bluuebunny/crossref_metadata_2025 huggingface dataset:
Self-ordering and organization of a staggered oblate particle pair in three-dimensional square ducts
Authors: Li Yang , Shao Chun , Huang Lizhong , Wang Ruijin , Liang Hong
Published: March 2024

We numerically investigate the formation and ordering of staggered oblate particle pairs in three-dimensional straight ducts with a square cross section. The lattice Boltzmann method is employed to simulate rigid particle pairs in a Newtonian liquid. The effects of initial axial spacing, Reynolds number, blockage ratio, and particle aspect ratio on the formation process, migration behavior, and interparticle spacing are explored in detail. Current results indicate that the process from initial to final steady state can be divided into two stages. The first stage is rapid migration from initial positions toward equilibrium positions under shear-induced lift force and wall-induced repulsive force. The second stage is the slow self-assembly of stable particle pairs in the axial direction due to the interparticle interaction. Interestingly, initial axial spacing significantly affects the formation process of particle pairs but does not affect the final steady state. It is found that the equilibrium positions of staggered particle pairs move slightly toward the duct walls, and the axial spacing increases with increasing Reynolds number or particle aspect ratio, or decreasing blockage ratio. For a staggered particle pair, the second particle will occupy the eddy center induced by the first focusing particle. Based on the existing data, a correlation is put forward to predict the axial interparticle spacing of staggered oblate particle pairs in duct flows. The present results may give insights into manipulating and comprehending non-spherical particle dynamics in microfluidic applications.
The infrared absorption spectrum of phenylacetylene and its deuterated isotopologue in the mid- to far-IR
Authors: Esposito Vincent J. , Ferrari Piero , Buma Wybren Jan , Fortenberry Ryan C. , Boersma Christiaan , Candian Alessandra , Tielens Alexander G. G. M.
Published: March 2024

Anharmonicity strongly influences the absorption and emission spectra of polycyclic aromatic hydrocarbon (PAH) molecules. Here, IR–UV ion-dip spectroscopy experiments together with detailed anharmonic computations reveal the presence of fundamental, overtone, as well as 2- and 3-quanta combination band transitions in the far- and mid-infrared absorption spectra of phenylacetylene and its singly deuterated isotopologue. Strong absorption features in the 400–900 cm−1 range originate from CH(D) in-plane and out-of-plane wags and bends, as well as bending motions including the C≡C and CH bonds of the acetylene substituent and the aromatic ring. For phenylacetylene, every absorption feature is assigned either directly or indirectly to a single or multiple vibrational mode(s). The measured spectrum is dense, broad, and structureless in many regions but well characterized by computations. Upon deuteration, large isotopic shifts are observed. At frequencies above 1500 cm−1 for d1-phenylacetylene, a one-to-one match is seen when comparing computations and experiments with all features assigned to combination bands and overtones. The C≡C stretch observed in phenylacetylene is not observed in d1-phenylacetylene due to a computed 40-fold drop in intensity. Overall, a careful treatment of anharmonicity that includes 2- and 3-quanta modes is found to be crucial to understand the rich details of the infrared spectrum of phenylacetylene. Based on these results, it can be expected that such an all-inclusive anharmonic treatment will also be key for unraveling the infrared spectra of PAHs in general.
Terahertz sum-frequency excitation of coherent optical phonons in the two-dimensional semiconductor WSe2
Authors: Kusaba Satoshi , Lin Haw-Wei , Tamaki Ryo , Katayama Ikufumi , Takeda Jun , Blake Geoffrey A.
Published: March 2024

