bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple Bloch surface wave excitation with gratings
Authors: Asilevi Atsu L. , Descrovi Emiliano , Pesonen Henri , Roussey Matthieu , Turunen Jari
Published: February 2024

We study the coupling of a finite number of Bloch Surface Waves (BSWs) propagating in different directions at the surface of a dielectric multilayer. These surface waves arise from a set of diffraction orders associated to a grating on the bottom surface of the substrate that is illuminated by a normally incident beam. Simultaneous excitation of multiple BSWs is possible with a set of diffraction orders having the same radial spatial frequency. Using rigorous electromagnetic theory, we design gratings for simultaneous excitation of two, four and six BSWs propagating in directions separated by π, π/2 and π/3 azimuthal intervals, respectively.
Stopping times occurring simultaneously
Authors: Protter Philip , Quintos Alejandra
Published: February 2024

Stopping times are used in applications to model random arrivals. A standard assumption in many models is that they are conditionally independent, given an underlying filtration. This is a widely useful assumption, but there are circumstances where it seems to be unnecessarily strong. We use a modified Cox construction along with the bivariate exponential introduced by Marshall and Olkin (1967) to create a family of stopping times, which are not necessarily conditionally independent, allowing for a positive probability for them to be equal. We show that our initial construction only allows for positive dependence between stopping times, but we also propose a joint distribution that allows for negative dependence while preserving the property of non-zero probability of equality. We indicate applications to modeling COVID-19 contagion (and epidemics in general), civil engineering, and to credit risk.
Global solar photospheric and coronal magnetic field over activity cycles 21–25
Authors: Petrie Gordon J. D.
Published: February 2024

The evolution of the global solar magnetic field from the beginning of cycle 21 (mid-1970s) until the currently-ascending cycle 25 is described using photospheric full-disk and synoptic magnetograms from NSO Kitt Peak Vacuum Telescope (KPVT) 512-channel and Spectromagnetograph (SPMG) and the Synoptic Optical Long-term Investigation of the Sun (SOLIS) Vector Spectro-Magnetograph (VSM) and Global Oscillations Network Group (GONG), and Stanford University’s Wilcox Solar Observatory (WSO). The evolving strength and symmetry of the global coronal field are described by potential-field source-surface models decomposed into axisymmetric and non-axisymmetric, and even- and odd-ordered magnetic multipoles. The overall weakness of the global solar magnetic field since cycle 23 splits the 50-year observing window into the stronger, simpler, more hemispherically symmetric cycles 21 and 22 and the weaker, more complex cycles 23 and 24. An anomalously large decrease in the global solar field strength occurred during cycles 23, and an anomalously weak axial/polar field resulted from that cycle, accompanied by an anomalously weak radial interplanetary magnetic field (IMF) during cycle 23 activity minimum and a weakened radial IMF overall since cycle 23. The general long-term decline in solar field strength and the development during cycle 24 of strong swings of hemispheric and polar asymmetry are analyzed in detail, including their transfer through global coronal structural changes to dominate mean in situ interplanetary field measurements for several years. Although more symmetric than cycle 24, the rise phase of cycle 25 began with the southern leading the northern hemisphere, but the north has recovered to lead this cycle’s polar field reversal. The mean polar flux (poleward of ±60°) has reversed at each pole, so far more symmetrically than the cycle 23 and 24 polar reversals.
S3-Leitlinie: Lungenerkrankung bei Mukoviszidose – Pseudomonas aeruginosa
Authors: Schwarz Carsten , Bend Jutta , Hebestreit Helge , Hogardt Michael , Hügel Christian , Illing Stephan , Mainz Jochen G. , Rietschel Ernst , Schmidt Sebastian , Schulte-Hubbert Bernhard , Sitter Helmut , Wielpütz Marc Oliver , Hammermann Jutta , Baumann Ingo , Brunsmann Frank , Dieninghoff Doris , Eber Ernst , Ellemunter Helmut , Eschenhagen Patience , Evers Caroline , Gruber Saskia , Koitschev Assen , Ley-Zaporozhan Julia , Düesberg Uta , Mentzel Hans-Joachim , Nüßlein Thomas , Ringshausen Felix C. , Sedlacek Ludwig , Smaczny Christina , Sommerburg Olaf , Sutharsan Sivagurunathan , Vonberg Ralf-Peter , Weber Ann-Katrin , Zerlik Jovita
Published: February 2024

Mukoviszidose (Cystic Fibrosis, CF) ist die häufigste autosomal-rezessiv vererbte Multisystemerkrankung. In Deutschland sind mind. 8000 Menschen betroffen. Die Erkrankung wird durch Mutationen im Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)-Gen verursacht, welche zu einer Fehlfunktion des Chloridkanals CFTR führen. Dadurch kommt es in den Atemwegen zu einer unzureichenden Hydrierung des epithelialen Flüssigkeitsfilms und somit zu einer Reduktion der mukoziliären Clearance.

Auch wenn seit einigen Jahren mit der CFTR-Modulatortherapie eine hochwirksame kausale CF-Therapie zur Verfügung steht und die Patienten größtenteils das höhere Erwachsenenalter erreichen, treten rezidivierende und chronische Infektionen der Atemwege sowie pulmonale Exazerbationen weiterhin auf. Im Erwachsenenalter zeigt sich v. a. die Kolonisation und chronische Infektion mit Pseudomonas aeruginosa (PA), die zu weiterem Verlust an Lungenfunktion führt. Für die medikamentöse Therapie der chronischen PA-Infektion stehen viele unterschiedliche Therapieoptionen zur Verfügung.

