bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular dynamics simulations of anisotropic particles accelerated by neural-net predicted interactions
Authors: Argun B. Ruşen , Fu Yu , Statt Antonia
Published: June 2024

Rigid bodies, made of smaller composite beads, are commonly used to simulate anisotropic particles with molecular dynamics or Monte Carlo methods. To accurately represent the particle shape and to obtain smooth and realistic effective pair interactions between two rigid bodies, each body may need to contain hundreds of spherical beads. Given an interacting pair of particles, traditional molecular dynamics methods calculate all the inter-body distances between the beads of the rigid bodies within a certain distance. For a system containing many anisotropic particles, these distance calculations are computationally costly and limit the attainable system size and simulation time. However, the effective interaction between two rigid particles should only depend on the distance between their center of masses and their relative orientation. Therefore, a function capable of directly mapping the center of mass distance and orientation to the interaction energy between the two rigid bodies would completely bypass inter-bead distance calculations. It is challenging to derive such a general function analytically for almost any non-spherical rigid body. In this study, we have trained neural nets, powerful tools to fit nonlinear functions to complex datasets, to achieve this task. The pair configuration (center of mass distance and relative orientation) is taken as an input, and the energy, forces, and torques between two rigid particles are predicted directly. We show that molecular dynamics simulations of cubes and cylinders performed with forces and torques obtained from the gradients of the energy neural-nets quantitatively match traditional simulations that use composite rigid bodies. Both structural quantities and dynamic measures are in agreement, while achieving up to 23 times speedup over traditional molecular dynamics, depending on hardware and system size. The method presented here can, in principle, be applied to any irregular concave or convex shape with any pair interaction, provided that sufficient training data can be obtained.
Excitation configuration analysis for divide-and-conquer excited-state calculation method using dynamical polarizability
Authors: Nishimura Ryusei , Yoshikawa Takeshi , Sakata Ken , Nakai Hiromi
Published: June 2024

The authors previously developed a divide-and-conquer (DC)-based non-local excited-state calculation method for large systems using dynamical polarizability [Nakai and Yoshikawa, J. Chem. Phys. 146, 124123 (2017)]. This method evaluates the excitation energies and oscillator strengths using information on the dynamical polarizability poles. This article proposes a novel analysis of the previously developed method to obtain further configuration information on excited states, including excitation and de-excitation coefficients of each excitation configuration. Numerical applications to simple molecules, such as ethylene, hydrogen molecule, ammonia, and pyridazine, confirmed that the proposed analysis could accurately reproduce the excitation and de-excitation coefficients. The combination with the DC scheme enables both the local and non-local excited states of large systems with an excited nature to be treated.
Numerical and experimental investigation on two-phase flow and oil capture efficiency of under-race lubrication for high-speed bearings
Authors: Jiang Le , Liu Zhenxia , Huang Weina , Lyu Yaguo , Li Yanjun , Hou Yankun , Liu Yewei
Published: June 2024

The increasing rotational speed and temperature levels in modern aeroengines impose higher demands on the lubrication and cooling design of the roller bearings supporting the main shaft. To design a compact and efficient under-race lubrication system, a comprehensive understanding of the characteristics of oil–air two-phase flow and the variations in oil capture efficiency is necessary. This study experimentally investigated the oil capture efficiency and employed numerical simulations to elucidate the mechanisms of oil–air two-phase flow. The results reveal a favorable consistency between the numerical simulations and experimental findings, both in terms of the oil capture efficiency and the oil–air distribution. The decreasing trend of oil capture efficiency gradually stabilizes when the jet distance exceeds 10 mm. To ensure stable and effective testing results for oil capture efficiency, the jet distance should be maintained within the range of 10–14 mm during experiments. Under different operating conditions, there exists an optimal jet angle that maximizes the oil capture efficiency. The corresponding optimal jet angle becomes smaller with lower oil supply pressure and higher rotational speed of the radial oil scoop. Within a momentum flux ratio range of 5–870, an innovative predictive correlation for the optimal jet angle is derived, with a maximum relative error between predicted and experimental values being 4.0%. The proposed correlation provides theoretical support and methodological basis for refining the design of radial under-race lubrication in aeroengines.
Memory effects in the efficiency control of energy transfer under incoherent light excitation in noisy environments
Authors: Dutta Rajesh , Bagchi Biman
Published: June 2024

