bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon nitride electric-field poled microresonator modulator
Authors: Zabelich Boris , Lafforgue Christian , Nitiss Edgars , Stroganov Anton , Brès Camille-Sophie
Published: January 2024

Stoichiometric silicon nitride is a highly regarded platform for its favorable attributes, such as low propagation loss and compatibility with complementary metal-oxide-semiconductor technology, making it a prominent choice for various linear and nonlinear applications on a chip. However, due to its amorphous structure, silicon nitride lacks second-order nonlinearity; hence, the platform misses the key functionality of linear electro-optical modulation for photonic integrated circuits. Several approaches have been explored to address this problem, including integration with electro-optic active materials, piezoelectric tuning, and utilization of the thermo-optic effect. In this work, we demonstrate electro-optical modulation in a silicon nitride microring resonator enabled by electric-field poling, eliminating the complexities associated with material integration and providing data modulation speeds up to 75 Mb/s, currently only limited by the electrode design. With an estimated inscribed electric field of 100 V/μm, we achieve an effective second-order susceptibility of 0.45 pm/V. In addition, we derive and confirm the value of the material’s third-order susceptibility, which is responsible for the emergence of second-order nonlinearity. These findings broaden the functionality of silicon nitride as a platform for electro-optic modulation.
Boron tin oxide for filterless intrinsic-narrowband solar-blind ultraviolet detectors with tunable photoresponse peak from 231 to 275 nm
Authors: Xu Cunhua , Zhang Chaofan , Jia Lemin , Wang Zhao , He Junfang , Zheng Wei
Published: January 2024

Solar-blind ultraviolet (SBUV) detection has a great prospect in a wide range of applications, in which the synthesis of semiconductor materials with a suitable bandgap can be an important research focus. In this work, BSnO films with good selectivity for SBUV were grown by magnetron sputtering with the bandgap adjusted from 4.1 to 5.3 eV. Based on the BSnO films, filter-less narrowband SBUV detectors were fabricated first, exhibiting a narrow detection range and an ultra-high responsivity (113 A/W) required by the detection of extremely weak SBUV signals. In addition, graphene/BSnO/SiC heterojunction photovoltaic detectors were also fabricated, with a high photo-to-dark current ratio and an ultra-fast response exhibited under 0 V bias, confirming their ability to handle the detection of transient signals.
Flow modulation mechanism in a cylinder with corrugated surfaces
Authors: Yu Haiyang , Hu Haoqi , Chen Wen-Li , Lu Yifan , Gao Donglai
Published: January 2024

Flow modulation mechanism in a cylinder with corrugated surfaces is investigated by wind tunnel experiments at Reynolds number Re=25 600. Experimental results include surface pressure measurement for the cylinder wall and particle image velocimetry (PIV) for the wake flow. A pair of corrugated surfaces are symmetrically installed on the cylinder wall. Corrugated surfaces are distributed at three different locations on the cylinder wall, i.e., the windward part (case 1), leeward part (case 2), and lateral part (case 3). Experimental results show that corrugated surfaces can modify surface pressure, aerodynamic forces, and vorticity evolution of the cylinder flow. Compared with the natural cylinder (baseline case), the mean drag and fluctuating lift forces of case 1 are reduced by 58% and 82%, which are optimal among all test cases. Flow modulation effects of case 2 on global cylinder wake flow are unobvious and that of case 3 are between cases 1 and 2. Corrugated surfaces can also modify modal properties of proper orthogonal decomposition (POD) of the cylinder wake. Moreover, characteristics of recirculation bubbles, velocity deficits, turbulence kinetic energy, and Reynolds stresses in the wake are all modulated. The main flow modulation mechanism is that shear-layer shapes and streamline distributions near the corrugated surfaces are changed based on zoom-in PIV results on the cylinder near-wall region.
Numerical investigation of the underwater explosion of a cylindrical explosive with the Eulerian finite-element method
Authors: Qin Hao , Liu Yun-Long , Tian Zhao-Li , Liu Wen-Tao , Wang Shi-Ping
Published: January 2024

The shock wave and bubble dynamics of an underwater explosion are significant in various fields. When the charge is non-spherical, the detonation process will remarkably affect the shock wave formation and the subsequent bubble motion. In this work, the underwater explosion of a cylindrical explosive is investigated numerically with the Eulerian finite-element method combined with the programed burn model treating the detonation process. The present model is validated by comparing the simulated results with the experimental ones. Then, several cases with different slenderness of the explosive charge in various buoyancy environments are simulated and analyzed. The results demonstrate a notable variation of the shock wave in different directions. The shock wave will reach the highest pressure peak and shortest pulse width at a certain angle determined by the ratio between the speeds of the detonation wave and the shock wave. Furthermore, the non-spherical initial expansion of the bubble casts a significant influence on the subsequent bubble evolution. Three typical jet morphologies are identified with different combinations of buoyancy parameter and oblateness ratios of the bubble, featured by a slightly oblique upward jet penetrating the bubble, a laminar jet that failed to penetrate the bubble continuously, and a pair of opposite horizontal jets penetrating the bubble. Meanwhile, the horizontal jets that happen under a weak buoyancy environment will reduce the upward migration.
Spin-transfer-torque induced spatially nonuniform switching in ferrimagnets
Authors: Zhang Xue , Xu Zhengde , Ren Jie , Qiao Yixiao , Fan Weijia , Zhu Zhifeng
Published: January 2024

