bluuebunny/crossref_metadata_2025 huggingface dataset:
Feasibility and Reliability of the Adapted Kagan Scales for Rating Conversations for People With Acquired Brain Injury: A Multiphase Iterative Mixed-Methods Design
Authors: Behn Nicholas , Power Emma , Prodger Penny , Togher Leanne , Cruice Madeline , Marshall Jane , Rietdijk Rachael
Published: February 2025

Purpose:

Rating the quality of conversations can assess communication skills in both people with acquired brain injury and their communication partners. This study explored the clinical feasibility and reliability of two conversation rating scales: the Adapted Measure of Participation in Conversation (MPC) and the Adapted Measure of Support in Conversation (MSC).

Method:

Raters were final-year speech and language therapy students (
n
= 14) and qualified clinicians (
n
= 2). Raters attended training on the Adapted MPC and MSC, watched 5 or 10 min of videotaped conversations (
n
= 23), and then scored them on the MPC and MSC scales. Data were collected over four phases, which varied according to the length of the training, sample length, number of samples rated, and level of clinical expertise. Feasibility data (time taken to score conversations and ease of use) were collected. Interrater reliability was assessed using intraclass correlations (ICCs: absolute agreement, single measures).

Results:

Raters took 30–45 min to score a 10-min sample, and they took 20–30 min to score a 5-min sample. Ease of use was rated highly across all phases. Overall reliability for rating 5 min of conversation (ICC = .52–.73) was better than for 10 min of conversation (ICC = .33–.68). Reliability for the MPC was moderate for both students (ICC = .69) and clinicians (ICC = .55), and for the MSC, it was moderate for both students (ICC = .73) and clinicians (ICC = .58). Reliability was better for students compared with clinicians.

Conclusions:

Rating a 5-min conversation in under 30 min was feasible, with more reliable results for 5-min compared with 10-min conversations. Implications for assessing conversation in the future are discussed.
Teletherapy and Multi-Tiered System of Support: Synergies and Challenges for School-Based Speech-Language Pathologists
Authors: Sylvan Lesley , Gouck Madeleine , Kwak Madelyn
Published: February 2025

Purpose:

This exploratory study examines the intersection of teletherapy and multi-tiered system of support (MTSS) in school-based speech-language services and explores ways in which the challenges related to MTSS vary by service delivery modality.

Method:

This study involved 10 interviews with five speech-language pathologists (SLPs) who have had experience in both in-person and teletherapy-based positions and were working for the same educational agency as teletherapists during the 2023–2024 school year. Qualitative data were collected about unique facilitators and barriers teletherapists face concerning MTSS and how the defining features of teletherapy (e.g., technology and on-site facilitation with a remote SLP) impact their engagement with MTSS in both helpful and constraining ways.

Results:

Participants, all of whom worked remotely with students attending schools in person, identified a number of opportunities and challenges related to engagement with MTSS. Some challenges were identified as common to both face-to-face and remote work (e.g., misunderstandings related to the role of SLPs in MTSS). Others were unique to teletherapy in ways that made implementation easier (e.g., intentionally planned and focused conversations) as well as harder (e.g., lack of visibility and spontaneity). There were pros and cons of how technology and on-site facilitation impacted MTSS implementation.

Conclusion:

As teletherapy and prevention-oriented work gain prominence in the postpandemic reality, this study offers initial insights into the synergies and challenges of engaging with the MTSS as a school-based teletherapist.
Caregiver Perceptions and Use of the Early Communication Indicator–Autism: Examining Differences Among Demographic Groups
Authors: Steinbrenner Jessica R. , Jenkins Kimberly , Nowell Sallie , Wilkinson Braden , Salley Brenda , Buzhardt Jay , Boyd Brian
Published: February 2025

Purpose:

This study aims to examine caregiver perceptions and use of the Early Communication Indicator–Autism (ECI-A), an adapted, naturalistic assessment to measure progress on communication skills, and explore differences across racial and ethnic groups to provide preliminary data about the cultural responsiveness of the newly adapted ECI-A.

Method:

A total of 215 caregivers and their autistic child completed the ECI-A. The research team collected data on caregiver- and researcher-reported ease of use of the ECI-A and caregiver ECI-A fidelity. Descriptive statistics are reported across racial and ethnic groups, and group differences are examined between groups with sufficient sample size (Black and White caregivers, Latino and non-Latino caregivers).

Results:

Overall, there was consistency in caregiver and researcher perceptions of ease of use and caregiver fidelity. The only statistically significant differences were for researcher-reported ease of use between Black and White caregivers and ECI-A fidelity for general procedures between Latino and non-Latino caregivers.

Conclusions:

The results suggest that the ECI-A is acceptable and feasible for use by caregivers from a range of racial and ethnic backgrounds. However, the two statistically significant differences suggest the need for careful attention to researcher biases for researcher-completed measures and more in-depth evaluation of the cultural responsiveness of the general ECI-A procedures, such as the number of play partners involved. It will be critical to continue work that informs and advances the use of culturally responsive assessment practices with autistic children and their families in the future.

