bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impurity transport driven by kinetic ballooning mode in the strong gradient pedestal of tokamak plasmas
Authors: Huang Shanni , Guo Weixin , Wang Lu 
Published: November 2024

Abstract
The impurity transport driven by kinetic ballooning mode (KBM) is theoretically studied in the DIII-D H-mode strong gradient pedestal plasmas. From the electromagnetic gyrokinetic equation, including the correction of the strong radial electric field, the dispersion relationship of KBM instability with non-trace impurity is firstly derived. Then, the turbulent impurity flux and ion heat flux, as well as the associated transport coefficients, are further calculated. Through the parametric dependence analysis of analytical results, it is found that dilution effects of light fully ionized impurities can reduce the drive of KBM by affecting the kinetic pressure gradient parameter

α

and diamagnetic effects, thus leading to a decrease in both the absolute value of the real frequency

|

ω
r
′

|

and the growth rate

γ

k

′

of KBM instability. Stronger dilution effects by increasing the impurity charge number

Z

or steepening the impurity density profile correspond to stronger effects. Moreover, the removal efficiency of light fully ionized impurities, quantified by the ratio between the impurity diffusivity and effective ion heat conductivity

D

z

χ

i

eff

≈

1
−

b

z

+

4

ω

Dz

/

ω
r
′

3

(

1
+

1

/

η

i

)

/

2

, increases with an increase of

Z

mainly due to the smaller impurity finite Larmor radius (FLR) effects reflected by

b

z

∝

1

/

Z

. Besides, the increase of the impurity density gradient can significantly enhance

D

z

/

χ

i

eff

, and this is because stronger impurity dilution effects make a larger magnetic drift term

|

ω

Dz

|

/

|

ω
r
′

|

(

ω

Dz

is the magnitude of impurity magnetic drift frequency) and

η

i

(the ratio of ion density gradient scale length to ion temperature gradient scale length). For heavy metal impurities with a concentration of

10

−
4

, the peaking factor (PF) is positive, which means that its density profile is inwardly peaked, and the PF decreases with the enhancement of impurity FLR effects. These results may provide some theoretical reference on understanding the physical mechanism of impurity transport in the pedestal of H-mode plasmas.
Ultralow phase noise optoelectronic oscillator
Authors: Yan Dongliang , Ge Jun , Liu Dan 
Published: November 2024

Abstract
The optoelectronic oscillator(OEO)’s main technological advantage over the traditional microwave oscillator is its ultra-low phase noise property. In this article, we have been using a high-power low-RIN laser, a long fiber loop, and an ultra-low noise optical connection to generate an OEO with a phase noise of -162.5dBc/Hz@10kHz at a frequency of 10 GHz to investigate the optoelectronic oscillator’s single-loop structure. More significant factors on OEO have been explored in this work, including residual phase noise of the optoelectronic link, linear operating state of the optical link, optical power input to the photodetector, and photodetector bias voltage.
Next-Generation Chip Scale Atomic Clocks
Authors: Kitching John , Hummon Matt , McGehee William , Wang Ying-Ju , Schima Susan 
Published: November 2024

Abstract
We describe three independent research directions focussed on the development of next-generation chip-scale atomic clocks, which combine small size, low power consumption and manufacturability with high frequency stability. The use of optical transitions in microfabricated vapor cells improves both short- and long-term frequency stability to near 10−13 at the cost of the added complexity of a chip-scale optical frequency comb. Chip-scale atomic beam microwave clocks have been successfully demonstrated and offer the potential for microsecond-level timing accuracy over one week. And finally, Sr vapor cells have been developed with lifetimes exceeding 250 hours and residual gas pressures below 1 Torr.
Contributions of the optical lattice clock NICT-Sr1 to TAI calibration and UTC(NICT) steering
Authors: Hachisu H , Nemitz N , Tønnes M , Ito H , Ohtsubo N , Miyauchi Y , Morikawa M , Matsubara K , Gotoh T , Ido T 
Published: November 2024