Fluctuations in energy gap and coupling constants between chromophores can play an important role in absorption and energy transfer across a collection of two-level systems. In photosynthesis, light-induced quantum coherence can affect the efficiency of energy transfer to the designated “trap” state. Theoretically, the interplay between fluctuations and coherence has been studied often, employing either a Markovian or a perturbative approximation. In this study, we depart from these approaches to incorporate memory effects by using Kubo’s quantum stochastic Liouville equation. We introduce the effects of decay of the created excitation (to the ground state) on the desired propagation and trapping that provides a direction of flow of the excitation. In the presence of light-induced pumping, we establish a relation between the efficiency, the mean survival time, and the correlation decay time of the bath-induced fluctuations. A decrease in the steady-state coherence during the transition from the non-Markovian regime to the Markovian limit results in a decrease in efficiency. As in the well-known Haken–Strobl model, the ratio of the square of fluctuation strength to the rate plays a critical role in determining the mechanism of energy transfer and in shaping the characteristics of the efficiency profile. We recover a connection between the transfer flux and the imaginary part of coherences in both equilibrium and excited bath states, in both correlated and uncorrelated bath models. We uncover a non-monotonic dependence of efficiency on site energy heterogeneity for both correlated and uncorrelated bath models.
Experimental study of dynamic behavior of impacting droplets on vibrating super-hydrophobic surfaces
Authors: Xing Lei , Zhang Xingliang , Jiang Minghu , Zhao Lixin , Guan Shuai
Published: June 2024

The dynamic behaviors of droplets impacting on a vibrating solid surface are complex and interesting, as the differences in the initial phase angle can result in various droplet behaviors. The dynamic behavior of free-falling droplets impacting vibrating superhydrophobic substrates was investigated via high-speed photography. The effects of the initial phase angle (φ), Weber number (We), and vibration frequency (f) on the morphology evolution and energy dissipation were analyzed. Herein, 12 initial phase angles were selected as variables to investigate the evolution of droplet morphology with various initial phase angles. The effect of different initial phase angles on the maximum spreading diameter of droplets can cause variations of over 10%. The initial phase angles enhancing or restricting the droplet spreading were quantitatively defined. The Weber number and initial phase angle which can produce daughter droplets are obtained quantitatively. Meanwhile, a correlation between dimensionless spreading coefficient and dimensionless time was established for various vibration frequencies (f), revealing the effects of f on the maximum spreading diameter of droplet. Furthermore, a mathematical relationship for predicting the maximum spreading diameter of droplet impacting on a vibrating substrate was established based on the derivation of energy conservation. The error of the prediction mathematical model was proved to be less than 2% by the experimental results. These results provide fundamental understanding of droplet impacting on a vibration wall and could be useful for related engineering applications.
Experimental and numerical investigations to the aeroelastic response of flexible thin airfoil
Authors: Shang Hengrui , Wang Zhuo , Du Lin , Wang Yuwei , Sun Xiaofeng
Published: June 2024

The paper investigates the phenomenon of the aeroelastic response of flexible thin airfoils under various angles of attack (AOAs) and flow velocities through wind tunnel experiments and numerical simulations. The vibration modal characteristics are explored, including vibration frequencies, amplitudes, modal transition, and instantaneous characteristics. Vibration is directly measured using non-contact laser sensors, and the numerical model is appropriately configured to simulate the fluid–structure interaction (FSI) problem under large deformation. Experiments cover a range of AOAs (1°–20°) and incoming velocities (from 10 to 73 m/s), with dynamic responses measured using four laser sensors. Both average and instantaneous modal response features are analyzed, revealing multi-modal characteristics as velocity and AOA increase. The vibration mode transitions from pure bending to higher-order modes as incoming velocity increases. Specifically, at higher velocities and increased AOA, the high-order vibration component shifts from bending-torsional coupled mode to pure-torsional mode. Comparison of vibration frequencies between experimental measurements and finite element method simulations highlights significant shifts, particularly in the pure-torsional mode. Furthermore, employing commercial software ANSYS CFX and ANSYS Mechanical, a two-way three-dimensional FSI model successfully replicates flutter boundaries observed experimentally at 1° AOA and approximately incoming velocity 73 m/s. This FSI model is extended to simulate the multi-modal vibrations at 15° AOA, yielding insights into flow phenomena contributing to multi-modal vibration at this AOA. An explanation is provided for the multi-modal vibration phenomenon observed in the experiments based on the above insight. Finally, the differences between the experimental and numerical simulations are speculated upon.
Large eddy simulation investigation of micro-vortex generator control effect on early stage sheet cavitation
Authors: Mou Chengqi , Che Bangxiang , Zhang Jiansheng , Wang Yuxuan , Cao Linlin , Wu Dazhuan
Published: June 2024

The wall-adapting local eddy-viscosity large-eddy simulation method is employed for the numerical simulation of a hydrofoil, with transient calculations conducted to compare and analyze the near-wall flow characteristics and cavity morphologies of both the baseline and micro-vortex generator (mVG) hydrofoil models under conditions of high cavitation numbers. High-speed photography combined with numerical analysis revealed that mVGs generate a pair of counter-rotating vortices, boosting the transfer of momentum between the boundary layer and the main flow while reducing flow separation. These vortices induce a new mixed cavity structure at the leading edge, combining vortex cavitation with attached sheet cavitation. During cavity evolution, the mVGs prevent overall tail shedding in the baseline hydrofoil, confining shedding to the sides, while the central vortex cavitation structure remains stable. It enhances hydrofoil stability by reducing pressure fluctuations and guiding cavitation toward more predictable dynamics without causing significant pressure impacts. This research elucidates the mechanism of mVGs in guiding fluid attachment, transforming the structure and shedding cycle of attached cavities, and emphasizing its effectiveness by controlling early-stage sheet cavitation.
A theory of fluid–solid coupling in a porous medium for evaluating bioelastomers-assisted tissue remodeling using ultrasound
Authors: Jiang Chuanyang , Yang Sheng , Guo Kaixuan , You Zhengwei , Yu Jiao , Cao Lu
Published: June 2024