Mit dieser S3-Leitlinie wird eine evidenzbasierte Diagnostik und Therapie der PA-Infektion dargelegt, um eine Orientierung bei der individuellen Therapieentscheidung zu geben.
Task Force Dyspnoe Unit (DU)
Authors: Dellweg Dominic , Nilius Georg , Grünewaldt Achim , Günther Andreas , Held Matthias , Hetzel Martin , Schlesinger Andreas , Schlott Robin , Sofianos Georgios , Unnewehr Markus , Voshaar Thomas , Randerath Winfried
Published: February 2024

Die akut aufgetretene Dyspnoe ist eines der häufigsten internistischen Symptome in der Notaufnahme. Sie entsteht bei einer akuten Erkrankung oder aus der Exazerbation einer chronischen Erkrankung heraus. Für die Leitsymptome des akuten Schlaganfalls sowie bei akutem Brustschmerz existieren mit den Stroke und Chest Pain Units bereits symptombezogene Notfallstrukturen und entsprechende Strukturvorgaben. Diese fehlen in Deutschland für das Leitsymptom Dyspnoe, obwohl in anderen Ländern der Nutzen dieser Strukturen bereits bewiesen wurde. Die Deutsche Gesellschaft für Pneumologie und Beatmungsmedizin hat nun zusammen mit dem Verband Pneumologischer Kliniken eine Task Force ins Leben gerufen, deren Aufgabe es ist, sich mit dem Thema auseinanderzusetzten und entsprechende Strukturvorgaben solcher „Dyspnoe Units“ für Deutschland zu erarbeiten. Am Ende des Prozesses steht fakultativ die Zertifizierung derartiger Einheiten an deutschen Krankenhäusern.
Rare Example of abnormal vocal resonance: a case from Balzacʼs novel
Authors: Berezutskyi Volodymyr , Berezutska Maryna
Published: February 2024

Ungewöhnliche klinische Fälle wecken bei praktizierenden Ärzten immer wieder Interesse und ermöglichen es ihnen, ihre Wissensbasis zu erweitern und ihre Fähigkeiten zum klinischen Denken zu verbessern. Der Zweck dieser Studie besteht darin, einen klinischen Fall von Stimmresonanz beim Singen bei einem schwindsüchtigen Teenager aus dem Roman „Der Landarzt“ von Honoré de Balzac unter Verwendung induktiver und deduktiver Methoden des klinischen Denkens zu analysieren. Stimmresonanzen beim Singen in Schwindsucht können als pathognomonisches Zeichen für eine kavernöse Tuberkulose gewertet werden, da nur mit dem Bronchus verbundene Hohlräume als Helmholtz-Resonator wirken. Trotz der Einzigartigkeit ist das Gehäuse durchaus realistisch, da es nicht im Widerspruch zu den Gesetzen der Akustik steht. Praktizierende Ärzte verfügen über die Kenntnisse der medizinischen Physik, Morphologie und Physiologie, die zum Verständnis der Pathogenese der klinischen Manifestation einer Lungenhöhle erforderlich sind. Dieser Fall zeigt deutlich die Vor- und Nachteile klinischer Denkmethoden, die in der Praxis eingesetzt werden. Dank der Kombination aus Originalität und Realismus kann der Fall von Stimmresonanz aus Balzacs Roman „Der Landarzt“ seinen rechtmäßigen Platz in der persönlichen Sammlung klinischer Fälle eines jeden Lungenarztes einnehmen.
Charge carrier trapping management in Bi3+ and lanthanides doped Li(Sc,Lu)GeO4 for x-ray imaging, anti-counterfeiting, and force recording
Authors: Lyu Tianshuai , Dorenbos Pieter
Published: February 2024

Discovering energy storage materials with rationally controlled trapping and de-trapping of electrons and holes upon x-rays, UV-light, or mechanical force stimulation is challenging. Such materials enable promising applications in various fields, for instance in multimode anti-counterfeiting, x-ray imaging, and non-real-time force recording. In this work, photoluminescence spectroscopy, the refined chemical shift model, and thermoluminescence studies will be combined to establish the vacuum referred binding energy (VRBE) diagrams for the LiSc1−xLuxGeO4 family of compounds containing the energy level locations of Bi2+, Bi3+, and the lanthanides. The established VRBE diagrams are used to rationally develop Bi3+ and lanthanides doped LiSc1−xLuxGeO4 storage phosphors and to understand trapping and de-trapping processes of charge carriers with various physical excitation means. The thermoluminescence intensity of x-ray irradiated LiSc0.25Lu0.75GeO4:0.001Bi3+,0.001Eu3+ is about two times higher than that of the state-of-the-art x-ray storage phosphor BaFBr(I):Eu2+. Particularly, a force induced charge carrier storage phenomenon appears in Eu3+ co-doped LiSc1−xLuxGeO4. Proof-of-concept non-real-time force recording, anti-counterfeiting, and x-ray imaging applications will be demonstrated. This work not only deepens our understanding of the capturing and de-trapping processes of electrons and holes with various physical excitation sources, but can also trigger scientists to rationally discover new storage phosphors by exploiting the VRBEs of bismuth and lanthanide levels.
Unveiling non-flat profiles within magnetic islands in tokamaks
Authors: Tae Wonjun , Yoon E. S. , Hur Min Sup , Choi G. J. , Kwon J. M. , Choi M. J.
Published: February 2024

