bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the Synergy Between AI and VR: Advancing Film, Gaming, and E-Learning
Authors: Zhang Zhiyao
Published: April 2024

The main thrust of this essay is to delve into the impact of virtual reality on traditional industries, especially in the fields of entertainment and education. In an age where technology and information go hand in hand, traditional ways of working have changed dramatically, with the aim of increasing efficiency and creating entirely new results. The study focuses on two companies that are utilizing virtual reality technology for innovation in the entertainment and education sectors respectively. A comparative analysis of the approaches of these two companies provides insight into the significance and innovative applications of virtual reality technology in these areas. As a revolutionary and innovative technology, virtual reality is having a wide and far-reaching impact on people’s lives. It shows great potential for improving efficiency and outcomes, but is still in the early stages of exploration and experimentation. Therefore, more advanced technical support is urgently needed and the application of virtual reality technology is constantly being improved. Virtual reality technology is at the forefront of innovation in this day and age, and it opens a door to the future.
Nuanced Management of a Skull Base Tumor in the Setting of Relapsed Acute Lymphoblastic Leukemia
Authors: Jung Geena , Buckner-Wolfson Emery , Tal Adit , Fatemi Ryan , Kim Timothy , Liriano Genesis , Kobets Andrew
Published: April 2024

Introduction Relapsed acute lymphoblastic leukemia (ALL) involving the central nervous system (CNS) is a significant issue that contributes to both morbidity and mortality. Given the poor outcomes in patients with CNS relapse, understanding how ALL involving intracranial relapse presents and is treated is critical. Here, we present a complex case of relapsed recurrent ALL in a pediatric patient.

Case Report An 11-year-old patient presented with double relapse of ALL in the form of an extensive skull base lesion and again with leptomeningeal disease. For the skull base lesion, she was treated nonsurgically with chemotherapy and radiation, which led to a remarkable reduction in the size of the lesion. However, she was found to have early recurrence with leptomeningeal enhancement resulting in hydrocephalus 5 months after completing therapy. A shunt was placed successfully. Currently, she is being managed with monthly intrathecal chemotherapy with cerebrospinal fluid sampling and bone marrow biopsies every 2 months.

Discussion We report the significant effect of chemotherapy and radiotherapy in reducing the size of the extensive skull base lesion, saving the patient from the risks associated with surgery. This patient's initial relapse, with a large skull base lesion that had intracranial involvement, is an unusual presentation of relapsed ALL. The additional early recurrence of leptomeningeal disease further makes this case unique and the management even more nuanced. Here, we demonstrate a multidisciplinary approach for the successful treatment of our patient, which can help guide the management of similar patients in the future.
A multi-dimensional analysis of interpreted and non-interpreted English discourses at Chinese and American government press conferences
Authors: Sheng Dandan , Li Xin
Published: April 2024

This study uses a multidimensional analysis (MDA) proposed by Douglas Biber to investigate the difference in communicative functions between the interpreted and non-interpreted political discourses, based on a comparable corpus of English interpretations of Chinese government press conferences and original English of U.S. government press conferences. The findings show that MDA distinguishes the interpreted from the non-interpreted discourse along several communicative dimensions and that the former is just as persuasive as the latter but has a higher information density and yet a lower degree of involvement, more non-narrative content, higher reference clarity, more abstract information, and a slightly lower degree of information elaboration. These differences can be explained by the nature of the interpretation of government press conferences as an institutional discourse, the interpreting norms, the interpreters’ professional habitus, as well as the working and broadcasting modes of consecutive interpretations in a political setting. MDA used in this study proves its effectiveness in identifying the differences in stylistics and discourse functions between the interpreted and non-interpreted discourse in similar communicative contexts and settings.
Cucker–Smale type flocking models on a sphere
Authors: Choi Sun-Ho , Kwon Dohyun , Seo Hyowon
Published: April 2024

We present a Cucker–Smale type flocking model on a sphere including three terms: a centripetal force, multi-agent interactions on a sphere, and inter-particle bonding forces. We consider a rotation operator to compare velocity vectors on different tangent spaces. Due to the geometric restriction, the rotation operator is singular at antipodal points and the relative velocity between two agents located at these points is not well-defined. We assume that the communication rate between two antipodal points is zero to establish a well-defined flocking operator. We obtain the global-in-time existence and uniqueness of the solution to the flocking model. From the geometric property of the sphere, it is difficult to control the position difference between agents to avoid this singular position without bonding force. With a positive bonding force, we present a sufficient condition for the emergence of flocking.
Improved accuracy and robustness of electron density profiles from JET’s X-mode frequency-modulated continuous-wave reflectometers
Authors: Morales R. B. , Salmi A. , Abreu P. , Amador C. H. S. , Appel L. , Carman P. , Fessey J. , Flanagan J. , Fontana M. , Frassinetti L. , Giroud C. , Hacquin S. , Heuraux S. , Meneses L. , Ronchi G. , Sabot R. , Silva A. , Sirinelli A. , Szepesi G. , Taylor D. , Terranova D.
Published: April 2024