A theory of fluid–solid coupling in a porous medium for application to the ultrasonic evaluation of tissue remodeling using bioelastomers is presented in this paper. A theoretical model was developed by considering the soft porous bioelastomer as a fluid-saturated solid. Taking into account the relative motion between the fluid and solid in an aggregate, we derived an expression for a characteristic fluid–solid coupling parameter that can be employed as a measure of tissue recovery. Four cases were studied to investigate the dependence of the fluid–solid coupling parameter on related variables. The theory has potential applications in the acellular in situ tissue engineering for noninvasive monitoring of the complex mechanical remodeling process of tissue regeneration and bioelastomer degradation.
Ab initio quasi-harmonic thermoelasticity of molybdenum at high temperature and pressure
Authors: Gong X. , Dal Corso A.
Published: June 2024

We present the ab initio thermoelastic properties of body-centered cubic molybdenum under extreme conditions obtained within the quasi-harmonic approximation including both the vibrational and electronic thermal excitation contributions to the free energy. The quasi-harmonic temperature-dependent elastic constants are calculated and compared with existing experiments and with the quasi-static approximation. We find that the quasi-harmonic approximation allows for a much better interpretation of the experimental data, confirming the trend found previously in other metals. Using the Voigt–Reuss–Hill average, we predict the compressional and shear sound velocities of polycrystalline molybdenum as a function of pressure for several temperatures, which might be accessible in experiments.
Roaming in acetaldehyde
Authors: Krajňák Vladimír , Wiggins Stephen
Published: June 2024

We investigate roaming in the photodissociation of acetaldehyde (CH3CHO), providing insights into the contrasting roaming dynamics observed for this molecule compared to formaldehyde. We carry out trajectory studies for full-dimensional acetaldehyde, supplemented with an analysis of a two-degree-of-freedom restricted model and obtain evidence for two distinct roaming pathways. Trajectories exhibit roaming at both shorter (9–11.5 au) and larger (14.5–22.9 au) maximum CH3–HCO separations, characterized by differing amounts of HCO rotation. No roaming trajectories were found in the intervening gap region. The roaming dynamics near 14.5–22.9 au are well-reproduced by the restricted model and involve passage through a centrifugal barrier, analogous to formaldehyde roaming. However, the shorter-range 9–11.5 au roaming appears unique to acetaldehyde and is likely facilitated by repulsive interactions absent in the simplified models. Phase space analysis reveals that this additional roaming pathway is inaccessible in the reduced dimensionality system. The findings suggest that acetaldehyde’s increased propensity for roaming compared to formaldehyde may arise from the presence of multiple distinct roaming mechanisms rather than solely the higher roaming fragment mass.
Toward ultra-efficient high-fidelity predictions of wind turbine wakes: Augmenting the accuracy of engineering models with machine learning
Authors: Santoni C. , Zhang D. , Zhang Z. , Samaras D. , Sotiropoulos F. , Khosronejad A.
Published: June 2024

This study proposes a novel machine learning (ML) methodology for the efficient and cost-effective prediction of high-fidelity three-dimensional velocity fields in the wake of utility-scale turbines. The model consists of an autoencoder convolutional neural network with U-Net skipped connections, fine-tuned using high-fidelity data from large-eddy simulations (LES). The trained model takes the low-fidelity velocity field cost-effectively generated from the analytical engineering wake model as input and produces the high-fidelity velocity fields. The accuracy of the proposed ML model is demonstrated in a utility-scale wind farm for which datasets of wake flow fields were previously generated using LES under various wind speeds, wind directions, and yaw angles. Comparing the ML model results with those of LES, the ML model was shown to reduce the error in the prediction from 20% obtained from the Gauss Curl hybrid (GCH) model to less than 5%. In addition, the ML model captured the non-symmetric wake deflection observed for opposing yaw angles for wake steering cases, demonstrating a greater accuracy than the GCH model. The computational cost of the ML model is on par with that of the analytical wake model while generating numerical outcomes nearly as accurate as those of the high-fidelity LES.
Dynamic modeling of a cantilever reed valve considering squeeze flow with experimental validation
Authors: Zhang Mingming , Zhu Yuchuan , Li Linfei , Ling Jie
Published: June 2024