The presence of non-flat profiles on magnetic island is studied for the first time through gyrokinetic simulations alongside a simplified Lagrangian model. We have identified that inside a magnetic island, the non-flatness of density and temperature profiles is controlled by a dimensionless parameter α≡w*ŝϵ/qρ*, which is a function of normalized island width w*=w/a0, magnetic shear ŝ, inverse aspect ratio ϵ=a0/R, safety factor q, and normalized gyroradius ρ*=ρ/a0. The gyroradius ρ* dependence of the control parameter α leads to a species-selective transition of profiles from flat to concave only for electrons having high α∼O(1). The finding elucidates that electron profiles tend to increasingly deviate from the flat state for a larger magnetic island, in contrast to the conventional wisdom.
Sensitivity enhancement of radical-pair magnetoreceptors as a result of spin decoherence
Authors: Luo Jiate
Published: February 2024

Electron spin relaxation is, on many occasions, considered an elephant in the room that challenges the idea of a radical-pair compass, a leading hypothesis for the navigation of migratory avian species. It has been widely recognized that an effective radical-pair magnetoreceptor requires a relaxation time that is long enough for an external magnetic field as weak as the geomagnetic field to significantly modify the coherent spin dynamics. However, previous studies proposed that certain spin relaxation, far quicker than the radical recombination reactions, could enhance, rather than degrade, the directional sensitivity of a radical-pair magnetoreceptor. Here, I investigate relaxation effects on the singlet–triplet interconversion of a model radical pair and find that the enhancement effect originates from population relaxation over a period of several microseconds as a result of efficient spin decoherence. Insights into the truncated spin systems shed light on the physics behind them. I further investigate the possibilities of such enhancement in cryptochrome-based magnetoreception, in which electron hopping takes place between tryptophan residues.
Toward innovative approaches for exploring the mechanically regulated tumor-immune microenvironment
Authors: Kalli Maria , Stylianopoulos Triantafyllos
Published: February 2024

Within the complex tumor microenvironment, cells experience mechanical cues—such as extracellular matrix stiffening and elevation of solid stress, interstitial fluid pressure, and fluid shear stress—that significantly impact cancer cell behavior and immune responses. Recognizing the significance of these mechanical cues not only sheds light on cancer progression but also holds promise for identifying potential biomarkers that would predict therapeutic outcomes. However, standardizing methods for studying how mechanical cues affect tumor progression is challenging. This challenge stems from the limitations of traditional in vitro cell culture systems, which fail to encompass the critical contextual cues present in vivo. To address this, 3D tumor spheroids have been established as a preferred model, more closely mimicking cancer progression, but they usually lack reproduction of the mechanical microenvironment encountered in actual solid tumors. Here, we review the role of mechanical forces in modulating tumor- and immune-cell responses and discuss how grasping the importance of these mechanical cues could revolutionize in vitro tumor tissue engineering. The creation of more physiologically relevant environments that better replicate in vivo conditions will eventually increase the efficacy of currently available treatments, including immunotherapies.
Controllable spin transport in a zigzag silicene nanoribbon embedding multiple rectangular quantum dots
Authors: Gao Xiang , Deng Zhihong , Ma Cheng , Li Lei , Zhang Xiaowei , Li Xu , Zhou Zigang
Published: February 2024

Based on the recursive Green-function method together with Landauer–Büttiker formalism, the spin-dependent transport properties of electrons in a zigzag silicene nanoribbon embedding multiple rectangular quantum dots (QDs) are investigated. According to an analysis of the energy band under the periodically distributed electric field and exchange ferromagnetic field, the parallel exchange field induced by the ferromagnetic insulators eliminates the spin degeneracy, which leads to spin-polarized transport in the proposed structure. By tuning a periodic electric field, we found the relationship between the number of QDs and the splitting peak for conductance in the anti-parallel exchange field. We discover the population of electrons near QDs by calculating the local density of states. The effect of the geometry of periodic QDs on the shift of resonance peak is evaluated. The spin polarization is further explored for various configurations of electric field and exchange field in order to manipulate the spin filtering more effectively. The results provide an avenue to design a controllable spin bandpass filter with the modulation of electric field and exchange field.
On the shock wave boundary layer interaction in slightly rarefied gas
Authors: Liu Hualin , Li Qi , Chen Weifang , Wu Lei
Published: February 2024

The shock wave and boundary layer interaction (SWBLI) plays an important role in the design of hypersonic vehicles. However, discrepancies between the numerical results of high-temperature gas dynamics and experiment data have not been fully addressed. It is believed that the rarefaction effects are important in SWBLI, but the systematic analysis of the temperature-jump boundary conditions and the role of translational/rotational/vibrational heat conductivities are lacking. In this paper, we derive the three-temperature Navier–Stokes–Fourier (NSF) equations from the gas kinetic theory, with special attention paid to the components of heat conductivity. With proper temperature-jump boundary conditions, we simulate the SWBLI in the double cone experiment. Our numerical results show that, when the three heat conductivities are properly recovered, the NSF equations can capture the position and peak value of the surface heat flux, in both low- and high-enthalpy inflow conditions. Moreover, the separation bubble induced by the separated shock and the reattachment point induced by impact between transmitted shock and boundary layer are found to agree with the experimental measurement.
One-pot heat-up synthesis of short-wavelength infrared, colloidal InAs quantum dots
Authors: Lee J. , Zhao T. , Yang S. , Muduli M. , Murray C. B. , Kagan C. R.
Published: February 2024