JET’s frequency-modulated continuous wave (FMCW) reflectometers have been operating well with the current design since 2005, and density profiles have been automatically calculated intershot since then. However, the calculated profiles had long suffered from several shortcomings: poor agreement with other diagnostics, sometimes inappropriately moving radially by several centimeters, elevated levels of radial jitter, and persistent wriggles (strong unphysical oscillations). In this research, several techniques are applied to the reflectometry data analysis, and the shortcomings are significantly improved. Starting with improving the equilibrium reconstruction that estimates the background magnetic field, adding a ripple correction in the reconstructed magnetic field profile, and adding new inner-wall reflection positions estimated through ray-tracing, these changes not only improve the agreement of reconstructed profiles to other diagnostics but also solve density profile wriggles that were present during band transitions. Other smaller but also persistent wriggles were also suppressed by applying a localized correction to the measured beat frequency where persistent oscillations are present. Finally, the burst analysis method, as introduced by Varela et al. [Nucl. Fusion 46 S693 (2006)], has been implemented to extract the beat frequency from stacked spectrograms. Due to the strong suppression of spurious reflections, the radial jitter that sometimes would span several centimeters has been strongly reduced. The stacking of spectrograms has also been shown to be very useful for stacking recurring events, like small gas puff modulations, and extracting transport coefficients that would otherwise be below the noise level.
Review of robotic systems for thoracoabdominal puncture interventional surgery
Authors: Wang Cheng , Guo Li , Zhu Jianjun , Zhu Lifeng , Li Chichi , Zhu Haidong , Song Aiguo , Lu Ligong , Teng Gao-Jun , Navab Nassir , Jiang Zhongliang
Published: April 2024

Cancer, with high morbidity and high mortality, is one of the major burdens threatening human health globally. Intervention procedures via percutaneous puncture have been widely used by physicians due to its minimally invasive surgical approach. However, traditional manual puncture intervention depends on personal experience and faces challenges in terms of precisely puncture, learning-curve, safety and efficacy. The development of puncture interventional surgery robotic (PISR) systems could alleviate the aforementioned problems to a certain extent. This paper attempts to review the current status and prospective of PISR systems for thoracic and abdominal application. In this review, the key technologies related to the robotics, including spatial registration, positioning navigation, puncture guidance feedback, respiratory motion compensation, and motion control, are discussed in detail.
Spin-flop process identified in heteroepitaxial rare-earth films of Er and Ho
Authors: Xiao Xiangshang , Zhao Kunlong , Cui Yifan , Yuan Bin , Jadhav Vijaykumar V. , Paul Amitesh
Published: April 2024

Bulk-like heteroepitaxial Er, Ho, and Tb films were grown on alumina substrates. They show reduced magnetization that can be related to oscillation of moments returning an average magnetization due to the usual existence of conical, helical (cycloidal), and/or helifan phases along the temperature scale. Interestingly, below 20 K and at finite field values, the temperature of the conical phase in Er and Ho, we find the existence of various spin-flop processes due to the dominating degenerate bidirectional fluctuations arising from competing anisotropies within the conical phase. Plateaus in the magnetometric loops are identified as fingerprints of spin-flops in periodically arranged blocks of moments, which deviate from conventional spin-flop behavior in generic low-anisotropy antiferromagnets. Such spin-flops are manifestations of moments that are arranged in a pattern, comprising alternate blocks of regularly spaced members commensurate with the lattice. With a larger conical angle in Ho as compared to Er, the spin-flops occur more frequently, which provides an insight into how magnetic anisotropy can be manifested in rare-earth metals in realizing magnetic sub-states. By tailoring the conical structure, one can in principle regulate the magnetic sub-states in the future for applications.
A dynamic light scattering inversion method based on regularization matrix reconstruction for flowing aerosol measurement
Authors: Hu Junhua , Xing Xuening , Shen Jin , Li Xinqiang , Liu Wei , Wang Yajing
Published: April 2024

Tikhonov regularization, or truncated singular value decomposition (TSVD), is usually used for dynamic light scattering (DLS) inversion of particles in suspension. The Tikhonov regularization method uses a regularization matrix to modify all singular values in the kernel matrix. The modification of large singular values cannot effectively reduce the variance of the estimated values but may introduce bias in the solution, resulting in poor disturbance resistance in the inversion results. The TSVD method, on the other hand, truncates all small singular values, which leads to the loss of particle size information during the inversion process. The shortcomings of the two methods mentioned above do not have a significant impact on the inversion of high signal-to-noise ratio data. However, compared to the classical DLS particle size inversion for non-flowing suspended particles, the DLS inversion of flowing aerosols is more significantly affected by noise, and the extraction of particle size information is more difficult due to the effect of flow velocity, resulting in worse inversion results with increasing aerosol flow velocity for both methods. To improve the accuracy of the particle size distribution (PSD) of flowing aerosols, we introduced a kernel matrix into the regularization matrix, and based on the principles of the two methods, the spectral information of the kernel matrix was utilized to make the modification of small singular values by the regularization matrix. Correspondingly, weak or no modification was made according to the values of large singular values to reduce the introduction of bias. The inversion results of simulated and measured data indicate that the reconstruction of the regularization matrix improves the anti-disturbance performance and avoids the loss of particle size information during the regularization inversion process, thereby significantly improving the PSD accuracy, which is affected by the dual effects of flow velocity and noise in the DLS measurement of flowing particles. The peak error and distribution error of the inversion results by reconstructing the regularization matrix are lower than those of Tikhonov regularization.
Structurally tunable acoustic transmission-coded metamaterials
Authors: Cui Qinghao , Wang Jilai , Tang Xuefeng , Li Quhao , Men Junhui , Wan Yi
Published: April 2024