Piezoelectric hydraulic pumps play a pivotal role in more electric aircraft and all-electric aircraft utilizing power-by-wire technology, owing to their high power density and reliability. The cantilever reed valve (CRV) serves as a crucial component within these pumps, and its dynamic behavior within the fluid directly impacts the pumps' output power. A precise mathematical model of the CRV is essential for understanding its motion mechanisms. However, existing models for the CRV inadequately capture its dynamics and fail to explain the observed motion phenomena. Further exploration into dynamic modeling of the CRV is warranted. This paper employs finite element analysis to investigate CRV's dynamics, revealing the significant impact of squeeze flow on CRV's dynamics and identifying the cause of slow closure. Based on this, a novel lumped parameter model incorporating squeeze force is proposed to accurately depict CRV's dynamics, particularly focusing on the phenomenon of slow closure. To validate the proposed model's accuracy, an experimental system capable of independently driving the CRV is constructed to eliminate interference resulting from integrating the CRV into the pumps. The results show that the dynamic response during closure, as predicted by the proposed model, is in good agreement with the outcomes from finite element analysis. Notably, the proposed model exhibits an 11.11% higher prediction accuracy for experimental closing times compared to the traditional model that neglects squeeze forces. This study offers guidance for optimizing CRV's dynamics and improving the performance of piezoelectric hydraulic pumps in future applications.
Selective loading of a micrometer-scale particle into a magneto-gravitational trap by sublimation-activated release
Authors: Murphy Connor E. , Duenas Mario , Iron Daniel , Nelson Tobias , D’Urso Brian
Published: June 2024

In this paper, we discuss a technique for selectively loading a particle into a magneto-gravitational trap using the sublimation of camphor to release particles from a tungsten probe tip directly into the trapping region. This sublimation-activated release (SAR) loading technique makes use of micropositioners with tungsten probe tips, as well as the relatively fast rate of sublimation of camphor at room temperature, to selectively load particles having diameters ranging from 8 to 100 μm or more. The advantages of this method include its ability to selectively load unique particles or particles in limited supply, its low loss compared to alternative techniques, the low speed of the particle when released, and the versatility of its design, which allows for loading into traps with complex geometries. SAR is demonstrated here by loading a particle into a magneto-gravitational trap, but the technique could also be applicable to other levitated optomechanical systems.
Novel S–N/WO3: Optimization of photocatalytic performance of WO3 by simultaneous existence of S and N in WO3 against MB dye
Authors: Younas Ayesha , Munir Rana Mustansar , Rizvi Hassan Imam , Iqbal Tahir , Afsheen Sumera , Riaz K. N. , Syed Asad , Elgorban Abdallah M. , Wong Ling Shing
Published: June 2024

In this work, pure and S–N/WO3 (1%–7%) nanoparticles (NPs) have been developed for the degradation of MB dye. Optical properties, vibrational analysis, morphology, structural analysis, and photocatalytic activity of the samples have been evaluated using a variety of characterization techniques, including UV–vis, PL, FTIR, SEM, and x-ray diffraction (XRD). The XRD patterns showed that the stability of the orthorhombic phase of WO3 was affected by the concentrations of S and N. In SEM, nanospheres with an average size of 80 nm of NPs have been observed. The PL results showed that the e−, h+ recombination rate for the S–N7%/WO3 sample was the lowest. The degradation of MB dye has also been investigated in order to investigate the photocatalytic performance. Remarkably, S–N7%/WO3 shows the best results, with a maximum degradation of 90% in 120 min. The stability of the improved catalyst was tested using recycling and trapping studies. S–N7%/WO3 catalyst’s exceptional photocatalytic activity highlights its potential use in wastewater treatment. This study will be helpful for manufacturing innovation.
Heat effects on supersonic jet screech: a linear stability analysis based on parabolized stability equations
Authors: Li Binhong , Xu Jiali , Lyu Benshuai
Published: June 2024

In this paper, we use the parabolized stability equations (PSEs) to investigate heat effects on supersonic jet screech. The PSE is derived from the linear Euler equations, and the computations are performed on an empirical mean flow profile. Employing PSE, we can examine several important characteristics of the shear-layer instability waves, including the convection velocity, the growth rate, and the location where the instability waves attain the maximal total amplification. Equipped with these knowledge, we further explore their impacts on the jet screech. Specifically, using a newly proposed iteration scheme, we first identify a more suitable convective Mach number to predict the screech frequency in both heated and cold jets. Second, we find that the transition of the screech mode from the axisymmetric to the helical mode may be explained by the shift in the most amplified instability modes. Using this criterion, we can predict a transition Mach number for the mode staging. Third, by assuming that the effective source location is the position where the instability wave attains its maximal amplitude and using the newly obtained convective Mach number, we can predict the screech mode staging in cold and heated jets using Gao's model. The predictions agree well with the experimental data. Finally, we investigate the heat effects on screech amplitude. It is found that compared to cold jets, the difference between the frequency of the most amplified instability wave and the frequency of the jet screech is much bigger in heated jets, which may lead to a lower screech amplitude.
Surface engineering of FAPbI3 based organic–inorganic hybrid perovskite for memristors
Authors: Lee Ji Hyeon , Shim Eun Soo , Kim Yeong Eun , Jo Jea Woong
Published: June 2024

