bluuebunny/crossref_metadata_2025 huggingface dataset:
A validated numerical methodology for flow-induced vibration of a semi-spherical end cantilever rod in axial flow
Authors: Mao Wenyu , Iacovides Hector , Cioncolini Andrea , Li Hao , Nabawy Mostafa R. A.
Published: July 2024

This study presents a simulation method for turbulent flow-induced vibrations of cantilever rods with a semi-spherical end exposed to axial flow, a configuration investigated for the first time. This simulation strategy has been developed using solids4Foam, a toolkit for the open-source package OpenFOAM, which uses the finite-volume approach. The fluid and solid domain equations are solved separately. Coupling is achieved with the Interface Quasi-Newton Inverse Least-Squares (IQN-ILS) algorithm. The mean flow is described by the unsteady Reynolds-averaged Navier–Stokes equations. Turbulence is modeled through either the stress-transport model of Launder, Reece, and Rodi or the effective-viscosity k–ω shear stress transport model, both with the wall-function approach accounting for near-wall turbulence. The methodology is validated using experimental data produced during this study. The simulations show good agreement with the measured values of the oscillation amplitude and frequency for both flow directions (toward rod free-end and away from it). Turbulence model comparisons show that (a) Reynolds stress transport models are necessary to reproduce the vibration amplitude and (b) wall functions enable the simulations to be completed in realistic time scales. The significance to the fluid–solid-interaction (FSI) process of a so far overlooked (with the exception of a couple of recent studies) dimensionless number, the ratio of the flow dynamic pressure to the rod's Young's modulus of elasticity, is also explored. Simulations, which decouple the variation of this dimensionless number from that of the Reynolds number, demonstrate this number's strong effect on the vibration amplitude. This finding is important to the contact of further FSI studies and the scaling of FSI data.
High-precision high-speed nanopore ping-pong control system based on field programmable gate array
Authors: Mi Zhuang , Chen Xiaoyu , Zhao Xinjia , Tang Haitao , Wang Wenyu , Shan Xinyan , Lu Xinghua
Published: July 2024

“Molecular ping-pong,” emerging as a control strategy in solid-state nanopore technology, presents a highly promising approach for repetitive measurements of single biomolecules, such as DNA. This paper introduces a high-precision, high-speed nanopore molecular ping-pong control system consisting of a home-built trans-impedance amplifier (TIA), a control system based on a Field Programmable Gate Array (FPGA), and a LabVIEW program operating on the host personal computer. Through feedback compensation and post-stage boosting, the TIA achieves a high bandwidth of about 200 kHz with a gain of 100 MΩ, along with low input-referred current noise of 1.6 × 10−4 pA2/Hz at 1 kHz and 1.1 × 10−3 pA2/Hz at 100 kHz. The FPGA-based control system demonstrates a minimum overall response time (tdelay) of 6.5 μs from the analog input current signal trigger to the subsequent reversal of the analog output drive voltage signal, with a control precision of 1 μs. Additionally, a LabVIEW program has been developed to facilitate rapid data exchange and communication with the FPGA program, enabling real-time signal monitoring, parameter adjustment, and data storage. Successful recapture of individual DNA molecules at various tdelay, resulting in an improvement in capture rate by up to 2 orders of magnitude, has been demonstrated. With unprecedented control precision and capture efficiency, this system provides robust technical support and opens novel research avenues for nanopore single-molecule sensing and manipulation.
Anticancer transmission effects induced by hybrid plasma bubble-activated medium
Authors: Zhu He , Xu Yujing , Wu Tong , Zhou Renwu , Zhang Hao , Liu Dingxin , Rong Mingzhe , Yang Xiaojian , Cullen Patrick J.
Published: July 2024

As an indirect application of cold atmospheric plasma, the use of plasma-activated solutions has recently attracted significant attention for intracavity tumor perfusion therapy. Here, an underwater plasma-bubble reactor with three discharge modes was applied to activate a cell culture medium, with the aim of inhibiting the growth of bladder cancer T24 cells in vitro. The results showed that although the reactive species in cell culture medium generated by the underwater bubble plasma varied between the dielectric barrier discharge (DBD) mode, spark mode, and hybrid mode, the plasma-activated cell culture medium (PAM) corresponding to all three discharge modes effectively decreased the viability of T24 cells. However, after co-culturing the PAM-pretreated T24 cells with normal T24 cells, it was observed that normal T24 cells were not affected by either the DBD or spark mode; however, the hybrid mode PAM-pretreated T24 cells further induced inactivation and apoptosis of normal T24 cells. Further studies suggested that the aqueous reactive species generated by the underwater bubble plasma in hybrid mode not only induced the apoptosis of T24 cells directly but also triggered PAM-pretreated T24 cell-derived exosome-mediated anticancer activity toward cancer cells. These results may provide a strategy for enhancing the anticancer extent and effect of PAM as well as advancing its clinical application.
Carrier diffusion in long wavelength InGaN quantum well LEDs after injection through V-defects
Authors: Yapparov Rinat , Tak Tanay , Ewing Jacob , Wu Feng , Nakamura Shuji , DenBaars Steven P. , Speck James S. , Marcinkevičius Saulius
Published: July 2024