The introduction of metasurfaces has renewed Snell's law, and the metasurfaces can manipulate sound waves flexibly. In this paper, a coding metasurface with a simple and adjustable coding unit for sound wave transmission is proposed. By changing the orientation of a movable part in a fixed structure, conversion is achieved between two types of units with a phase difference of 180° and high transmittance (>75%). By combining the two types of units, the phases of sound waves can be regulated dynamically. Structural simulations are performed using finite-element software, and the beam splitting of the transmitted sound wave is verified by theoretical analysis and experiments under plane wave incidence in the frequency range of 4.7–5.7 kHz. In addition, the two types of units are used to design a coding Fresnel lens, and its simulated focusing performance is verified by experiments at 4.7–5.7 kHz.
Analysis of chaos and capsizing of a class of nonlinear ship rolling systems under excitation of random waves
Authors: Wei Zhouchao , Li Yuxi , Kapitaniak Tomasz , Zhang Wei
Published: April 2024

The action of wind and waves has a significant effect on the ship’s roll, which can be a source of chaos and even capsize. The influence of random wave excitation is considered in order to investigate complex dynamic behavior by analytical and numerical methods. Chaotic rolling motions are theoretically studied in detail by means of the relevant Melnikov method with or without noise excitation. Numerical simulations are used to verify and analyze the appropriate parameter excitation and noise conditions. The results show that by changing the parameters of the excitation amplitude or the noise intensity, chaos can be induced or suppressed.
A programmable metasurface based on acoustic black hole for real-time control of flexural waves
Authors: Su Kun , Li Lixia
Published: April 2024

The time-modulated active medium with linear independent frequency conversion method has been demonstrated to enable wave orientation and reconstruction. However, due to the symmetric scattering field, this technique requires intricate microcircuit designs. To overcome this limitation, this paper proposes a tunable piezoelectric metasurface based on acoustic black holes (ABHs) to redirect flexural wave reflections. The system can convert an incident flexural wave into a reflected wave of any direction and frequency. This is accomplished through the linear time modulation of the sensing signal, which breaks the constraints of Snell’s law inherent in traditional designs and is insensitive to the incident amplitude. The coupling of the ABH damping system with a linear independent frequency conversion mechanism allows for the conversion of an incident flexural wave into a reflected wave in any direction and frequency while also eliminating the influence of second harmonic reflection on the wave field and simplifying the time modulation circuit. In addition, this paper demonstrates arbitrary angle reflection, focusing, beam splitting, and frequency conversion of the incident wave. By improving the flexibility of elastic wave manipulation, this paper introduces a new approach for active control of elastic waves and provides a design method that can be employed in a variety of applications ranging from vibration protection of engineering structures to vibration sensing and evaluation.
Clustering coefficients for networks with higher order interactions
Authors: Ha Gyeong-Gyun , Neri Izaak , Annibale Alessia
Published: April 2024

We introduce a clustering coefficient for nondirected and directed hypergraphs, which we call the quad clustering coefficient. We determine the average quad clustering coefficient and its distribution in real-world hypergraphs and compare its value with those of random hypergraphs drawn from the configuration model. We find that real-world hypergraphs exhibit a nonnegligible fraction of nodes with a maximal value of the quad clustering coefficient, while we do not find such nodes in random hypergraphs. Interestingly, these highly clustered nodes can have large degrees and can be incident to hyperedges of large cardinality. Moreover, highly clustered nodes are not observed in an analysis based on the pairwise clustering coefficient of the associated projected graph that has binary interactions, and hence higher order interactions are required to identify nodes with a large quad clustering coefficient.
Forecasting with an N-dimensional Langevin equation and a neural-ordinary differential equation
Authors: Malpica-Morales Antonio , Durán-Olivencia Miguel A. , Kalliadasis Serafim
Published: April 2024

