quantum wells region on a modified green light-emitting diode epiwafer. Simulations of the longitudinal light field distribution reveal effective confinement of the light field within the multiple quantum wells region due to the presence of the single porous layer. The porous layer also demonstrates sufficient conductivity as determined through calculations and serves as an effective method for thermal dispersion. Under optical pumping, all microdisks exhibit clear whispering gallery mode (WGM) lasing at room temperature, with the lowest threshold of 13.50 μJ/cm2 achieved in a 2-μm-diameter microdisk. These findings suggest that integrating the single porous layer into GaN microdisks is a highly promising approach for achieving high-efficiency WGM micro-laser diodes with effective electrical injection and heat dispersion.
Traveling Alfvén waves in inhomogeneous plasma flows along magnetic field
Authors: Churilov S. M.
Published: August 2024

In the framework of ideal magnetohydrodynamics, a one-dimensional problem of linear Alfvén waves propagation is considered in a stationary flow of inhomogeneous plasma along straight uniform magnetic field. Four families of flows are found, in which accelerated and retarded by the flow waves of arbitrary shape can propagate independently of each other, that is, without reflection. It is shown that in two of these families both waves have a similar structure, but in the other two their structures differ significantly.
Multiphase flow analysis of complex wellbore–fracture–cave connections in condensate gas reservoirs
Authors: Pan Quanyu , Cheng Linsong , Jia Pin , Da Yinpeng , Li Jianhui , Cao Chong , Jia Zhihao , Cao Renyi
Published: August 2024

The significant heterogeneity of fracture-caved gas reservoirs and the phase transition behavior with pressure depletion pose great challenges for flow behavior analysis and property estimation. Therefore, the objective of this paper is to develop robust and novel pressure transient analysis models for condensate-gas flow under pressure depletion in fracture-caved gas reservoirs. To characterize the complex connections between wellbore, fracture region, and caves, four conceptual models of wellbore–fracture–cave distributions are determined. The fracture region is considered as a dynamic three-zone (dry gas zone, condensate-gas two-phase zone, and transition zone) to characterize the phase transition during pressure depletion, while a variable storage concept is introduced to describe the phase transition in the wellbore and caves. The results indicate that six typical flow stages can be observed from the type curves: constant wellbore storage flow, variable wellbore storage flow, fracture linear flow (FLS), constant cave storage flow, variable cave storage flow, and transition flow. Moreover, the phase transition behavior in the fracture region is reflected in the changes of one-half slope straight lines during the FLS period, while the phase transition behavior in the wellbore and caves is reflected in the pressure derivative curve as a positive upward bending of the straight line with unit slope at later stage. The property estimation in the fracture-caved gas reservoirs (i.e., length and permeability of the fracture region, the storage coefficient of wellbore and cave) by matching with the actual pressure monitoring data provides a better understanding of the geological evidence.
Lattice Boltzmann simulation on particle suspensions containing porous particles in a narrow channel
Authors: Li Zhitao , Tao Shi , Zhang Chunhua , Jia Zhouxia , Wang Liang , Lu Gui
Published: August 2024

The suspension of porous particles in fluids occurs widely in various natural and industrial processes. However, the sedimentation behavior of porous particles is not extensively understood as the solid impermeable counterparts. In this work, the drafting–kissing–tumbling (DKT) phenomenon in a narrow channel containing porous particles is investigated by the multi-relaxation-time (MRT) lattice Boltzmann method (LBM). The initial particle spacing Lp* (1.5∼6) and Darcy number Da (8×10−6∼6×10−2) are examined on the sedimentation process of two particles under three initial arrangements, i.e., the trailing particle is porous (case 1), the leading particle is porous (case 2), and both the particles are porous (case 3). The results show that the presence of porous particles can enhance the interactions between two particles, and increasing the penetrability reduces the particle drag force to accelerate sedimentation. The drafting time is insensitive to Da at small Lp*, and it decreases with Da at large Lp* in cases 1 and 3 while it changes to increase with Da in case 2. A phase diagram with respect to Da and Lp* is further extracted to identify three sedimentation modes of particle pairs. It is found that the transition between the one-off DKT and repeated DKT modes is not affected by Lp* in cases 2 and 3, while the critical condition for the non-DKT and one-off DKT modes depends strongly on Da and Lp* in case 2.
Three-dimensional lattice Boltzmann flux solver for three-phase/component flow
Authors: Zhang Da , Li Yan , Gong Liang , Zhu Chenlin , Shu Chang
Published: August 2024