The efficiency of operation of GaN-based light emitting diodes (LEDs) to a large degree relies on realization of a uniform hole distribution between multiple quantum wells (QWs) of the active region. Since the direct thermionic transport between the QWs is inefficient, the hole injection through semipolar 101¯1 QWs that form on the facets of V-defects has been suggested as an alternative approach. However, for an efficient LED operation, the carrier distribution should be uniform not only vertically, between the QWs but also laterally, within individual QWs. In this work, the lateral carrier distribution in long wavelength InGaN/GaN QW LEDs is studied by the scanning near-field optical microscopy. The measurements have shown that emission is concentrated around the V-defect injectors. At high currents, the diffusion length of holes in polar QWs was found to be ∼0.6–1 μm and the hole diffusion coefficient ∼0.6 cm2/s. The obtained data should aid design of the V-defect injectors for a laterally uniform carrier distribution in the active region QWs.
Uncovering the binding nature of thiocyanate in contact ion pairs with lithium ions
Authors: Deshmukh Samadhan H. , Nachaki Ernest O. , Kuroda Daniel G.
Published: July 2024

Ion pair formation is a fundamental molecular process that occurs in a wide variety of systems, including electrolytes, biological systems, and materials. In solution, the thiocyanate (SCN−) anion interacts with cations to form contact ion pairs (CIPs). Due to its ambidentate nature, thiocyanate can bind through either its sulfur or nitrogen atoms, depending on the solvent. This study focuses on the binding nature of thiocyanate with lithium ions as a function of the solvents using FTIR, 2D infrared spectroscopy (2DIR) spectroscopies, and theoretical calculations. The study reveals that the SCN− binding mode (S or N end) in CIPs can be identified through 2DIR spectroscopy but not by linear IR spectroscopy. Linear IR spectroscopy shows that the CN stretch frequencies are too close to one another to separate N- and S-bound CIPs. Moreover, the IR spectrum shows that the S–C stretch presents different frequencies for the salt in different solvents, but it is related to the anion speciation rather than to its binding mode. A similar trend is observed for the anion bend. 2DIR spectra show different dynamics for N-bound and S-bound thiocyanate. In particular, the frequency–frequency correlation function (FFCF) dynamics extracted from the 2DIR spectra have a single picosecond exponential decay for N-bound thiocyanate and a biexponential decay for S-bound thiocyanate, consistent with the binding mode of the anion. Finally, it is also observed that the binding mode also affects the line shape parameters, probably due to the different molecular mechanisms of the FFCF for N- and S-bound CIPs.
Spin Hall effect in doped ferroelectric HfO2
Authors: Zhang Qin , Chen Xu , Yu Yue , Li Huinan , Dou Mingbo , Gurung G. , Wang Xianjie , Tao L. L.
Published: July 2024

The spin Hall effect (SHE) enables charge-to-spin conversion by electrical means and is promising for spintronic applications. Here, we report on the intrinsic spin Hall effect in the prototypical ferroelectric material HfO2 with charge doping using density functional theory calculations and theoretical analysis. We show that ferroelectric displacements are insensitive to charge doping and are sustained up to a large doping concentration of 0.4 electrons or holes per unit cell volume. In addition, the large spin Hall conductivity in the vicinity of the band edges is well preserved. Intriguingly, we demonstrate the giant spin Hall efficiency characterized by the sizable spin Hall angle of ∼0.1 in doped HfO2. These results add unexplored functionality to ferroelectric HfO2 and open opportunities for potential device applications.
Dibutyl phthalate released by solitary female locusts mediates sexual communication at low density
Authors: Cui Weichan , Ge Jin , Chen Dafeng , Nie Xin , Dong Liushu , Wang Xianhui , Kang Le
Published: July 2024

Sex pheromones play a crucial role in mate location and reproductive success. Insects face challenges in finding mates in low-density environments. The population dynamics of locusts vary greatly, ranging from solitary individuals to high-density swarms, leading to multiple-trait divergence between solitary and gregarious phases. However, differences in sexual communication between solitary and gregarious locusts have not been sufficiently explored. Herein, we found that solitary locusts but not gregarious ones heavily rely on a single compound, dibutyl phthalate (DBP), for sexual communication. DBP is abundantly released by solitary female locusts and elicits strong attraction of male solitary and gregarious locusts. Solitary adult males display much higher electrophysiological responses to DBP than adult females. Additionally, LmigOr13 was identified as the DBP-specific odorant receptor expressed in neurons housed in basiconic sensilla. Male

