bluuebunny/crossref_metadata_2025 huggingface dataset:
Praxisrelevante Aspekte zur biochemischen und molekulargenetischen
Diagnostik bei seltenen Knochenerkrankungen – vom Netzwerk Seltene
Osteopathien (NetsOs*)
Authors: Grasemann Corinna , Barvencik Florian , Siggelkow Heide , Kocijan Roland , Tsourdi Elena , Högler Wolfgang , Kornak Uwe
Published: December 2023

Seltene hereditäre Skeletterkrankungen können zu einer abnormen
Länge, Stärke oder Form der Knochen führen. Basierend
auf dem klinischen und radiologischen Phänotyp und dem Genotyp wird
diese Erkrankungsgruppe in mehr als 500 verschiedene und sehr heterogene
Erkrankungen unterteilt. Eine schnelle und präzise Diagnosestellung ist
für die Patientenversorgung dringend erforderlich und beruht auf der
Kombination von klinischen, biochemischen, radiologischen und genetischen
Analysen. Neue und verbesserte genetische Testverfahren haben die Diagnostik
revolutioniert und spielen eine große Rolle in der Beratung von
Patienten und Familien. Um die optimale Versorgung dieser Patienten zu
ermöglichen, wird ein krankheitsspezifisches Langzeitmanagement in einem
multidisziplinären Team in hochspezialisierten Zentren empfohlen. Dieser
Artikel gibt einen praxisrelevanten Überblick über die
biochemischen Analysen bei Kindern und Erwachsenen und ihre Anwendung in
Verbindung mit humangenetischen Tests zur Identifizierung, Charakterisierung und
Verlaufsbewertung dieser seltenen Skeletterkrankungen.
Mobilising volunteer groups, communities and agencies during the pandemic: a rapid realist view of the evidence
Authors: Kneale Dylan , Bangpan Mukdarut , Hartley Kathryn , Hou Meihui
Published: December 2023

The COVID-19 pandemic represented a rise in ‘people power’ globally, expressed through manifold acts of kindness, solidarity and mutualism as communities organised and came together where governments could or would not. In this study we were interested in the mechanisms through which communities and agencies extended existing practices and structures to respond to the pandemic or adopted new ways of organising. We undertook a rapid realist systematic review, following established steps and drawing on the Volunteer Process Model as our core theory. We worked with 59 studies to identify the mechanisms through which individuals, agencies and organisations, and communities mobilised and we identified six mechanisms. Gaining experience and developing role identity were key in mobilising volunteers to undertake activities and also resulted in positive outcomes for the volunteers themselves. Adaptability ensured that individuals, groups and local agencies and organisations were able to respond to the changing needs of beneficiary groups. Co-ordination helped communities, agencies and mutual aid groups to work together rather than in competition. Emotional support, support in the form of social and material recognition, and support through training were important in sustaining a volunteer workforce and protecting the wellbeing of the volunteer workforce. Altruism was a key motivator for stepping up during the pandemic and becoming a volunteer while greater trust was linked with the extent to which groups and communities were able to scale up efforts to respond to higher demands during the pandemic. While the COVID-19 pandemic represented a period of great social upheaval, it illuminated the ‘power of people’ working together. Our findings identify six key mechanisms that supported this mobilisation, which may be critical to activate in future health emergencies, but are also largely reflective of investments made before the pandemic to support the development of social capital and the development of volunteering infrastructure.
The dark web privacy dilemma: linguistic diversity, talkativeness, and user engagement on the cryptomarket forums
Authors: Chen Zhicong , Meng Xiang , Wang Cheng-Jun
Published: December 2023

The users of the Dark Web require a secure and highly anonymous environment to exchange information while protecting their online privacy, which presents a privacy dilemma. This paper examines the digital footprints of user behavior on the three most popular cryptomarket forums on the Dark Web, namely Silk Road 1, Silk Road 2, and Agora. The results indicate that users who engage in more conversations and employ a wider range of vocabulary are more likely to discontinue their participation on the forum. Intriguingly, no significant relationship is found between network characteristics and user engagement. These findings emphasize that the risk of exposure within anonymous communities primarily stems from the potency of information rather than social connections, which sheds light on the privacy dilemma inherent in the Dark Web and provides deeper insights into the online user behavior surrounding anonymity-granting technologies on the Internet.
Transmission properties of time-dependent one-dimensional metamaterials
Authors: Ammari H. , Cao J. , Hiltunen E. O. , Rueff L.
Published: December 2023

We solve the wave equation with periodically time-modulated material parameters in a one-dimensional high-contrast resonator structure in the subwavelength regime exactly, for which we compute the subwavelength quasifrequencies numerically using Muller’s method. We prove a formula in the form of an ODE using a capacitance matrix approximation. Comparison of the exact results with the approximations reveals that the method of capacitance matrix approximation is accurate and significantly more efficient. We prove various transmission properties in the aforementioned structure and illustrate them with numerical simulations. In particular, we investigate the effect of time-modulated material parameters on the formation of degenerate points, band gaps and k-gaps.
Synchronization and decoherence in a self-excited inertia-wheel multiple rigid-body dynamical system
Authors: Yakir G. , Gottlieb O.
Published: December 2023

