bluuebunny/crossref_metadata_2025 huggingface dataset:
Un dispositif de formation initiale innovant sur la réflexivité des masseurs-kinésithérapeutes en situation clinique
Authors: Guyet Delphine , Saillot Eric
Published: April 2024

Contexte et problématique : Cet article s’appuie sur l’analyse d’un dispositif de formation innovant, issu d’une recherche-action, mis en place en formation initiale de masso-kinésithérapie (MK), visant à stimuler la réflexivité des étudiants en situation clinique. Il s’inscrit dans l’ingénierie didactique professionnelle qui vise à articuler des analyses du travail pour la formation, et des analyses de la formation pour le travail. L’innovation pédagogique s’est notamment appuyée sur la modélisation systémique « penser-dire-faire-observer/écouter » qui vise l’analyse des activités d’ajustement. L’objectif pédagogique visé est l’analyse réflexive de situations vécues en stage et la mise en lumière des indicateurs sur lesquels les étudiants s’appuient pour réaliser leur activité professionnelle avec le patient. Objectif : Comprendre comment les étudiants en MK s’ajustent face aux patients qu’ils rencontrent en stage et quelles analyses réflexives ils en font, afin de favoriser des prises de conscience et l’émergence de stratégies d’action. Méthodes : Cette recherche appréhende une séquence pédagogique de quatre journées, dont l’une des originalités est le croisement de regards entre des cadres théoriques des sciences de l’éducation et de la formation (SDEF) et des cadres théoriques de la formation des masseurs-kinésithérapeutes. Les traces d’activités produites à l’issue de ce dispositif ont été étudiées à partir des productions écrites de travaux de groupes (enregistrement des diapositives), des supports des présentations orales ou des remarques dans les échanges (prises de notes des formateurs). Résultats : Le détour réalisé grâce à ce dispositif innovant d’analyse des co-ajustements permet d’amorcer un virage réflexif des étudiants et de les rendre sensibles et attentifs à des éléments singuliers transmis par le patient et produits au cours de la séance, que ce soit par le contact corporel ou par les interactions langagières. Conclusion : Avec l’intégration universitaire en cours, les deux approches « santé » et issues des sciences de l’éducation et de la formation se complètent et peuvent s’enrichir réciproquement de ces collaborations dans un rapport gagnant-gagnant.
Empowerment von Seeleuten durch Informations- und Kommunikationstechnologien
Authors: Reck Chiara , Oldenburg Marcus
Published: April 2024

Wenngleich das Thema Mental Health (MH) in der Schifffahrt in den letzten Jahren zunehmend an Aufmerksamkeit gewonnen hat, haben Symptome, die auf Depressionen, Angststörungen oder andere psychische Störungen hinweisen, unter Seeleuten zugenommen 1. Zurückzuführen ist diese Entwicklung u. a. auf die COVID-19-Pandemie sowie auf wirtschaftliche und politische Krisen. Trotzdem sind MH-Probleme oftmals ein Tabuthema unter Seeleuten. Grund hierfür sind Sorgen, ihre Seetauglichkeit und somit ihre Weiterbeschäftigung zu verlieren. Informations- und Kommunikationstechnologien (IKT) bieten neue Chancen, Seeleute dabei zu unterstützen, ihre Fähigkeiten zur individuellen Gesundheitsförderung zu verbessern.
Severity Identification of Graves Orbitopathy via Random Forest
Algorithm
Authors: Wang Minghui , Li Gongfei , Dong Li , Hou Zhijia , Zhang Ju , Li Dongmei
Published: April 2024

This study aims to establish a random forest model for detecting the severity of
Graves Orbitopathy (GO) and identify significant classification factors. This is
a hospital-based study of 199 patients with GO that were collected between
December 2019 and February 2022. Clinical information was collected from medical
records. The severity of GO can be categorized as mild, moderate-to-severe, and
sight-threatening GO based on guidelines of the European Group on Graves’
orbitopathy. A random forest model was constructed according to the risk factors
of GO and the main ocular symptoms of patients to differentiate mild GO from
severe GO and finally was compared with logistic regression analysis, Support
Vector Machine (SVM), and Naive Bayes. A random forest model with 15 variables
was constructed. Blurred vision, disease course, thyroid-stimulating hormone
receptor antibodies, and age ranked high both in mini-decreased gini and mini
decrease accuracy. The accuracy, positive predictive value, negative predictive
value, and the F1 Score of the random forest model are 0.83, 0.82, 0.86, and
0.82, respectively. Compared to the three other models, our random forest model
showed a more reliable performance based on AUC (0.85 vs. 0.83 vs. 0.80 vs.
0.76) and accuracy (0.83 vs. 0.78 vs. 0.77 vs. 0.70). In conclusion, this study
shows the potential for applying a random forest model as a complementary tool
to differentiate GO severity.
Standardization of Emergency Department Clinical Note Templates: A Retrospective Analysis across an Integrated Health System
Authors: Evans Christopher S. , Bunn Barry , Reeder Timothy , Patterson Leigh , Gertsch Dustin , Medford Richard J.
Published: April 2024

Background and Objective Clinical documentation is essential for conveying medical decision-making, communication between providers and patients, and capturing quality, billing, and regulatory measures during emergency department (ED) visits. Growing evidence suggests the benefits of note template standardization; however, variations in documentation practices are common. The primary objective of this study is to measure the utilization and coding performance of a standardized ED note template implemented across a nine-hospital health system.