Driving fundamental excitations via strong light fields is one of the most important issues in solid state physics, which opens up new avenues to control material properties. Two-dimensional materials are fruitful platforms for future semiconductor applications, including opto-electronic and phononic devices, yet the phonon dynamics and nonlinear phonon–phonon coupling remain under-explored. Here, we demonstrate coherent phonon excitation in thin films of the layered two-dimensional semiconductor WSe2 induced by intense and broadband ultrafast terahertz (THz) pulses. We performed THz Kerr effect spectroscopy and observed coherent phonon oscillations assigned to the E2g optical phonon mode. The phonon amplitude displays a quadratic THz field strength dependence, indicating a sum-frequency THz excitation process. Furthermore, pump–probe polarization and crystal orientation relationships, supported by symmetry analysis of the nonlinear susceptibility and Raman tensors, provide helpful insight into nonlinear phonon–phonon interactions and potential coherent control schemes for the manipulation of phonon polarization and material properties in WSe2.
Diagonalizing the Born–Oppenheimer Hamiltonian via Moyal perturbation theory, nonadiabatic corrections, and translational degrees of freedom
Authors: Littlejohn Robert , Rawlinson Jonathan , Subotnik Joseph
Published: March 2024

This article describes a method for calculating higher order or nonadiabatic corrections in Born–Oppenheimer theory and its interaction with the translational degrees of freedom. The method uses the Wigner–Weyl correspondence to map nuclear operators into functions on the classical phase space and the Moyal star product to represent operator multiplication on those functions. These are explained in the body of the paper. The result is a power series in κ2, where κ = (m/M)1/4 is the usual Born–Oppenheimer parameter. The lowest order term is the usual Born–Oppenheimer approximation, while higher order terms are nonadiabatic corrections. These are needed in calculations of electronic currents, momenta, and densities. The separation of nuclear and electronic degrees of freedom takes place in the context of the exact symmetries (for an isolated molecule) of translations and rotations, and these, especially translations, are explicitly incorporated into our discussion. This article presents an independent derivation of the Moyal expansion in molecular Born–Oppenheimer theory. We show how electronic currents and momenta can be calculated within the framework of Moyal perturbation theory; we derive the transformation laws of the electronic Hamiltonian, the electronic eigenstates, and the derivative couplings under translations; we discuss in detail the rectilinear motion of the molecular center of mass in the Born–Oppenheimer representation; and we show how the elimination of the translational components of the derivative couplings leads to a unitary transformation that has the effect of exactly separating the translational degrees of freedom.
High-repetition-rate injection-seeded terahertz-wave parametric generation pumped by a 1.5 μm sub-nanosecond laser
Authors: Nishida Mio , Notake Takashi , Takida Yuma , Hirosawa Kenichi , Ohata Nobuo , Minamide Hiroaki
Published: March 2024

Injection-seeded terahertz (THz)-wave parametric generation (is-TPG) using a nonlinear optical crystal of MgO-doped lithium niobate (MgO:LiNbO3) has made it possible to obtain THz waves with high peak powers and narrow linewidths. To achieve stable THz-wave generation from the MgO:LiNbO3 crystal under strong excitation, the photorefractive effect in the MgO:LiNbO3 crystal would be crucial, which could be eliminated by using a longer pump wavelength than the conventional 1-μm spectral band. Here, we propose to use a 1.5-μm near-infrared (NIR), high-repetition-rate, sub-nanosecond laser source based on a unique Er,Yb:glass planar waveguide amplifier (PWA) as the pump source for the is-TPG using the MgO:LiNbO3 crystal. At a repetition rate of 25 kHz, the frequency tunability from 1.3 to 2.5 THz was obtained with a maximum THz-wave average output power of 0.14 mW at 1.77 THz.
A fast general thermal simulation model based on Multi-Branch Physics-Informed deep operator neural network
Authors: Lu Zibo , Zhou Yuanye , Zhang Yanbo , Hu Xiaoguang , Zhao Qiao , Hu Xuyang
Published: March 2024