III–V colloidal quantum dots (QDs) promise Pb and Hg-free QD compositions with which to build short-wavelength infrared (SWIR) optoelectronic devices. However, their synthesis is limited by the availability of group-V precursors with controllable reactivities to prepare monodisperse, SWIR-absorbing III–V QDs. Here, we report a one-pot heat-up method to synthesize ∼8 nm edge length (∼6.5 nm in height) tetrahedral, SWIR-absorbing InAs QDs by increasing the [In3+]:[As3+] ratio introduced using commercially available InCl3 and AsCl3 precursors and by decreasing the concentration and optimizing the volume of the reducing reagent superhydride to control the concentration of In(0) and As(0) intermediates through QD nucleation and growth. InAs QDs are treated with NOBF4, and their deposited films are exchanged with Na2S to yield n-type InAs QD films. We realize the only colloidal InAs QD photoconductors with responsivity at the technologically important wavelength of 1.55 μm.
Electronic friction near metal surface: Incorporating nuclear quantum effect with ring polymer molecular dynamics
Authors: Bi Rui-Hao , Dou Wenjie
Published: February 2024

The molecular dynamics with electronic friction (MDEF) approach can accurately describe nonadiabatic effects at metal surfaces in the weakly nonadiabatic limit. That being said, the MDEF approach treats nuclear motion classically such that the nuclear quantum effects are completely missing in the approach. To address this limitation, we combine Electronic Friction with Ring Polymer Molecular Dynamics (EF-RPMD). In particular, we apply the averaged electronic friction from the metal surface to the centroid mode of the ring polymer. We benchmark our approach against quantum dynamics to show that EF-RPMD can accurately capture zero-point energy as well as transition dynamics. In addition, we show that EF-RPMD can correctly predict the electronic transfer rate near metal surfaces in the tunneling limit as well as the barrier crossing limit. We expect that our approach will be very useful to study nonadiabatic dynamics near metal surfaces when nuclear quantum effects become essential.
Control of the flow around a finite-height square cylinder with slot blowing near its free-end side edges
Authors: Zhu Jing , Wang Hanfeng , Zeng Lingwei
Published: February 2024

This paper describes an active control technique that uses symmetric downward slot blowing from the free-end side edges of a finite-height square cylinder to suppress the aerodynamic forces. The width (d) of the tested cylinder is 40 mm and the aspect ratio H/d is 5. The Reynolds number based on the oncoming flow velocity U∞ and d is 2.67 × 104. The tested blowing ratio Cb (=Ub/U∞, where Ub is the blowing velocity at the slot exit) ranges from 0 to 4, and two typical included angles of θ = 5° and 45° are considered. The experimental results indicate that free-end slot blowing effectively suppresses the aerodynamic forces on the cylinder. The maximum reduction in the aerodynamic forces occurs with θ = 5° and Cb = 3.0, whereupon the mean drag, fluctuating drag, and fluctuating lateral force are reduced by 6.80%, 48.52%, and 69.38%, respectively. Furthermore, slot blowing control introduces a strong downward entrainment into the near wake of the cylinder, weakening its spanwise vortex shedding. This successfully converts the alternating spanwise vortex shedding into symmetric shedding, especially near the free end from which the downward blowing issues.
Investigating microstructure evolution in block copolymer membranes
Authors: Cooper Anthony J. , Grzetic Douglas J. , Delaney Kris T. , Fredrickson Glenn H.
Published: February 2024

Block copolymer self-assembly in conjunction with nonsolvent-induced phase separation (SNIPS) has been increasingly leveraged to fabricate integral-asymmetric membranes. The large number of formulation and processing parameters associated with SNIPS, however, has prevented the reliable construction of high performance membranes. In this study, we apply dynamical self-consistent field theory to model the SNIPS process and investigate the effect of various parameters on the membrane morphology: solvent selectivity, nonsolvent selectivity, initial film composition, and glass transition composition. We examine how solvent selectivity and concentration of polymers in the film impact the structure of micelles that connect to form the membrane matrix. In particular, we find that preserving the order in the surface layer and forming a connection between the supporting and surface layer are nontrivial and sensitive to each parameter studied. The effect of each parameter is discussed, and suggestions are made for successfully fabricating viable block copolymer membranes.
Large eddy simulation of end effects on a cylinder rotor
Authors: Liu Jianhan , Ma Wenyong , Jin Longqian , Liu Qi
Published: February 2024

Due to the limited length of cylinders, their use in practical engineering inevitably involves end effects, which results in three-dimensional flows at the ends of cylinders. These flow fields are the main factor influencing the aerodynamic and flow field characteristics of cylinders. Regarding a finite-length cylinder rotor, a specific pattern of tip vortices will form under the action of rotation, resulting in notable differences in the aerodynamic characteristics between an ideal two-dimensional cylinder and a finite-length cylindrical rotor. In the present study, the large eddy simulation method is used to systematically investigate cylinder rotors with various aspect ratios. By analyzing the sectional aerodynamic and flow field characteristics, the variation laws of the aerodynamic force, wind pressure, and flow field characteristics of cylinder rotors under the influence of end effects were summarized. The results show that the influence range and intensity of the tip vortices on the rotor flow field and sectional aerodynamic characteristics are dominated by the dimensionless rotating speed, which in turn affects the range of the end effects. The development trend of the tip vortices is analyzed and discussed from multiple aspects, including sectional aerodynamics, the pressure coefficient, and the flow correlation, and an attempt is made to explain changes in the phenomenon.
Hybridized magnonic materials for THz frequency applications
Authors: To D.-Q. , Rai A. , Zide J. M. O. , Law S. , Xiao J. Q. , Jungfleisch M. B. , Doty M. F.
Published: February 2024

