bluuebunny/crossref_metadata_2025 huggingface dataset:
Verification of the kinetic electron role in the microinstabilities in a negative triangularity model equilibrium
Authors: Li Jessica L. , Chang C. S. , Hager Robert , Reiman Allan , Zarnstorff Michael C.
Published: October 2024

Effect of kinetic electrons on negative triangularity plasmas has been investigated and compared against the corresponding positive triangularity plasmas, using the global gyrokinetic code X-point Gyrokinetic Code with scale-separated delta-f option without Coulomb collisions. Our model magnetic equilibria have strong positive and negative triangularities and weak magnetic shear. However, unusually large ρi/a and low density plasmas are chosen to maximize the nonlocal effect to investigate the finite ρi effect and to be clearly away from kinetic ballooning modes. Similar conclusions to previous flux tube and global simulations have been obtained in this highly nonlocal model plasma: it is essential to include kinetic electrons in the micro-instability study of negative triangularity plasmas. Most physics findings agree with existing reports, with some disagreement. We offer a new “effective trapping fraction” concept that can add to the explanation of the growth rate difference between NT and PT plasmas, pointing to the significant variation in trapped particle fractions that have turning points in the mode growth regions.
Multi-resonance terahertz (THz) generation from magnetized cylindrical and spherical nanoclusters of AlAs and InP nanoparticles
Authors: Manendra  , Sharma Mukesh Kumar , Gautam Yogendra K. , Jewariya Mukesh , Malik Anil K.
Published: October 2024

We report a theoretical model for THz generation from the interaction of Gaussian laser beams with semiconductor nanoparticles suspended in argon gas in the presence of a DC magnetic field. Our investigations include two different shapes of nanoparticles [spherical (SNPs) and cylindrical (CNPs)]. The laser fields ionize nanoparticles converting them into plasma, which takes the form of spherical and cylindrical periodic nanoclusters with the electron density profile n=n0+nqeiqz, where q is the wave number of the density ripple and nq is the amplitude of density modulation. In our investigations, nanoparticles of AlAs and InP semiconductors are considered. Resonance condition is obtained when the laser beat frequency matches with the surface plasmon frequency of nanoparticles. We obtain resonances at two different frequencies when we apply a DC magnetic field. The resonance frequencies of THz fields shift with the nanoparticles' shape and orientation. THz field amplitude varies with material properties, spacing, size, and orientation of the nanoparticles. The applied magnetic field enhances the THz field and also helps in controlling the field profile. A THz field ∼0.1GV/cm with ∼2% efficiency is obtained for an optimized set of parameters for CNPs.
Solid, structured composite neutron detectors with high dynamic range capability
Authors: Wiggins Brenden W. , Richards Cameron G. , Mclean Thomas D. , Iliev Metodi , Favalli Andrea , Hehlen Markus P.
Published: October 2024

Neutron detectors are essential across disciplines such as fundamental science, nuclear security, safeguards, and civilian applications. While 3He-filled gas proportional counters have long been revered for their efficacy in detecting thermal neutrons and praised for their efficiency, neutron/gamma discrimination, and stability, the scarcity of 3He has spurred a search for alternatives. Here, we explore a solid structured scintillating particle composite (SPC) consisting of 6Li-containing scintillating glass particles within an acrylic matrix as a neutron detector for high dynamic range applications. We show for the first time that an SPC neutron detector can boast an intrinsic detection efficiency of 0.261% for pure 252Cf fission neutrons and an overall neutron detection efficiency of (0.546 ± 0.003)% at the Neutron Free-in-Air facility while being able to function in an intense gamma-ray environment. We also show that the SPC neutron detector supports fast neutron capture times and enables a dual-readout scheme that extends the detector dynamic range to high incident neutron fluxes. A scalable fabrication process allows for tailoring the SPC detector properties to the requirements of specific applications. Good agreement is found between the experimental results taken with a National Institute of Standards and Technology traceable 252Cf source and the coupled MCNP6 and optical-ray-tracing simulations.
The effect of a constant electric field in an undisturbed plasma on the stability of the electron beam–gas discharge collisional plasma system
Authors: Sukhomlinov Vladimir S. , Mustafaev Alexander S. , Badr Abdul H. , Timofeev Nikolai A.
Published: October 2024

This work is devoted to the study of a fast non-relativistic electron beam–gas discharge plasma system within the framework of the kinetic theory of stability. The influence of a constant electric field, collinear beam velocity, on the stability of the system in an undisturbed plasma is studied. It is shown that even a relatively small electric field, which does not significantly affect the energy of the electron beam, can lead to significant changes in the parameters of harmonic disturbances propagating in the electron beam–plasma system in the region of its instability. It was found that the reason for such changes is the drift of plasma electrons, which, as a consequence, leads to a change in the frequency of disturbances in the coordinate system associated with the plasma due to the Doppler effect. The results obtained are demonstrated by calculations based on the kinetic theory of perturbation parameters in a low-voltage beam discharge in rare gases, which is used in the development of plasma electronics devices. The effect of electron-atomic collisions on the stability of the electron beam–plasma system is investigated and compared with the results of other authors' works.
Multi-stage precipitation modeling for AA 7050 hole repairs in additive friction stir deposition
Authors: Feng Bill , Rajanna Manoj R. , Lua Jim , Hahn Greg , Knight Kendall , Murray Gabriel , Timmons Alan , Phan Nam
Published: October 2024