Ferrimagnet (FiM), (FeCo)1−xGdx, attracts research attention due to its ultrafast magnetic dynamics and finite net magnetization. Incorporating FiM into the magnetic tunnel junction will be beneficial to further improve the writing speed of magnetic random access memory. It is commonly assumed that the FeCo and Gd atoms are switched together due to the strong exchange coupling, which remains valid even if one performs the two-sublattice macrospin simulation. Interestingly, using the atomistic model developed by our group, it is clearly seen that different atoms are not switched together. In addition, our study reveals that the nature of switching is spatially nonuniform even in the small sample with the dimension of 20 × 20 nm2. Furthermore, the characteristics of nonuniformity are completely different for samples with different Gd compositions (x). When x is close to the magnetization compensation point, successful switching cannot be obtained, but is accompanied by the stable oscillation. The atom type that dominates the oscillation is different from that predicted by the two-sublattice macrospin model. In addition, the size of a singular region is a non-monotonic function of current density. All these results can only be understood by considering the spatial nonuniform magnetization dynamics.
Spectroscopic analysis of polymer and monolayer MoS2 interfaces for photodetection applications
Authors: McGinn Christine K. , Harrington Daniel M. , Heilweil Edwin , Hacker Christina A.
Published: January 2024

Polymer passivation has been leveraged to improve photodetection in two-dimensional transition metal dichalcogenide field-effect transistors. The relative passivation effects of common polymers, however, are not well understood. In this work, the interface of monolayer MoS2 and three common polymers, parylene N (Pa-N), polymethyl methacrylate (PMMA), and polyvinylidene difluoride trifluoroethylene (PVDF-TrFE), is assessed with multiple spectroscopic methods. Raman and photoluminescence spectroscopy demonstrate that Pa-N and PMMA provide an n doping effect, which increases photoconductivity and photogenerated charge in terahertz domain and time-resolved spectroscopy. Terahertz time-resolved spectroscopy shows significantly longer carrier lifetime for MoS2 coated with PVDF-TrFE compared to other polymers. These results suggest that PVDF-TrFE provides a unique benefit for photodetection applications.
Adaboost algorithm combined multiple random forest models (Adaboost-RF) is employed for fluid prediction using well logging data
Authors: Sun Youzhuang , Zhang Junhua , Zhang Yongan
Published: January 2024

Well logging fluid prediction is of great significance in oil and gas exploration. Based on data mining technology, this paper proposes an adaptive boosting random forest (Adaboost-RF) method for well logging fluid prediction. First, we use the Adaboost algorithm for feature selection, train a weak classifier by repeatedly weighting observations and correcting hard-to-classify samples, and obtain a combination of multiple weak classifiers. This method can effectively improve the accuracy and robustness of the classifier and can reduce the risk of overfitting. Then, we use random forest (RF) as a basic classifier to build an Adaboost-RF model for well logging fluid prediction. The combination of Adaboost and RF can further improve the stability and accuracy of the classifier. To verify the performance of this method, we performed experimental evaluation using real well logging data. Experimental results show that the Adaboost-RF method can have higher accuracy and stability in log fluid prediction than the traditional method (backpropagation neural network) and the method using RF alone. In summary, this method combines the characteristics of Adaboost and RF, which can improve the accuracy and stability of the classifier and is easy to implement and generalize, providing a new, efficient, and accurate fluid prediction method for the field of oil and gas exploration.
Local correlation, compressibility, and crossflow corrections of γ-Reθ transition model for high-speed flows
Authors: Fan Yuxiang , Liu Xiao , Zhao Rui , Zhang Xu , Yuan Wu , Liu Xiazhen
Published: January 2024

Based on the original γ-Reθ transition model framework, in this work, an improved local correlation-based transition closure model is developed for high-speed flows. The local correlation between the vorticity Reynolds number and the momentum thickness Reynolds number obtained by compressible boundary-layer self-similar solutions, local compressibility correction including the pressure gradient parameter and momentum thickness Reynolds number, and local crossflow correlation are applied to improve the original γ-Reθ model for hypersonic transition predictions. The function Fonset1 used to control the transition onset and several relevant model parameters are also modified to make the improved model suitable for high-speed flow. The improved transition model is validated through several basic test cases under a wide range of flow conditions, including high-speed flat plates, sharp cones, double ramp, Hypersonic International Flight Research Experimentation, and complex hypersonic configuration X-33 vehicles. The numerical results show that the transition onset locations and the changes of heat transfer rate predicted by the present improved transition model are reasonably consistent with experimental results. The proposed model predicts the high-speed boundary layer transition behaviors induced by streamwise and crossflow instabilities with reasonable precision.
Numerical study on the blast mitigation effect of an inner-grooved straight tube
Authors: Sugiyama Yuta , Homae Tomotaka , Tamba Takahiro , Matsumura Tomoharu , Wakabayashi Kunihiko
Published: January 2024