Accurate prediction of electricity day-ahead prices is essential in competitive electricity markets. Although stationary electricity-price forecasting techniques have received considerable attention, research on non-stationary methods is comparatively scarce, despite the common prevalence of non-stationary features in electricity markets. Specifically, existing non-stationary techniques will often aim to address individual non-stationary features in isolation, leaving aside the exploration of concurrent multiple non-stationary effects. Our overarching objective here is the formulation of a framework to systematically model and forecast non-stationary electricity-price time series, encompassing the broader scope of non-stationary behavior. For this purpose, we develop a data-driven model that combines an N-dimensional Langevin equation (LE) with a neural-ordinary differential equation (NODE). The LE captures fine-grained details of the electricity-price behavior in stationary regimes but is inadequate for non-stationary conditions. To overcome this inherent limitation, we adopt a NODE approach to learn, and at the same time predict, the difference between the actual electricity-price time series and the simulated price trajectories generated by the LE. By learning this difference, the NODE reconstructs the non-stationary components of the time series that the LE is not able to capture. We exemplify the effectiveness of our framework using the Spanish electricity day-ahead market as a prototypical case study. Our findings reveal that the NODE nicely complements the LE, providing a comprehensive strategy to tackle both stationary and non-stationary electricity-price behavior. The framework’s dependability and robustness is demonstrated through different non-stationary scenarios by comparing it against a range of basic naïve methods.
High-temperature performance of InGaN-based amber micro-light-emitting diodes using an epitaxial tunnel junction contact
Authors: Sang Yimeng , Zhuang Zhe , Xing Kun , Zhang Dongqi , Yan Jinjian , Jiang Zhuoying , Li Chenxue , Chen Kai , Ding Yu , Tao Tao , Iida Daisuke , Wang Ke , Li Cheng , Huang Kai , Ohkawa Kazuhiro , Zhang Rong , Liu Bin
Published: April 2024

This study investigated the temperature-dependent electroluminescent (EL) performance of InGaN-based amber micro-light-emitting diodes (μLEDs) with a diameter of 40 μm using an epitaxial tunnel junction (TJ) contact for current spreading. The TJ-μLEDs could achieve a high electrical efficiency of 0.935 and a remarkable wall-plug efficiency of 4.3% at 1 A/cm2 at room temperature, indicating an excellent current injection efficiency of the TJ layers regrown by molecular beam epitaxy. Moreover, the current injection of the amber TJ-μLEDs at the forward bias could be further improved at elevated temperatures. The improvement can be explained by the enhanced tunneling probability and acceptor ionization in p-GaN based on the theoretical simulation. The redshift coefficient, which describes the temperature-dependent peak wavelength shift, is obtained as small as 0.05 nm/K, and the high-temperature-to-room-temperature EL intensity ratio is calculated as >0.56 even at a low current density of 0.5 A/cm2 at the temperatures up to 80 °C. This thermal droop behavior was attributed to the enhanced non-radiative recombination, which was confirmed by the shorter carrier lifetime measured at high temperatures.
Experiment study of m/n = 1/1 mode saturation level in high-βp discharge on the EAST tokamak
Authors: Wang Wei , Xu Liqing , Gong X. , Qian Jinping , Zhang Bin , Zhao Hailin , Li Pan , Liu Wenbin , Liang Ruirong , Hu Yunchan , Wang Zuhao , Guo Yutong , Chao Yan
Published: April 2024

The saturated internal kink mode with m/n = 1/1 has been observed in the H-mode discharge of the experimental advanced superconducting tokamak, characterized by high  βP and weak magnetic shear in the core. This observation was made using a combination of soft x-ray imaging and electron cyclotron emission diagnostics. It was noted that the repetitive bursting of m/n = 1/1 internal mode (large amplitude, short bursting duration) transitions into a long-lasting continuous one (small amplitude, constant frequency), when βp> 2.2 in H-mode, a much shorter bursting duration, transitioning into a long-lasting continuous one, with smaller amplitude and a constant frequency. Conversely, for typical βp< 1.5 in L/I discharge, the frequency of m/n = 1/1 mode decreases with time, associated with local poloidal electron diamagnetism drift velocity. The benign m/n = 1/1 mode in high βp has an amplitude much smaller than one in L-mode for high βP stabilization effect. By adjusting the power deposition of electron cyclotron resonance heating, it is found that the saturation level of m/n = 1/1 mode is independent of the local electron temperature gradient in H-mode discharge. It underscores that the flat current and, hence, weak magnetic shear are crucial factors influencing the saturation level of the m/n = 1/1 mode for both the off-axis electron cyclotron current driving current-dominant and off-axis bootstrap current-dominant cases. Furthermore, the outward movement with growth of the m/n = 1/1 mode in the process of L-H mode transition and the characteristic time of this process are close to the current diffusion time.
Hollow-core fiber loading of nanoparticles into ultra-high vacuum
Authors: Lindner Stefan , Juschitz Paul , Rieser Jakob , Fein Yaakov Y. , Debiossac Maxime , Ciampini Mario A. , Aspelmeyer Markus , Kiesel Nikolai
Published: April 2024

Many experiments in the field of optical levitation with nanoparticles today are limited by the available technologies for particle loading. Here, we introduce a particle loading method that solves the main challenges, namely deterministic positioning of the particles and clean delivery at ultra-high vacuum levels as required for quantum experiments. We demonstrate the efficient loading, positioning, and repositioning of nanoparticles in the range of 100–755  nm diameter into different lattice sites of a standing wave optical trap, as well as direct loading of 143–365  nm diameter particles into ultra-high vacuum, down to an unprecedented pressure below 10−9  mbar. Our method relies on the transport of nanoparticles within a hollow-core photonic crystal fiber using an optical conveyor belt, which can be precisely positioned with respect to the target trap. Our work opens the path for increasing nanoparticle numbers in the study of multiparticle dynamics and high turn-around times for exploiting the quantum regime of levitated solids in ultra-high vacuum.
Railway wagon bearing fault diagnosis method based on improved sparrow search algorithm optimizing variational mode decomposition and multi-level convolutional neural network
Authors: Men Zhihui , Chen Zhe , Li Yonghua , Guo Tao , Hu Chaoqun
Published: April 2024