In this article, an immiscible three-phase/three-component lattice Boltzmann flux solver (TPLBFS) based on diffusion interface method is proposed, which can achieve three-phase flow simulation with high density ratio (1:1000). This model quickly solved (1) the flux at the grid interface using the lattice Boltzmann method (LBM) solution format and (2) the Navier–Stokes (NS) equation and Cahn–Hilliard (CH) equation using a unified format. Compared to LBM, TPLBFS can be applied to unstructured networks. Moreover, TPLBFS can independently add or remove source items and has high secondary development features. Its outstanding computing power has been demonstrated by multiple two-dimensional/three-dimensional (2D/3D) examples, including 2D liquid lens as well as 3D bubble absorption and bubble rising in a three-phase system.
Climate, demography, immunology, and virology combine to drive two decades of dengue virus dynamics in Cambodia
Authors: Brook Cara E. , Rozins Carly , Bohl Jennifer A. , Ahyong Vida , Chea Sophana , Fahsbender Liz , Huy Rekol , Lay Sreyngim , Leang Rithea , Li Yimei , Lon Chanthap , Man Somnang , Oum Mengheng , Northrup Graham R. , Oliveira Fabiano , Pacheco Andrea R. , Parker Daniel M. , Young Katherine , Boots Michael , Tato Cristina M. , DeRisi Joseph L. , Yek Christina , Manning Jessica E.
Published: August 2024

The incidence of dengue virus disease has increased globally across the past half-century, with highest number of cases ever reported in 2019 and again in 2023. We analyzed climatological, epidemiological, and phylogenomic data to investigate drivers of two decades of dengue in Cambodia, an understudied endemic setting. Using epidemiological models fit to a 19-y dataset, we first demonstrate that climate-driven transmission alone is insufficient to explain three epidemics across the time series. We then use wavelet decomposition to highlight enhanced annual and multiannual synchronicity in dengue cycles between provinces in epidemic years, suggesting a role for climate in homogenizing dynamics across space and time. Assuming reported cases correspond to symptomatic secondary infections, we next use an age-structured catalytic model to estimate a declining force of infection for dengue through time, which elevates the mean age of reported cases in Cambodia. Reported cases in >70-y-old individuals in the 2019 epidemic are best explained when also allowing for waning multitypic immunity and repeat symptomatic infections in older patients. We support this work with phylogenetic analysis of 192 dengue virus (DENV) genomes that we sequenced between 2019 and 2022, which document emergence of DENV-2 Cosmopolitan Genotype-II into Cambodia. This lineage demonstrates phylogenetic homogeneity across wide geographic areas, consistent with invasion behavior and in contrast to high phylogenetic diversity exhibited by endemic DENV-1. Finally, we simulate an age-structured, mechanistic model of dengue dynamics to demonstrate how expansion of an antigenically distinct lineage that evades preexisting multitypic immunity effectively reproduces the older-age infections witnessed in our data.
Multiomics of a rice population identifies genes and genomic regions that bestow low glycemic index and high protein content
Authors: Badoni Saurabh , Pasion-Uy Erstelle A. , Kor Sakshi , Kim Sung-Ryul , Tiozon Rhowell N. , Misra Gopal , Buenafe Reuben James Q. , Labarga Luster May , Ramos-Castrosanto Ana Rose , Pratap Vipin , Slamet-Loedin Inez , Steimker Julia von , Alseekh Saleh , Fernie Alisdair R. , Kohli Ajay , Khush Gurudev S. , Sreenivasulu Nese
Published: August 2024

To counter the rising incidence of diabetes and to meet the daily protein needs, we created low glycemic index (GI) rice varieties with protein content (PC) surpassing 14%. In the development of recombinant inbred lines using Samba Mahsuri and IR36 amylose extender (IR36ae) as parental lines, we identified quantitative trait loci and genes associated with low GI, high amylose content (AC), and high PC. By integrating genetic techniques with classification models, this comprehensive approach identified candidate genes on chromosome 2 (
qGI2.1/qAC2.1
spanning the region from 18.62 Mb to 19.95 Mb), exerting influence on low GI and high amylose. Notably, the phenotypic variant with high value was associated with the recessive allele of the
starch branching enzyme 2b
(
sbeIIb
). The genome-edited
sbeIIb
line confirmed low GI phenotype in milled rice grains. Further, combinations of alleles created by the highly significant SNPs from the targeted associations and epistatically interacting genes showed ultralow GI phenotypes with high amylose and high protein. Metabolomics analysis of rice with varying AC, PC, and GI revealed that the superior lines of high AC and PC, and low GI were preferentially enriched in glycolytic and amino acid metabolisms, whereas the inferior lines of low AC and PC and high GI were enriched with fatty acid metabolism. The high amylose high protein recombinant inbred line (HAHP_101) was enriched in essential amino acids like lysine. Such lines may be highly relevant for food product development to address diabetes and malnutrition.
Quantum Fisher information in acceleration parallel to a planar wall
Authors: Yang Ying , Fu Xiangyun , Jing Jiliang
Published: August 2024