A multi-stage precipitation model is formulated to predict the microstructural evolution and explain the high performance of additive friction stir deposited aluminum alloy 7050 (AA 7050) for hole repair. The first stage is the heating process due to the high-temperature thermomechanical process of the stir. In this process, small η precipitates dissolve as they lose their stability with increasing temperature, and this causes the volume fraction of η precipitates to decrease and the concentration of Mg and Zn in the matrix to increase. The second stage is the cooling process at the end of the repair where material feeding ends and the tool is lifted away. Heterogeneous nucleation of η precipitates may occur and as the temperature cools below 250 °C, Guinier–Preston (GP) zones start to form. The final stage is the natural aging process, where the η′ precipitate starts to grow. The volume fraction and precipitate radius are predicted for each type of precipitate. Furthermore, the fine η′ precipitates and GP zones with a decent volume fraction improve the material strength and fatigue life.
Techno-economic, energy, and environmental impact assessment of hydrogen supply chain: A comparative study of large-scale production and long-distance transportation
Authors: Li Miao , Ming Pingwen , Jiao Hongyu , Huo Ran
Published: October 2024

Hydrogen energy has made significant progress as one of the technological pathways that can facilitate the green transformation of various sectors, including the chemical industry, steel production, transportation, and power generation. However, areas with high demand for hydrogen are typically located thousands of kilometers away from large-scale production facilities. Hydrogen transported from the most cost-competitive large production sites to areas that lack hydrogen resources requires converting gaseous hydrogen into a high-density liquid. Thus, global market trade is important for hydrogen carriers in long-distance and large-scale transportation. In this study, liquefied hydrogen (LH2) and ammonia (NH3), which are hydrogen-based energy carriers, are analyzed and compared in terms of economic costs, energy efficiency, and carbon dioxide (CO2) emissions. It has been demonstrated that the LH2 supply chain is more energy-efficient and has higher CO2 emissions compared to the NH3 supply chain. Furthermore, this study shows that the levelized cost of hydrogen transportation (LCoHT) delivered from Australia to Ningbo, China, is lower for NH3 (19.95 yuan/kg-H2) compared to LH2 (22.83 yuan/kg-H2). Meanwhile, the LCoHT for the two supply chains is in a similar range (27.82 yuan/kg-H2 and 21.53 yuan/kg-H2 for LH2 and NH3, respectively) from Norway to Ningbo, China. The impacts of important parameters on the LCoHT, energy efficiency, and CO2 emissions of the LH2/NH3 supply chain are also considered through a sensitivity analysis.
Correction of instrument temperature dependence of detector responsivity for measurements of comet 67P acquired by Rosetta’s Visible and InfraRed Thermal Imaging Spectrometer, Mapping channel (VIRTIS-M)
Authors: Kappel D. , Arnold G. , Filacchione G. , Capaccioni F. , Tosi F. , Erard S. , Ciarniello M. , D’Aversa E. , Raponi A. , Leyrat C. , Moroz L. V.
Published: October 2024

The Mapping channel of the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS-M) aboard Rosetta acquired many hyperspectral images of comet 67P/Churyumov–Gerasimenko (hereafter 67P). The VIS channel detector responsivity was dependent on the VIS detector temperature (TVIS). This affects the absolute values of the measured spectra (for a TVIS increase of 1 K between 0.06% increase at 0.55 μm and 1.2% increase at 1 μm) and the spectral slopes. Here, we derive a simple parameterization of this CCD-typical effect based on a statistical analysis of the TVIS-related bias of the measurements. At this, we include all measured VIS spectra excluding acquisitions with little nucleus surface information or at opposition geometry, thereby achieving a high statistical significance and representativity. The corresponding VIS detector responsivity correction, slightly different for measurements acquired when the IR cryocooler was off or on, makes the spectra measured at different instrument temperatures consistent over the entire Rosetta mission phase at 67P. This will improve future quantitative analyses of the data.
Effect of phase angle on thermohydraulic performance of an annular tube formed by co-twisted oval tubes
Authors: Song KeWei , Tian Zhen , Hu LuoYu , Luo Chao , Tagawa Toshio , Wu Xiang , Zhang Qiang
Published: October 2024