The capability of magnons to hybridize and strongly couple with diverse excitations offers a promising avenue for realizing and controlling emergent properties that hold significant potential for applications in devices, circuits, and information processing. In this Letter, we present recent theoretical and experimental developments in magnon-based hybrid systems, focusing on the combination of magnon excitation in an antiferromagnet with other excitations, namely, plasmons in a topological insulator, phonons in a 2D antiferromagnetic (2D AFM), and photons. The existence of THz frequency magnons, plasmons, and phonons makes magnon-based hybrid systems particularly appealing for high-operating-speed devices. In this context, we explore several directions to advance magnon hybrid systems, including strong coupling between a surface plasmon and magnon polariton in a topological insulator /AFM bilayer, a giant spin Nernst effect induced by magnon–phonon coupling in 2D AFMs, and control of magnon–photon coupling using spin torque.
Effects of swirling inflow on the stability and combustion mode of rotating detonations
Authors: Shao Xinke , Zhang Zijian , Shi Lisong , Huang Hanli , Wen Chihyung
Published: February 2024

In this study, a novel approach for enhancing the stability of rotating detonation waves (RDWs) with the use of a swirling inflow strategy is presented. A series of numerical simulations are carried out by solving the two-dimensional reactive Navier–Stokes equations. The effects of the swirling angle on the stability of the RDWs and the combustion mode are analyzed. The results show that the formation of the burnt gas bumps is suppressed by the implementation of a swirling inflow. The swirling inflow also contributes to an increased homogeneity of the reactant within the fuel refill zone. As a result, a remarkable enhancement of the stability of the RDWs in terms of their oscillations in heights and inclined angles is achieved without an apparent compromise of the heights of the RDWs. The propagation speeds of the RDWs are controllable within a wide range approximately from 81% to 114% of the Chapman–Jouguet detonation speed by adjusting the swirling angle. Moreover, the oscillations in the instantaneous fuel consumption rates of both detonative and deflagrative combustion are dominated by the oscillation in the height of the RDW; hence, the swirling inflow reduces the oscillations in these two fuel consumption rates and subsequently the detonation fraction. Consequently, the smoothness of the performance output in terms of specific impulses can be significantly improved with a reduced standard deviation of oscillation up to 84% by the implementation of swirling inflows, and the averaged specific impulse only encounters a small deficit of no more than 7.4%.
Reconstruction refinement of hybrid background-oriented schlieren tomography
Authors: Hu Wei , Yang Lijun , Zhang Yue , Wang Pengcheng , Li Jingxuan
Published: February 2024

This paper introduces a hybrid method that leverages the advantages of both the window-based separate algorithm and the regularization-based unifying algorithm to refine the three-dimensional refractive index field measured by the background-oriented schlieren (BOS) tomography. Two image-warping approaches, under paraxial and non-paraxial ray-tracing assumption, are developed as a connecting link between coarse and refined reconstruction. An orthogonal test is conducted to examine the influence of various factors on the reconstruction fields in the hybrid approach, providing insights into the impact of factors such as the ray-tracing assumption, initial value for refractive index iteration, and image displacement algorithm. Various synthetic and real BOS cases demonstrate that our hybrid method reconstructs a more detailed and robust field, outperforming conventional BOS reconstruction methods in scenarios with small or large density gradients, as well as laminar or turbulent structures.
Investigation on the performance of a torque-driven undulatory swimmer with distributed flexibility
Authors: Wang Wenkang , Chu Xu
Published: February 2024

The locomotion of fish provides insight for the design of efficient swimming robotic devices. The current study presents a systematic investigation of the locomotion performance of a fish-like swimmer with a wide range of parameter settings. Two-dimensional simulations with the immersed boundary method in the framework of Navier–Stokes equations are employed for the fluid–structure interaction analysis. Unlike most previous studies where the kinematics of the swimmer is predetermined, the locomotion of the current swimmer is the response of a single periodic torque applied to the anterior part. In addition, current simulations applied a direct correspondence between code units and real-world units, providing more engineering-related guidance for the future design of microrobotic swimmers. The effect of the distribution of body stiffness on swimming performance and propulsion generation is discussed with different pitch frequencies and amplitudes. It was shown that swimmers with a more flexible posterior part have an advantage in undulatory swimming performance when the pitch angle is low or moderate. However, such an advantage disappears when the pitch angle or actuating frequency exceed a certain level. An analysis of the phase-averaged vorticity field and thrust sequence is given to clarify the change in performance due to the variation of flexibility.
Design criteria of load split and chord length ratio for highly loaded compressor tandem cascades
Authors: Mao Xiaochen , Wang Yunyu , Ding Zhihua , Cheng Hao , Liu Bo
Published: February 2024