Abstract
Our efforts with the optical lattice clock NICT-Sr1 are now focused on contribution to both the international and the local timescale. Since 2018, NICT-Sr1 has been recognized as a secondary frequency standard and frequently contributed to BIPM’s monthly calibration of the rate of the international atomic time TAI. This fulfils one of the criteria that the Consultative Committee for Time and Frequency has set for the redefinition of the SI second. Another, ancillary condition is addressed by NICT-Sr1’s contributions to the generation of Japan Standard Time, which began in 2021 and enabled a reduction of the deviation from the international timescale to typically 4 ns over more than two years.
Robust design and performance of NPL Cs fountain clocks
Authors: Szymaniec K , Hendricks R J , Whale J , Wilson A , Walby S , Knapp M , Foot C J 
Published: November 2024

Abstract
We report on developments in the atomic fountain systems being built and operated at NPL. An improved generation of Cs fountains has been developed, with units being constructed for use by both NPL and commercial customers. These systems combine world-class stability and accuracy with increased reliability and can run for long periods of time without maintenance. Here we describe how the NPL fountains work, and present performance data for the latest systems. We describe some of the applications of these fountains, both in time scale implementation and fundamental science. We also present an overview of a miniature atomic fountain that is being developed, which will help make fountain technology accessible to a wider range of sectors.
Incorporation of hydrogen masers into a free ensemble timescale aimed for optically steered UTC(k)
Authors: Ido T , Ito H , Hachisu H , Nemitz N , Ohtsubo N , Miyauchi Y , Morikawa M , Tønnes M , Matsubara K 
Published: November 2024

Abstract
The combination of a single hydrogen maser and an intermittently operated optical clock can generate a highly accurate timescale, but it is difficult to address a sudden deterioration of the hydrogen maser. This issue can be resolved by the use of an ensemble. By estimating the frequency drift of multiple individual hydrogen masers, it is possible to incorporate them as the main contributors to an ensemble time scale that benefits from their long-term stability. Such a timescale is in operation at UTC(NICT) since August 2023. To determine the required adjustments for frequency offset and drift of the free-running timescale, we refer to a separate timescale generated from a hydrogen maser steered according to intermittent operation of an optical clock. In combination, this realizes a robust and accurate timescale.
Progress on the optically detected magnetic-state-selected cesium beam clock
Authors: Li Yuanhao , Chen Sifei , Liu Chen , Fan Lifeng , Li Chaojie , Wang Yanhui 
Published: November 2024

Abstract
The optically detected magnetic-state-selected cesium beam clock is a new type of compact cesium clock developed by Peking University. The principle and performance of our clock are introduced in the article as well as our recent researches on beam optics, signal-to-noise ratio, spectrum linewidth and light shift.
Progress in the miniature trapped ion optical clock development with 16 cc sealed trap tube
Authors: Hoang Thai M. , Zhang Wei , Le Thanh , Mulholland Sean , Langlois Mehdi , Park Yuna , Matsko Andrey B. , Prestage John , Yu Nan 
Published: November 2024

Abstract
Optical clocks have well surpassed the frequency stability performance of microwave clocks. They have been mainly limited to tabletop setups and large rack-mount systems. Miniaturizing optical clocks will make the new technology and capability more ubiquitously applied to applications from navigation to fundamental science. Here we aim to develop a miniature space optical clock (mSOC) with the size of a compact microwave clock and capable of achieving a short-term stability of 10−14
τ
−1/2 and noise floor of 10−16. In this paper, we will describe the mSOC concept, discuss the experimental setup, and present recent results. We have demonstrated trapping single ions and characterized the ion lifetime in a 16-cc trap tube. The trap tube is completely sealed off without any active pump. We also constructed a clock laser referenced to a small ultra-low expansion reference cavity at a low 10−14 level and observed the clock transition.
A compact cold atom cavity clock
Authors: Bregazzi A. , Batori E. , Lewis B. , Affolderbach C. , Mileti G. , Griffin P. , Riis E. 
Published: November 2024