This study introduces a novel annular tube configuration consisting of co-twisted oval tubes with different phase angles between the inner and outer tubes. The effect of the inner tube's phase angle on the flow and heat transfer characteristics was numerically investigated over a Reynolds number range of 1000–10 000. The performance of the proposed annular tube configuration was compared with that of a conventional straight annular tube. The results indicate that the twisted oval tube induces a strong secondary flow inside the tube, which significantly enhances the heat transfer. The average Nu and f values of the annular tube with twisted oval tubes are higher than those of the conventional straight annulus. The phase angle between the inner and outer tubes significantly influences the heat transfer and comprehensive thermal performances, especially within the laminar flow region. As the phase angle increases, the average Nu increases first and then decreases. Optimal phase angles of 60° and 45° exist for Re < 6000 and Re ≥ 6000, respectively, with the largest heat transfer ability and comprehensive heat transfer performance. In comparison with a conventional straight annulus, the twisted annulus exhibits an increase in both Nu and f, with maximum enhancements of 89% and 58%, respectively. Moreover, the highest attainable thermal performance factor for the twisted annular tube was 1.66, reflecting a 66% enhancement in thermal performance compared to the conventional straight annulus.
Particle response to oscillatory flows at finite Reynolds numbers
Authors: AlAli Omar , Tarver Benjamin , Coimbra Carlos F. M.
Published: October 2024

The response of spherical particles to oscillatory fluid flow forcing at finite Reynolds numbers exhibits significant deviations from classical analytical predictions due to nonlinear convective contributions. This study employs finite element simulations to explore the long-term (stationary) behavior of such particles across a wide range of conditions, including various external and particle Reynolds numbers, Strouhal numbers, and fluid-to-particle density ratios. Key contributions of this work include determining the range of validity of Tchen's equation of motion for infinitesimal and finite Reynolds numbers and correlating particle response for a wide range of density ratios and flow conditions at high frequency oscillations. This work introduces a modified form of the history drag term in a newly proposed Lagrangian equation of motion. The new equation incorporates a parameter-dependent fractional-order derivative tailored to accommodate nonlinearities due to convective effects. These novel correlations not only extend the operational range of existing model equations but also provide accurate estimates of particle response under a range of external flow conditions, as validated by comparison with numerical solutions of the Navier–Stokes flow around the particles.
A modified variational approach to noisy cell signaling
Authors: Cai Ruobing , Lan Yueheng
Published: October 2024

Signaling in cells is full of noise and, hence, described with stochastic biochemical models. Thus, an efficient computation algorithm for these fluctuating reactions is much needed. Apart from the very popular Monte Carlo simulation, methods based on probability distributions are frequently desired due to their analytical tractability and possible numerical advantages in diverse circumstances, among which the variational approach is the most notable. In this paper, new basis functions are proposed to better depict possibly complex distribution profiles, and an extra regularization scheme is supplied to the variational equation to remove occasional degeneracy-induced singularities during the evolution. The new extension is applied to four typical biochemical reaction models and restores the Gillespie results accurately but with greatly reduced simulation time. This modified variational approach is expected to work in a wide range of cell signaling networks.
Brownian colloids in optothermal field: An experimental perspective
Authors: Pavan Kumar G. V.
Published: October 2024

Colloidal matter undergoing Brownian motion serves as a model system to study various physical phenomena. Understanding the effect of external perturbation on the assembly and dynamics of “Brownian colloids” has emerged as a relevant research issue in soft matter and biological physics. Optical perturbation in the form of photonic forces and torques has added impetus to this exploration. In recent years, optothermal effects arising due to optical excitation of mesoscale matter have expanded the toolbox of light–colloidal matter interactions. In this perspective, we present an experimental viewpoint on some of the developments related to the assembly and dynamics of Brownian colloids driven by the optothermal field. Furthermore, we discuss some interesting prospects on driven colloidal matter that can have implications on soft matter physics and soft photonics.
Optogenetically engineered Septin-7 enhances immune cell infiltration of tumor spheroids
Authors: Chen Jiaxing , Hnath Brianna , Sha Congzhou M. , Beidler Lynne , Schell Todd D. , Dokholyan Nikolay V.
Published: October 2024

Chimeric antigen receptor T cell therapies have achieved great success in eradicating some liquid tumors, whereas the preclinical results in treating solid tumors have proven less decisive. One of the principal challenges in solid tumor treatment is the physical barrier composed of a dense extracellular matrix, which prevents immune cells from penetrating the tissue to attack intratumoral cancer cells. Here, we improve immune cell infiltration into solid tumors by manipulating septin-7 functions in cells. Using protein allosteric design, we reprogram the three-dimensional structure of septin-7 and insert a blue light-responsive light-oxygen-voltage-sensing domain 2 (LOV2), creating a light-controllable septin-7-LOV2 hybrid protein. Blue light inhibits septin-7 function in live cells, inducing extended cell protrusions and cell polarization, enhancing cell transmigration efficiency through confining spaces. We genetically edited human natural killer cell line (NK92) and mouse primary CD8
+
T-cells expressing the engineered protein, and we demonstrated improved penetration and cytotoxicity against various tumor spheroid models. Our proposed strategy to enhance immune cell infiltration is compatible with other methodologies and therefore, could be used in combination to further improve cell-based immunotherapies against solid tumors.
Magnetically oriented nanosheet interlayer for dynamic regeneration in lithium metal batteries
Authors: Ju Zhengyu , Zheng Tianrui , Zhang Bowen , Dolocan Andrei , Marschilok Amy C. , Takeuchi Esther S. , Takeuchi Kenneth J. , Yu Guihua
Published: October 2024