Supplemental Material:

https://doi.org/10.23641/asha.28216151
Deep learning interpretability analysis for carbon star identification in Gaia DR3
Authors: Ye Shuo , Cui Wen-Yuan , Li Yin-Bi , Luo A-Li , Jones Hugh R.A.
Published: February 2025

A large fraction of asymptotic giant branch (AGB) stars develop carbon-rich atmospheres during their evolution. Based on their color and luminosity, these carbon stars can easily be distinguished from many other kinds of stars. However, numerous G, K, and M giants also occupy the same region as carbon stars on the HR diagram. Despite this fact, their spectra exhibit differences, especially in the prominent CN molecular bands. We aim to distinguish carbon stars from other kinds of stars using Gaia's XP spectra while providing attributional interpretations of key features that are necessary for identification and even discovering new key spectral features. We propose a classification model named "GaiaNet," an improved one-dimensional convolutional neural network specifically designed for handling Gaia's XP spectra. We utilized SHapley Additive exPlanations (SHAP), an approach for interpretability based on game theoretic, to determine SHAP values for each feature in a spectrum, enabling us to explain the output of the GaiaNet model and provide further meaningful analysis. Compared to four traditional machine learning methods, the GaiaNet model exhibits an average classification accuracy improvement of approximately 0.3% on the validation set, with the highest accuracy reaching 100%. Utilizing the SHAP model, we present a clear spectroscopic heatmap highlighting molecular band absorption features primarily distributed around CN_ and CN_ and we summarize five key feature regions for carbon star identification. Upon applying the trained classification model to the CSTAR sample with Gaia "xp_sampled_mean" spectra, we obtained 451 new candidate carbon stars as a by-product. Our algorithm is capable of discerning subtle feature differences from low-resolution spectra of Gaia, thereby assisting us in effectively identifying carbon stars with typically higher temperatures and weaker CN features while providing compelling attributive explanations. The interpretability analysis of deep learning holds significant potential in spectral identification.
KOBE-1: The first planetary system from the KOBE survey
Authors: Balsalobre-Ruza O. , Lillo-Box J. , Silva A. M. , Grouffal S. , Aceituno J. , Castro-González A. , Cifuentes C. , Standing M. R. , Faria J. P. , Figueira P. , Santerne A. , Marfil E. , Abreu A. , Aguichine A. , González-Ramírez L. , Morales J. C. , Santos N. , Huélamo N. , Delgado Mena E. , Barrado D. , Adibekyan V. , Barros S. C. C. , Berihuete Á. , Morales-Calderón M. , Nagel E. , Solano E. , Sousa S. G. , Agüí Fernández J. F. , Azzaro M. , Bergond G. , Cikota S. , Fernández-Martín A. , Flores J. , Góngora S. , Guijarro A. , Hermelo I. , Pinter V. , Vico Linares J. I.
Published: February 2025

Context. K-dwarf stars are promising targets in the exploration of potentially habitable planets. Their properties, falling between G and M dwarfs, provide an optimal trade-off between the prospect of habitability and ease of detection. The KOBE experiment is a blind-search survey exploiting this niche, monitoring the radial velocity of 50 late-type K-dwarf stars. It employs the CARMENES spectrograph, with an observational strategy designed to detect planets in the habitable zone of their system.

Aims. In this work, we exploit the KOBE data set to characterize planetary signals in the K7 V star HIP 5957 (KOBE-1) and to constrain the planetary population within its habitable zone.

Methods. We used 82 CARMENES spectra over a time span of three years. We employed a generalized Lomb–Scargle periodogram to search for significant periodic signals that would be compatible with Keplerian motion on KOBE-1. We carried out a model comparison within a Bayesian framework to ensure the significance of the planetary model over alternative configurations of lower complexity. We also inspected two available TESS sectors in search of planetary signals.

Results. We identified two signals: at Pb = 8.5 d and Pc = 29.7 d. We confirmed their planetary nature through ruling out other non-planetary configurations. Their minimum masses are 8.80 ± 0.76 M⊕ (KOBE-1 b), and 12.4 ± 1.1 M⊕ (KOBE-1 c), corresponding to absolute masses within the planetary regime at a high certainty (>99.7%). By analyzing the sensitivity of the CARMENES time series to additional signals, we discarded planets above 8.5 M⊕ within the habitable zone. We identified a single transit-like feature in TESS, whose origin is still uncertain, but still compatible within 1σ with a transit from planet c.