To investigate the design strategy for load split (LS) and chord length ratio (CR) of highly loaded compressor tandem cascades, the parameterization study of the tandem cascades with different LS and CR was carried out. The parameterization results show that the LS is a crucial design parameter that can be used to regulate performance under off-design conditions. Specifically, lower LS enhances performance at positive incidence angles but comes at the cost of degraded performance at negative incidence angles. Moreover, relatively large CR (2–4) can improve performance under off-design conditions and also plays a role in achieving robust design, but it comes at the expense of optimal performance. To further explore the LS and CR effects on the flow field of the tandem cascades, three additional tandem cascades with LS = 0.5 and different CR were conducted. At large negative incidence angles (LS < 0.5), large CR (2.828) helps mitigate the accumulation of low-energy fluid on the pressure surface of the front blade and enhances the strength of the gap jet. Identically, at large positive incidence angles (LS > 0.5), the large CR mitigates the risk of corner stall and induces a transition in the stall mode of the front blade from corner stall to boundary layer separation over the entire span, further improving the tandem cascade performance. Based on the flow field analysis, the overall design strategy for LS and CR was summarized.
Buried InGaAs/InP quantum wells selectively grown on SOI for lateral membrane laser diodes
Authors: Fu Donghui , Ren Zhaojie , Jin Yunjiang , Han Yu , Yu Siyuan
Published: February 2024

The monolithic integration of energy-efficient and high-speed III–V lasers on silicon-on-insulator (SOI) platform in a cost-effective and scalable manner is the crux for the ubiquitous application of Si photonics in various applications. Here, aiming for lateral p-i-n membrane laser diodes, we report the growth of InGaAs/InP multi-quantum wells (MQWs) buried inside InP membranes on (001) SOI wafers using the lateral aspect ratio trapping method. We first obtain uniform InP membranes through careful tuning of a low-temperature nucleation layer, effectively trapping crystalline defects at the InP/Si heterogeneous interface and obtaining dislocation-free InP crystals away from the interface. We then construct buried (110)-oriented InGaAs/InP MQWs emitting in the telecom wavelengths by engineering the faceting of the InP membrane to enable the epitaxy of InGaAs alloy on (110) planes. These as-grown InGaAs/InP MQWs are fully embedded inside the InP membrane and provide effective confinement of both light and charged carriers. Our results demonstrate an elegant solution for future lateral membrane laser diodes directly grown on SOI wafers.
Analysis of vortex structure, temperature distribution, and near-wall flow development for an inclined jet interacting with crossflow of different boundary layer conditions
Authors: Shi Bo , Li Xueying , Ren Jing
Published: February 2024

In modern gas turbines, film cooling confronts complex near-wall flow conditions. Because of the low velocity ratio and the inclined injection in film cooling, the jet is more attached to the wall, making the influence of the local boundary layer critical. This paper investigates the interaction between the inclined jet and the mainstream boundary layer using large eddy simulation (LES). Four inflow boundary layer conditions were investigated, including a thin laminar case (δ/D = 0.5) and three turbulent cases with different thicknesses (δ/D = 0.5, 1.0, and 2.0). The jet velocity ratios are 0.23, 0.46, and 0.91 for each inflow condition. To consistently extract vortices of varying intensities, a local threshold was proposed using λci criterion. Based on the extracted vortices, a comprehensive analysis of the vortical strength, size, and position for horseshoe vortex (HSV), counter-rotating vortex pair (CRVP), and shear layer vortices (SLV) is performed under different inflow conditions. The results provide a clear picture of how HSV and CRVP form and evolve. Quantitative patterns are disclosed for the vortex lifting and vortical decay. Moreover, the thermal transport effects of HSV, CRVP, and SLV are examined. It was proven that these vortices dominate the coolant coverage, coolant core lifting, and thermal diffusion, respectively. Meanwhile, the jet has a significant impact on the near-wall flow development. The length of transition and the magnitude of thickening were discovered to be correlated with the jet velocity ratio and inflow thickness. Overall, these findings present a fresh perspective in understanding the flow and heat transport processes for inclined jet-in-crossflow.
Azimuthal phase-dependent electromagnetically induced transparency and the generation of spatial light in a microwave-assisted four-level Y-type system
Authors: Akhtar Samim , Saha Jayanta K , Hossain Md Mabud
Published: February 2024

We present an azimuthal phase-dependent scheme to study the spatially dependent electromagnetically induced transparency (EIT) and the generation of spatial light in a closed-loop four-level Y-type system. A structured control beam and a microwave (MW) field are adopted in the closed-loop structure. Interestingly, the weak non-vortex probe beam responses explicitly depend on the orbital angular momentum (OAM) of the control beam along with the MW-assisted quantum interference. The regions of spatially dependent EIT are demonstrated at different azimuthal angles. It is found that the intensity of the structured control beam and the relative phase arising out of the beams participating in the closed-loop can be used as the controlling knobs to tailor the shape and the angular location of the spatially dependent EIT.
Competition of multiphoton ionization pathways in lithium
Authors: Tóth Balázs , Tóth Attila , Csehi András
Published: February 2024

We study the three-photon ionization of atomic lithium by intense, short light pulses, via numerically solving the time-dependent Schrödinger equation. Two-photon Rabi oscillations are induced between the 2s and 4s states, which are damped due to single-photon ionization to the p continuum. Developing a minimal three-level model, we analyze the spectral features of the Autler–Townes (AT) doublet that is formed upon the resonant coupling with the laser pulse. Furthermore, we show that this