Lithium (Li) metal has been recognized as a promising anode to advance the energy density of current Li-based batteries. However, the growth of the solid–electrolyte interphase (SEI) layer and dendritic Li microstructure pose significant challenges for the long-term operation of Li metal batteries (LMBs). Herein, we propose the utilization of a suspension electrolyte with dispersed magnetically responsive nanosheets whose orientation can be manipulated by an external magnetic field during cell operation for realizing in situ regeneration in LMBs. The regeneration mechanism arises from the redistribution of the ion flux and the formation of an inorganic-rich SEI for uniform and compact Li deposition. With the magnetic-field-induced regeneration process, we show that a Li||Li symmetric cell stably operates for 350 h at 2 mA cm
−2
and 2 mA h cm
−2
, ~5 times that of the cell with the pristine electrolyte. Furthermore, the cycling stability can be significantly extended in the Li||NMC full cell of 3 mA h cm
−2
, showing a capacity retention of 67% after 500 cycles at 1C. The dynamic Li metal regeneration demonstrated here could bring useful design considerations for reviving the operating cells for achieving high-energy, long-duration battery systems.
Meta-learning of human motor adaptation via the dorsal premotor cortex
Authors: Sugiyama Taisei , Uehara Shintaro , Izawa Jun
Published: October 2024

Meta-learning enables us to learn how to learn the same or similar tasks more efficiently. Decision-making literature theorizes that a prefrontal network, including the orbitofrontal and anterior cingulate cortices, underlies meta-learning of decision making by reinforcement learning. Recently, computationally similar meta-learning has been theorized and empirically demonstrated in motor adaptation. However, it remains unclear whether meta-learning of motor adaptation also relies on a prefrontal network. Considering hierarchical information flow from the prefrontal to motor cortices, this study explores whether meta-learning is processed in the dorsolateral prefrontal cortex (DLPFC) or in the dorsal premotor cortex (PMd), which is situated upstream of the primary motor cortex, but downstream of the DLPFC. Transcranial magnetic stimulation (TMS) was delivered to either PMd or DLPFC during a motor meta-learning task, in which human participants were trained to regulate the rate and retention of motor adaptation to maximize rewards. While motor adaptation itself was intact, TMS to PMd, but not DLPFC, attenuated meta-learning, impairing the ability to regulate motor adaptation to maximize rewards. Further analyses revealed that TMS to PMd attenuated meta-learning of memory retention. These results suggest that meta-learning of motor adaptation relies more on the premotor area than on a prefrontal network. Thus, while PMd is traditionally viewed as crucial for planning motor actions, this study suggests that PMd is also crucial for meta-learning of motor adaptation, processing goal-directed planning of how long motor memory should be retained to fit the long-term goal of motor adaptation.
Transmission electron microscopy of epitaxial semiconductor materials and devices
Authors: Dong Jiawei , Bai Hongjie , Deng Yong , Liu Shuo , Wang Xiaoyi , Qiu Yang , Shi Yuechun , Walther Thomas
Published: October 2024

The transmission electron microscope (TEM) is a powerful imaging, diffraction and spectroscopy tool that has revolutionized the field of microscopy. It has contributed to numerous breakthroughs in various scientific disciplines. TEM-based techniques can offer atomic resolution as well as elemental analysis, which benefit the study of epitaxial semiconductors and their related optoelectronic devices on the atomic scale. The design and optimization of the device performance depend on three key factors: the control of strain at nanometer scale, control of the formation and propagation of defects as well as the control of local electronic properties. Manipulation and optimization are only possible if the key factors can be characterized precisely. Herein, the TEM techniques for strain analysis, defect characterization and bandgap evaluation are reviewed and discussed. Lately, with the development of in-situ TEM techniques, researchers have been able to observe dynamic processes and study the behaviour of materials and devices under realistic conditions (in gaseous atmosphere or in liquids, at elevated or cryogenic temperatures, under strain, bias or illumination) in real-time with extremely high spatial resolution. This review explores the impact and significance of in-situ TEM in the field of semiconductors.
Effect of charge state on alkaline OER activity in FeN4–Gr catalyst supported on Ni (111) substrate
Authors: Wang Qianru , Zhang Quan , Zhang Shengli , Zhang Yang
Published: October 2024

The catalysts of transition metal single–atom embedded in N–doped graphene (TMN4–Gr) have attracted significant attention due to the high utilization of transition metal atoms, remarkable selectivity and tunable catalytic activity. In this study, we have employed first–principles study to investigate alkaline oxygen evolution reaction (OER) activity of FeN4–Gr system supported on a Ni (111) substrate (FeN4–Gr/Ni). The results show that the Ni substrate can significantly enhance the OER activity of FeN4–Gr catalyst. The overpotential of FeN4–Gr/Ni catalyst is 0.63 V, much lower than 0.79 V of the FeN4–Gr, which is closely related to the strong interaction from the Ni substrate. By subtracting electrons from the FeN4–Gr/Ni catalyst, a positive charge environment can be created. It is found that, between the FeN4–Gr and the Ni substrate, a significant electron transfer phenomenon is observed, and the amount can be regulated by the charge state. Besides, the charge state can obviously tune the adsorption strength of *OOH intermediate through the interaction of Ni substrate, further optimizing the OER activity thermodynamically favorable. As the charge state increases to +1.55, the overpotential decreases to 0.23 V. By analyzing the integrated crystal orbital Hamilton populations, the chemical bond strength of Fe–O is discussed. Our results reveal that the Ni substrate can significantly enhance the OER activity of the FeN4–Gr catalyst, and the charge state can also tune the overpotential, offering valuable insights for the design of high–efficiency single–atom catalysts utilizing metal substrate.
Ultralow magnetic susceptibility in pure and Fe(Bi)-doped Au-Pt alloys improved by structural strain regulation
Authors: Ma Jun-Tao , Xiao Ye-Lei , Zhang Butian , Wang Shun , Zhou Ze-Bing , Fu Hua-Hua
Published: October 2024