Methods This was a retrospective study before and after the implementation of a standardized ED note template. A multi-disciplinary group consensus was built around standardized note elements, provider note workflows within the electronic health record (EHR), and how to incorporate newly required medical decision-making elements. The primary outcomes measured included the proportion of ED visits using standardized note templates, and the distribution of billing codes in the 6 months before and after implementation.

Results In the preimplementation period, a total of six legacy ED note templates were being used across nine EDs, with the most used template accounting for approximately 36% of ED visits. Marked variations in documentation elements were noted across six legacy templates. After the implementation, 82% of ED visits system-wide used a single standardized note template. Following implementation, we observed a 1% increase in the proportion of ED visits coded as highest acuity and an unchanged proportion coded as second highest acuity.

Conclusion We observed a greater than twofold increase in the use of a standardized ED note template across a nine-hospital health system in anticipation of the new 2023 coding guidelines. The development and utilization of a standardized note template format relied heavily on multi-disciplinary stakeholder engagement to inform design that worked for varied documentation practices within the EHR. After the implementation of a standardized note template, we observed better-than-anticipated coding performance.
Hypoalgesia and Conditioned Pain Modulation in Blood Flow Restriction
Resistance Exercise
Authors: Yang Jinghui , Rolnick Nicholas , Merriwether Ericka , Rao Smita
Published: April 2024

We compared the magnitude of exercise-induced hypoalgesia and conditioned pain
modulation between blood-flow restriction (BFR) resistance exercise (RE) and
moderate-intensity RE. Twenty-five asymptomatic participants performed
unilateral leg press in two visits. For moderate-intensity RE, subjects
exercised at 50% 1RM without BFR, whereas BFR RE exercised at 30% 1RM with a
cuff inflated to 60% limb occlusion pressure. Exercise-induced hypoalgesia was
quantified by pressure pain threshold changes before and after RE. Conditioned
pain modulation was tested using cold water as the conditioning stimulus and
mechanical pressure as the test stimulus and quantified as pressure pain
threshold change. Difference in conditioned pain modulation pre- to post-RE was
then calculated. The differences of RE on pain modulations were compared using
paired t-tests. Pearson’s r was used to examine the correlation between
exercise-induced hypoalgesia and changes in conditioned pain modulation. We
found greater hypoalgesia with BFR RE compared to moderate-intensity RE
(p=0.008). Significant moderate correlations were found between exercise-induced
hypoalgesia and changes in conditioned pain modulation (BFR: r=0.63,
moderate-intensity: r=0.72). BFR RE has favorable effects on pain modulation in
healthy adults and the magnitude of exercise-induced hypoalgesia is positively
correlated with conditioned pain modulation activation.
Brønsted Acid Catalyzed Intramolecular Allylic Substitution Reaction of Allylic Alcohols: A Facile Synthesis of 2-Vinylchromans
Authors: Ding Chang-Hua , Xu Bin , Li Yun-Fan , Xi Yu-Ting , Hu Kai-Ji , Tan Qitao
Published: April 2024

Brønsted acid catalyzed intramolecular allylic substitution reaction of secondary and tertiary allylic alcohols has been developed. A variety of 2-vinylchromans were efficiently prepared in moderate to excellent yields. The given method features wide substrate scope, operational simplicity, and mild, metal-free reaction conditions. The practicability of the method was demonstrated by a gram-scale reaction and further derivations of the product. Preliminarily studies on a catalytic asymmetric reaction were also undertaken.
Expedient Synthesis of gem-CF2-2H-Thiophenes from Enaminothiones
Authors: Zhang Zhengyu , Jiang Yaojia , Zhang Xinyu , Zhang Xuheng , Fu Rui
Published: April 2024

An expedient and easy-to-handle synthetic platform has been established for the constructing of 2H-thiophenes carrying fluorine atoms through [4+1] cyclization of enaminothiones with fluorinated carbene precursors. This simple reaction system is well compatible with a wide range of substrates under completely metal-free conditions. The resulting 2H-thiophenes can undergo further late-stage modifications to yield a wide range of fluorine-substituted heterocycles.
Contemporary Treatment of Microtia–Atresia
Authors: Romo Thomas , Horne Sylvia , Ferzli George
Published: April 2024

Microtia–atresia is a congenital deformity affecting the external ear and ear canal that can present with varying degrees of severity and morbidity. Treatment occurs along a spectrum and primarily centers on improving aesthetic appearance. Many cases of microtia will not be effectively treated with conservative measures and will require some form of reconstruction. There are several options available, including porous polyethylene implants, autologous rib grafting, and autologous chondrocyte frameworks. Equally significant is the treatment of hearing loss, as many patients with microtia–atresia will have a component of conductive hearing loss. This article aims to comprehensively review contemporary treatment modalities for microtia–atresia and discuss the advantages, disadvantages, and practicality of each. Treatment and reconstruction often take a multidisciplinary and multistaged approach to achieve optimal results, with ideal management determined by each patient's individualized needs.
Signaling to creditors and voters: the determinants of national fiscal rules
Authors: Aaskoven Lasse
Published: April 2024