A series of numerical simulations were conducted to clarify the shock–structure interaction inside an inner-grooved straight tube and the mitigation effect of the groove structure on the expansion of the blast wave at the exit. The results showed that the periodic grooves of the groove structure generate multiple reflected shock waves. Each time a shock wave reaches a groove, some of the shock wave and gas flow behind it propagates directly through the downstream groove, and the rest is reflected to the upstream groove. This splitting decreases the shock wave strength inside the tube. To clarify the blast mitigation effect of the configuration of the groove structure, parametric studies were conducted that changed the height and interval of the periodic grooves. The flow characteristics inside the tube were analyzed to understand the blast mitigation efficiency of the groove structure. The groove height had a significant impact on the blast mitigation efficiency, and the optimal interval for maximum blast mitigation efficiency depended on the groove height. The total energy release rate from the tube exit is a characteristic value of the blast wave strength at the exit, and it can be used to scale the blast wave strength outside.
Present and future of micro-transfer printing for heterogeneous photonic integrated circuits
Authors: Roelkens Gunther , Zhang Jing , Bogaert Laurens , Soltanian Emadreza , Billet Maximilien , Uzun Ali , Pan Biwei , Liu Yang , Delli Evangelia , Wang Dongbo , Oliva Valeria Bonito , Ngoc Tran Lam Thi , Guo Xin , Li He , Qin Senbiao , Akritidis Konstantinos , Chen Ye , Xue Yu , Niels Margot , Maes Dennis , Kiewiet Max , Reep Tom , Vanackere Tom , Vandekerckhove Tom , Lufungula Isaac Luntadila , De Witte Jasper , Reis Luis , Poelman Stijn , Tan Ying , Deng Hong , Bogaerts Wim , Morthier Geert , Van Thourhout Dries , Kuyken Bart
Published: January 2024

We present the current state of the art in micro-transfer printing for heterogeneously integrated silicon photonic integrated circuits. The versatility of the technology is highlighted, as is the way ahead to make this technology a key enabler for next-generation photonic systems-on-chip.
High index dielectric films on metals: An island of emission
Authors: Maytin Andrew , Gruebele Martin
Published: January 2024

Fluorescent emitters are quenched near the surfaces of metals via rapid energy transfer to the metal, via surface plasmons, waveguide modes, and absorption. Commonly, this quenching is reduced by introducing a polymeric or dielectric spacer but requires large distances, at least a fraction of the wavelength, between the metal and chromophore. Using the classical theory for a dipole above a metal/dielectric substrate, we investigate the fluorescent yield for emitters above a wide range of metals and spacers. For metals with low loss and low plasma frequencies, a high index spacer is shown to be advantageous for obtaining higher fluorescent yield in an “island of emission” at finely tuned spacer thickness just 20–30 nm from the metal surface. For such metal–dielectric combinations, fluorophores can be placed surprisingly close to the metal surface while remaining significantly emissive.
Dynamic analysis of beam structure of linear vibrating screen
Authors: Long Hui , Huang Chang-Zheng , Li Dong-Chang
Published: January 2024

This paper presents a novel model for calculating the dynamic stress of a beam structure in a vibrating screen. The proposed model employs a dynamic screen box model as a foundation and utilizes the flow method to establish the mass of the screening materials within the screen box. By considering the motion characteristics of beam structures, the dynamic model for the beam structure of a vibrating screen is derived. The results indicate that the dynamic model can reveal the internal relationship between the dynamic characteristics of beam structures and the structural and material parameters. Finally, a validation example is presented to demonstrate the effectiveness of the proposed dynamic model. The presented model not only contributes to the understanding of the dynamic behavior of beam structures in vibrating screens but also provides a reliable and accurate method for predicting the dynamic stress in beam structures. The proposed model can be applied to optimize the design and performance of vibrating screens, which have wide applications in mining, metallurgy, and other industries. Further research can be conducted to explore the potential of the proposed model for other types of structures subjected to dynamic loads.
Research on intelligent active disturbance rejection control algorithm for shock train leading edge of dual-mode scramjet
Authors: Liang Shuang , Guo Mingming , Tian Ye , Le Jialing , Song Wenyan
Published: January 2024

To prevent scramjet inlet unstart, stringent control over the shock train's leading edge in the isolator is necessary. Therefore, this study proposes a fuel flow active control scheme combining an adaptive particle swarm optimization algorithm (APSO) and active disturbance rejection control (ADRC) to enhance the traditional control (such as proportional-integral-derivative, PID) system's stability and anti-interference capabilities in complex and uncertain environments. Within this context, a simple, semi-empirical mathematical model of a dual-mode scramjet is constructed. An ADRC controller is designed to counteract the nonlinearity and disturbance of the dual-mode scramjet. ADRC, not requiring an accurate mathematical model, utilizes its extended state observer to estimate all uncertain factors affecting the controlled object based on the relationship between the shock train's leading edge and the controller's output, treating them as unknown disturbances for compensation, thereby exhibiting strong anti-interference capabilities. In order to optimize the performance, the APSO is introduced to fine-tune the ADRC controller parameters. The APSO reduces the rise time of ADRC from 22.28 to 11.39 ms, and the adjustment time from 40.05 to 13.64 ms. The APSO effectively tunes the parameters of the ADRC controller, which ensures rapidity comparable to the PID and all-coefficient adaptive control (ACAC) in managing the shock train's leading edge. At the same time, ADRC has stronger anti-interference ability and adaptive ability than ACAC and PID. This research preliminarily verifies the feasibility and advancement of the ADRC for shock train leading-edge control in scramjet isolators.
Collocations of fictive motion verbs in adventure tourism
Authors: Jiménez-Navarro Eva Lucía , Durán-Muñoz Isabel
Published: January 2024