LmigOr13
−/−

mutants generated by CRISPR/Cas9 have low electrophysiological responses and behavioral attraction to DBP in both laboratory and field cage experiments. Notably, the attractiveness of DBP to male locusts becomes more evident at lower population densities imposed by controlling the cage size. This finding sheds light on the utilization of a sex pheromone to promote reproductive success in extremely low-density conditions and provides important insights into alternative approaches for population monitoring of locusts.
Loss of tolerance precedes triggering and lifelong persistence of pathogenic type I interferon autoantibodies
Authors: Fernbach Sonja , Mair Nina K. , Abela Irene A. , Groen Kevin , Kuratli Roger , Lork Marie , Thorball Christian W. , Bernasconi Enos , Filippidis Paraskevas , Leuzinger Karoline , Notter Julia , Rauch Andri , Hirsch Hans H. , Huber Michael , Günthard Huldrych F. , Fellay Jacques , Kouyos Roger D. , Hale Benjamin G. ,   The Swiss HIV Cohort Study, Abela Irene A. , Aebi-Popp Karoline , Anagnostopoulos Alexia , Battegay Manuel , Bernasconi Enos , Braun Dominique Laurent , Bucher Heiner , Calmy Alexandra , Cavassini Matthias , Ciuffi Angela , Dollenmaier Günter , Egger Matthias , Elzi Luisa , Fehr Jan , Fellay Jacques , Furrer Hansjakob , Fux Christoph , Günthard Huldrych Fritz , Hachfeld Anna , Haerry David , Hasse Barbara , Hirsch Hans , Hoffmann Matthias , Hösli Irene , Huber Michael , Jackson-Perry David , Kahlert Christian , Kaiser Laurent , Keiser Olivia , Klimkait Thomas , Kouyos Roger Dimitri , Kovari Helen , Kusejko Katharina , Labhardt Niklaus , Leuzinger Karoline , Martinez de Tejada Begogna , Marzolini Catja , Metzner Karin Jutta , Müller Nicolas , Nemeth Johannes , Nicca Dunja , Notter Julia , Paioni Paolo , Pantaleo Giuseppe , Perreau Matthieu , Rauch Andri , Salazar-Vizcaya Luisa , Schmid Patrick , Speck Roberto , Stöckle Marcel , Tarr Philip , Trkola Alexandra , Wandeler Gilles , Weisser Maja , Yerly Sabine
Published: July 2024

Autoantibodies neutralizing type I interferons (IFN-Is) can underlie infection severity. Here, we trace the development of these autoantibodies at high-resolution using longitudinal samples from 1,876 well-treated individuals living with HIV over a 35-year period. Similar to general populations, ∼1.9% of individuals acquired anti-IFN-I autoantibodies as they aged (median onset ∼63 years). Once detected, anti-IFN-I autoantibodies persisted lifelong, and titers increased over decades. Individuals developed distinct neutralizing and non-neutralizing autoantibody repertoires at discrete times that selectively targeted combinations of IFNα, IFNβ, and IFNω. Emergence of neutralizing anti-IFNα autoantibodies correlated with reduced baseline IFN-stimulated gene levels and was associated with subsequent susceptibility to severe COVID-19 several years later. Retrospective measurements revealed enrichment of pre-existing autoreactivity against other autoantigens in individuals who later developed anti-IFN-I autoantibodies, and there was evidence for prior viral infections or increased IFN at the time of anti-IFN-I autoantibody triggering. These analyses suggest that age-related loss of self-tolerance prior to IFN-I immune-triggering poses a risk of developing lifelong functional IFN-I deficiency.
Changing behind the scenes
Authors: McGeachy Mandy J.
Published: July 2024

Th17 cell plasticity is associated with pathogenicity in chronic inflammation. In a model of periodontitis, McClure et al. (https://doi.org/10.1084/jem.20232015) describe location-dependent divergence in Th17 plasticity, with surprisingly limited conversion in inflamed gingiva but emergence of protective exTh17-TfH cells in draining LN that enhance protective antibody.
Quantum Tunneling Enhanced Hydrogen Desorption from Graphene Surface: Atomic versus Molecular Mechanism
Authors: Tong 童 Yangwu 洋武 , Yang 杨 Yong 勇
Published: July 2024

We study the desorption mechanism of hydrogen isotopes from graphene surface using first-principles calculations, with focus on the effects of quantum tunneling. At low temperatures, quantum tunneling plays a dominant role in the desorption process of both hydrogen monomers and dimers. In the case of dimer desorption, two types of mechanisms, namely the traditional one-step desorption in the form of molecules (molecular mechanism), and the two-step desorption in the form of individual atoms (atomic mechanism), are studied and compared. For the ortho-dimers, the dominant desorption mechanism is found to switch from the molecular mechanism to the atomic mechanism above a critical temperature, which is ∼ 300 K and 200 K for H and D, respectively.
Efficient determination of Born-effective charges, LO-TO splitting, and Raman tensors of solids with a real-space atom-centered deep learning approach
Authors: Malenfant-Thuot Olivier , Ryczko Kevin , Tamblyn Isaac , Côté Michel
Published: July 2024

We introduce a deep neural network (DNN) framework called the Real-space Atomic Decomposition NETwork (radnet), which is capable of making accurate predictions of polarization and of electronic dielectric permittivity tensors in solids and aims to address limitations of previously available machine learning models for Raman predictions in periodic systems. This framework builds on previous, atom-centered approaches while utilizing deep convolutional neural networks. We report excellent accuracies on direct predictions for two prototypical examples: GaAs and BN. We then use automatic differentiation to efficiently calculate the Born-effective charges, longitudinal optical-transverse optical (LO-TO) splitting frequencies, and Raman tensors of these materials. We compute the Raman spectra, and find agreement with ab initio results. Lastly, we explore ways to generalize the predictions of polarization while taking into account periodic boundary conditions and symmetries.
Online LiDAR-camera extrinsic parameters self-checking and recalibration
Authors: Wei Pengjin , Yan Guohang , You Xin , Fang Kun , Ma Tao , Liu Wei , Yang Jie
Published: July 2024