Fiscal rules are spreading fast among countries. However, why and when governments enact fiscal rules and strengthen their national fiscal legal frameworks are less well understood. This article argues that governments use fiscal rules to signal commitment to fiscal prudence to both creditors and national voters. It investigates this theoretical argument empirically by using a worldwide panel of countries from 1985 to 2015. The empirical analyses find robust evidence that fiscal rules enactment becomes more likely, and that fiscal rules stringency increases when government debt is high and in election years but less evidence that being under an IMF program increases the strength of fiscal rules.
Philosophical practice and its development in China: opportunities and challenges
Authors: Ding Xiaojun , Xie Caifeng , Yu Feng
Published: April 2024

This paper examines the application and evolution of philosophical practice in China, which employs philosophical principles and methods to facilitate insights and address life’s complexities. We aim to bridge the knowledge gap regarding the trajectory and contemporary landscape of China’s philosophical practice and its impact on individual and societal flourishing. Guided by the research question, “How has philosophical practice evolved in China, and what are its challenges and future prospects?” this study adopts a qualitative research methodology, including a literature review, historical analysis, and case studies from Chinese philosophical communities. Findings indicate a burgeoning growth of philosophical practice in China, with traditional Chinese philosophies being adapted to provide practical guidance for contemporary issues. The spread of philosophical practice communities across China reflects a growing embrace of these practices. This paper outlines the hurdles and prospects for philosophical practice, pinpointing opportunities for further research and cross-cultural engagement. The insights furnished by this study offer a framework for scholars, practitioners, and policymakers to enhance philosophical practice’s role in personal growth and societal well-being, both within China and internationally.
AI technologies affording the orchestration of ecosystem-based business models: the moderating role of AI knowledge spillover
Authors: Chin Tachia , Ghouri Muhammad Waleed Ayub , Jin Jiyang , Deveci Muhammet
Published: April 2024

Due to the extraordinary capacity of artificial intelligence (AI) to process rich information from various sources, an increasing number of enterprises are using AI for the development of ecosystem-based business models (EBMs) that require better orchestration of multiple stakeholders for a dynamic, sustainable balance among people, plant, and profit. However, given the nascency of relevant issues, there exists scarce empirical evidence. To fill this gap, this research follows the affordance perspective, considering AI technology as an object and the EBM as a use context, thereby exploring how and whether AI technologies afford the orchestration of EBMs. Based on data from Chinese A-share listed companies between the period from 2014 to 2021, our findings show an inverted U-shape quadratic relationship between AI and EBM, moderated by knowledge spillover. Our results enhance the understanding of the role of AI in configuring EBMs, thus providing novel insights into the mechanisms between AI and a specific business practice with societal concerns (i.e., EBM).
Complete synchronization of three-layer Rulkov neuron network coupled by electrical and chemical synapses
Authors: Ge Penghe , Cheng Libo , Cao Hongjun
Published: April 2024

This paper analyzes the complete synchronization of a three-layer Rulkov neuron network model connected by electrical synapses in the same layers and chemical synapses between adjacent layers. The outer coupling matrix of the network is not Laplacian as in linear coupling networks. We develop the master stability function method, in which the invariant manifold of the master stability equations (MSEs) does not correspond to the zero eigenvalues of the connection matrix. After giving the existence conditions of the synchronization manifold about the nonlinear chemical coupling, we investigate the dynamics of the synchronization manifold, which will be identical to that of a synchronous network by fixing the same parameters and initial values. The waveforms show that the transient chaotic windows and the transient approximate periodic windows with increased or decreased periods occur alternatively before asymptotic behaviors. Furthermore, the Lyapunov exponents of the MSEs indicate that the network with a periodic synchronization manifold can achieve complete synchronization, while the network with a chaotic synchronization manifold can not. Finally, we simulate the effects of small perturbations on the asymptotic regimes and the evolution routes for the synchronous periodic and the non-synchronous chaotic network.
On the existence and stability of stationary solutions for the compressible micropolar fluids
Authors: Cui Wanchen , Cai Hong
Published: April 2024

We consider the existence, uniqueness and nonlinear stability of stationary solutions for the three-dimensional compressible micropolar fluids with the external force of general form. More precisely, with the weighted L2 and L∞ estimates on solutions to the linearized problem, we show the existence and uniqueness of stationary solutions in some suitable function space by the contraction mapping principle. The stability of the steady flow is studied by an elementary energy method.
Symmetry breaking and self-interaction correction in the chromium atom and dimer
Authors: Maniar Rohan , Withanage Kushantha P. K. , Shahi Chandra , Kaplan Aaron D. , Perdew John P. , Pederson Mark R.
Published: April 2024