We investigate the synchronization and decoherence of a self-excited inertia wheel multiple rigid-body dynamical system. We employ an Euler–Lagrange formulation to derive a nondimensional state space that governs the dynamics of a coupled pendula array where each element incorporates an inertia wheel. The dynamical system exhibits multiple equilibria, periodic limit-cycle oscillations, quasiperiodic, and chaotic oscillations and rotations. We make use of a combined approach including a singular perturbation multiple time scale and numerical bifurcation methodologies to determine the existence of synchronized and decoherent solutions in both weakly and strongly nonlinear regimes, respectively. The analysis reveals that synchronous oscillations are in-phase, whereas quasiperiodic oscillations are anti-phase. Furthermore, the non-stationary rotations are found to exhibit combinations of oscillations and rotations of the individual elements that are asynchronous. A Kuramoto order parameter analysis of representative solutions in various bifurcation regimes reveals the existence of chimera-like solutions where two elements are synchronized, whereas the third is desynchronized. Moreover, synchronous solutions were found to coexist with stable chimera solutions with a constant phase difference between the oscillators.
The impacts of atmospheric icing on performance and behavior of a controlled large-scale wind turbine
Authors: Sahin Mustafa , Farsadi Touraj
Published: December 2023

Icing degrades turbine performance by altering the geometry of blade airfoils, reducing turbine power output, and increasing structural loads. In this study, the impacts of atmospheric icing on the full performance and behavior of a controlled large-scale wind turbine are thoroughly investigated. Using the Mustafa Sahin bladed wind turbine simulation model, the National Renewable Energy Laboratory 5 MW turbine is simulated with and without iced blades. The turbine blades are considered fully covered by light icing at the leading edge, which causes a reduction of up to 9.27% in Cl and an increase of up to 48% in Cd data of blade airfoils. Turbine static performance and behavior are examined at different uniform winds between cut-in and cut-out wind speeds, while the dynamic performance and behavior are estimated under turbulent winds at below (region II) and above (region III) rated regions. Simulation results are presented in terms of various turbine parameters, such as rotor power, thrust, their coefficients, blade pitch angle, rotor speed, etc. Results show that such light icing alters the turbine's aerodynamic characteristics and dynamics, increasing the turbine's cut-in and rated wind speeds, and reducing the thrust and maximum power coefficients by 5.5% and 13.35%, respectively. Under the same uniform winds, due to icing, turbine static performance and behavior are drastically disrupted in below rated region, resulting in reduced rotor speed, turbine efficiency, thrust, and power output by up to 4.77%, 39.7%, 7.63%, and 40%, respectively. In region III, however, thrust increases by up to 15% although the power output, rotor speed, and turbine efficiency do not change considerably. When the dynamic responses are examined under turbulent wind with a mean of 7.9 m/s in region II, mean power and fluctuations reduce by 14.17% and 10.88%, respectively. The mean thrust decreases by 6.86%, while its fluctuations reduce by 11.33%. The mean rotor speed reduces by 3.83%, and its fluctuations decrease by 12.84%. Under turbulent wind with a mean of 15.7 m/s in region III, the mean power and fluctuations decrease by 0.053% and 1.95%, respectively. The mean thrust increases by 11.99% and its fluctuations drop by 0.84%. The mean rotor speed does not change much, but its fluctuations increase by 0.132%. The mean blade pitch angle reduces by 9.39%, while its fluctuations increase by 7.39%.
Nowhere coexpanding functions
Authors: Cook Andrew , Hammerlindl Andy , Tucker Warwick
Published: December 2023

We define a family of C1 functions, which we call “nowhere coexpanding functions,” that is closed under composition and includes all C3 functions with non-positive Schwarzian derivatives. We establish results on the number and nature of the fixed points of these functions, including a generalization of a classic result of Singer.
Dynamical noise can enhance high-order statistical structure in complex systems
Authors: Orio Patricio , Mediano Pedro A. M. , Rosas Fernando E.
Published: December 2023

Recent research has provided a wealth of evidence highlighting the pivotal role of high-order interdependencies in supporting the information-processing capabilities of distributed complex systems. These findings may suggest that high-order interdependencies constitute a powerful resource that is, however, challenging to harness and can be readily disrupted. In this paper, we contest this perspective by demonstrating that high-order interdependencies can not only exhibit robustness to stochastic perturbations, but can in fact be enhanced by them. Using elementary cellular automata as a general testbed, our results unveil the capacity of dynamical noise to enhance the statistical regularities between agents and, intriguingly, even alter the prevailing character of their interdependencies. Furthermore, our results show that these effects are related to the high-order structure of the local rules, which affect the system’s susceptibility to noise and characteristic time scales. These results deepen our understanding of how high-order interdependencies may spontaneously emerge within distributed systems interacting with stochastic environments, thus providing an initial step toward elucidating their origin and function in complex systems like the human brain.
Mechanisms for insulation recovery during repetitive breakdowns in gas gaps
Authors: Li Longjie , Chen Jiaxin , Yi Chen , Xu Xianfeng , Xu Guimin , Wang Biao
Published: December 2023