Conclusions. The KOBE-1 multi-planetary system, consisting of a relatively quiet K7-dwarf hosting two sub-Neptune-minimum- mass planets, establishes the first discovery from the KOBE experiment. We have explored future prospects for characterizing this system, concluding that Gaia DR4 will be insensitive to their astrometric signature. Meanwhile, nulling interferometry with the Large Interferometer For Exoplanets (LIFE) mission could be capable of directly imaging both planets and characterizing their atmospheres in future studies.
Dark matter fraction derived from the M31 rotation curve
Authors: Hammer F. , Yang Y. B. , Amram P. , Chemin L. , Mamon G. A. , Wang J. L. , Akib I. , Jiao Y. J. , Wang H. F.
Published: February 2025

Mass estimates of a spiral galaxy derived from its rotation curve must account for the galaxy’s past accretion history. There are several lines of evidence indicating that M31 experienced a major merger 2 to 3 Gyr ago. In this work, we generated a dynamical model of M31 as a merger remnant that reproduces most of its properties, including from the central bar to the outskirts. The model accounts for M31’s past major merger and reproduces the details of its rotation curve, including its 14 kpc bump and the observed increase of velocity beyond 25 kpc. We find non-equilibrium and oscillatory motions in the gas of the merger-remnant outskirts caused by material in a tidal tail returning to the merger remnant. A total dynamical M31 mass of 4.5 × 1011 M⊙ within 137 kpc was obtained after scaling it to the observed HI rotation curve. Within this radial distance, we find that 68% of the total dynamical mass is dark.
Numerical study of ice crystal movement and melting in rotating blade channels
Authors: ZHANG Lifen , ZHAO Jianhui , YU Bangtuo , LYU Yaguo , LIU Zhenxia
Published: February 2025

The motion and melting characteristics of ice crystals in the rotating blade channel are investigated. Firstly, the method of calculating local collection coefficient is proposed for rotating parts. Secondly, the numerical simulation of ice crystal movement and melting in the rotating blade channel is carried out to analyze the influence of ice crystal geometry parameters and working condition changes on the ice crystal impact location and ice crystal melting rate. The results show: ① the collection coefficient of ice crystal at the leading edge of the blade is the highest, the trailing edge of the pressure surface is also the area where the ice crystal may impact, while the root of the blade is less affected by centrifugal force; ② the larger the ice crystal content, the larger the collection rate of ice crystal at the same position on the blade surface; the larger the ice crystal diameter, the larger the collection rate of ice crystal at the suction surface, the smaller the collection rate of ice crystal at the pressure surface; the higher the non-spherical degree of ice crystal, the more likely the ice crystal will impact on the pressure surface; the higher the non-sphericity of ice crystals, the easier it is for the ice crystals to impact on the pressure surface; when the rotational speed decreases, the ice crystals are more likely to impact on the suction surface, and the impact area is also larger and closer to the blade root; ③ The melting ice crystals impacting on the pressure surface are more widely distributed, and the pressure surface is more prone to ice crystal adhesion and freezing than the suction surface; while, there are also melted ice crystals on the suction surface near the trailing edge, where ice crystals may also adhere; the larger the ice crystal content, the larger the diameter, the larger the non-sphericity, and when the rotational speed increases, the melting rate of ice crystals decreases.
Topology optimization design of wing rib based on bi-directional evolutionary structural optimization method
Authors: HUANG Chenglei , FAN Qingming , LIU Hongjun , YU Boya
Published: February 2025

As an important part of the solar UAV, the weight of the wing occupies the majority of the proportion of the overall structure. However, the solar UAV has very strict requirements on the weight of its own structure. The topological optimization of the wing fin structure can be usually carried out to meet the structural strength and reduce the quality of the wing structure as much as possible, which is of great significance for improving the overall performance of the UAV. Taking the wing of a solar UAV with high aspect ratio as the research object, based on the objective function of the minimum strain energy of the whole wing and the volume fraction of the wing fin, the topology optimization design of the wing fin was carried out by using the bidirectional progressive structure optimization method. The internal materials of the wing fin were added or deleted reasonably according to the element stress, and the optimized wing fin was redesigned. Finally, the overall weight of the wing was reduced by 29.7%. The results show that this method can obtain the optimal configuration of the wing fin, effectively improve the utilization rate of materials, and greatly reduce the weight of the wing structure, which provides a certain reference for the lightweight research of solar UAV.
Reliability analysis of landing gear operation based on improved support vector machine-based decomposed-coordinated
Authors: ZHANG Lei , CHEN Junyu , FENG Jun , FENG Yunwen , LIU Lei
Published: February 2025

An improved support vector machine-based decomposed-coordinated (ISVM-DC) is proposed to improve the accuracy and efficiency of landing gear operation reliability analysis. The decomposition and coordination strategy decompose the composite failure problem into multiple mathematical models, and then builds the relationship between the total output response and the variable parameters according to the hierarchical relationship. The improved support vector machine aims to optimize the performance of the limit state function in each sub-mathematical model by applying multi-stage adaptive point position control of hyperparameters. Taking the wheel brake temperature difference of main landing gear as an example, the verification of the proposed method in reliability modelling and simulation is carried out. The case results show that the proposed ISVM-DC can accurately decompose and coordinate the architecture of landing gear operational failure, and efficiently construct and solve the reliability performance function.
Numerical and experimental investigation of the steering performance of a ringsail parachute
Authors: HUANG Yunyao , WU Shiqing , WANG Yongbin , ZHANG Yang
Published: February 2025