Density functional approximations to the exchange–correlation energy can often identify strongly correlated systems and estimate their energetics through energy-minimizing symmetry-breaking. In particular, the binding energy curve of the strongly correlated chromium dimer is described qualitatively by the local spin density approximation (LSDA) and almost quantitatively by the Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA), where the symmetry breaking is antiferromagnetic for both. Here, we show that a full Perdew–Zunger self-interaction-correction (SIC) to LSDA seems to go too far by creating an unphysical symmetry-broken state, with effectively zero magnetic moment but non-zero spin density on each atom, which lies ∼4 eV below the antiferromagnetic solution. A similar symmetry-breaking, observed in the atom, better corresponds to the 3d↑↑4s↑3d↓↓4s↓ configuration than to the standard 3d↑↑↑↑↑4s↑. For this new solution, the total energy of the dimer at its observed bond length is higher than that of the separated atoms. These results can be regarded as qualitative evidence that the SIC needs to be scaled down in many-electron regions.
Stretchable stiffness-tuning of liquid metal elastomer triggered by homocrystal seeds
Authors: Wang Ju , Hao Yangtai , Yao Yuchen , Li Jingyi , Song Yujia , Gao Jianye , Liu Jing
Published: April 2024

The hybrid structure of liquid metal units and organic elastomer has huge potential in achieving stretchable and reversible stiffness regulation, while such tuning is often restrained by high energy consumption for liquid metal solidification. Here, we conceive to solve the above challenge through introducing the fully leveraging interaction between supercooled liquid metal and homocrystal seeds within silicone elastomer. It is disclosed that the supercooled liquid metal-elastomer can maintain an extremely stable soft state until the supercooling is eliminated by modulating the mechanical force and elastomer deformation. This circumvents the utilization of intricate refrigeration equipment and offers a highly efficient and concise strategy for stiffness regulation. Moreover, conceptual experiments were performed to demonstrate the practical values of this technology through designing and testing the new shape memory materials, temperature-sensitive switches, and controlled circuits. The solidification mechanisms of supercooled Ga triggered by homocrystal seeds were interpreted. Overall, the present finding has generalized purposes and holds promise to significantly extend the theoretical and technological categories of classical stiffness tunable materials.
Soluto-thermal Marangoni convection in stationary micro-bioreactors on heated substrates: Tool for in vitro diagnosis of PSA
Authors: Rathaur Vidisha Singh , Panda Siddhartha
Published: April 2024

The investigation of antigen-laden droplet deposition patterns on antibody-immobilized substrates has potential for disease detection. Stationary droplets that contain antigens on surfaces immobilized with antibodies can function as microreactors. Temperature modulation enhances reaction efficiency and reduces detection time in droplet-based systems. Thus, the aim of this study is to explore the impact of substrate heating on the structures of protein deposits and the influence of substrate temperature on thermo-solutal Marangoni convection within the droplets. Previous research has explored deposition patterns as diagnostic tools, but limited investigations have focused on the effects of substrate heating on protein deposit structures and the influence of substrate temperature on thermo-solutal Marangoni convection within droplets, creating a knowledge gap. In this study, we conducted experiments to explore how heating the substrate affects the deposition patterns of droplets containing prostate-specific antigen (PSA) on a substrate immobilized with anti-PSA IgG. Additionally, we investigated the thermo-solutal Marangoni convection within these droplets. Our findings reveal distinct deposition patterns classified into dendritic structures (heterogeneous), transitional patterns, and needle-like (homogeneous) structures. The presence of prominent coffee rings and the variation in crystal size across different groups highlight the interplay between thermal and solutal Marangoni advection. Entropy analysis provides insights into structural differences within and between patterns. This work optimizes substrate temperatures for reduced evaporation and detection times while preserving protein integrity, advancing diagnostic tool development, and improving understanding of droplet-based systems.
Johnson–Cook yield functions for cyclotetramethylene-tetranitramine (HMX) and cyclotrimethylene-trinitramine (RDX) derived from single crystal plasticity models
Authors: Sen Oishik , Seshadri Pradeep K. , Rai Nirmal Kumar , Larentzos James , Brennan John , Sewell Tommy , Picu Catalin R. , Udaykumar H. S.
Published: April 2024

High-fidelity constitutive models are critical for accurate meso-scale continuum modeling and prediction of shock initiation of crystalline energetic materials (EMs). While empirically calibrated or atomistic-guided anisotropic elastoplastic models of EM such as cyclotetramethylene-tetranitramine (HMX) and cyclotrimethylene-trinitramine (RDX) capture important micromechanical phenomena (such as dislocation evolution, slip-resistance, and anisotropic elasticity), the computational cost of using anisotropic single-crystal plasticity models can become prohibitive for meso-scale computations of void-collapse and hotspot formation in microstructures. Thermo-mechanically representative, isotropic, pressure, temperature, and rate-dependent material constitutive models are practical alternatives for meso-scale simulations of the shock response of microstructures. To this end, this work constructs physically consistent isotropic plasticity from anisotropic single-crystal plasticity models for HMX and RDX. State-of-the-art crystal plasticity models for HMX and RDX are used to compute the stress states in single crystals oriented in three different directions relative to shocks generated by impact at velocities ranging from 100 to 1000 m/s. Post-shock von Mises stress fields for the three orientations are then used to calibrate the strain-rate hardening coefficient and the reference strain rate for a rate-dependent Johnson–Cook (JC) yield surface model. We compare the pressures and the post-shock von Mises stresses between the JC and the anisotropic models to show that the isotropic computations closely approximate the averaged deformation response of the three different crystal orientations. We then model the interaction of a shock generated by a 500 m/s impact with a 0.5 μm void and show that the pressures and the deviatoric stresses obtained using the isotropic model closely match those computed from anisotropic models for both HMX and RDX. The resulting isotropic J2 plastic flow model for HMX and RDX can be employed to perform meso-scale simulations for energy localization due to shear bands and void collapse in the two materials.
A self-referenced interferometer for in situ cryogenic wafer curvature measurements
Authors: Samuels Margaret H. , Kramer Alan R. , Richardson Christopher J. K.
Published: April 2024