Designing and manufacturing multi-component alloy samples with ultralow magnetic susceptibility χ (<10−6 cm3 mol−1) is crucial for producing high-quality test masses to successfully detect gravitational wave in the LISA and TianQin projects. Previous research has idenfified AuPt alloys as a potential candidate for test masses, capable of achieving ultralow magnetic susceptibility that meets the requirements from both theoretical and experimental perspectives. In this study, we discover that the structural strain regulation (i.e. tensile and stress) can effectively optimize and further reduce the ultralow magnetic susceptibility of AuPt allpys, while fully understanding their underlying physical mechanisms. More importantly, even when doped with trace elements such as Fe or Bi impurity, strain regulation can still effectively reduce the magnetic susceptibility of the doped AuPt alloy to the desired range. Our theoretical calculations also reveal that, when the strain ratio η is controlled within in a relatively small range (<2.0%), the regulaton effect on the ultralow magnetic susceptibilities of pure or doped-AuPt alloys remains significant. This property is beneficial for achieving ultralow or even near-zero magnetic susceptibility in real AuPt alloy samples.
Low-dose radiographic inspection of welding by a novel aperiodic reverse stochastic resonance method
Authors: Shen Mengen , Yang Jianhua , Sanjuán Miguel A F , Zheng Yuqiao , Zheng Yanzhao , Wang Zhongqiu
Published: October 2024

Low-dose radiographic inspection is a growing trend in industry to minimize radiation risks to humans and the environment. However, reduction in radiation dose often introduces significant noise, which affects image quality and hinders accurate identification of subtle defects. This study addresses this issue by introducing a novel phenomenon called aperiodic reverse stochastic resonance (ARSR), observed in nonlinear systems excited by aperiodic binary signals. ARSR enables simultaneous amplitude amplification and reversal of signals under specific noise conditions. Leveraging ARSR, we propose an image denoising framework for low-dose radiographic inspections. First, a set of projection data is obtained by using Radon transform to reduce the dimensionality of x-ray images from different angles. Then, the projection data is modulated based on the ARSR system. Finally, the image is reconstructed based on the inverse Radon transform. Simulations and experimental comparison results in welding applications validate the effectiveness of the framework, demonstrating significant improvements in image quality for low-dose radiographic defect detection. Unlike advanced methods such as Gaussian filtering, BM3D, and DnCNN, which operate at the pixel level, ARSR performs denoising at the projection data stage, reducing noise impact, preserving original information, and focusing on physical data processing during imaging. This approach enhances the detection of subtle defects, highlighting the potential of stochastic resonance in image processing.
Incipient fault detection for the spindle bearing of a cement grinding machine based on vibrational resonance
Authors: Xiao Lei , Zhao Hailong , Gao Shaofeng , Zhou Qihong
Published: October 2024

The spindle bearing of a circulation fan is an important component of a cement grinding machine. In addition to the faults on the spindle bearing, impeller wear and ash accumulation may cause dynamic unbalance and complex vibration interference as noise, which decreases the accuracy of fault detection based on vibrational signals and traditional signal processing-based methods at the early stage of a bearing fault. To address this issue, this paper presents a new fault detection method for the spindle bearing by utilizing extra injected noise and vibrational resonance. To enhance the fault signature and resonance performance, the nonlinear system of the traditional vibrational resonance is replaced by a new hybrid steady-state system, and the underdamped term is considered in the new system. The proposed system provides more possibilities to achieve resonance by adjusting the system parameters and overcomes the limitations of output saturation caused by the classical bistable system. The proposed method is validated by analyzing the collected vibration signals from a spindle bearing of a circulation fan in practice and is compared with other noise-elimination fault detection methods. The results demonstrate the effectiveness and superior performance of the proposed method.
Ion motion in strongly magnetized cluster laser plasma
Authors: Andreev A A , Platonov K Yu , Lecz Zs
Published: October 2024

This paper investigates the interaction of high intensity, circularly polarized, short laser pulses with heavy cluster plasma through analytical modeling and numerical simulations. The optimal parameters were found for the generation of several GigaGs quasi-stationary magnetic field by using the upgraded analytical model and detailed 3D PIC simulations. It is confirmed that a field of such strength slows down the thermal expansion of the cluster core in the direction transverse to the laser beam axis, which can be used in nuclear physics. The generated inward shocks produce ion core compression, which is relevant to nuclear fusion. The electrostatic interaction between the rotating laser field, electrons and ions leads to an ion spiral density distribution in the cluster’s transversal plane, which is absent in a cluster irradiated by linearly polarized pulses with the same parameters.
Initial results from neoclassical tearing mode stabilization experiment in KSTAR high normalized beta plasmas
Authors: Park Y S , Woo M H , Sabbagh S A , Han H S , Park B H , Kang J S , Kim H S
Published: October 2024