The insulation recovery during repetitive breakdowns in gas gaps is a fundamental scientific issue in both traditional and emerging electrical technology fields, which has received extensive attention over the years. This paper provides a systematic review of research methods for insulation recovery in repetitive breakdowns of gas gaps, progress made in understanding the thermal–hydrodynamic processes involved in this recovery (dissipation of deposited energy and restoration of neutral gas density), as well as the memory effect resulting from repetitive discharges and breakdowns (dominant factors and their underlying mechanisms). Based on current results, it is proposed that the insulation recovery of repetitive gas gaps breakdowns results from the synergistic effect between post-breakdown thermal-hydrodynamic processes and memory effects. This review aims to clarify the boundary and interplay between hydrodynamic processes and memory effects, as well as reveal their coupling relationship and synergistic mechanism. It also seeks to overcome barriers between related research fields, ultimately facilitating a resolution to the issue.
Hong–Ou–Mandel interference of spin–orbit hybrid entangled photons
Authors: Hong Ling , Cao Xiyue , Chen Yuanyuan , Chen Lixiang
Published: December 2023

Structured photons are a crucial resource in both classical and quantum technologies, particularly in spin–orbit hybrid photons, enabling various practical applications ranging from ultra-sensitive metrology techniques to quantum-enhanced information processing tasks. However, the two-photon interference of spin–orbit hybrid photons, which combines polarization modes and complex transverse spatial structures across the beam profile, remains unexplored. Here, we present an experimental observation of Hong–Ou–Mandel (HOM) interference of spin–orbit hybrid photons. The tunable q-plates that work as spin–orbit coupler devices are used to prepare various forms of spin–orbit hybrid entangled photons. By harnessing the match degree in the temporal domain, the coalescence and anti-coalescence effects resulting from the symmetric and anti-symmetric properties of the incident quantum states are observed. Moreover, we demonstrated the feasibility of quantum-enhanced photon polarization gears through HOM interference and theoretically analyze the noise-resilient advantages based on coherent HOM measurements. These results provide an alternative route toward quantum experiments with structured photons that allows for controlling their quantum interference in a compact, stable, and efficient way.
Local structure and ordering of Al atoms in AlxGa1−xN epilayers
Authors: Spindlberger Anna , Ciatto Gianluca , Adhikari Rajdeep , Yadav Ashok-Kumar , Bonanni Alberta
Published: December 2023

In this study, we investigate the local structure of aluminum (Al) in a comprehensive series of AlxGa1−xN epilayers, where the Al concentration spans from the dilute limit to 100%. We analyze grazing incidence Al K-edge tender x-ray absorption spectroscopy data using both linear combination fitting based on reference limit spectra and full quantitative analysis. The results indicate deviations from random cation distribution with varying signs within the explored concentration range. Additionally, we observe a reduction in cationic interatomic distances over a wide concentration range, which contrasts with some previous studies conducted at hard x-ray absorption edges.
A method for evaluating spectral down-shifting materials applied to solar cells
Authors: Song Guoxiang , Lou Chaogang , Diao Han , Zhu Ruiqi
Published: December 2023

Spectral down-shifting materials convert the photons in the solar spectrum that are less efficiently utilized into photons that can be fully used by solar cells, providing an attractive idea for improving the photoelectric conversion efficiency (PCE) of the solar cells. However, there is currently no parameter that can reliably assess the photoelectric excitation effect of the down-shifting materials on solar cells. Here, a calculation method that can reliably evaluate the photoelectric excitation effect of the down-shifting materials on the solar cells is proposed, which introduces the solar spectrum, the quantum yield of materials, and the external quantum efficiency of the solar cells. Then, the calculation method is described in detail with the relevant physical processes, taking the down-shifting materials acting on crystalline silicon solar cells as an example. Finally, the Pearson correlation coefficient between the parametric photoelectric excitation efficiency (PEE) calculated using the method and the ΔPCE value obtained experimentally was 0.999 51, demonstrating the reliability of the calculation method. The PEE calculated using this method is an inherent property of the down-shifting material for a specific solar cell and does not change with external conditions. Therefore, PEE can be used as a parameter for down-shifting materials to facilitate the selection of materials with better effects on solar cells from an enormous number of down-shifting materials and is suitable for various types of solar cells.
Electrical coupling of superparamagnetic tunnel junctions mediated by spin-transfer-torques
Authors: Schnitzspan Leo , Kläui Mathias , Jakob Gerhard
Published: December 2023

In this work, the effect of electrical coupling on stochastic switching of two in-plane superparamagnetic tunnel junctions (SMTJs) is studied, using experimental measurements as well as simulations. The coupling mechanism relies on the spin-transfer-torque effect, which enables the manipulation of the state probability of an SMTJ. Through the investigation of time-lagged cross-correlation, the strength and direction of the coupling are determined. In particular, the characteristic state probability transfer curve of each SMTJ leads to the emergence of a similarity or dissimilarity effect. The cross-correlation as a function of applied source voltage reveals that the strongest coupling occurs for high positive voltages for our SMTJs. In addition, we show state tunability as well as coupling control by the applied voltage. The experimental findings of the cross-correlation are in agreement with our simulation results.
A refractory medium-entropy alloy with ultrahigh specific yield strengths for elevated-temperature applications
Authors: Xiao Yake , Peng Xianghe
Published: December 2023