A self-referenced interferometer to measure time-varying curvature in mechanically unstable environments is needed in many applications. One application that demands this measurement technique with fast data acquisition, 2D sensitivity, and insensitivity to vibration is the measurement of thermal strain in thin films in operational environments. The diverging beam interferometer described here demonstrates an angular sensitivity to the local curvature using interferograms captured by a CMOS camera. Two-dimensional Fourier analysis is used to extract curvature changes. The interferometer demonstrates an experimental sensitivity to curvature changes on the order of 10−4 m−1 and is used to measure thermal stresses in a cryogenic environment of a polycrystalline titanium nitride thin film on a silicon wafer that exhibits anisotropic curvature.
Anisotropy of optical transitions in
β-Ga2O3 investigated by polarized photoluminescence excitation spectroscopy
Authors: Meißner Moritz , Bernhardt Nils , Nippert Felix , Janzen Benjamin M. , Galazka Zbigniew , Wagner Markus R.
Published: April 2024

The monoclinic beta-phase of gallium oxide possesses an ultra-wide bandgap that surpasses other wide bandgap materials such as SiC and GaN, making it a promising candidate for power electronic device technologies. We investigate the first fundamental optical transitions in this material, which exhibit a strong directional dependence. To determine the energies and orientations of these transitions, temperature-dependent and angular resolved photoluminescence excitation spectroscopy is applied. We observe a distinct excitation channel located energetically between those of the first two optical transitions Γ1−1 and Γ1−2. While previous absorption edge and reflectance spectroscopy studies have assigned a transition in this spectral range to either the Γ1−1 or the Γ1−2 transition, our findings demonstrate no pronounced polarization dependence of this excitation channel within the (010) plane, an observation not reflected in calculations of the band-to-band transitions in β-Ga2O3.
Observation of dynamic nanoscale thermal expansion in mirrors and graphene-aided heat dissipation by an advanced chromatic confocal microscopy
Authors: Tseng Wei-Shiuan , Pan Yu-Chi , Liao Tzin-Hsin , Hsiao Shih-Hsiang , Chan Ming-Che
Published: April 2024

In this Letter, dynamic nano-thermal expansion images of reflective mirrors from high-intensity incident laser beams were observed in situ. The inspections are based on rapid 3D surface morphology changes on the reflective surfaces, captured by a Chromatic Confocal Microscope with Nanoscale Sensitivity (CCMNS). Nano-expansions of two types of coatings were studied: the E02 dielectric coating (coating 1) and the graphene-on-E02 complex film (coating 2), both applied to the same fused silica substrate. The superior thermal dissipation properties of coating 2, including enhanced heat dissipation, suppressed wavefront distortion, and its unique negative expansion coefficient, were observed. In addition to studying the effects of graphene coating, the CCMNS demonstrates an accurate and efficient approach for evaluating reflective mirrors. Moreover, the proposed methodology possesses enormous potential across various fields, ranging from estimating photonic elements dealing with high-intensity beams to physical thermal conductivity measurements.
Kinetics of the plastic crystal transition in neopentyl glycol
Authors: Somodi Chase B. , McCormick Kristin , Tabor Daniel P. , Pentzer Emily , Shamberger Patrick J.
Published: April 2024

The thermal hysteresis exhibited in plastic crystal compounds greatly reduces their cyclic efficiency, limiting their potential for replacing current environmentally harmful refrigerants. A mechanistic understanding of the origins of this hysteresis has yet to be established. Here, we systematically investigate the transformation kinetics of the model plastic crystal, neopentyl glycol (NPG), through microscopic and calorimetric techniques. We reveal an asymmetry between the forward (heating) and reverse (cooling) transitions. We also demonstrate that the forward transformation is rate-limited by the rate of growth of rotationally disordered domains. In contrast, the reverse transformation is rate-limited by the nucleation of the ordered crystal domain, demonstrated by the sharp exothermic peaks in calorimetry and rapid self-nucleation phenomena observed optically. This nucleation limitation is largely responsible for the large thermal hysteresis in NPG, which we observe to be as large as 16.7 °C for an approximately 10 mg sample cooled at 0.5 °C min−1. These findings demonstrate the underlying origin of the thermal hysteresis and introduce a direction to mitigate hysteresis in plastic crystal transformations.
Research on adaptive shooting algorithm for unmanned aerial vehicles under typical operating conditions of overhead transmission lines
Authors: Fu Zifeng , Hu Hongwei , Liu Zhuang
Published: April 2024