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pathway is the dominant process, if the duration of the laser pulse exceeds a certain value. For shorter pulses, ionization through the 2p state (

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u
m

) gradually becomes the dominant process, provided that the pulse is strong enough to induce several Rabi floppings. Here, we trace the competition of these ionization pathways by observing the structural changes in the shape of the AT doublet.
Poly-Si/a-Si/4H-SiC p-n heterojunction broadband photodetector prepared by magnetron sputtering
Authors: Li Zihao , Zhang Mingkun , Fu Zhao , Zhang Zeyang , Wu Shaoxiong , Zhang Yuning , Lin Dingqu , Hong Rongdun , Cai Jiafa , Chen Xiaping , Zhang Feng
Published: February 2024

With the increasing complexity of scenarios, there is a growing need for broadband photodetectors (PDs). In this work, we report a polycrystalline-Si (poly-Si)/amorphous-Si (a-Si)/4H-SiC p-n heterojunction PD with efficient response in a broad spectral range of ultraviolet–visible–near-infrared. The poly-Si/a-Si/4H-SiC heterojunction was achieved by magnetron sputtering and annealing. The fabricated heterojunction device has a low dark current of 1 pA at −40 V and a fast response time of 3 ns due to the outstanding rectification characteristics of the heterojunction combined with narrow bandgap and wide bandgap material. In addition, the carrier behavior of the heterojunction exposed to broadband light is analyzed in detail by constructing the energy band diagram.
First-principles prediction of n-type diamond: novel co-doped structure using N and Be impurities
Authors: Sun Xiang , Shen Wei , Cheng Chunmin , Wu Gai , Liang Kang , Zhang Dongliang , Wang Shizhao
Published: February 2024

To address the limitation of diamond-based electronic devices, a comprehensive study on n-type diamond is crucial. A novel dopant structure, nitrogen–beryllium co-doping, is proposed for achieving n-type doping. The dopant structure, electronic property, synthesis route and internal strain are analyzed using first-principles density functional theory. The formation energy and ionization energy of xN–Be (x = 1–4) are compared to elucidate the distinct doping effects associated with varying numbers of N atoms. The formation energy initially decreases and then gradually increases with an incensing number of N atoms. Notably, 3N–Be and 4N–Be exhibit appealing n-type diamond properties, with low ionization energies of 0.30–0.41 eV (3N–Be) and 0.23–0.37 eV (4N–Be). To facilitate the preparation of 3/4N–Be co-doped diamond, a non-molecular synthetic route is proposed, involving the prior generation of the 3N-V and 4N-V. The 3/4N–Be co-doped diamond exhibits relatively small strain energy. Finally, this investigation highlights the potential of 3/4N–Be co-doping as excellent choices for n-type dopants, providing a greater variety of n-type structures with similar ionization energy compared to 4N–Li co-doping.
A comprehensive survey of machine remaining useful life prediction approaches based on pattern recognition: taxonomy and challenges
Authors: Zhou Jianghong , Yang Jiahong , Qian Quan , Qin Yi
Published: February 2024

Predictive maintenance (PdM) is currently the most cost-effective maintenance method for industrial equipment, offering improved safety and availability of mechanical assets. A crucial component of PdM is the remaining useful life (RUL) prediction for machines, which has garnered increasing attention. With the rapid advancements in industrial internet of things and artificial intelligence technologies, RUL prediction methods, particularly those based on pattern recognition (PR) technology, have made significant progress. However, a comprehensive review that systematically analyzes and summarizes these state-of-the-art PR-based prognostic methods is currently lacking. To address this gap, this paper presents a comprehensive review of PR-based RUL prediction methods. Firstly, it summarizes commonly used evaluation indicators based on accuracy metrics, prediction confidence metrics, and prediction stability metrics. Secondly, it provides a comprehensive analysis of typical machine learning methods and deep learning networks employed in RUL prediction. Furthermore, it delves into cutting-edge techniques, including advanced network models and frontier learning theories in RUL prediction. Finally, the paper concludes by discussing the current main challenges and prospects in the field. The intended audience of this article includes practitioners and researchers involved in machinery PdM, aiming to provide them with essential foundational knowledge and a technical overview of the subject matter.
Critical pulse in multi-shot femtosecond laser ablation on metallic surfaces
Authors: Wang Pengjie , Kong Xiangguang , Qi Fugong , Zhou Jiyu , Ding Haimin , Peng Qing
Published: February 2024

Thermal effect remains a thorny issue for femtosecond-laser surface engineering and nanostructuring on metallic targets with high pulse energies or high repetition rates, which needs to be paid adequate attentions. Herein, we have experimentally investigated the heat diffusion and accumulations during single-shot and multi-shot femtosecond laser ablation on metallic surfaces. We have for the first time observed a novel phenomenon that the thermal effect was intensified abruptly when the laser-pulse number goes over a threshold (approximately between 10 and 20 for aluminum alloy with laser fluence of 6 J cm−2), accompanied with a dramatic reduction of ablated depth and complicated plasma dynamics. Based on both optical and thermodynamic analysis, we introduced a defocusing-dominated plasma-assistant model for this abnormal thermal effect. This work explored the critical experimental parameters for femtosecond-laser surface modification and processing in micro-scale engineering applications.
Improving respiratory signal prediction with a deep neural network and simple changes to the input and output data format
Authors: Hirai Ryusuke , Mori Shinichiro , Suyari Hiroki , Ishikawa Hitoshi
Published: February 2024