Active stabilization of neoclassical tearing modes (NTMs) is critical for high beta plasma operation in the KSTAR tokamak. In recent device operation, an experiment was conducted to develop a m/n = 2/1 NTM stabilization in high normalized beta (β
N) plasmas having β
N > 3 by using electron cyclotron current drive (ECCD). The experiment is designed to first demonstrate the direct mode stabilization effect of the device EC system by varying the ECCD deposition location around the mode rational surface to prepare for future NTM stabilization in KSTAR using feedback schemes. In the experiment, the toroidal magnetic field strength, B
T, is reduced to 1.5–1.6 T to create a highly localized ECCD profile on a large island width expected to produce a high stabilization effect. To align the ECCD with the mode, B
T is varied between discharges by keeping the EC wave injection angles fixed to move the current deposition location across the q = 2 mode rational surface in ∼1 cm steps along the plasma midplane. The result shows a prompt reduction of the mode amplitude by ∼60% with a partial recovery of the loss of stored energy when the ECCD with 0.7 MW power is applied promptly after the mode onset at B
T = 1.54 T. This abrupt reduction of the mode amplitude is significantly weaker or disappears in other discharges having slightly different B
T in which the ECCD is deposited a few centimeters away. This result indicates a direct interaction between the driven EC current and the radially localized island structure first observed in the device. The EC ray-tracing analysis using the TORAY code shows that the applied EC-driven current aligns with the mode rational surface when the mode amplitude is observed to decrease. The stability of the observed 2/1 NTM is examined by constructing the modified Rutherford equation (MRE). The calculated EC power requirement for complete mode stabilization by assuming perfect alignment of ECCD on the mode is 0.8–1.7 MW by considering the uncertainties in the equation. This MRE-computed mode stability agrees with the experiment. The result projects that the present KSTAR EC system can stabilize the 2/1 NTM disrupting high β
N plasmas, and provides the requirement of the mode-ECCD alignment for complete mode stabilization in future experiments in which an accurate alignment is planned to be made by feedback schemes being developed.
Accelerating quantum information transfer in a three-level system via a specified intermediate Hamiltonian
Authors: Huang Chun-Rong , Chen Ye-Hong
Published: October 2024

We propose a general approach to speed up quantum adiabatic processes for fast quantum information transfer in a three-level system. In the approach, by using an intermediate Hamiltonian which is assumed to be formed by the original Hamiltonian

H

0

(
t
)

and its counterdiabatic driving Hamiltonian

H
cd

(
t
)

with a simple linear relationship, we design exact dynamics following the eigenstates of the intermediate Hamiltonian to speed up the desired population processes. We apply the present approach to a three-level system to show that by suitably choosing the parameters, not only the population processes could be sped up, but also the existence of the undesired off-diagonal terms, the populations of the intermediate states, and even the shapes of the pulses would be controllable in the speeding up scheme.
A fractional-order improved FitzHugh–Nagumo neuron model
Authors: Kumar Pushpendra , Erturk Vedat Suat
Published: October 2024

We propose a fractional-order improved FitzHugh–Nagumo (FHN) neuron model in terms of a generalized Caputo fractional derivative. Following the existence of a unique solution for the proposed model, we derive the numerical solution using a recently proposed L1 predictor–corrector method. The given method is based on the L1-type discretization algorithm and the spline interpolation scheme. We perform the error and stability analyses for the given method. We perform graphical simulations demonstrating that the proposed FHN neuron model generates rich electrical activities of periodic spiking patterns, chaotic patterns, and quasi-periodic patterns. The motivation behind proposing a fractional-order improved FHN neuron model is that such a system can provide a more nuanced description of the process with better understanding and simulation of the neuronal responses by incorporating memory effects and non-local dynamics, which are inherent to many biological systems.
Four-wave mixing Bragg scattering for small frequency shift from silicon coupled microrings
Authors: Zhao 赵 Chang 畅 , Wu 吴 Chao 超 , Zhu 朱 Pingyu 枰谕 , Du 杜 Yuxing 昱星 , Wang 王 Yan 焱 , Yu 余 Miaomiao 苗苗 , Zhang 张 Kaikai 凯凯 , Xu 徐 Ping 平
Published: October 2024

Frequency conversion is pivotal in nonlinear optics and quantum optics for manipulating and translating light signals across different wavelength regimes. Achieving frequency conversion between two light beams with a small frequency interval is a central challenge. In this work, we design a pair of coupled silicon microrings wherein coupled-induced mode-splitting exists to achieve a small frequency shift by the process of four-wave mixing Bragg scattering. As an example, the signal can be up or down converted to the idler which is 15.5 GHz spaced when two pumps align with another pair of split resonances. The results unveil the potential of coupled microring resonators for small interval frequency conversion in a high-fidelity, all-optical, and signal processing quantum frequency interface.
Phase transition in modified thermodynamics of Kerr-AdS black holes*
Authors: Liu 刘 Qin 琴 , Wu 吴 Xiaoning 小宁 , Zhang 张 Xiao 晓
Published: October 2024