We consider typical environmental conditions, such as different shooting backgrounds, lighting, and shooting distances, and study adaptive shooting algorithms for unmanned aerial vehicle (UAV) on-site environments under typical working conditions to achieve high-quality acquisition of UAV inspection images and reduce the technical difficulty of artificial intelligence recognition of inspection images. Based on the collected high-quality images and the characteristics of unmanned aerial vehicle inspection images, a deep learning technology framework is adopted to study the intelligent identification method of hidden dangers in transmission line equipment and channel environment, achieving the intelligent recognition of pin level fine particle defects.
Experimental study on control of transverse jet mixing by arrayed plasma energy deposition
Authors: Chao Zhenhou , Gao Feng , Wang Hongyu , Wang Gang , Li Jie
Published: April 2024

The efficient and prompt mixing of fuel is crucial in the operation of scramjet engines. This paper presents the findings from wind tunnel experiments that examined the influence of plasma energy deposition on transverse jets at a Mach number of 6.13. The study took into account various inlet flow total pressures and momentum flux ratios between the jet and the main flow. Utilizing a database containing time-resolved intensities from instantaneous schlieren images, we perform turbulence analysis employing various techniques such as the root mean square, fast Fourier transform, proper orthogonal decomposition, and the two-point correlation method. Specifically, we aim to compare and analyze the pulsation characteristics and spatial self-organization of the jet flow field, both with and without energy deposition control. The findings reveal that intermittent “hot bubbles” created by plasma energy deposition interact with the bow shock induced by the jet, resulting in the formation of an array of large-scale vortices. These vortices emerge as the dominant structures within the jet, effectively amplifying its pulsations. At low inlet flow pressures, energy deposition primarily disrupts the jet, causing large-scale vortices to propagate primarily within the jet plume region. However, at high inlet flow pressures, the impact of energy deposition extends to both the jet and the turbulent boundary layer, encompassing their respective disturbance ranges. Increasing the inlet flow pressure constraints the evolution of large-scale vortices, thus limiting the efficacy of energy deposition in governing the mixing process.
Bias-dependent electron velocity and short-channel effect in scaling sub-100 nm InAlN/GaN HFETs
Authors: Wang Mingyan , Zhou Heng , Liu Chao , Lin Zhaojun , Zeng Yuping , Cui Peng
Published: April 2024

This work reports on the extraction and simulation of the electron velocity–gate voltages relationship for sub-100 nm InAlN/GaN heterojunction field-effect transistors (HFETs). A peak electron velocity (ve) at an electron density (ns) of 0.41 × 1013 cm−2 was observed at 1.06 × 107 cm/s in an InAlN/GaN HFET with 60 nm gate length (Lg) by delay time analysis. The ve at a high ns of 1.5 × 1013 cm−2 was observed at 0.6 × 107 cm/s. This peak ve behavior is explained by polarization Coulomb field (PCF) scattering and optical phonon scattering based on a Monte Carlo method. As Lg scaled from 350 to 60 nm, the current gain cutoff frequency (fT) and transconductance (gm) were improved. However, the thermal performance was degraded with a bad figure of merit P150 °C. Although a weakening of the control capability of Vgs on ns (Δns/ΔVgs) was observed in the shorter Lg device, which leads to a decrease in device gm, the larger electron velocity by the increased lateral electric field (E) and the larger Δve/ΔVgs by the increased PCF scattering still enhance the peak gm. Results indicate that the enhancement of Δve/ΔVgs is a vital method to strengthen the modulation of the gate on current and to suppress the short channel effect in GaN HFET. Our work supports a deeper understanding and analysis of sub-100 nm InAlN/GaN HFET device performance and physical mechanisms.
Origin of near-failure in Au contacts to polycrystalline β-Ga2O3 at high temperatures using interfacial studies
Authors: Kaur Damanpreet , Dahiya Rohit , Shivani  , Kumar Mukesh
Published: April 2024

Suitable contacts to gallium oxide are a controversial topic with contact behavior depending heavily on the pre- and post-processing conditions. Especially for the extreme environment applications such as those involving high temperatures, contact chemistry is varied and severely lacks understanding. Herein, we report on conventional pure Au contacts to polycrystalline β-Ga2O3, used as Schottky contacts, and explore the origin of their near-failure at high temperature up to 850 °C. For this purpose, β-Ga2O3 with Au interdigitated electrodes is subjected to high temperature annealing and their interface chemistry is studied and correlated with device performance for solar-blind photodetection. Around the optimized temperature of 450 °C, the performance of the PDs is found to be maximum, whereas it reduces drastically at 850 °C. Physical damage to the electrodes along with the formation of intermetallic gold-gallium alloy is observed via XPS depth profile studies and found to be the reason for the near-failure of device at extreme conditions. Although the alloy formation begins to slightly appear at 650 °C and reduces the performance, still it does not lead to device breakdown. This study proves that unlike its counterparts GaN and GaAs, which have reported alloy formation at lower temperatures, β-Ga2O3 shows a higher resilience to the formation of Au–Ga alloy and can withstand higher temperatures before the actual device failure is reached. The proposed study shows the stability of standard metal contacts to Ga2O3 based devices, which have far-reaching implications for the future commercialization of wideband gap semiconductor based (opto)electronics.
Strain-dependent ultrafast carrier dynamics and spin–lattice interaction in LaMnO3 films
Authors: Wang Jun , Jiang Yaohua , Ran Xiongxiong , Liu X. H. , Mi Yang
Published: April 2024