This paper investigates the collocations produced by a set of fictive motion verbs found in a specialized corpus
representing the language of adventure tourism. Since our ultimate aim is to contribute to the characterization of this
specialized language, we defined two specific objectives: (1) to analyze the motion verbs and their meanings extracted from the
Advencor corpus, and (2) to identify the collocates of these verbs as well as the semantic roles they express. After
the application of our methodology, eight motion verbs produced 35 collocations satisfying all the established criteria. The
results focus on different aspects: (1) the verbs convey distinct meanings, such as motion on a vertical axis or direction towards
a destination; (2) the most recurrent combination is noun + verb, where the former describes the inanimate entity that seems to
perform motion; (3) collocation production and collocation strength are not correlated; and (4) the collocates accompanying the
verbs under analysis shed light on the argument structure of these verbs, for they represent one of the participants. In
conclusion, this work provides relevant information about the phraseology of fictive motion verbs in the language of adventure
tourism and proves the specialization of this domain.
Introduction
Authors: Riazi A. Mehdi
Published: January 2024

This introductory chapter is organized into two
sections. The first section, the introduction, discusses
research methodology in Applied Linguistics (AL), considering
recent methodological debates. Each of the methodologies
included in this volume is presented in two chapters, a
theoretical and a showcase practical chapter. The second
section, therefore, provides a synopsis of each of the chapters.
The two sections of the introductory chapter provide a context
for the readers so that they develop a general idea of what will
follow in the body of the book.
The Multiperspectival Approach to Applied Linguistic
research
Authors: Crichton Jonathan , Hocking Darryl
Published: January 2024

This chapter explores the distinctive features
of the Multiperspectival Approach (MPA) to research: its
theoretical and philosophical background, the questions it
addresses, and the research orientations it enables. The chapter
explains how MPA offers researchers a heuristic that addresses
ontological and epistemological challenges to research that are
central to the language-context relationship and consequential
for any researcher who seeks to make claims about the meaning of
language in the lives of others at particular sites. The chapter
provides detailed background and guidance on what MPA involves
and its value as a practical ontology that enables researchers
to discover – rather than to search – the worlds of their
participants, iteratively to learn through this process of
discovery, developing warrants and finding themes to bridge
these worlds through multiple, mutually-corroborating
perspectives.
Topology-induced quantum transition in multiparticle systems in vicinity of a black hole
Authors: Jacak J E
Published: January 2024

The qualitative change of the type of particle trajectory homotopy in close vicinity of general-relativistic gravitational singularity affects quantum statistics in systems of identical indistinguishable particles at passing the photon sphere rim of a Schwarzschild black hole. This causes a local departure from the Pauli exclusion principle, which results in some high energy effects manifesting themselves when the matter is falling into a black hole. The release of the energy can take place at the rim of the photon sphere of a black hole due to the decay of Fermi spheres in highly compressed fermion systems entering this region. The effect is observable at activity of quasars or at collapses of neutron star mergers. The related supplementation to conventional models of the accretion disc luminosity by additional radiation from close vicinity of the event horizon of a massive black hole powering super-luminous quasar is proposed and compared with observations. The source of short-lasting gamma-ray bursts has been also identified at collapses of unstable neutron star mergers due to the decay of Fermi sphere of neutrons. The duration and spectrum of the related e-m radiation bursts estimated by the Fermi golden rule for the Fermi sphere decay agree with observations. The quantum statistics effect contributes also to the radiation of transients of micro-quasars and short lasting brightening episodes in closer active galactic nuclei. The proposed quantum effect changes the premises for the current discussion of the information paradox and hypothesis of the black hole firewall.
Enhanced effective spin Hall efficiency contributed by the extrinsic spin Hall effect in Pt1-
x
Ta
x
/CoFeB structures
Authors: Xu Zhan , Tang Jiaxuan , Hu Sicong , Liu Er , Xu Feng , Bian Leixiang , Lew Wen Siang
Published: January 2024

High effective spin Hall efficiency and low magnetic damping constant are essential to achieve efficient spin-charge conversion for energy-efficient spintronic devices. We report the measurements of effective spin Hall efficiency and magnetic damping constant of Pt1-

x
Ta
x
/CoFeB structures using spin-torque ferromagnetic resonance (ST-FMR) techniques. With the increase of Ta content, the spin Hall efficiency increases and peaks x = 0.15 with the value of