Thermal simulation plays a crucial role in various fields, often involving complex partial differential equation (PDE) simulations for thermal optimization. To tackle this challenge, we have harnessed neural networks for thermal prediction, specifically employing deep neural networks as a universal solver for PDEs. This innovative approach has garnered significant attention in the scientific community. While Physics-Informed Neural Networks (PINNs) have been introduced for thermal prediction using deep neural networks, existing methods primarily focus on offering thermal simulations for predefined relevant parameters, such as heat sources, loads, boundaries, and initial conditions. However, any adjustments to these parameters typically require retraining or transfer learning, resulting in considerable additional work. To overcome this limitation, we integrated PINN methods with the DeepONet model, creating a novel model called PI-DeepONet for thermal simulation. This model takes both relevant parameters and coordinate points as simultaneous input functions, presenting a fresh computational perspective for thermal simulation. Based on the PaddlePaddle deep learning framework, our research demonstrates that after sufficient training, this model can reliably and rapidly predict parameter solutions. Importantly, it significantly surpasses traditional numerical solvers in terms of speed by several orders of magnitude, without requiring additional training. This groundbreaking research framework holds vast application potential and promises substantial advancements in the field of thermal simulation.
Local swelling effect of flexible entangled polymer chains in athermal solvents
Authors: Wang Jiayi , Gao Ping
Published: March 2024

Solutions of flexible, entangled polymer chains dissolved in athermal solvents have been widely studied; however, the influence of the local swelling effects on the overall dynamics of such systems remains incompletely understood. In this study, we performed coarse-grained simulations to compute the concentration dependence of plateau modulus of such systems. Initially, we examined the concentration dependence of entanglement length, denoted as Ne, through simulations. Our findings revealed a concentration scaling relationship for Ne, demonstrating Ne=AΦ−5/4+B, where A and B are chain length independent constants, and Φ is polymer concentration. To account for the local swelling effects, we employed the concept of blobs to represent the chains confined in athermal solvents. Each blob was characterized by a diameter ξ, a number of connected beads g, and a volume Ωb∼ξ3. Our simulations showed that the blob diameter followed the excluded volume relationship, with ξ∼g3/5. By combining the local swelling effect and the non-zero constant B, we derived a concentration scaling relationship for the plateau modulus G of solutions of flexible polymer chains in athermal solvents: G∼Φ(Ne/g)Ωb∼Φ2.30. This scaling exponent aligns with experimental observations ranging from dilute to highly concentrated systems, as well as our simulations, where values of 2.0–2.3 were observed.
Optimization of low-temperature multi-stage submersible pump based on blade load
Authors: Cui Baoling , Chen Huiyu , Zhu Zuchao , Sun Lilong , Sun Lidong
Published: March 2024

The multi-stage submersible pump is a power conveyor for low-temperature media, which is conveyed by the rotating of centrifugal impellers. In this study, the impellers of a multi-stage submersible pump were optimized to improve the efficiency under the premise of the constant total blade load and head. Based on the analysis of performance and flow for each stage of the 18-stage submersible pump, the optimization scheme composed of the first stage, the middle stage, and the last stage was determined. The blade outlet angle, average blade wrapping angle, and blade wrapping angle difference were selected as optimization parameters through Plackett–Burman experimental design and significance analysis, and the blade profile was redrawn by changing the blade load distribution. The performance prediction model was built based on the Kriging response surface model, and then, the global optimal blade profile was found by non-dominated Sorting Genetic Algorithm II. The efficiencies of the 3-stage submersible pump and 18-stage submersible pump with optimized impeller increased by 2.35% and 2.01%, respectively. Under the design condition, the flow rate loss and pressure pulsation at the impeller outlet decreased and the stator–rotor interaction between the impeller and guide vane was weakened. This will lead to a reduction in unstable flow such as secondary flow and vortices, and an improvement of flow stability at the impeller outlet.
A CsPbBr3/CdS-based hybrid bidirectional optoelectronic device with light-emitting, modulation, and detection functions
Authors: Tan Qin , Yang Xin , Sun Xingxia , Zhu Chenguang , Liu Yong , Liu Huawei , Qu Junyu , Liu Chenxi , Zhu Xiaoli , Wang Xiaoxia , Li Dong , Chen Shula , Pan Anlian
Published: March 2024