During production, smart cars are equipped with calibrated LiDARs and cameras. However, due to the vibrations that inevitably occur during driving, the sensors’ extrinsic parameters may change slightly over time. It is a significant challenge to ensure the ongoing security of these systems throughout the car’s lifetime. To address this issue, we propose a self-checking and recalibration algorithm that can continuously detect the sensor data of intelligent vehicles. If the sensor’s miscalibration is detected, the data can be repaired promptly to ensure the vehicle’s reliability. Our self-checking algorithm extracts features from the point cloud and image and performs pixel-wise comparisons. To improve feature quality, we utilize the patch-wise transformer to enhance local information exchange, which also benefits the subsequent extrinsic recalibration. To facilitate the study, we generate two customized datasets from the KITTI dataset and the Waymo Open Dataset. The experiments conducted on these datasets demonstrate the effectiveness of our proposed method in accurately calibrating the LiDAR and camera systems throughout the car’s lifetime. This study is the first to highlight the importance of continually checking the calibrated extrinsic parameters for autonomous driving. Our findings contribute to the broader goal of improving safety and reliability in autonomous driving systems. The dataset and code are available at https://github.com/OpenCalib/LiDAR2camera_self-check.
Research on wavelet packet energy entropy extraction method for acoustic signal of tunnel lining cavity
Authors: Boyang Fan , Weigang Zhao , Jinghui Ju , Xiushu Tian , Weikang Zheng , Yong Yang
Published: July 2024

Tunnel lining cavity is a common disease in high-speed railway tunnels, which seriously affects the safe operation of the line. At present, the commonly used method is manual knocking inspection, but it relies on manual judgment, subjective factors have great influence, and there are errors. This paper proposes a feature extraction method of acoustic vibration signal of tunnel lining cavity based on wavelet packet energy entropy and uses wavelet packet energy entropy to realize the identification of cavity defects. The full-scale simulation model of tunnel with a radius of 6 m was constructed by COMSOL and different cavity conditions were set up. The wavelet packet energy entropy characteristics of acoustic signals were extracted and analyzed. The mapping relationship between cavity depth and cavity size and wavelet packet energy entropy was explored. The wavelet packet energy entropy and frequency band distribution characteristics were extracted to realize the identification of cavity defects. The local model which can characterize the whole tunnel is designed and the embedded defects are verified by experiments. The results show that the wavelet packet energy entropy can be used as the identification feature of tunnel lining cavity defects. When the wavelet packet energy entropy is less than 2.53, the existence of tunnel lining cavity defects is characterized. When the wavelet packet energy entropy is in the range of 2.53–2.94, it characterizes the existence of the transition boundary between tunnel lining cavity defect and no disease. This index can be used to realize the rapid and effective identification of cavity defects.
L

q
-spectra of graph-directed planar non-conformal measures
Authors: Qiu Hua , Wang Qi , Wang Shufang
Published: July 2024

We estimate the upper and lower Lq
-spectra of measures generated by a class of graph-directed planar non-conformal iterated function systems. These systems are composed of

C

1
+
ϵ

contractions with lower triangular pointwise Jacobian. The estimation provides a criterion for the existence of the Lq
-spectra in certain case. As an application, we derive the box-counting dimension of planar self-affine sets generated by lower triangular matrices, whose geometric construction satisfies a finite overlapping type condition.
Scaling laws and exact results in turbulence
*
Authors: Novack Matthew
Published: July 2024

In this note, we address the validity of certain exact results from turbulence theory in the deterministic setting. The main tools, inspired by the work of Duchon and Robert (2000 Nonlinearity
13 249–55) and Eyink (2003 Nonlinearity
16 137), are a number of energy balance identities for weak solutions of the incompressible Euler and Navier–Stokes equations. As a consequence, we show that certain weak solutions of the Euler and Navier–Stokes equations satisfy deterministic versions of Kolmogorov’s

4
5

,

4
3

,

4
15

laws. We apply these computations to improve a recent result of Hofmanova et al (2023 arXiv:2304.14470), which shows that a construction of solutions of forced Navier–Stokes due to Bruè et al (2023 Commun. Pure Appl. Anal.) and exhibiting a form of anomalous dissipation satisfies asymptotic versions of Kolmogorov’s laws. In addition, we show that the globally dissipative 3D Euler flows recently constructed by Giri et al (2023 arXiv:2305.18509) satisfy the local versions of Kolmogorov’s laws.
Atwood machine automation using Arduino and LabVIEW
Authors: Indratno T K , Prasetya Y D , Prabowo Y D , Sukarelawan M I
Published: July 2024

The Atwood machine is an apparatus used in physics experiments to visualize the concept of Newton’s Second Law of Motion. However, the data collection on the Atwood machine, which is still done manually using a stopwatch, may cause errors and can be time-consuming. To improve the efficiency and accuracy of the experiment, this research developed Atwood machine automation using Arduino Uno microcontroller. The automation enables automatic release of weights and automatic data collection through a graphical user interface developed using LabVIEW. The experiment using the automated machine obtained satisfactory results in verifying the earth’s gravitational acceleration. Therefore, this machine can be used in physics learning, especially in physics experiment. The automation also enables remote utilization through internet connection, thus allowing easier and wider access for users.
A deep-learning-based surrogate model for Monte-Carlo simulations of the linear energy transfer in primary brain tumor patients treated with proton-beam radiotherapy
Authors: Starke Sebastian , Kieslich Aaron , Palkowitsch Martina , Hennings Fabian , G C Troost Esther , Krause Mechthild , Bensberg Jona , Hahn Christian , Heinzelmann Feline , Bäumer Christian , Lühr Armin , Timmermann Beate , Löck Steffen
Published: July 2024