θ

SH

eff

=
0.35

, before decreases for further Ta content. This non-monotonic variation is attributed to the interaction between the contribution of the extrinsic skew scattering mechanism and the spin-orbit coupling (SOC). The weakening of the SOC in the Pt1-x
Ta
x
layer leads to a decrease in the effective magnetic damping constant with increasing Ta concentration. High-temperature ST-FMR measurements confirm the influence of the Ta concentration on the spin Hall effect and magnetic damping mechanism. Additionally, the decrease in spin mixing conductance and the increase in spin diffusion length leads to a decrease in the interfacial spin transparency.
A novel monitoring method based on multi-model information extraction and fusion
Authors: Li Zhichao , Shen Mingxue , Tian Li , Yan Xuefeng
Published: January 2024

Modern industrial processes are increasingly complex, where multiple characteristics usually coexist in process data. Therefore, traditional monitoring methods based on a single model may ignore other data characteristics and obtain poor monitoring performance. Aiming at this problem, a novel monitoring method based on multi-model information extraction and fusion is proposed in this paper. Firstly, several methods are used to extract different characteristics from process data. For example, principal component analysis, independent component analysis and slow features analysis can be used to extract Gaussian, non-Gaussian and dynamic characteristics respectively. Secondly, features extracted from multiple models are combined into new potential features. Then, Lasso regression models between potential features and process variables are established. In this way, not only are multiple characteristics in process data considered during the reconstruction, but key potential features (KPFs) can be selected for each process variable. The KPFs for each process variable can form a monitoring subspace to enhance the sensitivity for fault detection. Furthermore, cluster analysis is used to reduce the redundancy of monitoring subspaces based on the similarity of each subspace. Process monitoring can be achieved by fusing the monitoring results of finally determined multiple subspaces and residual space. Case studies on three simulation processes and a real industrial process demonstrate the effectiveness and better performance.
Optimizing intracranial electric field distribution through temperature-driven scalp conductivity adjustments in transcranial electrical stimulation
Authors: Wang Minmin , Zhang Li , Hong Wenjun , Luo Yujia , Li Han , Feng Zhiying
Published: January 2024

Transcranial electrical stimulation (TES) is a promising non-invasive neuromodulation technique. How to increase the current intensity entering the skull and reduce scalp shunting has become a key factor significantly influencing regulatory efficacy. In this study, we introduce a novel approach for optimizing TES by adjusting local scalp temperature to modulate scalp conductivity. We have developed simulation models for TES-induced electric fields and for temperature-induced alterations in scalp conductivity. Two common types of stimulation montage (M1-SO and 4 × 1 montage) were adopted for the evaluation of effectiveness. We observed that the modulation of scalp temperature has a significant impact on the distribution of the electric field within the brain during TES. As local scalp temperature decreases, there is an increase in the maximum electric field intensity within the target area, with the maximum change reaching 18.3%, when compared to the electric field distribution observed under normal scalp temperature conditions. Our study provide insights into the practical implementation challenges and future directions for this innovative methodology.
The magnetic gradient scale length explains why certain plasmas require close external magnetic coils
Authors: Kappel John , Landreman Matt , Malhotra Dhairya
Published: January 2024

The separation between the last closed flux surface of a plasma and the external coils that magnetically confine it is a limiting factor in the construction of fusion-capable plasma devices. This plasma-coil separation must be large enough so that components such as a breeding blanket and neutron shielding can fit between the plasma and the coils. Plasma-coil separation affects reactor size, engineering complexity, and particle loss due to field ripple. For some plasmas it can be difficult to produce the desired flux surface shaping with distant coils, and for other plasmas it is infeasible altogether. Here, we seek to understand the underlying physics that limits plasma-coil separation and explain why some configurations require close external coils. In this paper, we explore the hypothesis that the limiting plasma-coil separation is set by the shortest scale length of the magnetic field as expressed by the

∇

B

tensor. We tested this hypothesis on a database of

>

40 stellarator and tokamak configurations. Within this database, the coil-to-plasma distance compared to the minor radius varies by over an order of magnitude. The magnetic scale length is well correlated to the coil-to-plasma distance of actual coil designs generated using the REGCOIL method (Landreman 2017 Nucl. Fusion
57 046003). Additionally, this correlation reveals a general trend that larger plasma-coil separation is possible with a small number of field periods.
Progress in the development of the ITER baseline scenario in TCV
Authors: Labit B , Sauter O , Pütterich T , Bagnato F , Camenen Y , Coda S , Contré C , Coosemans R , Eriksson F , Février O , Fransson E , Karpushov A N , Krutkin O , Marchioni S , Merle A , Pau A , Piron L , Vallar M , Van Mulders S , Voitsekhovitch I ,   the TCV team,   the MST1 team,   the EUROfusion tokamak exploitation team
Published: January 2024

Under the auspices of EUROfusion, the ITER baseline (IBL) scenario has been jointly investigated on AUG and TCV in the past years and this paper reports on the developments on TCV. Three ITER shapes, namely the JET, AUG and ITER IBL have been reproduced in TCV, illustrating that the higher the triangularity the larger the ELM perturbation and the more difficult it is to reach stationary states with q
95< 3.6. It is found that the performance of TCV IBL is mainly limited by (neoclassical) tearing modes, in particular 2/1 modes which are triggered after a large ELM. It is demonstrated that the shorter the ELM period the larger β