In this work, we devote to understand how boundaries can help improve parameter estimation against atomic decoherence and dissipation caused by relativistic motion. The system we considered is a two-level atom in uniform linear acceleration parallel to a planar wall in (3+1)-dimensional Minkowski spacetime, which is coupled to a massless scalar field with Dirichlet, Neumann or transparent boundary conditions at the wall. We find that the quantum Fisher information (QFI), which determines the ultimate estimation precision, depends on various factors, such as atomic motional trajectories, evolution time, atomic initial state, and the boundary condition. We identify the optimal estimation strategies that maximize the QFI through all the associated parameters, thus optimizing the estimation precision. Our results show that the QFI has different behaviors and even different magnitudes for different boundary cases. We also determine the boundary conditions that can effectively suppress the influence of atomic relativistic motion on the QFI. Our investigation may help advance the study of relativistic quantum information in cavity quantum electrodynamics.
Tracking dissociation pathways of nitrobenzene via mega-electron-volt ultrafast electron diffraction
Authors: Hegazy Kareem , Bucksbaum Phil , Centurion Martin , Cryan James , Li Renkai , Lin Ming-Fu , Moore Bryan , Nunes Pedro , Shen Xiaozhe , Weathersby Stephen , Yang Jie , Wang Xijie , Wolf Thomas
Published: August 2024

As the simplest nitroaromatic compound, nitrobenzene is an interesting model system to explore the rich photochemistry of nitroaromatic compounds. Previous investigations of nitrobenzene’s photochemical dynamics have probed structural and electronic properties. These investigations paint, at times, a convoluted and sometimes contradictory description of the photochemical landscape. We investigate the ultrafast dynamics of nitrobenzene triggered by photoexcitation at 267 nm for the first time using a structural probe with femtosecond time resolution. Our probe complements previous measurements of nitrobenzene’s electronic structure evolution and aids in determining the photochemical dynamics with less ambiguity. We employ megaelectronvolt ultrafast electron diffraction to follow nitrobenzene’s structural evolution within the first 5 ps after photoexcitation. We observe ground state recovery within

160
±
60

fs through nonadiabatic dynamics. Based on comparisons of the experimental signal with molecular dynamics simulations, we exclude a significant population of the triplet manifold. Furthermore, we do not observe fragmentation of nitrobenzene within the investigated time window, which indicates that previously observed photofragmentation reactions take place in the vibrationally ‘hot’ ground state on timescales considerably beyond 5 ps.
Controllable dual resonances of Fano and EIT in a graphene-loaded all-dielectric GaAs metasurface and its sensing and slow-light applications
Authors: Wang Zhichao , Huang Huahao , Zhang Hui , He Miao , Zhao Weiren
Published: August 2024

Active nanophotonic metasurfaces have attracted considerable attention for their promise to develop compact, tunable optical metadevices with advanced functions. In this work, we theoretically demonstrated the dynamically controllable dual resonances of Fano and electromagnetically induced transparency (EIT) using a graphene-loaded all-dielectric metasurface with U-shaped gallium arsenide (GaAs) nanobars operating in the near-infrared region. The destructive interference between a subradiant mode (i.e. a dark mode) supported by two vertical GaAs bars and two radiative modes (i.e. two bright modes) supported by a horizontal GaAs nanobar gives rise to a Fano resonance and an EIT window with high transmission and a large quality factor (Q-factor) in the transmission spectrum. Importantly, the transmission amplitudes can be flexibly modulated by adjusting the graphene Fermi levels without rebuilding the nanostructures. This modulation results from the controllable light absorption by the loaded graphene monolayer due to its interband losses in the near-infrared spectrum. Furthermore, the peak wavelengths of the Fano resonance and EIT window with high Q-factors are highly sensitive to variations in the refractive index (RI) of the surrounding medium, giving the proposed metasurface a relatively good sensitivity of ∼700 nm RIU−1 and a high figure of merit of 280, making it an effective RI sensor. Additionally, the metasurface features an adjustable slow light effect, indicated by the adjusted group delay time ranging from 0.12 ps to 0.38 ps. Therefore, the metasurface system proposed in this work offers a viable platform for advanced multi-band optical sensing, low-loss slow light devices, switches, and potential applications in nonlinear optical fields.
Tutorial: electrical measurements in nanosecond pulsed plasma reactors
Authors: Pavan Colin A , Rao Sankarsh R , Guerra-Garcia Carmen
Published: August 2024

This tutorial is intended to provide an introduction to transmission line theory (telegrapher’s equations), as the mathematical background needed to correctly perform and interpret electrical measurements in nanosecond pulsed plasma reactors. The mathematical framework is implemented in a numerical tool called VI-View which is made available to the community to aid with interpretation of electrical measurements and help explain discrepancies between different experimental arrangements and probe configurations. A series of user case studies are presented that summarize best practices when performing electrical and energy measurements in nanosecond pulsed discharge (NPD) reactors. Electrical measurements should always be included as part of the roster of diagnostics in NPD experiments and become particularly useful for industry-relevant setups, where other diagnostics may be difficult to deploy.
Effect of Sr substitution on the structural, dielectric and ferroelectric property of BaTiO3
Authors: Yadav Satish , Deshmukh Vaidehi , Tiwari Shivendra , Rawat R , Sathe Vasant , Singh Kiran
Published: August 2024