In order to investigate the steering performance of the ringsail parachute, the effect of two different steering approaches on the aerodynamic and gliding characteristics of a ringsail parachute is analyzed by using the numerical simulation and wind tunnel test. The first steering approach is to make ringsail parachute drift off course by changing the length of the suspension lines, while the second one is to make ringsail parachute close up by changing the length of the reefing control lines. Numerical simulation is performed using the arbitrary Lagrangian-Eulerian fluid-structure interaction method, and the corresponding wind tunnel test is conducted to compare with the results of numerical simulation. The results show that the first steering approach can effectively change the drag coefficient of the ringsail parachute, i.e., the drag coefficient is greatly reduced as the length of the suspension lines is shortened, and in the meanwhile, compared with the non-steering ringsail parachute, the improvement of the gliding ratio can be up to 80%, which demonstrates the benefits for the gliding ability; While the second steering approach has an significant impact on the drag characteristics of the ringsail parachute, i.e., as the length of reefing control lines is shortened, the reefing effect is enhanced and the drag characteristics is reduced, whereas compared with the non-steering ringsail parachute, the improvement of the gliding ratio only reaches up to 10%, which demonstrates that the reefing control has little effect on the gliding performance. Comparison between the results obtained by the wind tunnel test and numerical simulation shows that the trend of drag coefficient and drag characteristic curves are basically consistent, and the relative error between them is within 20%, indicating the reliability of the numerical method.
Study on the microstructures of SLM IN718 based on solidification model
Authors: XU Wei , WAN Jie , CHEN Yuzeng
Published: February 2025

During the selective laser melting(SLM) process of IN718, different process parameters have a significant impact on its microstructure. To analyze the interrelationship between process parameters and microstructure, in this study, the relationship between primary dendrite arm spacing(PDAS) and process parameters was established through a solidification model, and the accuracy of the model was verified through experiments. Both the calculation results and the experimental results show that when the laser power increases, PDAS increases accordingly; while as the scanning speed and hatch distance increase, PDAS decreases accordingly; and from the bottom to the top of the molten pool, PDAS gradually increases. At the same time, the top of the molten pool is more sensitive to the change of process parameters, while the middle and bottom are relatively insensitive. These research results are of certain guiding significance for the microstructure regulation of IN718.
RGB-D salient object detection based on BC2 FNet network
Authors: WANG Feng , CHENG Yongmei
Published: February 2025

In the face of complex scene images, the introduction of depth information can greatly improve the performance of salient object detection. However, up-sampling and down-sampling operations in neural networks maybe blur the boundaries of objects in the saliency map, thereby reducing the performance of salient object detection. Aiming at this problem, a boundary-driven cross-modal and cross-layer fusion network (BC2FNet) for RGB-D salient object detection is proposed in this paper, which preserves the boundary of the object by adding the guidance of boundary information to the cross-modal and cross-layer fusion, respectively. Firstly, a boundary generation module is designed to extract two kinds of boundary information from low-level features of RGB and depth modalities, respectively. Secondly, a boundary-driven feature selection module is designed, which is dedicated to simultaneously focusing on important feature information and preserving boundary details in the process of RGB and depth modality fusion. Finally, a boundary-driven cross-layer fusion module is proposed which simultaneously adds two kinds of boundary information in the process of up-sampling fusion on adjacent layers. By embedding this module into the top-down information fusion flow, the predicted saliency map can contain accurate objects and sharp boundaries. Simulation results on five standard RGB-D data sets show that the proposed model can achieve better performance.
Versorgung sichern
Authors: Lukuc Sarah
Published: February 2025

Das Bundeskabinett hat im Dezember den Entwurf zum Gesetz zur Stärkung der Pflegekompetenz beschlossen. Pflegekräfte sollen damit mehr Kompetenzen bei der Patientenversorgung bekommen.
Step by step
Authors: Keck Michael
Published: February 2025

Das Programm STEP ONE (Strukturiertes Einarbeitungskonzept Pflege – Onboarding Excellence) am Universitätsklinikum Freiburg basiert auf den 3 Säulen Pflegemanagement, -pädagogik und -wissenschaft. Die Erfolge durch individuelle Einarbeitung nach dem Tandemprinzip, Hospitationen, Reflexionsgespräche und Fortbildungen können sich sehen lassen.
A Retrospective Study Using a Novel Body-Shift Implant Design with a Novel Alloplastic Particulate Grafting Material in Immediate Extraction Sockets
Authors: O'Hooley Dominic B. , Nicolopoulos Costa , Worthing Mark G. , Yuvanoglu Petros , Melas Fotis , Fairbairn Peter J. M. , Kurtzman Gregori M.
Published: February 2025

With resurgence in immediate tooth replacement therapy (ITRT) as a method of preserving both hard and soft tissues for improved aesthetic outcomes, this multicenter, prospective study looked at two novel products and their effect on those outcomes. Thirty-one maxillary single-tooth implants were included, of these 54.8% were central incisors, 25.8% lateral incisors, and 19.4% canines. Three complications were reported; one case nondraining fistula, one case a nonseated provisional restoration, and one case a fractured zirconia abutment. The definitive restorations were delivered between 4 hours and 18 months postimplant placement and all restorations were screw-retained. ITRT is frequently utilized when a tooth to be extracted will be replaced by an implant aiding in preservation of the hard and soft tissue that may be lost due to resorption during healing of the extraction socket. The narrower neck region of the Inverta implant results in thicker crestal bone around the implant, where loading under function occurs. Grafting that area around the implant at placement with EthOss results in more predictable bone stability in the long term.
Dynamical analysis and preassigned-time intermittent control of memristive chaotic system via T–S fuzzy method
Authors: Wang Qiming , Wang Leimin , Wen Wudi , Li Yan , Zhang Guodong
Published: February 2025