Optoelectronic integrated circuits, with a broad photonic transportation bandwidth, have emerged as a promising solution to fulfill the escalating demands for high-volume information transportation and processing. However, challenges persist in developing optoelectronic integrated circuits based on low-dimensional nanostructures, including limited integration density and high energy consumption. Here, we demonstrate a bidirectional optoelectronic device by integrating a light-emitting/harvesting CsPbBr3 nanoplate with a waveguiding/modulating/detecting CdS nanobelt. By configuring the CsPbBr3 nanoplate in a Schottky-type device structure with a metal electrode, bright electroluminescence was attained at a bias voltage of 18 V. Thanks to the electric field-tuned phonon-coupling effect, the waveguided light in the CdS nanobelt exhibited a high modulation depth of up to 94%, rendering it an excellent building block as optical modulators and optical switches. Moreover, the integrated nanostructure device showcased functionality in the photodetection mode. The proposed device architecture holds promise for broader applications, potentially extending to other perovskite-coupled II–VI semiconductor optoelectronic integrated circuits for expanding integration capacity and enhancing optoelectronic performance.
Anti-ambipolar transport and logic operation in two-dimensional field-effect transistors using in-series integration of GeAs and SnS2
Authors: Kim Jung Ho , Moon Byoung Hee , Han Gang Hee
Published: March 2024

Germanium arsenide (GeAs) from the IV–V semiconductor family has drawn attention for its anisotropic optical and electrical characteristics as a robust p-type semiconductor with high mobility. Despite its potential, the scope of applications for two-dimensional (2D) GeAs remains limited. In this study, we investigate the in-series integration of GeAs and SnS2 for complementary inverter operation, a crucial element in logic circuits. Moreover, the resulting in-series field-effect transistors reveal a previously undocumented anti-ambipolar behavior in this configuration, with a peak-to-valley ratio exceeding 5000 at a drain-source bias of 2 V. This anti-ambipolar characteristic operates regardless of the direction of current flow, which is rarely seen in conventional anti-ambipolar transistors built with hetero-stacked p–n junctions. Moreover, the in-series structure demonstrates stable operation as a complementary inverter, highlighting the versatile potential of p-type 2D GeAs in diverse optoelectronic applications. This work contributes insights into the transport characteristics of GeAs and its interconnected arrangement with SnS2, offering valuable implications for the development of advanced 2D material-based devices.
On the airfoil leading-edge noise reduction using poro-wavy leading edges
Authors: Chen Weijie , Lei Hui , Xing Yudi , Wang Liangfeng , Zhou Teng , Qiao Weiyang
Published: March 2024

This paper presents numerical studies on airfoil leading-edge turbulence interaction noise reduction using poro-wavy leading edges. Three different bionic treatments including wavy leading edges, porous leading edges, and a novel combined poro-wavy leading edges are modeled. The turbulent flow field is solved using the improved delayed detached eddy simulation method. The aerodynamic noise is predicted using the Ffowcs Williams and Hawkings acoustic analogy theory. The inflow Mach number is approximately 0.12 with an angle of attack of 0°, and the chord-based Reynolds number is 400 000. The present numerical method is first validated against experimental data and previous studies. Then the effects of the three bionic treatments on the aerodynamic performance and the aeroacoustic performance are analyzed. The results show that all the three bionic treatments will increase the mean drag of the airfoil, especially for the airfoils with porous treatment, while the lift and drag fluctuations are significantly reduced by the three bionic treatments. The wavy leading edges are found to be more effective for the reduction of broadband noise, while the porous leading edges are more effective for the reduction of the tonal noise. For the poro-wavy leading edges, both the tonal noise and broadband noise are significantly reduced, which means that the combined poro-wavy leading edges possess both the advantages of the wavy and porous treatments. The underlying flow mechanisms responsible for the noise reduction are finally analyzed in detail.
Is there a finite mobility for the one vibrational mode Holstein model? Implications from real time simulations
Authors: Li Tianchu , Yan Yaming , Shi Qiang
Published: March 2024