We have performed a comprehensive study to explore the effect of Sr substitution on the structural and ferroelectric properties of BaTiO3 (BTO) with compositions Ba1-x
Sr
x
TiO3 for 0 ⩽ x ⩽ 1. The room temperature structural investigation inferred that the samples with compositions x > 0.30 has cubic phase instead of tetragonal as for pristine BTO. The temperature dependent dielectric studies illustrate that all well-known three structural phase transitions of BTO are coming closer to each other and the cubic phase is shifted towards lower temperature with increasing Sr content. The frequency dependent dielectric measurements show that there exists the mesoscopic subdomain, whose relaxation time decreases with increasing Sr concentration. The Sr substitution enhanced the ferroelectric properties and maximum remnant polarization at room temperature is observed for 20% Sr substituted sample. The frequency dependent dielectric measurements illustrate the relaxation which could be due to the mesoscopic subdomain, and its relaxation time decreases with increasing Sr concentration. The frequency dependent P–E measurements at room temperature infer that for 30% Sr substituted sample, the ferroelectric domain switching is dominated by the rate of nucleation whereas in other compositions for x < 0.3, it is governed by the domain wall speed. The Raman measurements infer the rearrangement of the domain configuration with Sr substitution. Modification in the intensity of the E(TO4) and A(TO3) Raman modes with electric field is also observed for 30% Sr substituted sample and the origin of this is also discussed.
First-principles calculations to investigate phase stability, elastic and thermodynamic properties of TiMoNbX (X=Cr, Ta, Cr and Ta) refractory high entropy alloys
Authors: Wang Yueyi , Liu Hongxi , Hao Xuanhong , Yang Chen , Liu Yaxia , Chen Lin , Zhang Xiaowei
Published: August 2024

This work uses first-principles calculations to investigate the phase stability, thermophysical and mechanical properties of refractory high entropy alloys (RHEAs) at finite temperatures. On the basis of plane wave quasi-potential and density functional theory, construct the structure model of a solid solution. The TiMoNbX (X = Cr, Ta, Cr and Ta) RHEAs have been determined to preserve a single body-centered cubic solid solution structure by calculations and the equilibrium lattice parameters and elastic modulus are consistent with experimental data obtained by laser cladding, which is combined with TC4 (Ti–6Al–4V) substrate. Using the quasi-harmonic Debye–Grüneisen model, the thermophysical characteristics of three RHEAs are investigated. The Voigt–Reuss–Hill scheme is used for calculating the Young’s modulus (E), bulk modulus (B), shear modulus (G), and Poisson’s ratio (ν), which indicates that all three RHEAs are ductile materials. Additionally, the modulus and hardness of materials decrease as temperature rises, whereas the properties of TiMoNbX RHEAs are predicted, as the nanoindentation hardness values at room temperature are comparable to, and slightly higher than the calculated values.
Thermodynamics and dynamics of coupled complex SYK models
Authors: Louw Jan C , van Manen Linda M , Jha Rishabh
Published: August 2024

It has been known that the large-q complex Sachdev-Ye-Kitaev (SYK) model falls under the same universality class as that of van der Waals (mean-field) and saturates the Maldacena-Shenker-Stanford (MSS) bound, both features shared by various black holes. This makes the SYK model a useful tool in probing the fundamental nature of quantum chaos and holographic duality. This work establishes the robustness of this shared universality class and chaotic properties for SYK-like models by extending to a system of coupled large-q complex SYK models of different orders. We provide a detailed derivation of thermodynamic properties, specifically the critical exponents for an observed phase transition, as well as dynamical properties, in particular the Lyapunov exponent, via the out-of-time correlator calculations. Our analysis reveals that, despite the introduction of an additional scaling parameter through interaction strength ratios, the system undergoes a continuous phase transition at low temperatures, similar to that of the single SYK model. The critical exponents align with the Landau–Ginzburg (mean-field) universality class, shared with van der Waals gases and various AdS black holes. Furthermore, we demonstrate that the coupled SYK system remains maximally chaotic in the large-q limit at low temperatures, adhering to the MSS bound, a feature consistent with the single SYK model. These findings establish robustness and open avenues for broader inquiries into the universality and chaos in complex quantum systems. We provide a detailed outlook for future work by considering the ‘very’ low-temperature regime, where we discuss relations with the Hawking–Page phase transition observed in the holographic dual black holes. We present preliminary calculations and discuss the possible follow-ups that might be taken to make the connection robust.
Image super-resolution reconstruction of vast-receptive-field pixel attention for precision measurement
Authors: Chen Ziyi , Zhang Jin , Sun Zhenxi , Liang Xiaohan , Gao Qiaorong , Xia Haojie
Published: August 2024