In this paper, we propose a novel fourth-order memristive chaotic system (MCS), in which both its dynamical behaviors and the preassigned-time stabilization problem are analyzed. First, the dynamical behaviors of the proposed MCS are studied in detail, such as the infinite unstable equilibrium points, the chaotic attractor, the Lyapunov exponents, the Kaplan–Yorke dimension, and the bifurcation. Then, the T–S fuzzy method is employed to characterize the MCS, and a simpler model is built to deal with the nonlinearity caused by the memristor in the MCS. In addition, two intermittent controllers are proposed to guarantee the preassigned-time stability and the settling time, which can be set freely, independent of system parameters and initial state. Finally, numerical simulations provide solid confirmation for the validity of these theoretical results.
Exploring complex dynamics in a Ricker type predator–prey model with prey refuge
Authors: Alsulami Ibraheem M. , Ahmed Rizwan , Ashraf Faraha
Published: February 2025

This study examines the complexities of a discrete-time predator–prey model by integrating the impact of prey refuge, with the goal of providing a more realistic understanding of predator–prey interactions. We explore the existence and stability of fixed points within the model, offering a thorough examination of these critical aspects. Furthermore, we use center manifold and bifurcation theory to thoroughly analyze the presence and direction of period-doubling and Neimark–Sacker bifurcations. We also provide numerical simulations to validate our theoretical findings and demonstrate the intricacy of the model. The findings suggest that the inclusion of prey refuge has a notable stabilizing impact on the predator–prey model, hence enhancing the overall stability and resilience of the ecosystem.
Formation and stability of Ge nanocrystals in polymorph converted Ga2O3: Temperature-driven journey
Authors: García-Fernández J. , Kjeldby S. B. , Zeng L. J. , Olsson E. , Vines L. , Prytz Ø.
Published: February 2025

The influence of germanium (Ge) implantation on β-Ga2O3 followed by ex situ annealing through polymorph conversion in air at various temperatures (600–1100 °C) is studied. Atomic resolution aberration-corrected scanning transmission electron microscopy is employed to examine the structural and microstructural changes induced by the annealing process. The results show that the thermal annealing process leads to the formation of Ge nanocrystals, which subsequently disappear, leaving nano-voids inside the Ge-doped Ga2O3 matrix. In addition, the microstructure displays distinct crystallographic relationships in annealed β-Ga2O3 forming layers with well-defined interfaces. This work reveals the unique effects of Ge-implantation, demonstrating the possible functionalization of Ga2O3 with Ge nanocrystals.
Performance characterization and comparison of two- and tri-electrode configurations in a DBD plasma channel thruster utilizing volumetric and surface discharge mechanisms
Authors: Ahangar Mahdy , Alebrahim Narges , Ahmadian Sarvgol
Published: February 2025

This study investigates performance enhancements in dielectric barrier discharge (DBD) plasma channel thrusters through the implementation of volumetric discharge (VD) mechanism. To investigate these enhancements, two configurations were examined: a conventional two-electrode design and a novel tri-electrode design. Experimental results demonstrate that the VD mechanism significantly enhances thrust generation in both configurations, with increases reaching up to 312% and 500% for the two- and tri-electrode designs, respectively, compared to their surface discharge counterparts. These significant thrust increases are accompanied by substantial improvements in thruster effectiveness, reaching 290% and 102% for the respective configurations. Notably, a maximum thruster effectiveness of 0.31 mN/W was achieved. Analysis of the observed performance trends revealed a strong power-law dependence of performance parameters on applied voltage. Furthermore, it demonstrates a strong correlation between thrust enhancement and the shift from volumetric to surface discharge characteristics, indicating that the VD mechanism effectively utilizes the applied power for efficient plasma generation and momentum transfer. These findings highlight the potential of the VD mechanism in combination with the tri-electrode design for developing high-thrust DBD plasma thrusters for micro-propulsion applications.
Nonlinear Kondo transport through serially coupled double quantum dots
Authors: Cheng YongXi , Gao Jie , Liao Yuan , Li ZhenHua , Wei JianHua , Yan YiJing
Published: February 2025

We study the transport property through the serially coupled double quantum dots (DQDs) system with Kondo resonance based on the dissipation equation of motion theory. A nonlinear behavior of the transport current is exhibited due to the competition between the interdot coupling strength of the two QDs and the Kondo effect. With the increase in interdot coupling strength, the transport current first increases at low interdot couplings and then decreases with the strong interdot couplings. The reason is that the interdot coupling strength will result in a continuous evolution from the Kondo singlet state of individual QDs to the spin singlet state forming between the two QDs. Moreover, we define the physical quantity ∂G/∂t as the differential function of differential conductance G with respect to interdot coupling strength t. The nonlinear transport behavior and the physical quantity ∂G/∂t with differential conductance at different bias voltages can be used to detect the potential Kondo resonance in the nonequilibrium transport experiments.
Experimental study on vortex-induced vibration and aerodynamic characteristics of a closed box girder with L-shaped deflectors
Authors: Zhao Xue , An Bang , Yang Xin , Li Jiawu , Bai Hua
Published: February 2025