Ensuring the safe operation of trains hinges on precise bearing condition monitoring, given the pivotal role bearings play in railway wagons. The status and maintenance of wagon bearings are of paramount concern, necessitating a shift from traditional maintenance approaches reliant on schedules and experience, which often lack real-time precision and efficiency. To address this challenge, our research focuses on enhancing the sparrow search algorithm by incorporating logistic chaos mapping and the levy flight strategy. This enhanced algorithm optimizes variational mode decomposition parameters, utilizing intrinsic mode components’ average dispersion entropy as the fitness function. This optimization is integrated with a multi-level convolutional neural network for bearing fault diagnosis. Our findings demonstrate the improved algorithm’s enhanced spatial search capabilities and reduced modal aliasing in the frequency components. Experimental validation on public datasets and the group’s experimental platform for railway wagons shows that multi-level convolutional neural networks have higher diagnostic accuracy and faster convergence speeds than traditional models such as LeNet-5, AlexNet, and convolutional neural network. Our research introduces a highly accurate and widely applicable methodology for mechanical equipment fault diagnosis, aligning with the requirements of the “smart” era.
Generation of a controllable multi-spiral beam by using the modulated helico-conical phases
Authors: Liu Shuo , Zheng Yi , Xiao Huiming , Shan Shengxiang , Liu Xuejuan , Ahmad Sohail , Rana Anwar Manzoor , Cheng Shubo , Yang Wenxing , Tao Shaohua
Published: April 2024

In this Letter, we propose a kind of controllable multi-spiral beam that can be generated using the modulated helico-conical phases with an axicon. The focal-field intensity distributions of the multi-spiral beams were investigated theoretically and experimentally. The relative distance between the two adjacent sub-beams of the multi-spiral beams was discussed based on the approximate mapping of the local spatial frequency. The result demonstrated that the relative distance between the two adjacent sub-beams was linearly dependent on the radial factor gradient Δα of the two sub-beams. When the radial factor gradient Δα is equal to a critical value (i.e., Δαc), the multi-spiral beam can be changed into an Archimedean spiral-shaped beam (the sub-beams of multi-spiral beams will be connected with each other). In addition, the dependence of the topological charge l on the critical radial factor gradient Δαc is also discussed. The result demonstrates that the critical radial factor gradient Δαc has a linear dependence on the topological charge l. The experimental results are in good agreement with the numerical simulation results. The controllable multi-spiral beams are potentially applied in three-dimensional optical micro-manipulation and information transmission.
Experimental investigation of mode transition process in a cavity-based scramjet
Authors: Meng Yu , Sun Wenming , Gu Hongbin , Chen Fang
Published: April 2024

A directly connected transient scramjet simulator was developed for supersonic combustion experiments to gain a deeper understanding of the process and mechanism of mode transitions in dual-mode scramjet engines. This study presents experimental simulations of flame development under constant combustor inlet conditions with increasing equivalence ratios, utilizing advanced high-speed measurement techniques such as high-frequency static pressure, schlieren imaging, and methylene radical chemiluminescence. The results demonstrated that abrupt changes occurred during the mode transition as the equivalence ratio increased. Specifically, lower equivalence ratios correspond to the shear layer mode, whereas higher equivalence ratios correspond to the jet-wake and jet-front modes. The stable position of the precombustion shock wave is determined by the heat released during combustion, whereas both the precombustion shock wave and the fuel-injection depth determine the combustion mode and flame-anchoring position. Finally, the dynamic variation of shock waves inside the combustor is significant in contributing to abrupt mode transitions.
Conceptual study of a new instrument for dynamic neutron scattering measurements—The modulated intensity with diffraction analysis spectrometer (MIDAS)
Authors: Benedetto Antonio , Kearley Gordon J. , Faraone Antonio
Published: April 2024

Dynamic neutron scattering probes unique nanoscale dynamics via measurement of energy exchanged between a sample and the neutrons. The two spectrometers that investigate processes with characteristic times around a nanosecond are backscattering (BS) and neutron spin-echo (NSE). We present a new method for measuring dynamics using an oscillating cosine-like energy-distribution neutron-package at the sample and measure solely the portion scattered into the elastic line. This portion corresponds to elastically scattered neutrons and, in addition, inelastic components that are scattered with a probability directly proportional to the cosine Fourier-coefficients of the exchanged-energy spectrum. The counts at the detector thus correspond to the van Hove intermediate scattering function. We denote this new method as “Fourier transform neutron scattering” (FTNS), it being broadly analogous to IR and Raman spectroscopies. Here, the realization of such a concept is investigated using an oscillating incident beam produced via a precession method and a secondary spectrometer identical to a BS instrument using crystal analyzers. The instrument is denoted “Modulated Intensity with Diffraction Analysis Spectrometer” (MIDAS). However, simpler approaches, e.g., choppers, may also be used for an FTNS instrument. The theory behind MIDAS is presented, supported by numerical calculations and in silico experiments. Finally, we present a Monte Carlo simulation to compare BS and MIDAS spectrometers. This shows that MIDAS has almost 100 times more incident flux than standard BS, but due to the better signal-to-noise ratio of BS, the final information acquisition rate gain of MIDAS is approximately a factor of 2.
Characterizing the spike timing of a chaotic laser by using ordinal analysis and machine learning
Authors: Boaretto Bruno R. R. , Macau Elbert E. N. , Masoller Cristina
Published: April 2024