Objective. This study explores the use of neural networks (NNs) as surrogate models for Monte-Carlo (MC) simulations in predicting the dose-averaged linear energy transfer (LET
d
) of protons in proton-beam therapy based on the planned dose distribution and patient anatomy in the form of computed tomography (CT) images. As LET
d
is associated with variability in the relative biological effectiveness (RBE) of protons, we also evaluate the implications of using NN predictions for normal tissue complication probability (NTCP) models within a variable-RBE context. Approach. The predictive performance of three-dimensional NN architectures was evaluated using five-fold cross-validation on a cohort of brain tumor patients (n = 151). The best-performing model was identified and externally validated on patients from a different center (n = 107). LET
d
predictions were compared to MC-simulated results in clinically relevant regions of interest. We assessed the impact on NTCP models by leveraging LET
d
predictions to derive RBE-weighted doses, using the Wedenberg RBE model. Main results. We found NNs based solely on the planned dose distribution, i.e. without additional usage of CT images, can approximate MC-based LET
d
distributions. Root mean squared errors (RMSE) for the median LET
d
within the brain, brainstem, CTV, chiasm, lacrimal glands (ipsilateral/contralateral) and optic nerves (ipsilateral/contralateral) were 0.36, 0.87, 0.31, 0.73, 0.68, 1.04, 0.69 and 1.24 keV µm−1, respectively. Although model predictions showed statistically significant differences from MC outputs, these did not result in substantial changes in NTCP predictions, with RMSEs of at most 3.2 percentage points. Significance. The ability of NNs to predict LET
d
based solely on planned dose distributions suggests a viable alternative to compute-intensive MC simulations in a variable-RBE setting. This is particularly useful in scenarios where MC simulation data are unavailable, facilitating resource-constrained proton therapy treatment planning, retrospective patient data analysis and further investigations on the variability of proton RBE.
Impact of optimized transcutaneous auricular vagus nerve stimulation on cardiac autonomic profile in healthy subjects and heart failure patients
Authors: Maestri Roberto , Pinna Gian Domenico , Robbi Elena , Cogliati Chiara , Bartoli Arianna , Gambino Giuseppina , Rengo Giuseppe , Montano Nicola , La Rovere Maria Teresa
Published: July 2024

Objective. To determine the optimal frequency and site of stimulation for transcutaneous vagus nerve stimulation (tVNS) to induce acute changes in the autonomic profile (heart rate (HR), heart rate variability (HRV)) in healthy subjects (HS) and patients with heart failure (HF). Approach. We designed three single-blind, randomized, cross-over studies: (1) to compare the acute effect of left tVNS at 25 Hz and 10 Hz (n = 29, age 60 ± 7 years), (2) to compare the acute effect of left and right tVNS at the best frequency identified in study 1 (n = 28 age 61 ± 7 years), and (3) to compare the acute effect of the identified optimal stimulation protocol with sham stimulation in HS and HF patients (n = 30, age 59 ± 5 years, and n = 32, age 63 ± 7 years, respectively). Main results. In study 1, left tragus stimulation at 25 Hz was more effective than stimulation at 10 Hz in decreasing HR (−1.0 ± 1.2 bpm, p < 0.001 and −0.5 ± 1.6 bpm, respectively) and inducing vagal effects (significant increase in RMSSD, and HF power). In study 2, the HR reduction was greater with left than right tragus stimulation (−0.9 ± 1.5 bpm, p < 0.01 and −0.3 ± 1.4 bpm, respectively). In study 3 in HS, left tVNS at 25 Hz significantly reduced HR, whereas sham stimulation did not (−1.1 ± 1.2 bpm, p< 0.01 and −0.2 ± 2.9 bpm, respectively). In HF patients, both active and sham stimulation produced negligible effects. Significance. Left tVNS at 25 Hz is effective in acute modulation of cardiovascular autonomic control (HR, HRV) in HS but not in HF patients (NCT05789147).
Experimental and simulation study of argon helicon discharge in multiple plasma simulation linear device (MPS-LD)
Authors: Wu Jintao , Sang Chaofeng , Sun Changjiang , Sun Bin , Gao Shuaishuai , Bian Yu , Peng Yao , Wang Qi , Wang Dezhen
Published: July 2024

To obtain a high-parameter plasma in the target region of a multiple plasma simulation linear device and to realize the experimental simulation environment of tokamak divertor plasma, experimental and numerical simulations of argon helicon discharge are carried out. Langmuir probes are used to diagnose the electron density (ne
) in the source and target regions with different experimental parameters (magnetic field, radio frequency power, puffing flow rate). A three-dimensional discharge model is developed using drift-diffusion equations of electron density and electron energy with the aid of COMSOL. Helicon discharge with a long straight plasma beam and a bright blue core is experimentally achieved. The simulation and experimental results are compared, validating the model. The corresponding spatial ne
distribution is obtained, and the dependence of ne
on the main experimental parameters is confirmed. The energy conversion relationship between the helicon and plasma is found. Helicon waves prefer to transfer energy to the plasma in the source region, where ne
is significantly increased. This results in a strong ne
gradient, which acts as a barrier to prevent the propagation of helicon waves. Therefore, localized standing helicon waves are formed, which limits the increase in plasma density in the target region. By increasing the magnetic field strength (B < 1500 G) and RF power (P < 1500 W), ne
in the source region can be increased, but they have little effect on ne
in the target region.
Liquid-to-gas transfer of sodium in a liquid cathode glow discharge
Authors: Srivastava Tanubhav , Dogariu Arthur , Morozov Anatoli , Bruggeman Peter
Published: July 2024