The question of whether there exists a finite mobility in the standard Holstein model with one vibrational mode on each site remains unclear. In this Communication, we approach this problem by employing the hierarchical equation of motion method to simulate model systems where the vibrational modes are dissipative. It is found that, as the friction becomes smaller, the charge carrier mobility increases significantly and a friction-free limit cannot be obtained. The current autocorrelation functions are also calculated for the friction-free Holstein model, and converged results cannot be obtained with an increase in the number of sites. Based on these observations, we conclude that a finite mobility cannot be defined for the standard Holstein model in the parameter regime explored in this work.
Effect of ion distribution on stress relaxation in polyelectrolyte complex gels
Authors: Gavrilov Alexey A. , Kramarenko Elena Yu.
Published: March 2024

Solutions of polyelectrolytes consisting of polycations and polyanions in equal proportions were studied in the present work. Due to the physical cross-links formed by the charged groups, physical gels were formed in such systems. The mechanical properties and structure of the obtained gels depending on the charge arrangement along the backbone and the dimensionless Bjerrum length λ were investigated. The response of the systems to a uniaxial affine deformation was studied first. It was found that the systems can be divided into three groups depending on the charge arrangement: showing an almost elastic response; showing a viscoelastic response with a very long relaxation time; and showing a weak viscoelastic response with a short relaxation time. Interestingly, no stable aggregates were formed in the systems with the charges located on spacers, probably because of the increased mobility of the charges in such systems. The obtained stress relaxation curves had different functional forms, indicating that the relaxation has at least two characteristic times, which are different for different systems. In order to understand the molecular nature of the observed mechanical response, the temporal evolution of the network structure of a system showing a viscoelastic response with a very long relaxation time was studied; the aggregates were found to be dynamic, which leads to the relaxation of the “subchains” conformation.
Impact of a nanodroplet on liquid surfaces
Authors: Wang Yi-Bo , Wang Yi-Feng , Wang Shao-Yu , Zhang Ben-Xi , Yang Yan-Ru , Wang Xiao-Dong
Published: March 2024

The present study investigates impact of nanodroplets on liquid films with varied film thicknesses over hydrophilic to hydrophobic surfaces via molecular dynamics simulations. A new crown pattern, hollow crown, is observed on medium liquid films for nanodroplets, whereas it is not reported for millimeter-sized droplets. Holes (or hollows) are attributed to capillary vibration of a nanometer-thick liquid film. The occurrence of holes is inhibited effectively for deep liquid films because the cavity thickness is much larger than the amplitude of capillary vibration. Surface wettability has a significant influence on thin and medium liquid films for nanodroplets, whereas it only affects thin liquid films for macrodroplets because the range of solid–liquid intermolecular forces is comparable to the size of droplets when the size of droplets reduces to the nanoscale. Subsequently, the accuracies of the existing macroscale models for predicting the time-dependent crown radius of nanodroplets are tested by simulated results. The results show that the macroscale models cannot capture the time-dependent crown radius of nanodroplets. On the basis of energetics analysis, we prove that the failure of macroscale models is attributed to the distinct difference in viscous dissipation mechanisms between macroscale and nanoscale droplets.
A novel accelerated convergence method for solving adjoint equations based on modal reduction
Authors: Li Xintao , Chen Wengang , Yang Wenkai , Zheng Hongyu , Zhang Weiwei
Published: March 2024