Refractory high- or medium-entropy alloys (RHEAs or RMEAs) with excellent high-temperature mechanical properties and softening resistance have been proven to be the potential candidates for advanced engineering applications. However, room temperature brittleness and high density have become an important challenge that needs to be addressed. In this work, the tensile mechanical behavior and the underlying deformation mechanisms of lightweight Ti40Zr20Nb13.33V26.67 RMEA at 298 and 873 K were investigated systematically. The results showed that the as-cast RMEA has a single body-centered cubic phase and low density (5.88 g/cm3) and exhibits excellent mechanical properties at 298 K, with yield strength of 1033.9 MPa, specific yield strength of 175.8 MPa·cm3/g, and tensile fracture strain of 5.3%. More importantly, it also exhibits ultrahigh strength and sufficient ductility at 873 K, with yield strength of 783.2 MPa, specific yield strength of 133.2 MPa·cm3/g, and tensile fracture strain of 5.7%. It showed that a large number of slip bands and dislocation bands are the main deformation products at 298 K, leading to excellent ductility. In comparison, high dislocation density was found between the slip bands in the samples deformed at 873 K, which can effectively hinder the motion of dislocations, resulting in strain hardening and the increase in strength. This work can provide a route for the design and fabrication of high-performance lightweight alloys, which would be beneficial for engineering applications.
Experimental investigation of a triple point in a dusty plasma
Authors: Singh Swarnima , Bandyopadhyay P. , Kumar Krishan , Sen A.
Published: December 2023

In this work, we present the first experimental observation of a triple point in a strongly coupled complex plasma medium. Initially, a 2D crystalline structure of the dust component consisting of monodisperse micrometer-sized particles is created. The evolution of this monolayer as a function of the discharge voltage is then investigated and, in the course of this evolution, the co-existence of three distinct phases of the system consisting of a liquid region and two crystalline regions with square and hexagonal lattice configurations is observed. Two different transition sequences are identified in the system, depending on the initial dust density of the monolayer. The particles in the fluid region have high kinetic energy. Before the emergence of a triple state, it is found that the particles in the different lattice geometries show different in-plane or out-of-plane oscillations. It is conjectured that a complex or mixed instability that originates in the system in a localized manner gives rise to the formation of the triple point in our experiments.
Identifying the switching topology of dynamical networks based on adaptive synchronization
Authors: Li Kezan , Yang Dan , Shi Changyao , Zhou Jin
Published: December 2023

This paper proposes an approach for identifying unknown switching topology in a complex dynamical network. The setup is divided into two components: a primary drive network and a specialized response network equipped with switched topology observers. Each class of observers is dedicated to tracking a specific topology structure. The updating law for these observers is dynamically adjusted based on the operational status of the corresponding topology in the drive network—active if engaged and dormant if not. The sufficient conditions for successful identification are obtained by employing adaptive synchronization control and the Lyapunov function method. In particular, this paper abandons the generally used assumption of linear independence and adopts an easily verifiable condition for accurate identification. The result shows that the proposed identification method is applicable for any finite switching periods. By employing the chaotic Lü system and the Lorenz system as the local dynamics of the networks, numerical examples demonstrate the effectiveness of the proposed topology identification method.
Effect of boundary conditions on energy harvesting of a flow-induced snapping sheet at low Reynolds number
Authors: Wang Zhaokun , Zhao Fuwang , Xu Bowen , Zeng Lingwei , Tang Hui
Published: December 2023

Recent studies on the snap-through motion of elastic sheets have attracted intense interest in energy-harvesting applications. However, the effect of boundary conditions (BCs) on energy extraction performance still remains an open question. In this study, we explored the snapping dynamics and energy-harvesting characteristics of the buckled sheet at various conditions using fluid–structure interaction simulations at a Reynolds number Re = 100. It was found that the front boundary condition (BC) dramatically affects the sheet's snapping dynamics, e.g., the pinned or relatively soft front BC triggers the sheet's instability easily and thus boasts the collection of potential energy. In the snap-through oscillation state, a stiffer rear BC results in a larger improvement in the sheet's energy collection compared with a minor effect of front BC. Meanwhile, the enhancement can also be achieved by adjusting the rear rotational spring stiffness up to 1.125 × 10−4, after which it remains nearly constant, as observed in the case of EI* = 0.004. This introduction of an elastic BC with krs* = 1.125 × 10−4 not only efficiently enhances energy extraction but significantly reduces stress concentration and, as a result, greatly prolongs the sheet's fatigue durability, especially for the stiffer sheet with EI* = 0.004. The effect of three other governing parameters, including the length ratio ΔL*, sheet's bending stiffness EI*, and mass ratio m*, on the sheet's energy-harvesting performance were also explored. The result shows that increasing ΔL* and EI* could improve the total energy harvested, primarily by enhancing the elastic potential energy, particularly in the aft half of the sheet. In contrast, increasing m* mainly enhances the kinetic energy collected by the sheet's central portion, thus improving the total energy-extracting performance. This study provides an in-depth insight into the dynamics of a buckled sheet under various BCs, which may offer some guidance on the optimization of relevant energy harvesters.
Improvement of thermoelectric performance of flexible compound Ag2S0.55Se0.45 by means of partial V-substitution for Ag
Authors: Sato Kosuke , Singh Saurabh , Yamazaki Itsuki , Hirata Keisuke , Ang Artoni Kevin R. , Matsunami Masaharu , Takeuchi Tsunehiro
Published: December 2023