This study investigates the vortex-induced vibration (VIV) performance of closed-box girders with and without L-shaped deflectors through synchronized vibration and pressure measurements in wind tunnel tests. Spectral proper orthogonal decomposition (SPOD) was employed to analyze the fluctuating wind pressure field during the VIV process. The results showed that the addition of L-shaped deflectors intensified vertical bending VIV while slightly suppressing torsional VIV by significantly altering the aerodynamic characteristics of the girder surface. Specifically, the deflectors increased the contributions of aerodynamic forces from the lower surface and windward-side top plate to VIV forces, leading to greater vertical bending vibration amplitudes. Conversely, they reduced the contributions from the windward top plate and inclined web, resulting in decreased torsional vibration amplitudes. SPOD analysis revealed that the first-order mode dominated the VIV process. The deflectors enhanced the peak intensity of acoustic wave modes on the upper surface during the peak of vertical bending VIV while reducing the wavenumber and weakening the modal evolution intensity during the peak of torsional VIV.
RADE: A reduced approach to density-functional expansion
Authors: Tu Yaoquan , Laaksonen Aatto
Published: February 2025

Density-functional theory (DFT) has become an extensively and successfully used tool in the studies of molecules and materials. However, DFT remains computationally expensive, especially for exploring the conformational space of molecular systems comprising a few hundred atoms. Here, we present a Reduced Approach to Density-functional Expansion (RADE), devised to substantially reduce the computational cost of standard DFT methods. RADE can be implemented fully non-empirically as an efficient first-principles electronic structure method. Preliminary results for molecules containing elements H, C, N, and O indicate that this method can, in general, reproduce well the results from standard DFT calculations.
A simple method to find temporal overlap between THz and x-ray pulses using x-ray-induced carrier dynamics in semiconductors
Authors: Kubota Yuya , Suzuki Takeshi , Owada Shigeki , Tamasaku Kenji , Osawa Hitoshi , Togashi Tadashi , Okazaki Kozo , Yabashi Makina
Published: February 2025

X-ray-induced carrier dynamics in silicon and gallium arsenide were investigated through intensity variations of transmitted terahertz (THz) pulses in the pico- to microsecond timescale with x-ray free-electron laser and synchrotron radiation. We observed a steep reduction in THz transmission with a picosecond scale due to the x-ray-induced carrier generation, followed by a recovery on a nano- to microsecond scale caused by the recombination of carriers. The rapid response in the former process is applicable to a direct determination of temporal overlap between THz and x-ray pulses for THz pump–x-ray probe experiments with an accuracy of a few picoseconds.
The impact of aging products on modified insulation oil–paper systems
Authors: Ding Can , Liu Youzhi , Sun Qiankun , Liu Luotian
Published: February 2025

With the rapid development of ultra-high voltage transmission projects, higher requirements have been placed on the performance of transformer insulation paper, which directly affects the safe and stable operation of transformers. The transformer oil–paper insulation system is subject to various factors, such as electrical stress, thermal stress, mechanical stress, and humidity, during long-term operation, leading to aging or failure. The aging products (such as H2O, CO2, CH4, and CHOOH) produced during this process will diffuse in the oil–paper insulation system, thereby reducing the insulation performance. This paper uses molecular dynamics simulation to build four models of insulation paper doped with aging products. By studying the diffusion coefficient, free volume, and interaction parameters, the performance parameters of meta aramid insulation paper insulation paper and cellulose insulation paper under aging gases are simulated and compared. It also analyzes whether the addition of nanoclusters can weaken the impact of aging products. In addition, the Confined Layer module is used to build an oil-cellulose mixed oil–paper insulation system. By studying the trajectory movement behavior of different aging gases, the interaction between different gases, and the impact of different types of insulation paper, this paper explores the diffusion behavior of multiple aging gases in the oil–paper insulation system, providing a theoretical basis for the development of a high-performance nano-modified insulation paper.
Shock compression of liquefied gases: Molecular dissociation and radiance change at the sample/LiF interface
Authors: Akram Muhammad Sabeeh , Fan Zhuo-Ning , Zhang Chao-Bo , Liu Qi-Jun , Liu Fu-Sheng
Published: February 2025