Abstract
A sample of laser cooled atoms are created inside an additively manufactured loop-gap microwave cavity using a grating magneto-optic trap requiring only a single laser cooling beam. Using a Ramsey excitation scheme with free evolution times of up to 20 ms and based on the 87Rb ground-state clock transition, we demonstrate a short-term stability of 1.5×10−11
τ
−1/2, averaging down to 2×10−12 after 100 s. The short-term stability limit is found to be dominated by the signal to noise ratio of the Ramsey fringes while for longer timescales the limitation is magnetic field noise due to the experiment being magnetically unshielded. Potential improvements to the setup and its operation point to a viable route forward for a miniaturised atomic microwave clock.
The development and future of the Faraday laser
Authors: Wang Zhiyang , Shi Hangbo , Liu Zijie , Miao Jianxiang , Shi Tiantian , Chen Jingbiao 
Published: November 2024

Abstract
Faraday lasers, distinguished by their utilization of the Faraday anomalous dispersion optical filter (FADOF), employ atomic transitions for mode selection. This sets them apart from other semiconductor diode lasers, which commonly employ gratings, interference filters, and etalons for frequency selection and initiating laser oscillation. A notable advantage of Faraday lasers is their resistance to noises in driving current and the temperature of the laser diodes. Additionally, the using of FADOF enables the output frequency of the laser to align with atomic transition lines immediately when powering the lasers with driving current above the threshold. This paper presents the advancements in Faraday laser system technology spearheaded by our group, outlining a forward-looking research agenda aimed at continually enhancing the performance of Faraday lasers. This endeavor seeks to establish these lasers as frontrunners in the next generation of laser used in precision spectroscopy, with specific applications in atomic physics, quantum metrology, and quantum precision measurement technology.
Trapping of triply charged thorium-229 for a nuclear clock
Authors: Yamaguchi A , Shigekawa Y , Haba H , Wada M , Katori H 
Published: November 2024

Abstract
We developed an ion trap system for triply charged thorium-229 (229Th3+). We used uranium-233 as the ion source, which supplied 229Th3+ ions in the nuclear ground state and low-lying isomeric state (229mTh3+) at 8.3 eV. Our ion trap system allows the laser spectroscopy of 229mTh3+ toward the nuclear clock.
Superradiant active optical atomic clocks: motivations and current challenges
Authors: Matusko Martina , Delehaye Marion 
Published: November 2024

Abstract
Current state-of-the-art frequency standards are passive optical atomic clocks where the frequency of an optical resonator is stabilized to a narrow atomic transition. Passive clocks have achieved unprecedented stabilities of 6.6 × 10−19 over one hour of averaging time [1]. However, they face intrinsic limitations, particularly due to thermal and mechanical fluctuations of the local oscillator. To surpass the limitations of the passive clocks and go beyond the state-of-the-art, the idea of building active optical atomic clocks emerges. These clocks would be optical counterparts of hydrogen masers, with the emitted frequency defined by the atomic transition and therefore inherently stable against cavity instabilities. This paper discusses the latest developments and future prospects in the field of active optical atomic clocks.
Dual-species atomic interferometric sensor for simultaneous inertial measurement and clock operation
Authors: Yan Peiqiang , Jia Weichen , Wang Shengzhe , Feng Yanying 
Published: November 2024

Abstract
The atomic interferometer, serving as a precise measurement tool for multiple physical quantities, holds the potential to establish a fully quantum autonomous “position, navigation, and timing (PNT)” unit. This paper introduces a method for simultaneous inertial measurement and clock operation based on atom interferometry with dual-isotope atomic beams. The corresponding related experimental progress is also reported. A 87Rb Raman-Mach-Zehnder interferometer is presented with a fringe contrast of C = 0.05, providing a foundational sample for further experiments.
Time-dependent Aharonov-Bohm effect for electromagnetic and gravitational scalar potentials
Authors: Chiao RY , Inan NA , Scheibner M , Sharping J , Singleton DA , Tobar ME 
Published: November 2024

Abstract
In this article, we review a new approach to the scalar Aharonov-Bohm effect for both the electromagnetic and gravitational interaction. For both interactions a quantum system is placed in a time-dependent electromagnetic or gravitational potential, but with no force (spatial derivative of the potential) acting on the quantum system. Nevertheless, we show that the energy levels of the quantum system develop side bands which can be detected as the signature of this version of the scalar Aharonov-Bohm effect. We briefly look at the specific experimental setups required to detect the energy side bands.
The effect of asymmetric rolling on aluminum alloy 5XXX series with scandium
Authors: Nikitina M.A. , Pesin A.M. , Tandon P. , Pustovoytov D.O. , Pesin I.A. , Lokotunina N.M. , Biryukova O.D. 
Published: November 2024