The effects of the partial V-substitution for Ag on the thermoelectric (TE) properties are investigated for a flexible semiconducting compound Ag2S0.55Se0.45. Density functional theory calculations predict that such a partial V-substitution constructively modifies the electronic structure near the bottom of the conduction band to improve the TE performance. The synthesized Ag1.97V0.03S0.55Se0.45 is found to possess a TE dimensionless figure-of-merit (ZT) of 0.71 at 350 K with maintaining its flexible nature. This ZT value is relatively high in comparison with those reported for flexible TE materials below 360 K. The increase in the ZT value is caused by the enhanced absolute value of the Seebeck coefficient with less significant variation in electrical resistivity. The high ZT value with the flexible nature naturally allows us to employ the Ag1.97V0.03S0.55Se0.45 as a component of flexible TE generators.
Effects of displacement velocity on interfacial reconstruction events during immiscible two-phase displacement
Authors: Yan Huan , Wang Xingguang , Liu Hongshuai , Guo Xiaokang
Published: December 2023

During the two-phase fluid displacement in porous media, with the increase in capillary number Ca, different wettability effects are suppressed; however, its potential control mechanism has not been clarified. Therefore, in this study, we have analyzed the pore scale process related to interface reconfiguration events in detail and profoundly clarified the nature of a series of interface reconfiguration events being suppressed. Based on typical pore throat, we elaborated and confirmed that the development and evolution direction of fluid displacement mode always follow the principle of minimum operating power. That is to say, in order to avoid extra work, the system will compare all the potential moving meniscus at the displacement front and always choose the local path with the minimum operating power (Po=ΔpQ) of the system for displacement. Under this theory, a series of interface reconfiguration events are considered energy favorable self-regulation events derived by the system in order to avoid extra energy consumption. However, the appearance and disappearance of interface reconstruction events are considered to be the result of the mechanism of “self-regulation of surface energy change rate” and “self-regulation of viscosity dissipation rate” in order to approach the minimum operating power. This study provides us with a sufficient physical explanation to understand the nature of the wettability effect being suppressed.
Equilibria when the temperature goes to zero
Authors: Thomsen Klaus
Published: December 2023

We present methods to construct flows with varying set of KMS∞ states on a given simple unital AF-algebra. It follows, for example, that for any pair D+ and D− of non-empty compact metric spaces there is a flow σ=(σt)t∈R on the CAR algebra whose set of KMS∞ states is homeomorphic to D+ while the set of KMS∞ states for the inverted flow (σ−t)t∈R is homeomorphic to D−. Remarkably the flows that realize all such pairs D± can be chosen to have isomorphic KMS bundles.
Numerical simulations of Sakiadis boundary-layer flow
Authors: Hattori Yuna
Published: December 2023

When a static fluid encounters a moving boundary, it experiences a large shear and forms a boundary layer. A self-similar solution of the boundary-layer equations for such flow was first revealed by Sakiadis in 1961. Despite the ubiquity of this type of flow, there are so far no published numerical simulations. In this article, we use OpenFOAM, a widely used open source software, to conduct a numerical simulation of the isothermal Sakiadis flow. The results are in good accord with the theoretical solution except near the leading edge, where the boundary-layer approximations are not fulfilled. We present that the boundary layer thickness is not zero at the beginning of the boundary-layer flow, although this condition has been extensively used. Currently, in boundary-layer research different definitions of boundary layer thickness are being employed. We also show that depending on the definition used, self-similarity appears at different stream-wise positions. The widest range of self-similarity can be obtained by using the definition of momentum thickness. Finally, we also present a new self-similar solution in wall normal direction near the leading edge. These results obtained from the simulation might well be applicable to many other boundary-layer flows, such as the Blasius flow.
How backreflection contributes to light absorption for high-performance radial junction photovoltaics
Authors: Zhang Shaobo , Wang Shuyi , Hu Ruijin , Cao Yunqing , Wang Junzhuan , Xu Jun , Yu Linwei
Published: December 2023