This study investigates the behavior of nitrogen and other liquefied gases under shock compression, with a focus on temperature variations and molecular dissociation. Through dynamic compression experiments on liquefied Ar, O2, CO, and N2, we aimed to understand shock-induced cooling and radiance changes at the sample/lithium fluoride (LiF) interface. The experiments were conducted using a setup involving a Doppler pin system and pyrometer to measure shock velocities, pressures, and temperatures across the interface between shocked liquids and LiF. Under the first-shock, molecular liquids experienced partial dissociation due to a rapid rise in pressure, density, and temperature within nanoseconds. Upon re-shocking at the sample/LiF interface, a radiance drop was observed for all liquids except Ar. Our data analysis suggests that the cooling effect is likely due to a chemical reaction occurring at the interface between reactive species, produced during the initial shock, and the layer of LiF at the surface under re-shock conditions. One probable interpretation is that this reaction formed a thin, partially transparent layer on the LiF, which absorbed a significant portion of the radiation emitted by the shocked fluid. Thus, the observed temperature drop in re-shocked liquid nitrogen is likely attributable to radiation reduction.
Comprehensive thermal property measurement of semiconductor heterostructures using the square-pulsed source (SPS) method
Authors: Song Shangzhi , Chen Tao , Jiang Puqing
Published: February 2025

Accurate thermal property measurements of multilayer heterostructures, especially in wide-bandgap semiconductor devices, are essential for optimizing device performance. While traditional methods, such as Time-Domain Thermoreflectance (TDTR) and Frequency-Domain Thermoreflectance (FDTR), are effective for thin films and interfaces, they encounter challenges with complex multilayer heterostructures. This paper presents an optical Square-Pulsed Source (SPS) method for comprehensive thermal property measurements of heterostructures. By combining the advantages of TDTR and FDTR, the SPS technique enables time-resolved signal observation and offers an adjustable heating frequency range from 1 Hz to 10 MHz. This allows for the simultaneous determination of multiple parameters, including the thermal conductivity and the heat capacity of each layer and the substrate, and interfacial thermal conductance between layers. Applied to epitaxially grown GaN/Si and ɛ-Ga2O3/SiC heterostructures, the SPS method demonstrates its simplicity, robustness, and precision for comprehensive thermal property analysis, essential for effective thermal management in advanced electronic devices.
Numerical simulation method of multi-fracture fracturing coupling proppant transport
Authors: Huang Luoyi , Sheng Guanglong , Zhao Hui , Ma Jialing , Zhou Yuhui
Published: February 2025

Hydraulic fracturing is a critical technology for the efficient development of unconventional reservoirs. It involves multi-physics coupling, making its numerical simulation an extremely challenging task. In this paper, an efficient hydraulic fracturing simulator is developed by integrating a simplified proppant transport model into the multi-fracture fracturing framework. In the fracture propagation model, the finite volume method is used to solve fluid flow, while the displacement discontinuity method is employed rock deformation. Proppant transport is realized by the simplified Eulerian–Eulerian method, which only needs to consider the one-dimensional fluid flow. The high-precision weighted essentially non-oscillatory scheme is used to solve the nonlinear proppant transport equation. Compared with the Eulerian–Lagrangian method, the proposed method enhances simulation efficiency by 2–3 orders of magnitude. The numerical model is verified through physical experiments and fracture analytical solutions. The fracture propagation and proppant transport models are implemented via a unidirectional coupling strategy. First, the fully coupled model calculates the fracture morphology, followed by the computation of proppant distribution at each time step. Four cases were established to analyze the effects of fracturing fluid injection time, injection rate, fracture cluster spacing, and the number of fracture clusters on the industrial-scale proppant distribution in fractures. This method can be applied to large-scale fracturing simulation, optimization of fracturing parameters and other fields requiring high computational efficiency.
Numerical analysis of blade height ratio effects on mixing efficiency and energy consumption in triple-blade concentric double-helix static mixers
Authors: Menni Younes , Sari Hassoun Zakaria , Kaid Noureddine , Alqahtani Ali Ahmed , Alqahtani Sultan , Jazaa Yosef
Published: February 2025

This work aims to find the optimum value of blade height ratio (R) for improving mixing performance and energy consumption of a Triple-Blade Concentric Double-Helix Static Mixer. In this study, mixing of two fluids at different concentrations subjected to laminar flow conditions is numerically analyzed by using finite element-based Computational Fluid Dynamics simulations. Different values of the R parameter are considered in a wide range of Reynolds numbers (Re = 200–1000). This analysis then carried out an in-depth study of R's effect on mixing performance, strength segregation, mixing index, helicity, velocity profile, pressure drop, pumping power, and efficiency. The findings showed that a blade height ratio of R = 2/3 gave the highest mixing index (MI), with the maximum value of 0.99 at a Re number of 600, which showed the best mixing performance in the channel. Helicity visualization also showed complex helicity patterns with increased vortex interactions for the 2/3 configuration. This geometry gave an improvement in MI by about 17.85% over Triple-Blade Concentric Single-Helix Static Mixer (TB-CSH-SM) with R = 0 at Re = 600. It is also important to mention that increasing the R value leads to an increase in pressure drop and, consequently, an increase in pumping energy consumption. Although R = 2/3 gives the best mixing performance, the energy consumption is relatively higher than that for R = 0, which has the lowest power input but a lower MI. The investigation concludes that R = 2/3 represents a balanced solution since it realizes an optimum mixing performance with a moderate energy consumption and hence is suitable for applications requiring an efficient compromise between mixing quality and energy consumption.
Enhanced plasma wave excitation in a tapered plasma channel through chirped laser beatwaves
Authors: Arefnia M. , Kim S. , Lee C. , Ghorbanalilu M. , Suk H.
Published: February 2025