In this study, we investigate the critical phenomena of Kerr-AdS black holes under the modified first law of thermodynamics. Specifically, we considered modified black hole thermodynamics that exhibit a van der Waals-like phase structure. All critical exponents were calculated, and then, a swallowtail diagram of free energy was plotted. Comparing with existing results, the main difference is the correspondence between the thermal quantities of Kerr-AdS black holes and the van der Waals system. In a previous study [Y. D. Tsai, X. N. Wu, and Y. Yang, Phys. Rev. D 85 044005 (2012)], the correspondence was

, while in our study, the correspondence was

. This difference was owing to the rotating effect. The modified black hole thermodynamics were associated with rotating observers. The free energy in such a reference contains extra rotating energy, which induces a Legendre transformation in the

cross-section, causing the difference in correspondence.
Ship model-based route optimisation for decision support in deep sea shipping
Authors: Kisialiou Y , Rialland A , Gribkovskaia V
Published: October 2024

We present a new approach and route optimization methodology to support analysis and planning of vessel and fleet performance in deep sea shipping for green, energy efficient, and safe navigation. The developed methodology combines the ship technical characteristics based on a ship model developed for a particular vessel type and energy-saving technology options and an optimization algorithm taking into account weather conditions. Optimization involves two stages: graph construction and Dynamic Programming labelling algorithm implemented to solve the shortest path problem with variable speed. The new approach is implemented as part of a decision-support tool EcoRouter enabling the user to conduct analysis of safe and Pareto optimal solutions. Several applications to support real fleet planning and ship performance analysis have been identified including project engineering for future energy-saving ship technologies, for example, wind-assisted propulsion.
Steering towards sustainability: the impact of autonomous shipping on achieving sustainable development goals
Authors: Tsvetkova Anastasia , Wróbel Krzysztof , Morariu Andrei-Raoul , Hellström Magnus , Björkqvist Jerker
Published: October 2024

This study examines the sustainability potential of Maritime Åutonomous Surface Ships (MÅSS) in achieving the United Nations’ Sustainable Development Goals. By engaging various stakeholders through a poll and interviews, the research explores both the anticipated benefits and possible negative impacts of MÅSS, as well as the potential for failed promises of autonomous shipping. The findings highlight the need for incorporating sustainability considerations in further development of autonomous shipping to ensure it positively contributes to sustainable development.
A Probabilistic Approach to Correct for Oblique Biases in Sea Ice Parametrization from Shipborne Cameras
Authors: Veggeland Oskar G. , Kim Ekaterina , Skjetne Roger
Published: October 2024

This work investigates the perception bias caused by ice floes occluding open water regions behind them when analyzing sea ice from shipborne cameras. We propose a method to model this effect by predicting an occlusion probability for a given surface region based on a stochastic representation of the sea ice fields. We further show how the proposed framework can be used to design an unbiased estimator for image-based sea ice concentration by correcting for these occlusions. The occlusion model and proposed sea ice concentration estimator have been verified through simulated experiments. Results from the experiments showed that predictions from the occlusion model align with the simulated observations and that the proposed estimator remains unbiased for all environments tested. The contributions of this study can be used in algorithms for automated identification and characterization of ice environments from surface ships and are thus an essential step towards improved autonomy in Arctic navigation.
Impact of automation and zero-emission propulsion on design of small inland cargo vessels
Authors: Bačkalov Igor , Burmeister Hans-Christoph , Isidorović Ljubisav , Jasa Justin , Josipović Marko , Kloch Kristoffer , Koimtzoglou Alexandros , Krasilnikov Vladimir , Krause Stefan , Mateienko Denys , Nordahl Håvard , Reinach Nathalie
Published: October 2024

Small inland waterways offer considerable capacity for modal shift of cargo transport. Revitalization of smaller inland waterways, however, may require new vessel designs as most of the existing small vessels are outdated and incompatible with the present state of the technology development and the current commercial and regulatory requirements. This paper investigates the possibilities for modernization of small inland vessel designs and offers a systematic analysis of impact of “automation” and “zero-emission propulsion technology” on reference designs of standard European inland cargo vessels of CEMT classes I, II, III, and IV. The adopted level of automation enables the vessels to be remotely operated without human crew onboard, whereas the adopted zero-emission propulsion concept is based on electrification of the powertrain. The paper identifies the impacts of the modernization on general arrangement, cargo capacity, safety, structural design, etc. and indicates the vessel classes which could be the most promising candidates for the design of a future small autonomous inland ships.
Understanding Operation of Automated Inland Vessels using Process Diagrams
Authors: Kerkmann Thomas , Sai Krishna Illuri Mohan , Bačkalov Igor , Spachtholz Eva , Glomsda Marvin , Etienne Kracht Frédéric
Published: October 2024