N
at the NTM onset. We show that these modes can be avoided with central X3 EC heating at relatively high q
95 and moderate β

N
. However, the lack of significant ECH at the high central densities obtained in TCV IBL scenario limits the duration of low q
95 cases to about four confinement times. During this time, density usually keeps peaking until (neoclassical) tearing modes are triggered. Nevertheless, the TCV IBL database covers the ITER target values (

H

98
y
2

∼

1,

β
N

∼

1.8 at

q

95

∼

3) and a slightly better confinement than requested for ITER is reported. Integrated modelling results show that ITG modes are the dominant instabilities, and show that, in TCV, fuelling also plays a role to sustain peaked density profiles. The role of profiles, sawteeth and ELMs regarding MHD stability are also discussed.
Feasibility study of an XPCI diagnostic to observe the evolution of micro-voids in an ICF target
Authors: Barbato F , Savino L , Schiavi A , Atzeni S
Published: January 2024

Bulk perturbations (voids or crystalline structure) inside the ablator of a capsule used for inertial confinement fusion are seeds for instabilities that can hinder the ignition. The study of these defects and their evolution during the implosion is one of the steps needed to achieve fusion. The current methods used by the field are to infer these effects indirectly with measurements of implosion velocity and neutron yield, among others. Observing them directly with an x-ray imaging diagnostic is difficult due to the small scale length of these defects. In this work we study the feasibility of a new diagnostic based on x-ray phase-contrast imaging. This technique has been demonstrated to perform better than standard x-ray absorption techniques in critical situations like this. By using a synthetic diagnostic we show the capabilities of this new possible approach and the limits in relation to the parameters of currently available laser facilities.
Insights into spatial inhomogeneity in an oxygen plasma from cavity ringdown spectroscopy
Authors: Rogers Samuel D A , Bond Amelia , Peverall Robert , Hancock Gus , Ritchie Grant A D
Published: January 2024

Cavity ringdown spectroscopy has been used to investigate the translational and rotational temperatures of the v = 0 and 1 vibrational levels of O2(X) in an inductively coupled plasma at 100 mTorr (13.332 Pa) pressure. All rotational states probed display a clear increase in temperature as plasma power increases: at fixed power, the translational temperature appears largest for rotational states in v = 1 (J= 7, 16, 17, 22) and lowest in the low energy states (J = 1, 18, 19) in v = 0; highly excited rotational states (J = 28, 30, 31) of v = 0 show intermediate behaviour. The rotational temperature values behave similarly. These observations are consistent with the effects of plasma inhomogeneity and can be interpreted with a simple one-dimensional model whereby the pressure, temperature and mole fractions of the various species across the chamber (and arms) are approximated with rational profiles and the corresponding line-of-sight averaged densities and temperatures calculated. This basic model is reasonably successful at reproducing the observations for O2(X, v = 0) and O(3P) densities. The fact that resolving several rotational transitions allows spatial variations within the plasma to be inferred from line-of-sight averaged measurements is an extremely powerful result that could be of great utility in future work.
Monolithic integration of superconducting-nanowire single-photon detectors with Josephson junctions for scalable single-photon sensing
Authors: Khan Saeed , Primavera Bryce A , Mirin Richard P , Woo Nam Sae , Shainline Jeffrey M
Published: January 2024

We demonstrate superconducting single-photon detectors (SPDs) that integrate signals locally at each pixel. This capability is realized by the monolithic integration of superconducting-nanowire SPDs with Josephson electronics. The motivation is to realize superconducting sensor elements with integrating capabilities similar to their CMOS-sensor counterparts. The pixels can operate in several modes. First, we demonstrate that photons can be counted individually, with each detection event adding an identical amount of supercurrent to an integrating element. Second, we demonstrate an active gain control option, in which the signal added per detection event can be dynamically adjusted to account for variable light conditions. Additionally, the pixels can either retain signal indefinitely to record all counts incurred over an integration period, or the pixels can record a fading signal of detection events within a decay time constant. We describe additional semiconductor readout circuitry that will be used in future work to realize scalable, large-format sensor arrays of superconducting SPDs compatible with CMOS array readout architectures.
Bose–Einstein condensates and the thin-shell limit in anisotropic bubble traps
Authors: Biral Elias J P , Móller Natália S , Pelster Axel , dos Santos F Ednilson A
Published: January 2024

Within the many different models, that appeared with the use of cold atoms to create BECs, the bubble trap shaped potential has been of great interest. However, the relationship between the physical parameters and the resulting manifold geometry remains yet to be fully understood for the anisotropic bubble trap physics in the thin-shell limit. In this paper, we work towards this goal by showing how the parameters of the system must be manipulated in order to allow for a non-collapsing thin-shell limit. In such a limit, a dimensional compactification takes place, thus leading to an effective 2D Hamiltonian which relates to up-to-date bubble trap experiments. At last, the resulting Hamiltonian is perturbatively solved for both the ground-state wave function and the excitation frequencies in the leading order of deviations from a spherical bubble trap.
Nonlinear squeezing of stochastic motion
Authors: Ornigotti Luca , Moore Darren W , Filip Radim
Published: January 2024