Objective.To improve respiratory gating accuracy and radiation treatment throughput, we developed a generalized model based on a deep neural network (DNN) for predicting any given patient’s respiratory motion.Approach.Our model uses long short-term memory (LSTM) based on a recurrent neural network (RNN), and improves upon common techniques. The first improvement is that the data input is not a one-dimensional sequence, but two-dimensional block data. This shortens the input sequence length, reducing computation time. Second, the output is not a scalar, but a sequence prediction. This increases the amount of available data, allowing improved prediction accuracy. For training and evaluation of our model, 434 sets of real-time position management data were retrospectively collected from clinical studies. The data were separated in a ratio of 4:1, with the larger set used for training models and the remaining set used for testing. We measured the accuracy of respiratory signal prediction and amplitude-based gating with prediction windows equaling 133, 333, and 533 ms. This new model was compared with the original LSTM and a non-recurrent DNN model.Main results.The mean absolute errors with the prediction window at 133, 333 and 533 ms were 0.036, 0.084, 0.119 with our model; 0.049, 0.14, 0.246 with the original LSTM-based model; and 0.041, 0.119, 0.16 with the non-recurrent DNN model, respectively. The computation time were 0.66 ms with our model; 0.63 ms the original LSTM-based model; 1.60 ms the non-recurrent DNN model, respectively. The accuracies of amplitude-based gating with the same prediction window settings and a duty cycle of approximately 50% were 98.3%, 95.8% and 92.7% with our model, 97.6%, 93.9% and 87.2% with the original LSTM-based model; and 97.9%, 94.3% and 89.5% with the non-recurrent DNN model, respectively.Significance.Our RNN algorithm for respiratory signal prediction successfully estimated tumor positions. We believe it will be useful in respiratory signal prediction technology.
A combined analytical and Monte Carlo method for detailed simulations of antiscatter grids in x-ray medical imaging: implementing scatter within the grid
Authors: Massera Rodrigo T , Bosmans Hilde , Rodriguez Perez Sunay , Marshall Nicholas
Published: February 2024

Objective. To implement a hybrid method, which combines analytical tracking and interaction simulation using Monte Carlo (MC) techniques, in order to model photon transport inside antiscatter grids (ASG) for x-ray imaging. Approach. A new tally was developed for PENELOPE (v.2018) and penEasy (v. 2020) MC code to simulate photon transmission through ASGs. Two established analytical algorithms from the literature were implemented in this tally. In addition, a new hybrid method was introduced by extending one of the analytical algorithms to include photon-interactions inside the grid, while preserving the imaged grid structure. Calculations of primary

(
T

P

)
,

scatter

(
T

S

)
,

and total

(
T

T

)

grid transmissions in addition to the Q factor (Q =

T

P

2

/

T

T

) were performed. The new tally was validated for a quadric geometry ASG, and experimental measurements with a PMMA phantom of several thicknesses. In addition, the contribution of the scatter inside the grid was studied for three interspace materials, and a high resolution image of the grid was simulated. Main results. An excellent agreement was found between the two analytical models compared with the quadric grid without scatter, and the hybrid method with the geometrical grid with scatter. Average deviations of 0.2% and 1.4% were found between

T

P

and

T

S

for the hybrid method and quadric grid, while for the hybrid method and experimental measurements these values were 1% and 20%. Antiscatter grids with aluminium as interspace material had the highest amount of scatter from inside the grid to the final image, followed up by paper fibre and air. The high resolution image of the grid was equivalent using the quadric geometry or the hybrid mode. Significance. The hybrid method provides a means of studying scattered radiation from the antiscatter grid with the advantage of higher performance, with results that are consistent with a full quadric geometry simulation of the ASG.
S-Net: an S-shaped network for nodule detection in 3D CT images
Authors: Zhang JingYu , Zou Wei , Hu Nan , Zhang Bin , Wang Jiajun
Published: February 2024

Objective. Accurate and automatic detection of pulmonary nodules is critical for early lung cancer diagnosis, and promising progress has been achieved in developing effective deep models for nodule detection. However, most existing nodule detection methods merely focus on integrating elaborately designed feature extraction modules into the backbone of the detection network to extract rich nodule features while ignore disadvantages of the structure of detection network itself. This study aims to address these disadvantages and develop a deep learning-based algorithm for pulmonary nodule detection to improve the accuracy of early lung cancer diagnosis. Approach. In this paper, an S-shaped network called S-Net is developed with the U-shaped network as backbone, where an information fusion branch is used to propagate lower-level details and positional information critical for nodule detection to higher-level feature maps, head shared scale adaptive detection strategy is utilized to capture information from different scales for better detecting nodules with different shapes and sizes and the feature decoupling detection head is used to allow the classification and regression branches to focus on the information required for their respective tasks. A hybrid loss function is utilized to fully exploit the interplay between the classification and regression branches. Main results. The proposed S-Net network with ResSENet and other three U-shaped backbones from SANet, OSAF-YOLOv3 and MSANet (R+SC+ECA) models achieve average CPM scores of 0.914, 0.915, 0.917 and 0.923 on the LUNA16 dataset, which are significantly higher than those achieved with other existing state-of-the-art models. Significance. The experimental results demonstrate that our proposed method effectively improves nodule detection performance, which implies potential applications of the proposed method in clinical practice.