Compared with traditional contact precision measurement, vision-based non-contact precision measurement has the features of low cost and flexible multi-point information extraction, but how to ensure the measurement accuracy of vision-based non-contact precision measurement is an urgent problem. Traditional thinking often focuses on hardware upgrades to improve image resolution, but this brings high costs and is limited by the physical characteristics of the hardware itself. In this paper, we start from the software aspect to improve the image resolution by using the super-resolution reconstruction algorithm and propose an image super-resolution reconstruction algorithm—Swin Transformer with a Vast-receptive-field Pixel Attention, which combines the vast-receptive-field pixel attention mechanism with the Swin Transformer self-attention mechanism, focuses on the learning of the high-frequency information features of the image. Experiments are conducted both in public datasets and real measurement images. Extensive experimental validation shows that the model can obtain more edge and high-frequency detail features in public datasets, and the objective evaluation index on Set5, Set14, B100, Urban100, and Manga109 datasets is improved by 0.06 dB on average compared with the existing algorithms. In actual measurements, the algorithm in this paper for USAF1951 resolution tablet, image super-resolution reconstruction image in the horizontal and vertical direction of the measurement accuracy increased by an average of 6.97%, the horizontal and vertical direction of the relative measurement accuracy of an average of 30.20% improvement. This study provides a potential development direction for vision-based non-contact precision measurement.
A compound fault diagnosis method for rolling bearings based on the IPSO-MOMEDA and Teager energy operator
Authors: Li Shengqiang , Yan Changfeng , Hou Yunfeng , Wang Huibin , Liu Xiru
Published: August 2024

Different types of faults interact with each other and are easily overwhelmed by strong noise, which makes it challenging to identify and isolate single fault features in rolling bearing compound faults (RBCFs). To address this problem, a diagnosis method for RBCFs with improved particle swarm optimization multipoint optimal minimum entropy deconvolution adjusted (IPSO-MOMEDA) and a Teager energy operator is proposed. The optimal settings for the period and filter length are automatically determined by the excellent optimization capabilities of IPSO, which leads to quick and efficient identification of the global optimum. Moreover, the optimal deconvolution of various fault types is obtained by the optimized MOMEDA. The Teager energy operator is introduced to enhance the shock and periodicity components of the deconvolution signal, which can ensure that the accurate fault period can be selected by MOMEDA. Envelope analysis is employed for identification of compound fault characteristics. Both the simulation and experimental results demonstrate that inner ring and outer ring faults, inner ring and ball faults, outer ring and ball faults, and inner–outer ring and ball faults can be accurately diagnosed using the proposed method.
Large-scale magnetic target state estimation using model parameter optimization
Authors: Lu Binjie , Zhang Xiaobing
Published: August 2024

Improved grey wolf optimizer-conjugate gradient least squares (IGWO-CGLS) algorithm is proposed to solve the state estimation problems of large-scale magnetic target location, target recognition and magnetic moment estimation. To address the state estimation problem of large-scale magnetic targets, a magnetic dipole array magnetic field observation model is established based on a single magnetic vector sensor, and the magnetic target model parameter inversion based on IGWO-CGLS is used to obtain the state of the magnetic target. The state of the target is obtained by inverting the parameters of the magnetic target model. Firstly, the signal preprocessing is carried out by thresholding and down sampling to extract the complete magnetic field passing characteristics, and then the IGWO is used to optimize the magnetic target position, speed, heading and length, and then the magnetic moment parameter is calculated by CGLS to obtain the state parameters of the magnetic target. And numerical experiments are designed to sublicense the influencing factors of state estimation accuracy. The numerical simulation results show that IGWO-CGLS has higher state estimation accuracy than particle swarm optimization-CGLS, artificial hummingbird algorithm-CGLS, artificial rabbits optimization-CGLS, GWO-CGLS, IGWO-stepwise regression. The ship model test results show that IGWO-CGLS can estimate the state parameters of the ship model better.
Advancing oil and gas pipeline monitoring with fast phase fraction sensor
Authors: dos Santos Eduardo Nunes , Reginaldo Natan S , Longo Jean N , da Fonseca Jr Roberto , Conte Marco G , Morales Rigoberto E M , da Silva Marco Jose
Published: August 2024

In the oil and gas sector, the design of monitoring equipment usually prioritizes durability and long-term reliability. However, such equipment does not provide resolution for scientific research, where capturing transient and dynamic events is crucial to enhancing flow understanding. This work describes the development of a capacitive sensor system optimized for phase fraction measurements in oil–gas industrial environments. The sensor features high sensitivity and temporal resolution to meet flow measurement investigative requirements. The measurement technique is based on the electrical capacitance variations of the flowing media and was validated with reference equipment. Six sensors were deployed across multiple test stations to analyze the slug flow regime and its evolution along the pipe. The data collected from these experiments were processed, and flow parameters were compared with a model that describes the elongated bubble shape found in the slug flow pattern. Results show a good agreement between the experimental data and the model, validating its capability to track the fast-changing phases of multiphase flow. The uncertainty analysis revealed a maximum absolute uncertainty of 1.41% for the gas fraction measurements. Further, the gas flow rate was evaluated with a good agreement against the reference gas flow meter, ensuring the sensor’s reliability in dynamic multiphase flow environments. By providing accurate experimental data from real-world industrial conditions, the developed sensor can significantly enhance the precision of flow models, thereby improving the understanding of complex flow phenomena.
Design and characterization of a novel turbidity sensor based on quadrature demodulation
Authors: Tang Bo , Ruan Jiaming , Wang Jie , Yu Zhi , Xu Ming , Cheng Yinbao
Published: August 2024