A robust radial junction (RJ) structure directly constructed upon the surface of a flexible Al foil substrate shows a promising potential to boost wearable and portable applications, where the silicon nanowire (SiNW) supported multilayer has proven beneficial in excellent mechanical stability and sufficient light harvesting. Assigned to the beneficial backreflection contributed by the Al foil, a much larger light current can be achieved than that on glass. While a comprehensive understanding of the light absorption under the backreflection of the substrate remains mainly unexplored. Herein, a straightforward comparison of light absorption of RJ units on Al and glass substrates, within a theoretical framework based on a finite-element simulation, is performed. Then, taking SiNW geometric parameters and i-layer thickness into account, the evolutions of light harvesting and the external quantum efficiency curves are systematically studied. These results indicate that, under the backreflection of the substrate, the light absorption shows a reduced dependency on SiNW geometry and i-layer thickness to some extent, laying a critical basis to establish a simpler/easier fabrication process for high-performance flexible RJ thin film photovoltaics.
Acoustically driven spin wave resonance in Ni/128° Y-cut LiNbO3 hybrid devices with the beam steering effect
Authors: Gao Runliang , Xue Jiangtao , Wu Huiliang , Ye Yuchen , Wang Jianbo , Liu Qingfang
Published: December 2023

We study the acoustically driven spin wave resonance (ADSWR) in a Ni film sputtered on a 128° Y-cut lithium niobate (LiNbO3) substrate under the condition that the beam steering effect exists due to the surface acoustic waves (SAWs) transmitted along several selected crystal orientations. SAW devices with that effect exhibit significantly different ADSWR spectra from devices without it. By using the magnetoelastic coupling theory and finite element simulation associated with SAW, we find that the beam steering effect of magnetoacoustic waves has an important influence on the acoustic attenuation. The relationship between its group velocity direction and the magnetization vector can be used to define the magnetoacoustic wave mode. The mode affects acoustic attenuation magnitude, which can break the fourfold symmetry. Increasing its power flow angle will significantly increase the maximum acoustic attenuation caused by magnon–phonon coupling.
A tri-point correlation method for ocean current estimation and its applications in near-bottom turbulent mixing on the shelf of the Northern South China Sea
Authors: Guo Shuang-Xi , Zhou Sheng-Qi , Qu Ling , Cen Xian-Rong , Huang Peng-Qi , Lu Yuan-Zheng , Han Guang-Hui
Published: December 2023

We propose a tri-point correlation method to estimate ocean currents using moored temperature observation data. The transit time for two time series of temperature is determined with the cross correlation technique, enabling the formulations of an equation system to determine the current speed and angle. To validate our method, we utilize a high-resolution temperature dataset collected at the shelf bottom of the northern South China Sea and compare the inferred currents with direct measurement results with a current meter. The results demonstrate a high level of agreement between the inferred currents and the directly measured ones. Using this temperature dataset and the synchronously inferred currents, we further estimate near-bottom turbulent mixing, including diapycnal mixing and vertical heat flux. During the observation period, the mean values of the turbulent kinetic energy dissipation rate, turbulent diffusivity, and vertical heat flux are 3.8×10−8 m2/s3,  2.6×10−4 m2/s, and 10.0 W/m2, respectively. These inferred turbulent mixing quantities exhibit a positive correlation with the dynamics of internal waves.
Adjustable gas adsorption and desorption via a self-shrinking nanoscroll
Authors: Wan Jing , Cai Kun , Kang Yuanyuan , Luo Yangjun , Qin Qinghua
Published: December 2023

In a gas adsorption–desorption process, gas desorption consumes energy, as well. Hence, the development of gas adsorption–desorption methods and/or adsorbent materials with low-energy consumption for precisely controlling the reversible process is still an open issue. Taking carbon dioxide as an example, this study proposed a carbon nanospring as a unit of an adsorbent model to control the capacity for gas adsorption (CGA), via expanding for adsorption or self-shrinking for desorption by the nanoscroll made from partly hydrogenated graphene ribbon (H-GR). The numerical results obtained from the molecular dynamics approach demonstrate that the CGA of H-GR can be precisely controlled by changing the deformation of H-GR. The adjustable scope of CGA, called capacity for gas desorption, depends on the gas density and the loading speed. However, the ratio of desorption slightly depends on the gas density, which benefits gas capturing in potential application of the present material model.
Polymer-dominant drag reduction in turbulent channel flow over a superhydrophobic surface
Authors: Zhang Linsheng , Garcia-Gonzalez Reyna I. , Crick Colin R. , Ng Henry C.-H. , Poole Robert J.
Published: December 2023

In this study, we focused on the integration of a flexible polymer (polyacrylamide) and a (randomly patterned) superhydrophobic surface in a large-scale turbulent channel flow rig to investigate their combined drag reduction effectiveness. Experimental results indicate that, prior to degradation, polyacrylamide (at a 100-ppm concentration) and superhydrophobic surfaces individually manifest drag reductions of 35% and 7%, respectively. However, when combined, the influence of polymer additives remained consistent, with the introduction of superhydrophobic surfaces yielding negligible differences. A clear predominance was evidenced in our facility looking at realistic pressure for applications, with polymer additives overshadowing the impact of superhydrophobic surfaces.
Demultiplexing of 40 acoustic orbital angular momentum wavelength-division multiplexing (OAM-WDM) channels by an improved virtual rotating receiver method
Authors: Liu Lianyun , Chu Zhigang
Published: December 2023