Semiconductor lasers with optical feedback are well-known nonlinear dynamical systems. Under appropriate feedback conditions, these lasers emit optical pulses that resemble neural spikes. Influenced by feedback delay and various noise sources, including quantum spontaneous emission noise, the dynamics are highly stochastic. A good understanding of the spike timing statistics is needed to develop photonic systems capable of using the fast-spiking laser output for novel applications, such as information processing or random number generation. Here we analyze experimental sequences of inter-spike intervals (ISIs) recorded when a sinusoidal signal was applied to the laser current. Different combinations of the DC value and frequency of the signal applied to the laser lead to ISI sequences with distinct statistical properties. This variability prompts an investigation into the relationship between experimental parameters and ISI sequence statistics, aiming to uncover potential encoding methods for optical spikes, since this can open a new way of encoding and decoding information in sequences of optical spikes. By using ordinal analysis and machine learning, we show that the ISI sequences have statistical ordinal properties that are similar to Flicker noise signals, characterized by a parameter α that varies with the signal that was applied to the laser current when the ISIs were recorded. We also show that for this dataset, the (α, permutation entropy) plane is more informative than the (complexity, permutation entropy) plane because it allows better differentiation of ISI sequences recorded under different experimental conditions, as well as better differentiation of original and surrogate ISI sequences.
A hot phonon bottleneck observed upon incorporation of SnF2 to MASnI3 films and its possible role in increasing photocarrier diffusion length
Authors: Xu Fan , Wei Haoming , Cao Bingqiang
Published: April 2024

While SnF2 is reported as an effective additive for improving the efficiency of lead-free tin-based perovskite solar cells, the mechanism is still unclear and requires further studies. Upon incorporating SnF2 into MASnI3, SnF2 reduces the intrinsic carrier density from 1018 to 1012 cm–3 and produces a longer carrier diffusion length as confirmed by the Hall measurements. The femtosecond transient absorption spectroscopy shows that SnF2 doping enhances the hot-phonon bottleneck effect of MASnI3. The slow cooling process of hot carriers may help to reduce non-radiative recombination, increase the fluorescence lifetime, and, therefore, improve the utilization rate of carriers. Finally, lead-free low bandgap perovskite MASnI3 is utilized as a light absorbing layer in solar cells, achieving high optical current and high voltage in tin-based perovskite solar cells. The final power conversion efficiency is 10.2%, while the power conversion efficiency for the control unit is 6.69%.
Electric charging effects on insulating surfaces in cryogenic liquids
Authors: Korsch Wolfgang , Broering Mark , Timsina Ashok , Leung Kent K. H. , Abney Joshua , Budker Dmitry , Filippone Bradley W. , He Jiachen , Kandu Suman , McCrea Mark , Roy Murchhana , Swank Christopher , Yao Weijun
Published: April 2024

This paper presents a new technique to study the adsorption and desorption of ions and electrons on insulating surfaces in the presence of strong electric fields in cryoliquids. The experimental design consists of a compact cryostat coupled with a sensitive electro-optical Kerr device to monitor the stability of the electric fields. The behavior of nitrogen and helium ions on a poly(methyl methacrylate) (PMMA) surface was compared to a PMMA surface coated with a mixture of deuterated polystyrene and deuterated polybutadiene. Ion accumulation and removal on these surfaces were unambiguously observed. Within the precision of the data, both surfaces behave similarly for the physisorbed ions. The setup was also used to measure the (quasi-)static dielectric constant of PMMA at T ≈ 70 K. The impact of the ion adsorption on the search for a neutron permanent electric dipole moment in a cryogenic environment, such as the nEDM@SNS experiment, is discussed.
Epitaxial growth and characterization of (110)-oriented YBCO/PBCGO bilayer and YBCO/PBCGO/YBCO trilayer heterostructures
Authors: Kandel Hom , Arndt Nathan , Li Zhongrui , Lee Jungwoo , Yao Yuchuan , Roy Susmita , Cunliffe-Owen Hillary , Reznik Dmitry , Eom Chang-Beom
Published: April 2024