Linearized stochastic nanomechanical systems operating at nonzero temperatures and constant frequency and damping are restricted in their capacity to reduce noise in nonlinear combinations of the canonical variables. Nonlinear dynamics are then required in order to overcome these limits. Here we demonstrate how to make these limits explicit in the form of a threshold for nonlinear squeezing of the motional variables. Noise suppression below the threshold cannot be explained by linearized dynamics and is helpful in low-noise nonlinear devices at an ambient temperature. We predict that a state of the art levitating particle, exposed to cubic or quartic trapping potentials for a short interval will display nonlinear squeezing of stochastic motion that cannot be replicated by linear motion.
Simulating dirty bosons on a quantum computer
Authors: Oftelie Lindsay Bassman , Van Beeumen Roel , Camps Daan , de Jong Wibe A , Dupont Maxime
Published: January 2024

Quantum computers hold the potential to unlock new discoveries in complex quantum systems by enabling the simulation of physical systems that have heretofore been impossible to implement on classical computers due to intractability. A system of particular interest is that of dirty bosons, whose physics highlights the intriguing interplay of disorder and interactions in quantum systems, playing a central role in describing, for instance, ultracold gases in a random potential, doped quantum magnets, and amorphous superconductors. Here, we demonstrate how quantum computers can be used to elucidate the physics of dirty bosons in one and two dimensions. Specifically, we explore the disorder-induced delocalized-to-localized transition using adiabatic state preparation. In one dimension, the quantum circuits can be compressed to small enough depths for execution on currently available quantum computers. In two dimensions, the compression scheme is no longer applicable, thereby requiring the use of large-scale classical state vector simulations to emulate quantum computer performance. In addition, simulating interacting bosons via emulation of a noisy quantum computer allowed us to study the effect of quantum hardware noise on the physical properties of the simulated system. Our results suggest that scaling laws control how noise modifies observables versus its strength, the circuit depth, and the number of qubits. Moreover, we observe that noise impacts the delocalized and localized phases differently. A better understanding of how noise alters the observed properties of the simulated system is essential for leveraging near-term quantum devices for simulation of dirty bosons, and indeed for condensed matter systems in general.
Physical phase field model for phagocytosis
Authors: Winkler Benjamin , Abu Hamed Mohammad , Nepomnyashchy Alexander A , Ziebert Falko
Published: January 2024

We propose and study a simple, physical model for phagocytosis, i.e. the active, actin-mediated uptake of micron-sized particles by biological cells. The cell is described by the phase field method and the driving mechanisms of uptake are actin ratcheting, modeled by a dynamic vector field, as well as cell-particle adhesion due to receptor-ligand binding. We first test the modeling framework for the symmetric situation of a spherical cell engulfing a fixed spherical particle. We then exemplify its versatility by studying various asymmetric situations like different particle shapes and orientations, as well as the simultaneous uptake of two particles. In addition, we perform a perturbation theory of a slightly modified model version in the symmetric setting, allowing to derive a reduced model, shedding light on the effective driving forces and being easier to solve. This work is meant as a first step in describing phagocytosis and we discuss several effects that are amenable to future modeling within the same framework.
Detailed investigations on stability and optoelectronic characteristics of the 1T-PdS2 monolayer
Authors: Priyanka  , Chowdhury Suman , Ritu  , Kumar Vinod , Kumar Ramesh , Chand Fakir
Published: January 2024

In this work, detailed theoretical elucidation on the structural stability and optoelectronic characteristics of the 1T-PdS2 monolayer is provided using density functional theory (DFT). The dynamical and mechanical stabilities of the structure are assessed through the analysis of phonon dispersion spectra and the Born-Huang stability criterion. The value of Young’s modulus comes out to be 68.75 Nm−1, which demonstrates high flexibility of the structure. Further, thermal stability of the structure is investigated using Ab-initio molecular dynamics simulations. The first-principle calculations by GGA + SOC (GGA + U) methods reveal that the monolayer is an indirect bandgap semiconductor having bandgap 1.14 eV (1.173 eV). The dielectric function displays its highest peak in the energy range 1.5–2 eV, whereas the maximum absorption coefficient lies in the ultraviolet region. Furthermore, the impact of vacancy defects are also investigated on the optoelectronic characteristics of the monolayer. The bandgap changes from indirect nature to direct one and reduces from 1.17 eV to 0.25 eV and 0.43 eV under single palladium and sulphur vacancies, respectively. The optical parameters also show enhancement with the introduction of these vacancies. The computational analysis reveals that 1T-PdS2 monolayer possesses advantageous attributes, making it a viable material for different optoelectronic applications.
Numerical characterization of dual-frequency capacitively coupled plasmas modulated by electron beam injection
Authors: Zhou Youyou , Wang Yu , Wu Hao , Wang Hongyu , Jiang Wei , Zhang Ya
Published: January 2024