The excitation of plasma waves by the beatwave of two-color laser beams within a tapered plasma channel has been investigated both analytically and through particle-in-cell (PIC) simulations. This study presents a promising approach for beatwave accelerators. The design aims to achieve a more stable and enhanced plasma wave amplitude, even under non-resonant conditions, compared to untapered channels. For the analytical description, we solved the plasma wave equation generated by two beating laser beams propagating through a tapered channel with a linear radial density profile. The study further validates its results by comparing the analytical predictions with PIC simulations of the beatwave phenomenon in the tapered channel. The findings confirm that this design significantly enhances plasma wave amplitude compared to untapered channels. In addition, we demonstrated that employing a chirped laser pulse with a fast rise time can significantly increase the strength of the plasma wave.
Facile synthesis of vanadium oxide thin films by atomic layer deposition and post-annealing
Authors: Sun Y. K. , Zhang G. D. , Hu L. , Zhang R. R. , Wei R. H. , Zhu X. B. , Sun Y. P.
Published: February 2025

We report the facile synthesis of vanadium oxide (VOx) thin films on sapphire substrates by atomic layer deposition (ALD) and post-annealing. Amorphous VOx thin films are grown by ALD employing tetrakis[ethylmethylamino]vanadium and ozone as precursors. Subsequent post-annealing of the as-grown VOx thin films at 500 °C in atmospheres of air, 1 Pa O2, and vacuum (10−4 Pa) could, respectively, result in the crystallization of V2O5, VO2, and V2O3 phases, as verified by x-ray diffraction and Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) reveals that the valence states of vanadium in the annealed thin films exhibit dramatic changes with the variation of annealing atmosphere toward the targeted phases. The VO2 thin film exhibits a sharp metal–insulator transition (MIT) near 340 K with a resistivity change exceeding three orders of magnitude. The V2O3 thin film features a characteristic MIT with obvious thermal hysteresis between the cooling and warming processes, whereas the V2O5 thin film is highly insulating. The spectral weight near the Fermi level revealed by the XPS in the valence band region coincides with the changes of VOx phases and consequent transport properties due to post-annealing. Our results demonstrate that the combination of ALD and post-annealing provides a facile method for the synthesis of multivalent VOx thin films for practical applications.
Nanoscopic structural and optical investigations on blue InGaN single quantum wells serving as layers beneath efficient red active layers
Authors: Zhang Zhaozong , Ishii Ryota , Shojiki Kanako , Funato Mitsuru , Ohkawa Kazuhiro , Iida Daisuke , Kawakami Yoichi
Published: February 2025

In state-of-the-art red InGaN light-emitting diodes (LEDs), an InGaN-based blue single quantum well (SQW) is used as an underlying layer to improve the red emission efficiency. However, the role of blue SQW is not fully understood. This study investigates the structural and optical properties of blue InGaN SQW by atomic force microscopy (AFM) and photoluminescence (PL) spectroscopy under scanning near-field optical microscopy (SNOM). The AFM images reveal deep and shallow V-pits, corresponding to screw and mixed threading dislocations (TDs). The SNOM-PL intensity image illustrates that all the V-pits correspond to dark spots. We also observe dark spots not associated with the V-pits; given the correspondence between the dark spot density and the edge TD density estimated via x-ray diffraction measurement, these dark spots likely originate from edge TDs. Unlike previous studies, we find that TDs act as nonradiative recombination centers (NRCs) in recent blue SQW, most likely because of the reduction of point defects by InGaN/GaN superlattices. Edge, screw, and mixed TDs have nearly the same impact on the integrated PL intensity of the blue InGaN SQW. Given the correlation of dark emission positions between the blue and red emissions in hybrid red InGaN LEDs in our prior study, all the TDs should function as NRCs in the red emission. The comparable dark spot density between the blue and red SQW suggests that blue SQW suppresses the generation of NRCs in red SQW.
Perspective on phase change composites in high-efficiency solar-thermal energy storage
Authors: Mai Zhizhao , You Kaijie , Chen Jianyong , Sheng Xinxin , Chen Ying
Published: February 2025

To clarify future research directions, this study first analyzes the heat transfer process of solar-thermal conversion and then reviews solar-thermal phase change composites for high-efficiency harnessing solar energy. The focus is on enhancing heat absorption and conduction while aiming to suppress reflection, radiation, and convection. Most advancements have concentrated on improving absorption and thermal conductivity, while reducing the aforementioned unfavorable processes remains less explored. In the current research, the best results show that the solar-thermal conversion efficiency has approached the theoretical limit (100%), and a typical thermal conductivity has reached 33.5 W/(m·K). However, further enhancement of the absorption and conduction remains a challenge, highlighting the need for structural modifications and grafting. Other factors hindering conversion efficiency have received limited attention and warrant further in-depth investigation, with the potential to reduce reliance on fossil fuels and contribute to environmental sustainability.