We have grown and characterized (110)-oriented YBa2Cu3O7−x (YBCO)/PrBa2(Cu0.8Ga0.2)3O7−x (PBCGO) bilayer and YBCO/PBCGO/YBCO trilayer heterostructures, which were deposited by pulsed laser deposition technique for the nanofabrication of (110)-oriented YBCO-based superconductor (S)/insulator (I)/superconductor (S) tunneling vertical geometry Josephson junction and other superconductor electronic devices. The structural properties of these heterostructures, investigated through various x-ray diffraction techniques (profile, x-ray reflectivity, pole figure, and reciprocal mapping), showed (110)-oriented epitaxial growth with a preferred c-axis-in-plane direction for all layers of the heterostructures. The atomic force microscopy measurement on the top surface of the heterostructures showed crack-free and pinhole-free, compact surface morphology with about a few nanometer root mean square roughness over the 5 × 5 μm2 region. The electrical resistivity measurements on the (110)-direction of the heterostructures showed superconducting critical temperature (Tc) values above 77 K and a very small proximity effect due to the interfacial contact of the superconducting YBCO layers with the PBCGO insulating layer. Raman spectroscopy measurements on the heterostructures showed the softening of the Ag-type Raman modes associated with the apical oxygen O(4) and O(2)-O(3)-in-phase vibrations compared to the stand-alone (110)-oriented PBCGO due to the residual stress and additional two Raman modes at ∼600 and ∼285 cm−1 frequencies due to the disorder at the Cu–O chain site of the PBCGO. The growth process and structural, electrical transport, and Raman spectroscopy characterization of (110)-oriented YBCO/PBCGO bilayer and YBCO/PBCGO/YBCO trilayer heterostructures are discussed in detail.
Investigation of the total pressure gain in rotating detonation combustors with dilution holes
Authors: He Xiao-Jian , Gong Xiao-Peng , Wang Jian-Ping , Ma John Z.
Published: April 2024

An investigation of the total pressure gain (TPG) in rotating detonation combustors (RDCs) with dilution holes is conducted by the experimental method in this study. The effects of pressure ratios (PR = 4.2–7.2) and equivalence ratios (ER = 0.5–1.5) on the total pressure gain are analyzed in four models, i.e., models A–D, of different throat areas A3.1 and dilution hole area A3.5. When the PR is small, the lowest ER causes the highest TPG, and when the PR is high, the highest ER leads to the highest TPG in Model A. While in models B–D, as ER increases, the TPG increases gradually in all the cases. Comparing the level of TPG between the four models, it is found that the increment of A3.1 and A3.5 results in the enhancement of the TPG. The present study's TPG shows superiority when compared with that of traditional RDC, which indicates that the RDC with dilution holes is more promising for achieving positive TPG in specific configurations. An empirical model considering the throat area A3.1, dilution hole area A3.5, outlet area A8, and heat (released by the fuel combustion) release rate Qv is proposed to better predict the performance of different RDC configurations. Positive total pressure gain is inferred to be promisingly attained at a high A3.1/A8, low A8/A3.5, and a high Qv. Total pressure measured by total pressure rake is verified by comparing with the data calculated by Mach-corrected-static-pressure and mass flow function methods, with relative errors in ±4% and ±15%, respectively.
Sound speed measurements in shock compressed cemented tungsten carbide: Evolution of elastic moduli with damage at pressures to 100 GPa
Authors: Wang B. , Prakash V.
Published: April 2024

The motivation of the present study is to gain insights into the evolution of elastic properties of cemented tungsten carbides (WC) shock compressed to 100 GPa. Seven plate impact experiments—two front surface impact and five release wave overtake—are conducted to make simultaneous measurements of Hugoniot states and longitudinal sound speeds in shocked WC with 3.7wt.% cobalt binder. The sound speeds along with estimates for bulk sound speeds, obtained using the Birch–Murnaghan EoS, are analyzed to determine the elastic moduli—longitudinal, bulk, and shear—as a function of Hugoniot stress. The longitudinal and bulk sound speeds at Hugoniot states of interest are found to increase linearly with longitudinal stress. Consistent with the increase in sound speeds, the longitudinal and bulk moduli also increase with Hugoniot stress; however, the increase in longitudinal modulus is modest when compared to predictions of theoretical models that account for pressure and temperature dependence of elastic moduli, but with no damage. The shear moduli remain nearly constant at ∼318 GPa over the range of Hugoniot states investigated. These values are, however, much lower than those predicted by the Steinberg–Guinan model with no damage. Poisson’s ratio decreases initially from its ambient value of 0.208 to ∼0.199 for Hugoniot stress ≤10 GPa indicating consolidation of the WC microstructure with low initial stress; however, with an increase in Hugoniot stress to ∼100 GPa, Poisson’s ratio increases to ∼0.317, indicating degradation of shear moduli with increasing stress. The product of density and Grüneisen parameter (ρΓ), after an initial spike, remains nearly constant for volumetric strains ≥0.07. The maximum average temperature rise is estimated to be ∼286°C at the highest Hugoniot stress employed in the study.
Global density equations for interacting particle systems with stochastic resetting: From overdamped Brownian motion to phase synchronization
Authors: Bressloff Paul C.
Published: April 2024