Turbidity is regarded as a comprehensive indicator in water quality monitoring, and the turbidity sensor deployed in the water supply network can record the dynamic changes of water quality in time. However, the weak photoelectric signal from the photodetector contains a quantity of noise. In order to improve signal-to-noise ratio, a novel on-line turbidity sensor based on quadrature demodulation principle has been proposed in this paper. A near-infrared light-emitting diode (LED) with a wavelength of 860 nm was selected as a stable monochromatic light source, and a photodiode with an angle of 90° to the incident light from the LED was selected as the photodetector. Using signal modulation and demodulation technology, the weak photoelectric signal extraction, conversion, amplification and output of the turbidity sensor were realized through the effective integration. A corresponding test apparatus of the turbidity sensor was established and experimental results showed that within a 0–5 NTU measurement range, the turbidity sensor had good linearity and stability, the relative measurement error was within ±1% and the limit of detection could reach as low as 0.0049 NTU. The developed turbidity sensor has good detection performance and can meet the needs of low turbidity detection of drinking water.
Obtaining and qualitative analysis of time-lagged correlations between seawater quality parameters
Authors: Zhu Qiguang , Shen Zhen , Wu Zhen , Zhang Hongbo , Yuan Junjun , Chen Ying
Published: August 2024

In the regulation of seawater quality, it is crucial to understand the interactions between parameters and the time-lagged effects. This paper focuses on the problem of how to obtain and analyze time-lagged correlations between seawater quality parameters, an issue that has not attracted the attention of researchers. In this paper, a graph neural network-based model, dynamic adjacency weight network, is proposed to model the time-lagged correlation between seawater quality parameters. By regarding the parameters as nodes, the proposed model retains the relationships between the parameters in a weighted adjacency matrix, overcoming the problem of traditional deep neural networks that are difficult to be visualized. Meanwhile, the proposed multivariate multistep shift prediction strategy enables the proposed model to accurately obtain the time-lagged correlation information between parameters at different time intervals. In addition, the proposed model also addresses some of the details worth considering when obtaining correlations between seawater quality parameters. The proposed model performs well in the prediction of water quality parameters. This indirectly verifies the validity of the obtained correlations and overcomes the difficulty of verifying the validity of statistical methods. This study provides new ideas and methods for seawater quality monitoring and research.
Rational construction of dicarbonous CB/CNT@PI composites toward low filler loading and low-frequency electromagnetic wave absorption
Authors: Qiu Hongfang , Cheng Yong , Fang Xiong , Lu Junyu , Di Xiaochuang , Lu Zhao , Chen Yang , Zou Huawei
Published: August 2024

With the application of low frequency radar and the demand for stealth of high temperature resistant components, it is increasingly urgent to develop absorbing materials with both low frequency and high temperature resistant properties. Here, we successfully prepared various carbon/polyimide composites as low-frequency electromagnetic wave (EMW) absorbing materials by simple blending method. The well-designed mesh lap structure introduces a large amount of free space, further optimizing the impedance matching of the material. At the same time, the multiple loss mechanism formed by the combination of carbon black dominated polarization and carbon nanotube dominated conductive loss enhances the loss of incident EMW. The results showed that only 10 wt% filler loading of the CB/CNT@PI is achieved in the low frequency range (1–4 GHz) with a minimum reflection loss strength of –18.3 dB, which has obvious advantages compared with other works in recent years. This study provides a way for the design and preparation of resin-based absorbing materials.
A liquid crystal based non-Hermitian metasurface for broadband full-Stokes polarization detection
Authors: Gao Fan , Han Yufan , Zhao Yujia , Zhou Tao , Deng Juan , Yan Bo
Published: August 2024

The ability to detect the polarization information of light is often crucial for various applications in optical systems. However, conventional polarization-sensitive photodetectors struggle to simultaneously achieve a wide band coverage and high-precision detection, severely hindering the development of polarization detectors. In this study, a reflective metasurface with full-Stokes detection capabilities over a wide range is proposed. It integrates four linear polarization filters and two circular polarization filters operating in the near-infrared region. By dynamically adjusting the refractive index of the liquid crystal covering the detector surface, high performance full-Stokes parameter detection can be achieved between 730–770 nm with detection error below 0.07. Therefore, this study provides a design approach for the potential application of Stokes polarization detection over a broadband spectrum.
Ultrasonic guided wave damage localization method for composite fan blades based on damage-scattered wave difference
Authors: Liu Hailong , Huang Meiao , Zhang Qingchen , Liu Qijian , Wang Yishou , Qing Xinlin
Published: August 2024