Orbital angular momentum (OAM) multiplexing/demultiplexing technology is crucial in increasing the data transmission rate for acoustic communication. However, the existing acoustic OAM multiplexing/demultiplexing is still limited to eight channels, and its combination with other communication techniques has not been verified experimentally. Here, we experimentally demonstrate the demultiplexing of up to 40 data channels using OAM multiplexing combined with wavelength-division multiplexing (WDM). The proposed demultiplexing method is improved from the virtual rotating receiver method used to detect the rotational Doppler effect of the OAM waves by a static array of microphones. The improved method has overcome the challenges of insufficient response, cross-talk, and signal aliasing, which often hinder the existing demultiplexing methods in the low-frequency region. The proposed demultiplexing method can be used to quickly decode the massive information concealed in a large number of acoustic OAM-WDM channels. Our work also shows practical prospects in underwater communication applications, especially in long-range communication using acoustic waves at low frequencies.
Oblique water entry of a curved foil with varying speed
Authors: Sun Shi Yan , Zeng Fanrong , Yang Yifeng , Wang Wenli
Published: December 2023

The hydrodynamic problem of a curved foil entering into water obliquely with varying speed is investigated through the boundary element method in time domain, and fully nonlinear boundary conditions on the deforming free surface are adopted. The process of foil entry begins with a single point at the lower edge; posing numerical challenges due to the extremely small wetted area, we utilize the stretched co-ordinate system method to address this. An auxiliary method is adopted to solve for pressure distribution. The whole process of the attached flow forming along the curved body and then detaching from the top edge is considered. We engage in extensive discussions on the effects of curvature, gravity, and acceleration, exploring their physical significance and potential applications, particularly within the context of surface-piercing propellers.
The effect of an electric field on the reaction kinetics of a charge carrier migrating within a one-dimensional chain
Authors: Chetverikov Artem O. , Borovkov Vsevolod I.
Published: December 2023

The aim of this study is to suggest a novel approach for estimating the intramolecular mobility of a charge carrier that migrates within a polymer chain and is involved in a pair reaction with a particle located on the same chain. The approach is based on the effect of an external electric field on the migration rate and, consequently, the kinetics of the reaction. As a first step, this problem is considered a stochastic one-step process with absorbing and reflecting boundaries, and an analytical solution is obtained in the case that the second reactant is immobile. With the use of computer simulations of stochastic migration, the effect of the mobility of both reactants and the influence of the Coulomb interaction between them are considered. It is found that the ratio of the pair reaction rates with and without an external field is relatively little dependent on these factors and that the analytical expressions derived can be applied to estimate the relative mobility of recombining particles with accuracy better than a factor of two in many realistic situations.
Stabilizing two-dimensional turbulent Kolmogorov flow via selective modification of inviscid invariants
Authors: Kumar Gaurav , Nair Aditya
Published: December 2023

We stabilize 2D turbulent Kolmogorov flow by selectively altering the time rate of change of inviscid invariants (energy and enstrophy) of the flow. This method has earlier been demonstrated to modify the 2D unforced decaying turbulent flow to reach steady states. However, Kolmogorov flow exhibits flow unsteadiness over a range of spatial and temporal scales which are driven by constant external forcing at wave number kf. The energy injected at scale (k≈kf) is distributed to large (k>kf) and small (k<kf) wave numbers through interactions of different scales called direct and inverse energy cascading, respectively. The selective modification strategy autonomously identifies additional forcing inputs into the governing equations which results in the transformation of Kolmogorov flow into a non-trivial steady state. We demonstrate that this method is highly effective in altering the inverse energy cascading, a particularly intricate challenge in fluid dynamics. Intriguingly, we have also found that the steady states achieved through this approach resemble an invariant solution of the original Kolmogorov flow, highlighting the potential significance of our method.
Three-dimensional laminar flow using physics informed deep neural networks
Authors: Biswas Saykat Kumar , Anand N. K.
Published: December 2023

Physics informed neural networks (PINNs) have demonstrated their effectiveness in solving partial differential equations (PDEs). By incorporating the governing equations and boundary conditions directly into the neural network architecture with the help of automatic differentiation, PINNs can approximate the solution of a system of PDEs with good accuracy. Here, an application of PINNs in solving three-dimensional (3D) Navier–Stokes equations for laminar, steady, and incompressible flow is presented. Notably, our approach involves deploying PINNs using feed-forward deep neural networks (DNNs) without depending on any simulation or experimental data. This investigation focuses on 3D square channel flow and 3D lid-driven cavity flow. For each case, one deep neural network was trained using only the governing equations and boundary conditions. Finally, the PINNs' results were compared with the computational fluid dynamics results. The goal was to assess the ability of PINNs (with DNN architectures) to predict the solution of Navier–Stokes equations in the 3D domain without any simulation or experimental data (unsupervised learning).
Integrated photonics beyond communications
Authors: Zhang Chong , Tran Minh A. , Zhang Zeyu , Dorche Ali E. , Shen Yang , Shen Boqiang , Asawa Kaustubh , Kim Glenn , Kim Nathan , Levinson Frank , Bowers John E. , Komljenovic Tin
Published: December 2023