The efficiency of adjoint-based aerodynamic shape optimization depends critically on the solution efficiency of adjoint equations. In this letter, we employ the Proper Orthogonal Decomposition (POD) method to analyze the adjoint field samples and project them from the physical space into a low-order modal space. Subsequently, the full-order adjoint equations are reduced to low-order equations using the POD modes. Thus, we can efficiently predict the initial values for pseudo-time marching, thereby accelerating the solution of adjoint equations. Results indicate that the high-order POD modes are crucial for constructing the low-dimensional system. Moreover, this method can be seamlessly integrated with our previously established Dynamic Mode Decomposition (DMD) acceleration method to form a POD+DMD acceleration approach. Application of this approach to the flow past a National Advisory Committee for Aeronautics 0012 airfoil demonstrates a noteworthy 80.9% reduction in iteration numbers when solving the adjoint equations. Even for the airfoil located on the upper boundary of sampling space, the number of iterations is still reduced by 72.6%. Therefore, we believe that the proposed method holds significant promise for improving the efficiency of adjoint-based aerodynamic shape optimization in future research.
Effect of non-local near-resonant interactions of Rossby waves on formation of large-scale zonal flows in unforced two-dimensional turbulence on rotating sphere
Authors: Hagimori Yusuke , Obuse Kiori , Yamada Michio
Published: March 2024

This study investigates the effect of nonlinear interactions of Rossby waves on large-scale zonal flow formation in two-dimensional turbulence on a rotating sphere. The coefficients of nonlinear interactions are first calculated. Then, the non-local, near-resonant, and non-local near-resonant interactions are investigated in detail. The results show that the formation of large-scale westward circumpolar zonal flows is directly caused by non-local energy transfer due to the three-wave near-resonant interactions of Rossby waves.
Unidirectional magnetoresistance in an insulating compensated ferrimagnet
Authors: Kim Hyeongyu , Cao Van Phuoc , Jo Younghun , Jeong Jong-Ryul , Kim Kab-Jin
Published: March 2024

We investigate the unidirectional magnetoresistance (UMR) in a GdIG(Gd3Fe5O12)/Pt bilayer. We find a suppression of the observed UMR as the magnetic field increases, suggesting a magnonic origin for the UMR effect. Furthermore, through the examination of the temperature dependence of UMR, we observe that the sign of the UMR remains unchanged at the compensation temperature. This observation indicates that the magnon contributing to the UMR is associated with the lowest magnon mode with a distinct handedness. Our results provide compelling evidence for the existence of magnonic UMR in compensated ferrimagnets, offering potential advantages for spintronic applications.
Flow over a radiating multi-filamentous structure with various opening angles: From disk-like to cone-like shape
Authors: Li Shiqing , Pan Dingyi , Zeng Lifang , Li Jun , Shao Xueming
Published: March 2024

Flow over a radiating multi-filamentous structure with various opening angles has been investigated numerically at low and moderate Reynolds numbers. The opening angle, as the major geometric parameter for investigation, varies from 180° to 40° and the overall shape changes from disk-like to cone-like. The overall model drag decreases monotonously as the magnitude of the opening angle decreases. The opening angle effects on the drag-enhancement are then investigated in terms of the velocity distributions, the structures of the recirculation region, and the pressure distributions. As the Reynolds number increases, the wake structure loses its steadiness and the optimal opening angle is found to be approximately 60° when the critical Reynolds number for a steady recirculation structure becomes maximum. The opening angle effects on the wake steadiness in terms of the intensity of the shear layer are investigated as well. On the one hand, the exit velocity—a quantitative indication of the rate of the base bleed—decreases with the decreasing of the opening angle, which promotes wake unsteadiness. This phenomenon can be attributed to the effective gap width between adjacent filaments and the intensity of the virtual barrier from both macro- and micro-perspectives. On the other hand, a small opening angle decreases the thickness of shear layer and thus the unsteadiness is suppressed. These two effects compete and the balance is reached when the opening angle is near 60°.
Great Australian Science Book
Authors: O'Neill Luke , Fährlin Linda
Published: March 2024

How do we measure the universe? How do our bodies repair themselves when we are ill? What species will exist on Earth in a million years' time?

Discover the answers to these questions and a lot more in The Great Australian Science Book. We’ll go on an incredible scientific journey from the very, very BIG to the very, very SMALL.