Organic–inorganic hybrid perovskites (OIHPs) have been spotlighted as emerging solution-processed electronics and show promise as economical, flexible, and stretchable emerging memristors. However, OIHPs suffer from considerable defects derived from solution processing; thus, post-processing is often required to alleviate such shortcomings. Treating alkyl ammonium organic salt on OIHP films is a representative approach to efficiently mediate the defect density. Here, we adopted n-octyl ammonium chloride (OACl) in our post-processing agent for organometal perovskite memristors (OPMs). The OACl-incorporated OPM showed an enlarged ON/OFF resistance ratio of 520 compared to OPM without passivation (3.91). Thin film analysis revealed that the synergistic insulating/passivating layer from OACl post-treatment retarded the interaction with the electroactive electrode (Ag). Additionally, the combined effects from the lower-dimensional OIHP induced by OA, including the p-doping of lead by chloride, enhanced the energetic barrier with Ag electrode to reduce the parasitic current at the high resistance state. This study offers deeper insights into the surface passivation of OIHPs and its effects on memristic performance.
New analysis of the temperature-dependent threshold density for electron self-trapping in gaseous helium
Authors: Borghesani A. F. , Bonifaci N. , Khrapak A. G. , Atrazhev V. M.
Published: June 2024

We present the results of a new analysis of the literature data on electron mobility μ in dense helium gas aimed at determining the existence of a threshold density for electron self-trapping in gaseous helium as a function of temperature. We have investigated the density dependence of μ and, when available, its dependence on the electric field. The experimental data are favorably rationalized by minimizing the excess free energy of the self-localized states within the optimum fluctuation model. It is shown that the formation of electron bubbles via the self-trapping phenomenon is determined by the delicate balance between the electron thermal energy, the density dependence of the electron energy at the bottom of the conduction band in the gas, and the work necessary to expand the bubble. We show that the self-trapping phenomenon is not limited to low temperatures but occurs at any temperatures for large enough densities.
Quantification and visualization of uncertainties in reconstructed penumbral images of implosions at Omega
Authors: Kunimune J. H. , Heuer P. V. , Reichelt B. L. , Johnson T. M. , Frenje J. A.
Published: June 2024

Penumbral imaging is a technique used in plasma diagnostics in which a radiation source shines through one or more large apertures onto a detector. To interpret a penumbral image, one must reconstruct it to recover the original source. The inferred source always has some error due to noise in the image and uncertainty in the instrument geometry. Interpreting the inferred source thus requires quantification of that inference’s uncertainty. Markov chain Monte Carlo algorithms have been used to quantify uncertainty for similar problems but have never been used for the inference of the shape of an image. Because of this, there are no commonly accepted ways of visualizing uncertainty in two-dimensional data. This paper demonstrates the application of the Hamiltonian Monte Carlo algorithm to the reconstruction of penumbral images of fusion implosions and presents ways to visualize the uncertainty in the reconstructed source. This methodology enables more rigorous analysis of penumbral images than has been done in the past.
A new setup for measurements of absolute saturation vapor pressures using a dynamical method: Experimental concept and validation
Authors: Nielsen Robin V. , Salimi Mohsen , Andersen John E. V. , Elm Jonas , Dantan Aurélien , Pedersen Henrik B.
Published: June 2024

We describe a new experimental system for direct measurements of the absolute saturation vapor pressures of liquid or solid samples. The setup allows the isolation of the sample under steady conditions in an ultra-high vacuum chamber, where the measurement of the sample’s vapor pressure as a function of its temperature can be performed in a range around room temperature and in a pressure range defined only by the applied absolute pressure sensor. We characterize the setup and illustrate its capability to measure saturation vapor pressures as well as enthalpies of evaporation around room temperature with explicit measurements on four liquid compounds (diethyl phthalate, 1-decanol, 1-heptanol, and 1-hexanol) for which accurate vapor pressures have previously been reported.
Enhanced imaging of electronic hot spots using quantum squeezed light
Authors: An Haechan , Najjar Amiri Ali , Goronzy Dominic P. , Garcia Wetten David A. , Bedzyk Michael J. , Shakouri Ali , Hersam Mark C. , Hosseini Mahdi
Published: June 2024

Detecting electronic hot spots is important for understanding the heat dissipation and thermal management of electronic and semiconductor devices. Optical thermoreflective imaging is being used to perform precise temporal and spatial imaging of heat on wires and semiconductor materials. We apply quantum squeezed light to perform thermoreflective imaging on micro-wires, surpassing the shot-noise limit of classical approaches. We obtain a far-field temperature sensing accuracy of 42 mK after 50 ms of averaging and show that a 256×256 pixel image can be constructed with such sensitivity in 10 min. We can further obtain single-shot temperature sensing of 1.6 K after only 10 μs of averaging, enabling a dynamical study of heat dissipation. Not only do the quantum images provide accurate spatiotemporal information about heat distribution but also the measure of quantum correlation provides additional information, inaccessible by classical techniques, which can lead to a better understanding of the dynamics. We apply the technique to both aluminum and niobium microwires and discuss the applications of the technique in studying electron dynamics at low temperatures.
Experimental investigation on dynamics of spray atomization, ignition, and flame propagation in an annular combustor
Authors: Zhu Zhixin , Hou Jing , Ma Chengbiao , Wang Gaofeng
Published: June 2024