Abstract
One of the directions of development of aluminum alloys is to increase strength characteristics without increasing density. Scandium is an effective additive for improving the strength characteristics of alloys with a high magnesium content. The main disadvantage of scandium-containing alloys is the high cost, the cost of ligature in Russia Al-2%Sc reaches $ 50 per kg. The high cost of semi-finished products is a deterrent to the use of aluminum-scandium alloys in various industries. In this paper, we consider the replacement of symmetric rolling with asymmetric rolling in the last passes of hot and cold rolling as one of the ways to reduce the cost in the production of semi-finished products. The research was carried out on an aluminum wrought non-heat-treatable alloy of the 5XXX series with scandium having the Russian marking 1545K. Rolled semi-finished products using symmetric rolling, as well as using asymmetric, were manufactured at the Zhilyaev Laboratory of the Nosov Magnitogorsk State Technical University using the unique laboratory industrial rolling mill 400. Asymmetric rolling is used for both hot and cold rolling. Asymmetric rolling made it possible to significantly reduce the force per pass, the pressure per pass became higher than when using standard technology. The obtained mechanical characteristics and the study of the micro-structure indicate a positive effect of asymmetric rolling. The use of this approach can significantly reduce costs in the manufacture of semi-finished products without reducing the quality of the resulting semi-finished products.
Effects of Cognitive Distraction on the Performance of Brain-Controlled Hand Exoskeleton
Authors: Liu Siyu , Liu Mengxin , Ming Zhiyuan , Zhao Yan , Liu Mengzhen , Luo Jianwei , Liu Ziyu , Chen Qiming , Ma Lingfei , Song Yifan , Zhang Jian , Yan Tianyi 
Published: November 2024

Abstract
Advances in brain-machine interfaces (BMIs) have greatly enhanced the control of assistive devices like hand exoskeletons, providing new rehabilitation possibilities for individuals with impaired hand function. However, the presence of cognitive distraction during device operation may negatively affect performance. This study explores the impact of cognitive interference on a brain-controlled hand exoskeleton system. Participants were required to perform hand movement tasks using the exoskeleton while engaging in a cognitive distraction task. The results showed a significant decline in task completion rate and a marked increase in response time as cognitive distraction intensified. These findings underscore the need to mitigate cognitive distraction in brain-controlled systems to enhance performance, especially in rehabilitation contexts. This study contributes valuable insights into the interaction between cognitive distraction and brain-controlled hand exoskeleton performance, laying the groundwork for improving BMI reliability and effectiveness in practical applications.
The study of the turbo-machines erosion caused by solid particles during the evacuation of combustion gases in a biomass power plant
Authors: Sangsawangmatum Thanate 
Published: November 2024

Abstract
Turbo-machines are recognized as a significant engineering device for transferring heat and mass, particularly solid particles in the transport medium. The biomass power plants turbo-machines, known as centrifugal fans, is normally used in the process of evacuating combustion. Due to their duty to continuously work in high concentrations of solid particles, unavoidable damage resulting from solid particle erosion must occur. This causes the system to shut down unexpectedly. To avoid system shutdown, the centrifugal impeller must be designed to withstand the solid particles from exhaust gas, which quickly deteriorate. The aims of the research paper are to study the behaviour of an erosion mechanism of the system using Computational Fluid Dynamics (CFD) verified against the various parameters obtained from actual operating data which were collected during the operating season. Steady-state turbulence modelling and discrete phase modelling (DPM) in powerful commercial software were used to predict the fluid kinetics of substances and the trajectories of individual solid particles, respectively. In the end, the study’s results not only aid users in understanding the system behaviour but also lead to engineering improvements in turbo-machinery technology.
Influence of preparation process on electromagnetic shielding and infrared properties of hydrogen-bonded bridged MXene thin films
Authors: Zhang Jinman , Liu Xinmin , Li Chuang 
Published: November 2024