Starting with the universe itself, we will travel through the galaxies and stars, onto our very own planet Earth and across its fabulous features, into our wonderful bodies and all their cells, and on down to the very elements and atoms that make up all things.

Discover how Australia has made huge contributions to science and do a few experiments yourself as you learn to think like a scientist.

Reading level varies from child to child, but we recommend this book for ages 8 to 14.

The Great Australian Science Book is an adaptation of The Great Irish Science Book (Gill Books, 2019).
Policies, projections, and the social cost of carbon: Results from the DICE-2023 model
Authors: Barrage Lint , Nordhaus William
Published: March 2024

The present study examines the assumptions, modeling structure, and results of DICE-2023, the revised Dynamic Integrated Model of Climate and the Economy (DICE), updated to 2023. The revision contains major changes in the treatment of risk, the carbon and climate modules, the treatment of nonindustrial greenhouse gases, discount rates, as well as updates on all the major components. Noteworthy changes are a significant reduction in the target for the optimal (cost-beneficial) temperature path, a lower cost of reaching the 2 °C target, an analysis of the impact of the Paris Accord, and a major increase in the estimated social cost of carbon.
Rapid and automated design of two-component protein nanomaterials using ProteinMPNN
Authors: de Haas Robbert J. , Brunette Natalie , Goodson Alex , Dauparas Justas , Yi Sue Y. , Yang Erin C. , Dowling Quinton , Nguyen Hannah , Kang Alex , Bera Asim K. , Sankaran Banumathi , de Vries Renko , Baker David , King Neil P.
Published: March 2024

The design of protein–protein interfaces using physics-based design methods such as Rosetta requires substantial computational resources and manual refinement by expert structural biologists. Deep learning methods promise to simplify protein–protein interface design and enable its application to a wide variety of problems by researchers from various scientific disciplines. Here, we test the ability of a deep learning method for protein sequence design, ProteinMPNN, to design two-component tetrahedral protein nanomaterials and benchmark its performance against Rosetta. ProteinMPNN had a similar success rate to Rosetta, yielding 13 new experimentally confirmed assemblies, but required orders of magnitude less computation and no manual refinement. The interfaces designed by ProteinMPNN were substantially more polar than those designed by Rosetta, which facilitated in vitro assembly of the designed nanomaterials from independently purified components. Crystal structures of several of the assemblies confirmed the accuracy of the design method at high resolution. Our results showcase the potential of deep learning–based methods to unlock the widespread application of designed protein–protein interfaces and self-assembling protein nanomaterials in biotechnology.
Black holes, conformal symmetry, and fundamental fields
Authors: Navarro-Salas José
Published: March 2024

Cosmic censorship protects the outside world from black hole singularities and paves the way for assigning entropy to gravity at the event horizons. We point out a tension between cosmic censorship and the quantum backreacted geometry of Schwarzschild black holes, induced by vacuum polarization and driven by the conformal anomaly. A similar tension appears for the Weyl curvature hypothesis at the Big Bang singularity. We argue that the requirement of exact conformal symmetry resolves both conflicts and has major implications for constraining the set of fundamental constituents of the Standard Model.
Quasinormal modes of Reissner–Nordström–AdS: the approach to extremality
Authors: Ficek Filip , Warnick Claude
Published: March 2024

We consider the quasinormal spectrum of scalar and axial perturbations of the Reissner–Nordström–AdS black hole as the horizon approaches extremality. By considering a foliation of the black hole by spacelike surfaces which intersect the future horizon we implement numerical methods which are well behaved up to and including the extremal limit and which admit initial data which is nontrivial at the horizon. As extremality is approached we observe a transition whereby the least damped mode ceases to be oscillatory in time, and the late time signal changes qualitatively as a consequence.
What topics of peer interactions correlate with student performance in physics courses?
Authors: Simpfendoerfer L N , Sundstrom Meagan , Dew Matthew , Holmes N G
Published: March 2024