The combustor employed in small and medium-sized turboshaft engines is characterized by a small flame tube height and a large distance between adjacent burners, rendering it challenging to ignition. Moreover, the process of spray ignition exhibits complexity and needs further investigation. This study will delve into the performances of spray atomization and spark ignition within an annular combustor. Our objective is to thoroughly elucidate the interplay among atomization characteristics and flame propagation, seeking to shed some light on the fundamental mechanisms underlying flame dynamics from the perspective of timescales during the light-round processes. Planar Mie scattering and high-speed imaging technologies are employed to capture droplet distribution and time-resolved flame images, respectively. We have developed an algorithm capable of precisely tracking the flame front, enabling us to map out the trajectories of flame propagation. An analysis of transient flames reveals that the movement of leading points can be elucidated by the characteristics of the flow field and the distribution of the spray. It is demonstrated that the velocity of the flame front is affected by factors such as the pressure drop, equivalence ratio, and the distance between adjacent burners. Through an analysis of numerous spark events, this work identifies three distinctive flame propagation patterns: swirling-entrainment, archlike-entrainment, and another archlike-entrainment pattern. It is noted that these patterns exhibit variations by alterations in pressure drop and equivalence ratio.
Fractal analysis of dimensionless permeability and Kozeny–Carman constant of spherical granular porous media with randomly distributed tree-like branching networks
Authors: Li Shaofu , Gao Jun , Xiao Boqi , Zhang Yidan , Long Gongbo , Li Yi
Published: June 2024

The seepage of porous media has garnered significant interest due to its ubiquitous presence in nature, but most of the research is based on the model of a single dendritic branching network. In this study, we derive a fractal model of the dimensionless permeability and the Kozeny–Carman (KC) constant of porous media consisting of spherical particles and randomly distributed tree-like branching networks based on fractal theory. In addition, three different types of corrugated pipes are considered. Then, the relationships between the KC constant, dimensionless permeability, and other structural parameters were discussed in detail. It is worth noting that the KC constant of the porous media composed of three types of pipes decreases sharply first and then increases with the increase in the internal diameter ratio, while the dimensionless permeability has the opposite trend and conforms to the physical law. In addition, empirical constants are not included in the analytical formulas of the present model, and the physical mechanism of fluid flow in spherical granular porous media with randomly distributed tree-like branching networks is clearly revealed.
Evaluation of a novel sub-acute Hospital in the Home model for providing inpatient geriatric and rehabilitation services
Authors: Suzuki Anya , Kyle Greg , Webb Clare , Cox Ruth , Wishart Laurelie , McCusker Melissa , McConnell Alex , Courtice Sally , Ward Elizabeth C. , Ross Leo
Published: June 2024

Objective To report on the development and implementation of a multidisciplinary, sub-acute Geriatric Evaluation and Management Rehabilitation Hospital in the Home (GEMRHITH) model of care with the initial 2 years’ service outcome data (October 2019 – September 2021). Methods A retrospective analysis was conducted using hospital centralised data, and the GEMRHITH internal service database. Descriptive statistics were used to describe the patient population. Student’s t-test was used for comparative data. Results Over 2 years, GEMRHITH admitted 617 patients (13%, n = 82 directly from the emergency department). Median age was 82 years (range, 32–102 years), with 60.5% (n = 373) being female and 39.5% (n = 244) presenting with moderate frailty. Most patients (79.6%, n = 491) entered from a medical speciality (28.5%, n = 178 from neurology). Average GEMRHITH stay was 6 days (range, 1–33 days). Average bed occupancy was 5.3 virtual beds. There was an average of 26 discharges per month with 97% of patients (n = 598) discharged to their own home. Transfers back to the emergency department with the same diagnosis-related group were low (3.6%). The 7–28 day re-admission rate was 2.3%. Service safety was high, with only eight hospital-acquired complications reported in seven patients. Significant improvements were noted for total and sub-scale Functional Independence Measure scores (P < 0.001). Conclusions The addition of rehabilitation and geriatric care to traditional HITH services provides opportunities for multidisciplinary teams to support a larger cohort of patients with various medical and surgical conditions and functional abilities, to efficiently transition home from hospital settings. There were minimal complications and occupied bed stays were saved within a hospital.
Referral reasons to a Victorian mental health triage service for individuals living with young-onset dementia
Authors: Loi Samantha M. , Velakoulis Dennis
Published: June 2024