Plasma-liquid interactions have been extensively studied with a focus on the transport of reactive species from the plasma to the liquid phase and their induced liquid phase chemistry and resulting applications. While solute transfer from the liquid to the gas phase in plasmas has been widely used in analytical chemistry, the underlying processes remain relatively unexplored. We report spatially and temporally resolved absolute density measurements of sodium in a plasma with a NaCl solution cathode using two-photon absorption laser induced fluorescence (TaLIF). The observed non-linear increase in sodium density with solution conductivity is shown to correlate with droplet generation as visualized by Mie scattering. The findings are explained by droplet generation by electrospray induced by Taylor cone formation as underpinning mechanism for the introduction of sodium in the plasma. An analytical sheath model combined with a scaling law shows an increase in electric field force with solution conductivity that is consistent with the observed non-linear increase in sodium density in the plasma with solution conductivity.
Phononic crystals with incomplete line defects: applications in high-performance and broadband acoustic energy localization and harvesting
Authors: Zhang Guo-Yu , Liu Zi-Jiang , Li Bing-Zu , Dou Xi-Long , Zhang Cai-Rong , Sun Xiao-Wei , Yang Yi-Man
Published: July 2024

Using phononic crystals (PnCs) to enhance the electrical output performance of piezoelectric energy harvesting (PEH) devices and broaden the frequency range of harvesting energy is crucial to solving the self-energy of low-power devices such as wireless sensors. In this work, an ultra-wide full-band gap PnC was designed. The concept of a PnC with an incomplete line defect was proposed. The energy localization and harvesting of incomplete line defect PnCs and traditional point defect and line defect PnCs were studied by finite element analysis. The results show that compared with a point defect and a line defect, the output electric power of an incomplete line defect was increased by 31.88 times and 2.51 times, respectively, and the energy localization and harvesting frequency band were widened. By exploring the influence of the periodicity of the vertical incomplete line defect direction on the electrical output performance of the PnC-based PEH system, it is found that the electrical output performance of the 5 × 3 incomplete line defect PnC is the best, and the maximum output voltage and output electric power are 27.36 V and 17.29 mW, respectively. This work provides new insights and ideas for improving the energy localization and harvesting performance of PnC-based PEH systems.
Is the dynamical quantum Cheshire cat detectable?
Authors: Hance Jonte R , Ladyman James , Rarity John
Published: July 2024

We explore how one might detect the dynamical quantum Cheshire cat proposed by Aharonov et al We show that, in practice, we need to bias the initial state by adding/subtracting a small probability amplitude (‘field’) of the orthogonal state, which travels with the disembodied property, to make the effect detectable (i.e. if our initial state is

|

↑
z

⟩

, we need to bias this with some small amount δ of state

|

↓
z

⟩

). This biasing, which can be done either directly or via weakly entangling the state with a pointer, effectively provides a phase reference with which we can measure the evolution of the state. The outcome can then be measured as a small probability difference in detections in a mutually unbiased basis, proportional to this biasing δ. We show this is different from counterfactual communication, which provably does not require any probe field to travel between sender Bob and receiver Alice for communication. We further suggest an optical polarisation experiment where these phenomena might be demonstrated in a laboratory.
Directional pre-sensitivity of the laser interferometer space antenna
Authors: Riegger F , Andersson F , Robertsson J
Published: July 2024

The space-based Laser Interferometry Space Antenna (LISA) is a gravitational waves observatory currently under development. It comprises three spacecraft, each traveling in a heliocentric orbit that is weakly eccentric and inclined. Gravitational waves comprise two polarization components. They will be detected by conducting interferometric Doppler measurements between the LISA spacecraft. Among other factors, the signal strength of the Doppler measurements will depend on the location of the GW source, the GW polarization angle, and the orbits of the spacecraft. Thus, the signal strength of the Doppler measurements will vary over time. For given spacecraft orbits, we derive bounds on the signal strength that are functions of the source location. These bounds are simple, explicit expressions, and we refer to them as the directional pre-sensitivity. Using the directional pre-sensitivity, we construct a metric for the relative change in the signal strength depending on the source location and the spacecraft orbits. We illustrate how this formalism can be used to assess the signal strength for several examples of chosen orbits.
Coupling elastic media to gravitational waves: an effective field theory approach
Authors: Belgacem Enis , Maggiore Michele , Moreau Thomas
Published: July 2024

The interaction of a gravitational wave (GW) with an elastic body is usually described in terms of a GW “force” driving the oscillations of the body's normal modes. However, this description is only possible for GW frequencies for which the response of the elastic body is dominated by a few normal modes. At higher frequencies the normal modes blend into a quasi-continuum and a field-theoretical description, as pioneered by Dyson already in 1969, becomes necessary. However, since the metric perturbation hμν
is an intrinsically relativistic object, a consistent coupling to GWs can only be obtained within a relativistic (and, in fact generally covariant) theory of elasticity. We develop such a formalism using the methods of modern effective field theories, and we use it to
provide a derivation of the interaction of elastic bodies with GWs valid also in the high-frequency regime, providing a first-principle derivation of Dyson's result (and partially correcting it).
We also stress that the field-theoretical results are obtained
working in the TT frame, while the description in terms of a force driving the normal modes is only valid in the proper detector frame. We show how to transform the results between the two frames. Beside an intrinsic conceptual interest, these results are relevant to the computation of the sensitivity of the recently proposed Lunar Gravitational Wave Antenna.
Dark radiation isocurvature from cosmological phase transitions
Authors: Buckley Matthew R. , Du Peizhi , Fernandez Nicolas , Weikert Mitchell J.
Published: July 2024