A wide range of phenomena in the natural and social sciences involve large systems of interacting particles, including plasmas, collections of galaxies, coupled oscillators, cell aggregations, and economic “agents.” Kinetic methods for reducing the complexity of such systems typically involve the derivation of nonlinear partial differential equations for the corresponding global densities. In recent years, there has been considerable interest in the mean field limit of interacting particle systems with long-range interactions. Two major examples are interacting Brownian particles in the overdamped regime and the Kuramoto model of coupled phase oscillators. In this paper, we analyze these systems in the presence of local or global stochastic resetting, where the position or phase of each particle independently or simultaneously resets to its original value at a random sequence of times generated by a Poisson process. In each case, we derive the Dean–Kawasaki (DK) equation describing hydrodynamic fluctuations of the global density and then use a mean field ansatz to obtain the corresponding nonlinear McKean–Vlasov (MV) equation in the thermodynamic limit. In particular, we show how the MV equation for global resetting is driven by a Poisson noise process, reflecting the fact that resetting is common to all of the particles and, thus, induces correlations that cannot be eliminated by taking a mean field limit. We then investigate the effects of local and global resetting on nonequilibrium stationary solutions of the macroscopic dynamics and, in the case of the Kuramoto model, the reduced dynamics on the Ott–Antonsen manifold.
The impact of salinity on the cohesion process of quartz substracts: A molecular dynamics study
Authors: Ouyang Yubing , Liu Yanming , Fan Yujian , Zhou Yang , Shi Tao
Published: April 2024

The moisture with salt ions adsorbed on the mineral soil surface is crucial to the cohesion process when the media is exposed to marine or coastal environments. However, the impact of salinity on the cohesion of soils is not well studied at the nanoscale. In this study, the salinity effect was investigated by studying the wettability and capillary force of NaCl solutions on quartz substrates via a molecular dynamics-based approach. Besides, a new visualization method was proposed to measure the contact angle of liquid droplets from the aspect of nanoscale. The results indicated that salt ions can weaken the wettability of the liquid on the quartz surface and inhibit the capillary force. Compared with water, the liquid with a 10% NaCl solution can achieve a capillary force reduction of around 70%, resulting in a detrimental effect on the cohesion of soils. Overall, this study enhanced the understanding of the nanoscale salinity effect on the cohesion process and provided insights into the modification of the mechanical properties of soils from the aspect of nanoscale.
Wall confinement effects on the dynamics of cavitation bubbles in thin tubes
Authors: Wang Nian , Xu Huashi , Wang Tianyou , Che Zhizhao
Published: April 2024

Cavitation is a common phenomenon in nature and has numerous applications. In contrast to a cavitation bubble in a free domain, a cavitation bubble in a thin tube is restricted by the tube wall, which is expected to significantly affect bubble evolution, but its mechanism is still unclear. In this study, the dynamics of a cavitation bubble in a thin circular tube is studied by numerical simulation, focusing on the confinement effects of the tube. The results show that besides affecting the size and lifetime of the bubble, the confinement effects of the tube lead to the generation of counter jets and a ring jet during the contraction process of the bubble, and the curvature of the two counter jets determines the ring jet's peak velocity. When the bubble deviates from the midpoint of the tube in the axial direction, the two sides of the bubble along the axial direction show asymmetric behaviors, which results in the bubble migrating toward the midpoint. The tube diameter, tube length, liquid viscosity, and initial bubble position can significantly influence the degree of confinement effects, which can be characterized by the variations of several key indicators, such as bubble size, lifetime, degree of deformation, counter jet velocity, ring jet velocity, and axial migration of the bubble.
A broadband multi-frequency microwave combined biological exposure setup
Authors: Zhao Xuelong , Li Zhihui , Liu Xiaoman , Wang Yuqing , Dong Guofu , Liu Qi , Wang Changzhen
Published: April 2024

With the rapid popularization of wireless electronic devices, there has been an increasing concern about the impacts of the electromagnetic environment on health. However, most research reports on the biological effects of microwaves have focused on a single frequency point. In reality, people are exposed to complex electromagnetic environments that consist of multiple frequency microwave signals in their daily lives. It is important to investigate whether multi-frequency combined microwave energies have different biological effects compared with single frequency microwave energy. Unfortunately, there are limited reports on this topic due to the lack of suitable platforms for research on multi-frequency microwave energy combined with biological exposure. To address this issue, this study presents a setup that has a very wide working frequency bandwidth and can be compatible with single frequency and multi-frequency microwave combined exposure. Moreover, it can achieve relatively equal exposure to multiple biological samples at any frequency point in the working frequency range, which is crucial for electromagnetic biology research. The experimental results are in good agreement with the simulation results, confirming its capability to facilitate the study of complex electromagnetic environment effects on organisms.
DL_POLY Quantum 2.0: A modular general-purpose software for advanced path integral simulations
Authors: London Nathan , Limbu Dil K. , Momeni Mohammad R. , Shakib Farnaz A.
Published: April 2024

DL_POLY Quantum 2.0, a vastly expanded software based on DL_POLY Classic 1.10, is a highly parallelized computational suite written in FORTRAN77 with a modular structure for incorporating nuclear quantum effects into large-scale/long-time molecular dynamics simulations. This is achieved by presenting users with a wide selection of state-of-the-art dynamics methods that utilize the isomorphism between a classical ring polymer and Feynman’s path integral formalism of quantum mechanics. The flexible and user-friendly input/output handling system allows the control of methodology, integration schemes, and thermostatting. DL_POLY Quantum is equipped with a module specifically assigned for calculating correlation functions and printing out the values for sought-after quantities, such as dipole moments and center-of-mass velocities, with packaged tools for calculating infrared absorption spectra and diffusion coefficients.