Ultrasonic guided wave (UGW) has a wide monitoring range and high accuracy, showing promise for monitoring damage in large-area composite fan blades. However, the multi-curvature characteristics of engine composite fan blades and their anisotropic material properties make damage localization difficult with conventional UGW monitoring methods. In order to realize the UGW damage monitoring of the blade, this paper proposes a damage localization method based on damage-scattered wave differences. This method addresses the challenge of locating damage in multi-curvature composite blades. First, the difference between the mutual excitation in a pair of sensors and the damage-scattered waves captured at reception was analyzed. It is concluded that the closer the damage is to the receiving sensor, the greater the damage index (DI). Next, a DI ratio of the mutually excited and received signals is computed for each sensor pair. This ratio is used to draw a vertical line on the propagation path, identified as the damage likelihood line (DLL). Finally, the DLL corresponding to the three largest DIs is selected, and their intersections were used for damage localization. A time-domain truncated signal processing method is proposed to enable the DI to more accurately represent the effects of damage and improve the localization accuracy of the method. An experiment on damage localization was conducted on a homemade composite fan blade, where the damage was tested at various locations and sizes. The results show that the damage localization on the blade is good and 3 mm tiny damage localization is achieved.
Coulomb excitation of hydrogen atoms by vortex ion beams
Authors: Maiorova A V , Karlovets D , Fritzsche S , Surzhykov A , Stöhlker Th
Published: August 2024

Coulomb excitation of hydrogen atoms by vortex protons is theoretically investigated within the framework of the non-relativistic first–Born approximation and the density matrix approach. Special attention is paid to the magnetic sublevel population of excited atoms and, consequently, to the angular distribution of the fluorescence radiation. We argue that both these properties are sensitive to the projection of the orbital angular momentum (OAM), carried by the projectile ions. In order to illustrate the OAM–effect, detailed calculations have been performed for the

1
s
→
2
p

excitation and the subsequent

2
p
→
1
s

radiative decay of a hydrogen target, interacting with incident Laguerre–Gaussian vortex protons. The calculation results suggest that Coulomb excitation can be employed for the diagnostics of vortex ion beam at accelerator and storage ring facilities.
Disruption runaway electron generation and mitigation in the Spherical Tokamak for Energy Production (STEP)
Authors: Fil A. , Henden L. , Newton S. , Hoppe M. , Vallhagen O.
Published: August 2024

Generation of Runaway Electrons (REs) during plasma disruptions is of great concern for ITER and future reactors based on the tokamak concept. Unmitigated RE generation in the current STEP (Spherical Tokamak for Energy Production) concept design is modelled using the code DREAM, with hot-tail generation found to be the dominant primary generation mechanism and avalanche multiplication of REs found to be extremely high. Varying assumptions for the prescribed thermal quench (TQ) phase (duration, final electron temperature) as well as the wall time, the plasma-wall distance, and shaping effects, all STEP full-power and full-current unmitigated disruptions generate large RE beams (from 10 MA up to full conversion). RE mitigation is first studied by modelling idealised mixed impurity injections, with ad-hoc particle transport arising from the stochasticity of the magnetic field during the TQ, but no combination of argon and deuterium quantities allows runaways to be avoided while respecting the other constraints of disruption mitigation. Initial concept of STEP disruption mitigation system is then tested with DREAM, assuming two-stage shattered pellet injections (SPI) of pure

D

2

followed by Ar+

D

2

. Such a scheme is found to reduce the generation of REs by the hot-tail mechanism, but still generates a RE beam of about 13 MA. Options for further optimising the SPI scheme, for mitigating a large RE beam in STEP (benign termination scheme), as well as estimations of required RE losses during the current quench (from a potential passive RE mitigation coil) will also be discussed.
Research on influence factors of small punch test to evaluate the mechanical properties of gradient nanostructured material
Authors: Yang Xinjun , Liao Xiangwei , Wang Dongxiang , Du Jiyun , Yuan Fangyang , Yu Wei , Li Qingsheng
Published: August 2024

The influence factors of small punch test (SPT) were investigated to evaluate the mechanical properties of gradient nanostructured (GNS) materials. The gradient nanostructure was prepared on the top layer of S30408 austenitic stainless steel by ultrasonic impact treatment (UIT). The mechanical properties of the GNS material were obtained using SPT and correlated with those obtained by standard tensile tests. The results indicate that, when the specimen thickness is 0.5 mm, the sphere diameter is 2.4 mm, the punch velocity is 0.5 mm min−1, and the gradient nano-grained layer is placed face-on in the mold, the GNS material exhibits better plastic deformability. The SPT specimen achieves better bearing capacity, and the mechanical properties of the GNS material obtained by SPT are more accurate. The yield strength and tensile strength of the GNS material were also evaluated by analytical and empirical methods in SPT. The error is approximately 10% compared with the standard tensile test results, which is within the allowable range.
Dispersion of ZnO or TiO2 nanoparticles onto P. australis stem-derived biochar for highly efficient photocatalytic removal of doxycycline antibiotic under visible light irradiation
Authors: Tuoi Nguyen Thanh , Nguyet Bui Thi Minh , Tuyen Tran Ngoc , Khac Lieu Pham , Khieu Dinh Quang , Van Hung Nguyen
Published: August 2024