Cosmological first order phase transitions are typically associated with physics beyond the Standard Model, and thus of great theoretical and observational interest. Models of phase transitions where the energy is mostly converted to dark radiation can be constrained through limits on the dark radiation energy density (parameterized by ΔN
eff). However, the current constraint (ΔN
eff < 0.3) assumes the perturbations are adiabatic. We point out that a broad class of non-thermal first order phase transitions that start during inflation but do not complete until after reheating leave a distinct imprint in the scalar field from bubble nucleation. Dark radiation inherits the perturbation from the scalar field when the phase transition completes, leading to large-scale isocurvature that would be observable in the CMB. We perform a detailed calculation of the isocurvature power spectrum and derive constraints on ΔN
eff based on CMB+BAO data. For a reheating temperature of T
rh and a nucleation temperature T
*, the constraint is approximately ΔN
eff ≲ 10-5 (T
*/T
rh)-4, which can be much stronger than the adiabatic result. We also point out that since perturbations of dark radiation have a non-Gaussian origin, searches for non-Gaussianity in the CMB could place a stringent bound on ΔN
eff as well.
Analytical perturbations of relativistic images in Kerr space-time
Authors: Aratore Fabio , Bozza Valerio
Published: July 2024

Light rays passing very close to black holes may wind several times before escaping. For any given electromagnetic source around the black hole, a distant observer would thus observe two infinite sequences of images on either side of the black hole. These images are generated by light rays performing an increasing numbers of loops. The strong deflection limit provides a simple analytic formalism to describe such higher order images for spherically symmetric metrics, while for axially symmetric black holes one typically resorts to numerical approaches. Here we present the leading order perturbation to higher order images when the black hole spin is turned on. We show that the images slide around the black hole shadow as an effect of space-time dragging. We derive analytical formulae for their shifts and the perturbation of their time delays. We also discuss how such simple analytical formulae for images by Kerr black holes can be of great help in many applications.
Realisation of the ultra-slow roll phase in Galileon inflation and PBH overproduction
Authors: Choudhury Sayantan , Karde Ahaskar , Panda Sudhakar , Sami M.
Published: July 2024

We demonstrate the explicit realisation of the ultra-slow roll phase in the framework of the effective field theory of single-field Galileon inflation. The pulsar timing array (PTA) collaboration hints at the scalar-induced gravity waves (SIGW) from the early universe as an explanation for the origin of the observed signal, which, however, leads to an enhancement in the amplitude of the scalar power spectrum giving rise to the overproduction of primordial black holes (PBHs). In the setup under consideration, we examine the generation of SIGW consistent with PTA (NANOGrav15 and EPTA) data, in addition to which we also consider the impact from QCD crossover at the nHz frequencies and address the PBH overproduction issue assuming linear approximations for the over-density without incorporating non-Gaussian effects from the comoving curvature perturbation. The framework is shown to give rise to SIGWs well consistent with the PTA signal with comfortable PBH abundance, 10-3≲fPBH < 1, of near solar-mass black holes.
Casimir wormholes inspired by electric charge in Einstein–Gauss–Bonnet gravity
Authors: Farooq Mushayydha , Zubair M , H Alkhaldi Ali , Ali Akram
Published: July 2024

This investigation assesses the feasibility of a traversable wormhole by examining the energy densities associated with charged Casimir phenomena. We focus on the influence of the electromagnetic field created by an electric charge as well as the negative energy density arising from the Casimir source. We have developed different shape functions by defining energy densities from this combination. This paper explores various configurations of Casimir energy densities, specifically those occurring between parallel plates, cylinders and spheres positioned at specified distances from each other. Furthermore, the impact of the generalized uncertainty principle correction is also examined. The behavior of wormhole conditions is evaluated based on the Gauss–Bonnet coupled parameter (μ) and electric charge (Q) through the electromagnetic energy density constraint. This is attributed to the fact that the electromagnetic field satisfies the characteristic ρ = −p

r
. Subsequently, we examine the active gravitational mass of the generated wormhole geometries and explore the behavior of μ and Q concerning active mass. The embedding representations for all formulated shape functions are examined. Investigations of the complexity factor of the charged Casimir wormhole have demonstrated that the values of the complexity factor consistently fall within a particular range in all scenarios. Finally, using the generalized Tolman–Oppenheimer–Volkoff equation, we examine the stability of the resulting charged Casimir wormhole solutions.
Probing inelastic signatures of dark matter detection via polarized nucleus*
Authors: Yun 云 Zai 在 , Sun 孙 Junwei 俊伟 , Zhu 祝 Bin 斌 , Liu 刘 Xuewen 学文
Published: July 2024