Objectives Mental health triage services are the first contact for people wanting support for their mental health and provide access to public mental health services in Victoria, Australia. People living with young-onset dementia and their families may contact triage services seeking assistance for behaviour changes and pathways to care as there are few alternative services available. Methods The authors reviewed the minimum triage dataset from one of the largest mental health services in Victoria, Australia from 2018 to 2021 investigating reasons for referral for people with young-onset dementia. Results Of the 1766 referrals for ‘dementia’, 145 were for young-onset dementia. Of these, 69% were referred for behaviour changes. About half of the referrals for behaviour changes were triaged as ‘advice only’. One-third of referrals were from general practitioners. Conclusions The availability of dementia-specific support services that could provide advice on dementia as well as advice for behaviour changes related to the disease could potentially ease the burden of phone calls received by mental health triage services.
Women in STEM becoming independent: Our shared motivation and enthusiasm are our driving force
Authors: Andreeva Liudmila , Bosurgi Lidia , Chong Shu Zhen , Chu Coco , Ge Yejing , Hoste Esther , Jurado Kellie A. , Lengefeld Jette , Mishra Archita , Wculek Stefanie , Young Arabella
Published: June 2024

This year at JEM, we are highlighting women in science by sharing their stories and amplifying their voices. In this Viewpoint, we hear from a cross section of women, across multiple research fields, discussing their science and the process of setting up a lab as an independent researcher.
Two-layered microwell-array device for preparation of single-neuron culture samples
Authors: Nakama Ayaka , Yasuda Takashi
Published: June 2024

When a single neuron is cultured in isolation from other neurons, its axon connects with its own dendrites to form a simple, independent network with no synaptic inputs from other neurons. This culture system enables detailed analysis of synaptic function and morphology change in neurites at the single-neuron level, which is useful for elucidating the pathogenesis of neurological diseases and for evaluating the efficacy of therapeutic drugs for them. However, there was previously no device technology capable of simultaneously forming multiple single-neuron samples while allowing co-culture with astrocytes, which is essential for culture of a single neuron isolated from other neurons. In this study, we propose a novel microwell-array device for preparing single-neuron samples. The device consists of an upper layer for cell seeding and a lower layer for cell culture. Each layer has 16 × 16 microwells, and the bottom of each well is made of a 1 μm thick silicon nitride membrane. The membrane of the upper well has one microhole for seeding a single neuron, and the lower membrane has multiple microholes for interaction between a single neuron and astrocytes which are co-cultured back-to-back on both sides of the membrane. When neurons are seeded into the upper well, only one of them passes through the microhole in the upper membrane and falls onto the lower membrane. We evaluated a seeding efficiency of single neurons by changing seeding hole diameter and seeding density. The results showed that the yield of more than 20% was obtained regardless of the seeding density when the seeding hole diameter was 13 μm. We also confirmed that single neurons seeded in this manner and co-cultured with astrocytes developed neurites and formed synapses. These results demonstrated the usefulness of this device for the preparation of single-neuron culture samples.
Study on the influence of transverse magnetic field on the arc and reignition characteristics of HVDC relays
Authors: Hou Guobin , Zhang Dandan , Li Zhenbiao , Wan Zhiyu , Shi Kexin
Published: June 2024

It is of great significance to clarify the influence of transverse magnetic field (TMF) on arc control in high-voltage direct current (HVDC) relays. In this paper, the influence of TMF in a wide range of 0–140 mT on the arc characteristics of HVDC relays is studied, the experimental observations of arc reignition are carried out and the effect of arc reignition on contact erosion, the criterion of arc reignition and the mechanism of TMF enhancement on arc reignition are further analyzed. The results show that the TMF enhancement is beneficial for shortening the arc voltage stagnation duration and accelerating the speed of arc elongation, arc dispersion and dispersed arc motion, thereby improving the arc extinguishing performance. However, higher TMF leads to more severe and earlier arc reignition, as also shown in the experimental observations. The arc reignition further causes a sudden drop in arc voltage, prolonged arc duration and uneven contact erosion. To evaluate the occurrence of arc reignition caused by TMF enhancement, a simplified breakdown criterion is proposed through the defined characteristic variable

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t
)

. Based on this, the mechanism by which the TMF enhancement more easily causes arc reignition is explained, that is the higher TMF leads to an earlier and faster increase in

C
¯

(
t
)

and slightly reduces the breakdown threshold

C
¯

∗

(

t
5

,
D
)

. Further, measures to suppress the arc reignition are proposed.
Recent progress in the study on phonon heat transport property of Earth’s lower mantle minerals
Authors: Dekura Haruhiko , Tsuchiya Taku
Published: June 2024

The lattice thermal conductivities (

κ

lat

) of Earth’s lower mantle (LM) minerals is a crucial parameter in the study of deep Earth dynamics and its determination is also one of the grand challenges in condensed matter physics. Here, we review recent progress on theoretical and experimental studies for the

κ

lat

under high pressure (P) and high temperature (T) condition up to 150 GPa and 4000 K. After the critical parameters necessary to obtain converged values of the