The functional design of a vessel requires a comprehensive understanding of vessel operations. This understanding can be enhanced through the development of process diagrams. The research presented here emphasizes the importance of developing diagrams that represent detailed process flows and allow the identification of appropriate interfaces between them. On remotely controlled and automated vessels, a number of functions performed by human operators are taken over by systems, requiring a clear understanding of the processes and the instances at which the handover between human and system takes place. This paper presents process diagrams for conventional, remotely controlled, and autonomous inland vessels. Such process diagrams can be used as blueprints for integration of automated systems on inland vessels, because they reveal the process interruptions which occur when the human operators are removed from the vessel.
Boredom, vigilance, and repetition during remote control room work for autonomous ships
Authors: Veitch Erik , Andreas Alsos Ole
Published: October 2024

Introduction: Remote Operating Centers (ROCs) enable human oversight of remotely operated and autonomous ships. However, the “human-in-the-loop” model of automated control oversight implies prolonged periods of inactivity punctuated by safety-critical action. This paper investigates the extent to which this role is aligned with humans’ innate attentional resources in terms of boredom, vigilance, and repetition. Method: A simulator study was completed with ROC operators (volunteer participants with relevant expertise). One group completed a short scenario (5 minutes; N = 16); the other completed a long scenario (30 minutes; N = 16). The duration marked the onset of a stimulus (an alarm), prompting manual takeover. In a mixed method approach, four sources of data were collected, consisting of pupillometry, questionnaire, interview, and video data. Results: Pupillometry data showed larger pupillary constrictions in the 30-minute group, indicative of decreased cognitive activity (effect size 0.25 mm). The questionnaire showed that operators in the 30-minute scenario were more likely to experience their tasks as unchallenging, understimulating, and lacking in meaning. Finally, a relationship was found between repetitive content and varying perceptions of time duration. Moreover, operators perceived scenarios as longer when they detected an “oddball” in the repetitive series (a gorilla passenger). Conclusion: ROC work as currently imagined is prone to boredom, vigilance decrement, and suppression of repetition. The study adds to the empirical research about boredom and its associated cognitive states in control room work. The study also contributes to design considerations impacting safety and organizational aspects like operator training and retention.
Perform assessment of COLREGs onboard a maritime autonomous surface ship: Narrow Channels and Traffic Separation Schemes
Authors: Koch Paul , Constapel Manfred , Burmeister Hans-Christoph
Published: October 2024

The usage of Maritime Autonomous Surface Ships in coastal and heavily used maritime environments necessitates advanced navigation systems capable of fully complying with the International Regulations for Preventing Collisions at Sea 1972 and not only open sea encounters. A significant challenge in this domain is enabling autonomous vessels to understand and navigate complex collision avoidance scenarios dictated by Rule 9 Narrow Channels and Rule 10 Traffic Separation Schemes. These rules are not well covered by research and only partial solutions have been proposed. To address this, we propose a ruleset for a system that can blend the traffic situation and geometric constraints extracted from Electronic Navigational Charts in S-57 format. The proposed ruleset extends our previous work on operationalization of COLREGs by introducing spatial features describing the maritime geometries relevant for traffic situations in Narrow Channels and Traffic Separation Schemes. We apply the ruleset to various traffic situations, showing how the inclusion of geometric context improves decision-making by reducing ambiguity and therefore enables the assessment of traffic situations and ship encounters in the vicinity of Narrow Channels and Traffic Separation Schemes. Our work outlines how the integration of spatial features into a rule-based system enables autonomous navigation capabilities of MASS for safe operations and compliance with maritime regulations.
Risk Assessment for Inland Vessels with Various Levels of Automation: a Hazard Identification Study
Authors: Spachtholz Eva , Glomsda Marvin , Sai Krishna Illuri Mohan , Kerkmann Thomas , Bačkalov Igor , Etienne Kracht Frédéric
Published: October 2024

The future viability of inland navigation is closely linked to the automation of inland vessels. This will make their use more attractive and efficient. Potential solutions for automation in the scope of this paper include remotely controlled inland vessels that do not require a boatmaster to be on board but are controlled from shore. The implementation of such new technologies involves unknown risks. It is therefore necessary to assess the safety and classify the risks associated with inland vessels of varying degrees of automation. To identify these risks, a Hazard Identification (HAZID) study has been conducted. The outcomes of the study may serve as a basis for adapting regulations and introducing novel technologies, which would facilitate increased automation of inland navigation
Comparison of methods for using risk information in path planning for autonomous surface vessels
Authors: Kristensen Susanna D. , Skjetne Roger , Utne Ingrid B.
Published: October 2024

Path planning is an essential part of autonomous surface vessel (ASV) operations. Risk models can be used to give estimates of risk related to the operation of technical systems, such as ASVs. Combining risk models directly with control systems can be a way to make autonomous systems more capable of assessing and evaluating risk, and in this way allow them to make better decisions. Focusing on path planning, this study aims at investigating how an online risk model used to inform an ASV of risk compares to a static safety domain. The results show that the paths selected when using the risk model can consider different environmental conditions, and the choice of path can be adapted based on how conservative the ASV should be with respect to risk. In this way the risk model provides a more detailed basis for making decisions than the static safety domain.