The development of photonic integrated circuits has historically been driven by communications. However, emerging markets and opportunities require platforms that can operate over a broader wavelength range, offer additional capabilities, or improve performance. This paper provides a perspective on these emerging opportunities and the most promising approaches for addressing them, with a focus on platforms that support on-chip light generation and amplification.
Maximum temperatures determine the habitat affiliations of North American mammals
Authors: Tourani Mahdieh , Sollmann Rahel , Kays Roland , Ahumada Jorge , Fegraus Eric , Karp Daniel S.
Published: December 2023

Addressing the ongoing biodiversity crisis requires identifying the winners and losers of global change. Species are often categorized based on how they respond to habitat loss; for example, species restricted to natural environments, those that most often occur in anthropogenic habitats, and generalists that do well in both. However, species might switch habitat affiliations across time and space: an organism may venture into human-modified areas in benign regions but retreat into thermally buffered forested habitats in areas with high temperatures. Here, we apply community occupancy models to a large-scale camera trapping dataset with 29 mammal species distributed over 2,485 sites across the continental United States, to ask three questions. First, are species’ responses to forest and anthropogenic habitats consistent across continental scales? Second, do macroclimatic conditions explain spatial variation in species responses to land use? Third, can species traits elucidate which taxa are most likely to show climate-dependent habitat associations? We found that all species exhibited significant spatial variation in how they respond to land-use, tending to avoid anthropogenic areas and increasingly use forests in hotter regions. In the hottest regions, species occupancy was 50% higher in forested compared to open habitats, whereas in the coldest regions, the trend reversed. Larger species with larger ranges, herbivores, and primary predators were more likely to change their habitat affiliations than top predators, which consistently affiliated with high forest cover. Our findings suggest that climatic conditions influence species’ space-use and that maintaining forest cover can help protect mammals from warming climates.
Widespread evidence for elephant exploitation by Last Interglacial Neanderthals on the North European plain
Authors: Gaudzinski-Windheuser Sabine , Kindler Lutz , Roebroeks Wil
Published: December 2023

Neanderthals hunted and butchered straight-tusked elephants, the largest terrestrial mammals of the Pleistocene, in a lake landscape on the North European plain, 125,000 years ago, as recently shown by a study of the Last Interglacial elephant assemblage from Neumark-Nord (Germany). With evidence for a remarkable focus on adult males and on their extended utilization, the data from this location are thus far without parallel in the archaeological record. Given their relevance for our knowledge of the Neanderthal niche, we investigated whether the Neumark-Nord subsistence practices were more than a local phenomenon, possibly determined by local characteristics. Analyzing elephant remains from two other Last Interglacial archaeological sites on the North European plain, Gröbern and Taubach, we identified in both assemblages similar butchering patterns as at Neumark-Nord, demonstrating that extended elephant exploitation was a widespread Neanderthal practice during the (early part of the) Last Interglacial. The substantial efforts needed to process these animals, weighing up to 13 metric tons, and the large amounts of food generated suggest that Neanderthals either had ways of storing vast amounts of meat and fat and/or temporarily aggregated in larger groups than commonly acknowledged. The data do not allow us to rule out one of the two explanations, and furthermore both factors, short-term larger group sizes as well as some form of food preservation, may have played a role. What the data do show is that exploitation of large straight-tusked elephants was a widespread and recurring phenomenon amongst Last Interglacial Neanderthals on the North European plain.
Triggering interfacial instabilities during forced imbibition by adjusting the aspect ratio in depth-variable microfluidic porous media
Authors: Lei Wenhai , Lu Xukang , Gong Wenbo , Wang Moran
Published: December 2023

We present a comprehensive description of the aspect ratio impact on interfacial instability in porous media where a wetting liquid displaces a nonwetting fluid. Building on microfluidic experiments, we evidence imbibition scenarios yielding interfacial instabilities and macroscopic morphologies under different depth confinements, which were controlled by aspect ratio and capillary number. We report a phenomenon whereby a smaller aspect ratio of depth-variable microfluidic porous media and lower capillary number trigger interfacial instability during forced imbibition; otherwise, a larger aspect ratio of uniform-depth microfluidic porous media and higher capillary number will suppress the interfacial instability, which seemingly ignored or contradicts conventional expectations with compact and faceted growth during imbibition. Pore-scale theoretical analytical models, numerical simulations, as well as microfluidic experiments were combined for characteristics of microscopic interfacial dynamics and macroscopic displacement results as a function of aspect ratio, depth variation, and capillary number. Our results present a complete dynamic view of the imbibition process over a full range of regimes from interfacial stabilization to destabilization. We predict the mode of imbibition in porous media based on pore-scale interfacial behavior, which fits well with microfluidic experiments. The study provides insights into the role of aspect ratio in controlling interfacial instabilities in microfluidic porous media. The finding provides design or prediction principles for engineered porous media, such as microfluidic devices, membranes, fabric, exchange columns, and even soil and rocks concerning their desired immiscible imbibition behavior.