κ

lat

are summarized, the theoretical

κ

lat

of the LM minerals, determined through various computational methodologies, is compiled along with experimental findings. Although significant scattering is found in the experimental results at LM P,T, the quantum anharmonic lattice dynamics theory combined with the phonon Boltzmann transport theory demonstrates a clear relationship in the

κ

lat

of the end-member LM phases, MgO, MgSiO3 bridgmanite (Brg) and post-perovskite (PPv),

κ

lat

MgO

>>

κ

lat

PPv

>

κ

lat

Brg

, and a discontinuous change in the

κ

lat

by ∼20%–50% expected across the Brg–PPv transition. Knowledge on the additional but geophysically important factors, such as the effects of iron solid solution, isotopic mass difference, and higher order crystal anharmonicity are also summarized in detail. Current problems and future perspectives are finally mentioned.
Extraction of amplitude-domain characteristics from dynamic electric signals that cause large errors in electricity metering
Authors: Wang Xuewei , Xie Shiyu , Yuan Ruiming , Zhao Cheng , Wang Guoxing , Wang Chen
Published: June 2024

Recent studies have shown that the power and current of high-power dynamic loads exhibit dynamic behaviors that cause large errors in electrical energy meters. Aimed at fast variations and large fluctuations in dynamic electric signals, this study examines a characteristic extraction method for small-time granularity and the impact of these characteristics on electrical energy meters. First, we constructed quasi-steady and dynamic model parameters for the dual-modal modulation models of current and power signals. Second, based on the two sets of signals sampled from the electrified railway traction substation and steelmaking arc furnace substation, we extracted quasi-steady and dynamic signal model parameters from fundamental active power signals. Third, we proposed three novel characteristic parameters by mapping the model parameter method, and extracted the four important characteristics. Finally, we designed a set of on-off-keying test signal experiments to determine the impact of the proposed characteristic parameters on the electric energy meter. The experimental results show that the electrical energy meter errors are sensitive to the proposed characteristic parameters, wherein the maximum impulse coefficient is the most sensitive characteristic of the EEM, which causes an error as large as −81.28%. The proposed characteristic parameters can be used as the input characteristic information of dynamic test signals for type testing and updating the test standards for electrical energy meters.
Smartphone-based experiments exploring the physical laws of guitar string vibrations
Authors: Yi Weisong , Deng Haiyou
Published: June 2024

Using smartphones to explore the physical laws of musical instruments is not only scientifically intriguing but also practically feasible. Here an experimental scheme based on a smartphone and mobile application (Phyphox) is devised to investigate the vibration law of guitar strings. By quantitatively measuring the length, diameter and vibration frequency of guitar strings, the experimental results convincingly demonstrate the validity of the vibration law of guitar strings. The research embodies the concept of ‘from life to physics, from physics to society’, and is beneficial for students to comprehend the physical laws of guitar string vibration as well as the principle behind guitar sounds. The smartphone-based physics experiments can be performed outside the classic physics laboratory, which expands the methods and space of teaching physics experiments, and relates reality to physics laws.
The impact of pulse repetition frequency on microbubble activity and drug delivery during focused ultrasound-mediated blood-brain barrier opening
Authors: Fletcher Stecia-Marie P , Zhang Yongzhi , Chisholm Amanda , Martinez Sofia , McDannold Nathan
Published: June 2024

Objective. Pulsed focused ultrasound (FUS) can deliver therapeutics to the brain by using intravenous microbubbles (MBs) to open the blood-brain barrier (BBB). MB emissions indicate treatment outcomes, like BBB opening (harmonics) and damage (broadband). Typically, a pulse repetition frequency (PRF) of 1 Hz is used, but the effect of PRF on MBs is not fully understood. We investigated the effect of PRF on MB activity and tracer delivery. Approach. The effect of PRF (0.125, 0.25, 0.5, 1, and 2 Hz) on MB activity was monitored through harmonic and wideband emissions during FUS sonications of the rat brain at 274.3 kHz. BBB opening was quantified through fluorescence imaging to estimate the concentration of Trypan Blue (TB) dye following a 75-pulse FUS exposure for PRFs of 1 and 0.25 Hz. Main results. At a fixed acoustic pressure, the percentage change in maximum harmonic amplitude compared to the control (PRF = 1 Hz) decreased with increasing PRF, with a median change of 73.8% at 0.125 Hz and −38.3% at 2 Hz. There was no difference in the pressure threshold for broadband emissions between PRFs of 0.25 and 1 Hz. PRF = 0.25 Hz, led to a 68.2% increase in the mean concentration of TB measured after FUS, with a 53.9% increase in the mean harmonic sum, compared with PRF = 1 Hz. Harmonic emissions-based control at PRF = 0.25 Hz yielded similar TB delivery, with less damage at histology, compared with 1 Hz. Significance. For a fixed number of FUS pulses, reducing the PRF was shown to increase the magnitude of harmonic emissions and TB delivery, but not the threshold for broadband emissions. While further research is necessary to understand the mechanisms involved, these results may be useful to improve clinical safety margins and sensitivity to detecting small harmonic signals from cavitating MBs.