Abstract
With the continuous development of communication technology and mobile electronic devices, the problem of electromagnetic interference is becoming more and more prominent, so the development of films with high tensile strength and excellent electromagnetic shielding and infrared camouflage properties has become an important research direction. We introduced hydrogen bonding by adding sodium alginate between the layers of two-dimensional material MXene to improve the tensile strength of the film, and compared the effects of film preparation processes such as sodium alginate concentration, vacuum-assisted filtration, and blade scraping method on the film properties. The results show that the hydrogen bonded bridged MXene films (HBMB) prepared by blade scraping method have high electrical conductivity, electromagnetic shielding performance, tensile strength, low infrared emissivity and good thermal camouflage performance.The tensile strength of HBMB films is nearly four times higher than that of vacuum-assisted filtration (HBM) films, and the electromagnetic shielding performance of the scraped films in the X-band against electromagnetic waves reaches 53.54 dB, and the absolute electromagnetic efficiency of 47,528 dB-cm2/g.
Investigation of steam-diluted hydrogen combustion in a counter-current nozzle configuration using LES
Authors: Wawrzak A , Tyliszczak A 
Published: November 2024

Abstract
The study concerns a co-axial counter-current jet configuration conceptualized as a wet hydrogen/air injector. Such an injector system induces a flow pattern beneficial for triggering global instability near a nozzle lip. Using high-fidelity LES, we explore how global instability alter the flame dynamics through adjustments in the strength of the counter-current flow for selected dilution level. In particular, we present regimes for lifted flames to mitigate hydrogen corrosion risk and enhance combustion efficiency.
Quantification of laminar mixing efficiency with negative index Sobolev norm
Authors: Fabisiak Jakub , Gepner Stanisław 
Published: November 2024

Abstract
The efficiency of stirring in the laminar mixing protocol resulting from the action by the nonstationary laminar flow through a longitudinally corrugated channel is evaluated using the negative exponent Sobolev norm of the concentration - the Mix-Norm. The Mix-norm is applied to a range of stirring velocity fields, resulting from the low Reynolds number destabilisation of the flow through a corrugated channel. The results are compared to the well-known quantifying measure, the concentration variance. The ability of the Mix-norm to include the stirring effect at the increasing Péclet number is illustrated.
Utilizing a pressure-based CFD solver for modelling wet steam flow in low-pressure turbine stages: a predictive approach to assessing flow losses
Authors: Shabani Sima , Majkut Miroslaw , Dykas Slawomir , Smolka Krystian 
Published: November 2024

Abstract
This research focuses on addressing a critical challenge in steam turbine operation, specifically condensation losses within the Low-Pressure (LP) section. Such losses have a significant impact on energy efficiency and operational costs in industries like power generation and manufacturing. The objective of this research is to predict condensation losses in the LP part of steam turbines. The simulation of the two-phase flow of wet steam is performed in the ANSYS CFX software. The geometry studied in this research is the actual geometry of the last stage of a steam turbine, which is modeled in three dimensions. The complexities of modeling three-dimensional flows, as well as providing relationships that can be used to calculate losses that can be generalized and used in different conditions, are distinctive features of this research.
PIV measurement of model nuclear fuel rod bundle
Authors: Duda Daniel , Yanovych Vitalii , Uruba Václav 
Published: November 2024

Abstract
The fuel rods are kept in their positions by using spacer grids. This grid is sometimes connected with mixing grid, which mixes the fluid between the fuel rods in order to enhance the heat transfer. One of the possible configurations is the usage of the mixing vanes, which divert the flow from the main channel (between 3 rods) to its narrower part (between 2 rods), possibly even into the neighboring channel. The technical details are top secret. Therefore, in order to test the measuring methodology, we designed and manufactured our own mixing grid. This grid is scaled to the sizes of UWB wind tunnel and its vanes have a parabolic profile. We show results of Stereo PIV (Particle Image Velocimetry) measurement. The studied plane is perpendicular to the stream-wise direction covering area behind two main channels ca 2mm behind the rod ends. Reynolds number of this experiment Re
E
≈ 7.8 · 104 (in reactor Re
R
≈ 2.6 · 105). The obtained data show focusing of the flow into the narrower part of channel, relatively fast turbulence decay and strong anizotropy of fluctuations.