We investigate the ultrafast carrier dynamics and spin–lattice interaction in strained and unstrained LaMnO3 films via temperature-dependent femtosecond transient optical spectroscopy. The transient reflectivity measurements show two characteristic relaxation processes in both types of films, which are attributed to electron–phonon coupling and phonon-assisted spin–lattice interaction, respectively. The carrier dynamics and coupling between lattice and spin system are well described with the three-temperature model; the spin–lattice relaxation time constant is dominated by the temperature-dependent spin specific heat. Both the electron–phonon coupling and the spin–lattice interaction are enhanced in the strained film, as a result of the modified band structure and orbital ordering under biaxial compressive strain. Our results reveal the critical role of strain in the photo-induced dynamical interactions in LaMnO3.
Impact of gravitational force on high repetition rate filamentation of femtosecond laser pulses in the atmosphere
Authors: Walch P. , Mahieu B. , Arantchouk L. , André Y.-B. , Mysyrowicz A. , Houard A.
Published: April 2024

We study the influence of the gravitational force on the generation of low-density channels of air left in the path of femtosecond laser filaments at high repetition rate. We observe a more important density variation along the filament longitudinal axis in the case of a vertically created filament as compared to a horizontal one. This leads to a more important reduction of the electrical breakdown field using vertical filament. This geometry induced difference is only observed at high repetition rate because it is directly related to the cumulative effect appearing above 100 Hz.
Numerical investigation on thermal-hydraulic performance of variable cross section printed circuit heat exchanger
Authors: Yuan Ping , Tian Hua , Wang Xuan , Zhang Xuanang , Zhang Hongfei , Liang Xingyu , Shu Gequn , Li Zhuqing
Published: April 2024

CO2 transcritical power cycle (CTPC) systems have attracted considerable research focus in the fields of thermoelectric conversion and waste heat recovery. The regenerator is a key component affecting the CTPC system's efficiency. To improve the comprehensive performance of the regenerator, extensive research has been conducted to optimize the regenerator flow channel design. However, the optimization of the traditional Z-channel printed circuit heat exchanger structure (ZPCHE) is limited to constant cross-sectional configurations along the flow direction, which can lead to low channel space utilization. To solve this problem, an efficient variable cross section Z-channel structure (UAPCHE) is proposed in this study. The structure is designed with different cross-sectional shapes along the flow direction to fit the flow path of the main fluid. UAPCHE achieves a coordinated optimization of the heat transfer (Nu), flow (dP), and compactness performance (Q/V) by increasing the effective utilization of the channel space and weakening the damage to the fluid boundary layer. The design principle of the UAPCHE is introduced, and based on this, the structural parameters of the UAPCHE are optimized to achieve the best comprehensive performance. The results show that, compared with the ZPCHE, Nu of UAPCHE can be increased by 16.79%, dP can be reduced by 19.48%, and Q/V can be increased by 22.65%.
Emulating biological synaptic characteristics of HfOx/AlN-based 3D vertical resistive memory for neuromorphic systems
Authors: Kim Juri , Lee Subaek , Seo Yeongkyo , Kim Sungjun
Published: April 2024

Here, we demonstrate double-layer 3D vertical resistive random-access memory with a hole-type structure embedding Pt/HfOx/AlN/TiN memory cells, conduct analog resistive switching, and examine the potential of memristors for use in neuromorphic systems. The electrical characteristics, including resistive switching, retention, and endurance, of each layer are also obtained. Additionally, we investigate various synaptic characteristics, such as spike-timing dependent plasticity, spike-amplitude dependent plasticity, spike-rate dependent plasticity, spike-duration dependent plasticity, and spike-number dependent plasticity. This synapse emulation holds great potential for neuromorphic computing applications. Furthermore, potentiation and depression are manifested through identical pulses based on DC resistive switching. The pattern recognition rates within the neural network are evaluated, and based on the conductance changing linearly with incremental pulses, we achieve a pattern recognition accuracy of over 95%. Finally, the device’s stability and synapse characteristics exhibit excellent potential for use in neuromorphic systems.
Shock-induced deflagration-enhanced characteristics of Cu-PTFE/Al tandem EFPs impacting multi-layer spaced plates
Authors: Su Chenghai , Zheng Yuanfeng , Wang Shipeng , Liu Aoxin , Wang Haifu
Published: April 2024