We investigate the inelastic signatures of dark matter-nucleus interactions, explicitly focusing on the ramifications of polarization, dark matter splitting, and the Migdal effect. Direct detection experiments, crucial for testing the existence of dark matter, encounter formidable obstacles, such as indomitable neutrino backgrounds and elusive determination of dark matter spin. To overcome these challenges, we explore the potential of polarized-target dark matter scattering, examining the impact of nonvanishing mass splitting, and the role of the Migdal effect in detecting dark matter. Our analysis demonstrates the valuable utility of the polarized triple-differential event rate as an effective tool for examining inelastic dark matter. It enables us to investigate angular and energy dependencies, providing valuable insights into the scattering process.
High performance power handling in the absence of an H-mode edge in negative triangularity DIII-D plasmas
Authors: Scotti F. , Marinoni A. , McLean A.G. , Paz-Soldan C. , Thome K.E. , Zhao M. , Allen S. , Austin M. , Burke M.G. , Eldon D. , Fenstermacher M. , Hyatt A. , Lasnier C.J. , Leonard A. , Lore J. , Nelson A.O. , Osborne T. , Sauter O. , Truong D. , Van Zeeland M.A. , Wang H.Q. , Wilcox R.
Published: July 2024

Experiments performed during strongly-shaped high-power diverted negative triangularity (NT) experiments in DIII-D achieved detached divertor conditions and a transient-free edge, showcasing the potential for application of NT to a core-edge integrated reactor-like scenario and providing the first characterization of the parametric dependencies for detachment onset. Detached divertor conditions will be required in future devices to mitigate divertor heat fluxes. Access to dissipative divertor conditions was investigated via an increase in upstream density. Detachment onset at the outer strike point was achieved with H-mode level confinement

H

98
−
y
2

∼
1

and reactor-relevant normalized pressures

β

N

∼
2

. Confinement degradation was observed with deeper detachment, associated with the loss of an electron temperature pedestal. Differences in geometry, radial transport, impact of cross field drifts are discussed to explain differences in access to detachment in NT discharges. Higher normalized densities, with respect to equivalent discharges in positive triangularity, were necessary to achieve detachment, partially explained by the shorter parallel connection length to the targets. The effect of cross-field particle drifts (E×B, B

×
∇

B) on access to detachment was demonstrated by the lower upstream density needed to access detachment with ion B

×
∇

B drift directed outside of the active divertor (Greenwald fraction

f

Gw

∼

0.9–1.0 vs

f

Gw

∼

1.3). The upstream density at detachment onset was observed to increase linearly with plasma current with ion B

×
∇

B drift into the divertor, consistent with the observed narrowing of the scrape-off layer heat flux width λ

q
. Edge fluid simulations capture separatrix densities needed to achieve detachment in NT plasma and their dependence on drift direction. The ability to reproduce detachment dynamics in NT plasma increases the confidence in future design studies for NT divertors.
Medium and Long Term Wind Power Generation Forecasting Method Based on Multi-model Fusion
Authors: Xiang Guangwei , Lan Tian , Liu Liping
Published: July 2024

Accurate, long-term wind power forecasting is crucial for effective power grid operation planning. It can enhance the stability and security of the power system. We propose a combined medium and long-term wind power generation prediction method based on multi-model fusion to study forecasting. By analyzing the connection between meteorological data and wind power generation, we identify the pivotal factors that impact wind power output and determine the best input data scheme. Based on the predictive outcomes, we select the suitable core predictive sub-models and use the particle swarm optimization algorithm to achieve the dynamic optimization of the weight for each sub-model. Afterwards, we allocate the optimized weights to each sub-model and establish a fused multi-model advantage-based combined predictive platform for wind power generation for the medium and long term. The wind power forecast is enhanced through the dynamic weighted combination forecasting technique, which significantly enhances forecast precision.
A TEMPEST Attack Implementation based on Hidden Markov model in Smart Grid
Authors: Qiao Hong , Wang Kaiyi , Huang TanLong , Xu Xianyong , Liu Shuai , Chen Junxingxu
Published: July 2024

A Smart Grid contains a large number of terminals to gather voltage, current, and power data. If these terminals are attacked by hackers to steal data and disrupt the operation of the grid, the grid will encounter a huge challenge. And side channel attack is an attack way that uses information signals (such as electromagnetic radiation, and computer hardware running sound) inadvertently released by the computer to decipher. The computer keyboard generates electromagnetic radiation signals during operation, and hackers may acquire your account and password through the keyboard’s tapping sound, resulting in the leakage of important data. This article analyzes the electromagnetic radiation leakage vulnerabilities of keyboards and designs a way to implement a TEMPEST (Transient Electromagnetic Pulse Emanation Surveillance Technology) Attack based on the Hidden Markov model, which can provide a foundation for avoiding potential risk.
A Fault Prediction Method for Secondary Electric Power Equipment Based on Multi-Round Undersampling Random Forest
Authors: Liu Wei , Zhou Ning , Ou Rui , Li Dezhi , Yang Yulu , Luo Yuanyuan , Zhou HuiDong
Published: July 2024

It is necessary to predict the fault states of the large number of power secondary equipment using intelligent methods. However, when compared to large-scale equipment, the number of negative samples representing faulty equipment is significantly smaller than the number of positive samples representing normal equipment. This leads to a pronounced imbalance between positive and negative samples in the task of fault prediction. In this paper, we propose a multi-round undersampling random forest method to predict the fault situations of secondary electric power equipment. First, we collect data from historical power system logs to build the dataset for power secondary equipment and preprocess it. The undersampling method is utilized to generate a balanced dataset of secondary power equipment with a smaller sample size. We generate multiple balanced datasets through rounds of random undersampling without replacement to train multiple random forest models. Subsequently, we predict fault situations in secondary electric power equipment through comprehensive decision-making by these multiple random forest models. We employ a real dataset from the power system of Chongqing, China, for experimental validation. The results demonstrate the superiority of our method over other machine learning prediction models used for comparison.