Biochar (BC) derived from reed stems was prepared by high-temperature pyrolysis, and two types of ZnO/biochar (ZBC) and TiO2/biochar (TBC) composite materials were synthesized via a simple hydrolysis method. These composites, compared to pure ZnO and TiO2, exhibit not only improved but significantly enhanced crystalline structures and larger specific surface areas. This enhancement in the physical and chemical properties of ZBC and TBC composites is a crucial aspect of our research, as it leads to a distinct red-shifted absorption edge and excellent visible-light absorption characteristics. The photocatalytic degradation efficiency of ZBC and TBC composite materials, a key finding of our study, was evaluated using doxycycline antibiotic as a simulated pollutant under visible-light irradiation. The results demonstrate a 6.0-fold and 7.3-fold increase in photocatalytic degradation efficiency of ZBC and TBC composites compared to pure ZnO and TiO2, respectively, further underscoring the significance of these enhanced properties. Furthermore, active species trapping experiments reveal that ·OH radicals are the dominant reactive species in the photocatalytic degradation process of doxycycline. A Langmuir–Hinshelwood kinetic model accurately represents this degradation process. Kinetic data indicate that the degradation rate constants (k) of ZBC and TBC catalysts are 4.314 × 10−2 min−1 and 3.416 × 10−2 min−1, respectively. The photocatalysts exhibit no significant decrease in degradation efficiency for ZBC and TBC even after the fourth cycle, indicating their relatively high reusability. These results suggest that ZBC and TBC materials can be used as stable, efficient, cost-effective, and sustainable photocatalytic composite materials for antibiotic-contaminated wastewater treatment.
Rules and Principles
Authors: Grabowski Andrzej , Lifante Vidal Isabel
Published: August 2024

In recent decades, the theoretical interest in the distinction between rules and principles gained momentum with Dworkin’s famous article: ‘Is Law a System of Rules?’ (1967) and the subsequent discussion it sparked on the adequacy of legal positivism as such. The chapter focuses on the presentation and critique of two continental European contributions to the theory of legal principles (defined as the special kind of legal norms, different from legal rules): the theory of principles as optimisation commands, developed by Robert Alexy in Germany, and the multidimensional theory of legal principles, developed by Manuel Atienza and Juan Ruiz Manero in Spain. Both theories laid special emphasis on the logical structure of rules and principles, and the phenomena of their fulfilment. This in turn has important consequences as far the justification of judicial decisions is concerned and explains why these theories have enjoyed a great impact on the theoretical and practical fields.
Analytical Legal Philosophy
Authors: Schiavello Aldo
Published: August 2024

This chapter examines the analytical legal philosophy’s birth, development, and crisis from the early 1950s. After identifying this legal philosophical tradition’s main features, the connection between analytical legal philosophy and legal positivism is explored. This link is particularly close if one looks at the legal analytical philosophy from a continental European legal-philosophical perspective. The decline of analytical philosophy is primarily linked to the crisis of legal positivism and, concerning this last point, the debate that has developed in continental Europe since the mid-1970s is strongly influenced by the Anglo-American debate, even if it does present original insights. The central issue concerns the neutrality of legal knowledge, which is a crucial assumption of both analytical legal philosophy and legal positivism. The interpretive turn in contemporary legal philosophy has cast doubt on the possibility of describing law irrespective of ideological assumptions and moral evaluations.
Legal System
Authors: Guastini Riccardo
Published: August 2024

The chapter analyses and discusses a number of conceptual issues concerning legal systems, such as their components, structure, and identity, as well as the very concept of a legal system (LS) as such. The first section bears upon the different kinds of rules (independent and derived, expressed and unexpressed, primary and secondary) that compose a (developed) LS. The second section is about the criterion of membership of rules to a LS, focusing on the problematic status of constitution and unconstitutional statutes, and distinguishing in particular between validity and existence. The third section analyses the structure of a LS, namely, the double (static and dynamic) foundation of rules, and the variety of hierarchical relationships among rules. The fourth section discusses the issue of the ultimate rule of a LS. Both Kelsen’s thesis of the ‘basic norm’ and Hart’s thesis of the ‘rule of recognition’ are analysed and criticised. The fifth section discusses the identity of a LS, distinguishing in particular a ‘formal’ and a ‘substantive’ view on the matter. The sixth section discusses the concept of a LS itself, understood as a set of rules. In particular the pivotal distinction between legal provisions (normative sentences) and their meaning contents (rules properly understood) is introduced. The dependence of the normative contents of a LS on the interpretive practice of legal scholars and judges is stressed. The seventh section introduces a further distinction among different kinds of rules of recognition, as well as a concise analysis of recognition statements.