Polytetrafluoroethylene/aluminum (PTFE/Al) reactive material is a pivotal research object in the aerospace, military, and mechanical engineering fields and can release chemical energy (CE) under shock or impact. However, its relatively low mechanical strength limits its applications. The present paper proposes a Cu-PTFE/Al (73.5wt. %/26.5wt. %) double-layer liner that can form tandem explosive formed projectiles (EFPs) under the shock of shaped charges, which not only retains the strong penetration ability but also shows a more significant lateral enhancement effect through the deflagration reaction. Here, the preparation process of the PTFE/Al liner is given, and an analytical model for the Cu-PTFE/Al tandem EFP of the damage process against multi-spaced plates is established, revealing the penetration and deflagration-enhanced mechanisms. Subsequently, a two-step segmented numerical simulation for the penetration–deflagration coupling effects is conducted, and the time-space interaction process and damage results between kinetic energy penetration and CE deflagration are obtained. A series of experiments of tandem EFPs against spaced plates are conducted, including the different materials, thickness ratio, and standoff. Experimental results show that compared with Cu–Cu tandem EFP with the same condition, the penetration ability of Cu-PTFE/Al composite EFP is reduced, but the damage enhancement effect is greatly improved; the maximum damage area of a single plate is increased by 220.1%, and the average damage area of a single plate is increased by 76.2%. This study provides important reference data and a theoretical basis for the design of metal-reactive tandem EFPs.
An experimental study of the flow structure in arrays of cold bidirectional swirling jets
Authors: Evdokimov Oleg A. , Guryanov Alexander I. , Veretennikov Sergey V.
Published: April 2024

Jets arrays have become a promising technology for industrial applications, including heat transfer and combustion processes. This paper presents the first experimental results of arrays of bidirectional swirling jets, including their flow structures and specific turbulent interactions. Particle image velocimetry of non-reacting linear arrays showed the formation of recirculation zones within each jet of the array. These regions are the most stable, with fluctuations less than 0.002 of the bulk inlet velocity Vin. In addition, jets merging locations also show a significant decrease in velocity fluctuations, with values V′/Vin < 0.005, which is most clearly seen at a smaller pitch distance. However, the highest turbulent fluctuations occur in shear layers, reaching values of V'/Vin ≈ 0.02 for linear arrays and V'/Vin ≈ 0.03 for planar configurations. The flow structure of planar arrays is more complex, leading to the formation of secondary vortex structures at locations of jet interaction. This results in a significant decrease in the flow swirl number, from an initial value of Sin = 2.1 in the vortex chamber, to S1 = 0.36–0.49 at z/dout2 = 1 and S2 = 0.19–0.27 at z/dout2 = 2 beyond the outlet nozzle. Strong cross-sectional motions are observed in planar arrangements, leading to the development of additional regions of negative axial velocity between the outlet nozzles. The boundaries of these regions have nearly zero axial velocity values and can provide reliable ignition and flame stabilization in the case of reactive bidirectional jets. Therefore, the flow structure in planar arrays forms a large stabilization zone, and the obtained results can be used to develop a new multipoint combustion technique.
Efficient generation and deterministic annihilation of a single skyrmion via pure localized heating
Authors: Wang Xuan , Li Mengda , Li Bo , Li Yaojin , Li Yang , Zheng Fu , Liu Liwang
Published: April 2024

A method for achieving rapid generation and annihilation of skyrmions is to apply local heating. However, the mechanism underlying heating-induced skyrmion formation is poorly understood, and achieving deterministic thermal excitation remains a major challenge. In this study, we utilized micromagnetic simulations to generate and annihilate individual skyrmions in a two-dimensional homogeneous ferromagnetic film with Dzyaloshinskii–Moriya interactions using a localized heating method without the assistance of an external magnetic field. By introducing pinning into the uniformly magnetized ferromagnetic background, the energy difference between the initial state and the skyrmion state is reduced, and the efficiency of generating skyrmions through local heating is improved. Additionally, deterministic annihilation of skyrmions can be achieved by exploiting the peculiarity that the energy of the skyrmion state is greater than that of the ground state. Based on this work, a practical application of skyrmions as a new type of information storage unit is proposed using a purely thermal approach.
The reduced-order model of 5 × 5 fuel rod bundles
Authors: Min Guangyun , Wang Laishun , Jiang Naibin
Published: April 2024

The fuel rod bundles are the core part of pressurized water reactors (PWRs), and its heat transfer characteristics directly impact the safety of PWRs. A computational fluid dynamics (CFD) model of 5 × 5 fuel rod bundles with a spacer grid is established, and the numerical simulation results are in excellent agreement with the experimental results. Then, the effects of four turbulence models, namely shear stress transport model, standard k–ε model, re-normalization group k–ε model, and realizable k–ε model on the thermal-hydraulic characteristics of the 5 × 5 fuel rod bundles are systematically investigated. Furthermore, two data-driven methods, namely proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD), are used to analyze the flow fields of the 5 × 5 fuel rod bundles. The two methods can extract key modes or features to enhance the comprehension and description of the dynamic behaviors within the flow fields of 5 × 5 fuel rod bundles. Finally, two reduced-order models (ROMs), called the POD-radial basis function neural network surrogate model and DMD method, are constructed, which can enable rapid prediction of the flow fields for 5 × 5 fuel rod bundles with high accuracy. The CFD simulation results presented in this paper can provide valuable insights for studying the thermal-hydraulic characteristics of the 5 × 5 fuel rod bundles. The two ROMs proposed in this paper can significantly reduce the computational costs associated with studying the thermal-hydraulic characteristics of 5 × 5 fuel rod bundles.