The modulated approach of electron beam (EB) injection can achieve favorable parameters for capacitive coupled plasmas (CCP). In this work, a one-dimensional particle-in-cell/Monte Carlo collision (PIC/MCC) model is used to simulate the stable dual-frequency CCP with EB injection. First, when the parameters of EB are kept constant at 0.01 A and 30 eV, the results demonstrate significant enhancements in electron density, self-bias voltage, and ion flux. Furthermore, the electron energy probability function (EEPF) appears to have a transition from a typical bi-Maxwellian distribution to a Maxwellian distribution, and the dominant heating mode shifts from the α-mode to the α-γ-mode. Secondly, when the EB current and energy are all changed, the basic parameters of DF-CCP can be achieved by different modulations. Furthermore, we also discuss the transition of the electron heating mode as the current increases from 0.001 A to 1 A and the energy increases from 10 eV to 490 eV. In particular, we conduct a comparative study among different cases of EB injection. According to these results, the modulation capability of EB injection in DF-CCP is thoroughly investigated, which can greatly benefit atom-scale etching in practical applications.
Realization of a strong ferroelectric metal by Nb-doping in strained EuTiO3
Authors: Xu Sheng , Gu Yanni , Zheng Chuanbo , Li Hui , Shen Xiao
Published: January 2024

Ferroelectric (FE) metals have been attracting attention as they possess both metallicity and ferroelectricity, the two seemingly incompatible physical properties. An important problem for both fundamental research and potential applications is how to realize a strong FE metal. One strategy is to dope a strong FE insulator and turn it into an FE metal, provided that the induced free electrons do not destroy FE distortion. Strained EuTiO3 is a strong FE ferromagnet and a promising candidate for such a strategy. Here, we calculate the structural, electronic, and polarization properties of Nb-doped strained EuTiO3 using the hybrid density-functional theory. The results show that the strained EuTi0.875Nb0.125O3 is a strong FE metal as the Nb doping induces metallicity without weakening the FE distortion. The underlying atomistic mechanism of the coexistence of metallicity and strong ferroelectricity is discussed. The findings show that combining doping and strain engineering is a promising way to realize new EuTiO3-based strong FE metals and may be used in other materials as well.
Power-duality in path integral formulation of quantum mechanics
Authors: Inomata Akira , Junker Georg
Published: January 2024

Power duality in Feynman's path integral formulation of quantum mechanics is investigated. The power duality transformation consists of a change in coordinate and time variables, an exchange of energy and coupling, and a classical angular momentum replacement. Two physical systems connected by the transformation form a power-dual pair. The propagator (Feynman's kernel) expressed by Feynman's path integral cannot be form-invariant under the transformation, whereas the promotor constructed by modifying Feynman's path integral is found form-invariant insofar as the angular momentum is classical. Upon angular quantization, the power duality breaks down. To save the notion of power duality, the idea of quasi power duality is proposed, which constitutes of an ad hoc angular momentum replacement. The power-dual invariant promotor leads to the quasi-dual invariant Green function. A formula is proposed, which determines the Green function for one of a dual pair by knowing the Green function for the other. As examples, the Coulomb-Hooke dual pair and a family of two-term confinement potentials for a zero-energy state are discussed.
A comparative DFT analysis of chiral laterally semi-fluorinated liquid crystals
Authors: Khan Obeidullah , Gandhi Sona , Gupta Deepak , Bhattacharjee Ayon
Published: January 2024

Liquid crystalline materials have the property to flow like a liquid while maintaining their molecular order. They are valuable material for technological integration. In this work, we have investigated a chiral semi-fluorinated liquid crystal material with the chemical structure C21H17F2NCS in two distinct laterally fluorine-substituted configurations. Employing density functional theory computations, we undertake a comprehensive comparative analysis of both configurations, assessing their charge dynamics, electrical characteristics, thermochemical properties, and nonlinear attributes. Intriguingly, the configuration featuring fluorine substitution on adjacent benzene rings exhibits remarkably superior properties in contrast to its counterpart, where fluorine is substituted on the same benzene ring. This research underscores the significance of structural nuances in elucidating the enhanced performance of liquid crystalline materials.
21cm signal sensitivity to dark matter decay
Authors: Facchinetti G. , Lopez-Honorez L. , Qin Y. , Mesinger A.
Published: January 2024

The redshifted 21cm signal from the Cosmic Dawn is expected to provide unprecedented insights into early Universe astrophysics and cosmology. Here we explore how dark matter can heat the intergalactic medium before the first galaxies, leaving a distinctive imprint in the 21cm power spectrum. We provide the first dedicated Fisher matrix forecasts on the sensitivity of the Hydrogen Epoch of Reionization Array (HERA) telescope to dark matter decays. We show that with 1000 hours of observation, HERA has the potential to improve current cosmological constraints on the dark matter decay lifetime by up to three orders of magnitude. Even in extreme scenarios with strong X-ray emission from early-forming, metal-free galaxies, the bounds on the decay lifetime would be improved by up to two orders of magnitude. Overall, HERA shall improve on existing limits for dark matter masses below 2 GeV/c
2 for decays into e+e- and below few MeV/c
2 for decays into photons.