Research suggests that interacting with more peers about physics course material is correlated with higher student performance. Some studies, however, have demonstrated that different topics of peer interactions may correlate with their performance in different ways, or possibly not at all. In this study, we probe both the peers with whom students interact about their physics course and the particular aspects of the course material about which they interacted in six different introductory physics courses: four lecture courses and two lab courses. Drawing on social network analysis methods, we replicate prior work demonstrating that, on average, students who interact with more peers in their physics courses have higher final course grades. Expanding on this result, we find that students discuss a wide range of aspects of course material with their peers: concepts, small-group work, assessments, lecture, and homework. We observe that in the lecture courses, interacting with peers about concepts is most strongly correlated with final course grade, with smaller correlations also arising for small-group work and homework. In the lab courses, on the other hand, small-group work is the only interaction topic that significantly correlates with final course grade. We use these findings to discuss how course structures (e.g. grading schemes and weekly course schedules) may shape student interactions and add nuance to prior work by identifying how specific types of student interactions are associated (or not) with performance.
Photonic curing for innovative fabrication of flexible metal oxide optoelectronics
Authors: Hsu Julia W P , Piper Robert T
Published: March 2024

Flexible optoelectronics, based on non-planar substrates, hold promise for diverse applications such as wearables, health monitors, and displays due to their cost-effective manufacturing methods. Despite the superior properties of metal oxides, the challenge of processing them at high temperatures incompatible with plastic substrates necessitates innovative annealing approaches. Photonic curing, which delivers microsecond to millisecond broadband (200–1500 nm) light pulses on a sample, emerges as a viable solution. Depending on the optical properties, the targeted film absorbs the radiant energy resulting in rapid heating while the transparent substrate absorbs a minimal amount of light and remains at ambient temperature. The light intensity can be high, but since the light pulse is short, the total energy absorbed by the sample remains low and will not damage the plastic substrate. This perspective explores the innovative application of photonic curing to fabricate flexible metal oxide optoelectronics, including thin-film transistors, metal–insulator–metal devices, solar cells, transparent conductors, and Li batteries, emphasizing the conversion of sol–gel precursors to metal oxides. However, this technique was initially developed for sintering metal nanoparticles to conductive patterns and poses intriguing challenges in explaining its mechanism for metal oxide conversion, especially considering the limited absorption of visible light by most sol–gel precursors. The review delves into UV-induced photochemistry, common flexible metal-oxide optoelectronic components, and non-intuitive distinctions between photonic curing and thermal annealing. By elucidating the distinctive role of photonic curing in overcoming temperature-related challenges and advancing the fabrication of flexible metal oxide optoelectronics, this perspective offers valuable insights that could shape the future of flexible optoelectronics.
A brief review of hybrid skin-topological effect
Authors: Zhu Weiwei , Li Linhu
Published: March 2024

The finding of non-Hermitian skin effect (NHSE) has revolutionized our understanding of non-Hermitian topological phases, where the usual bulk-boundary correspondence is broken and new topological phases specific to non-Hermitian system are uncovered. Hybrid skin-topological effect (HSTE) is a class of newly discovered non-Hermitian topological states that simultaneously supports skin-localized topological edge states and extended bulk states. Here we provide a brief review of HSTE, starting from different mechanisms that have been used to realize HSTE, including non-reciprocal couplings, onsite gain/loss, and non-Euclidean lattice geometries. We also review some theoretical developments closely related to the HSTE, including the concept of higher-order NHSE, parity–time symmetry engineering, and non-Hermitian chiral skin effect. Finally, we summarize recent experimental exploration of HSTE, including its realization in electric circuits systems, non-Hermitian photonic crystals, and active matter systems. We hope this review can make the concept of hybrid-skin effect clearer and inspire new finding of non-Hermitian topological states in higher dimensional systems.
GNSS-R snow depth retrieval algorithm based on PSO-LSTM
Authors: Hu Yuan , Qu Wei , Liu Wei , Yuan Xintai
Published: March 2024

The global navigation satellite system (GNSS)-interferometric reflectometry technique has been applied to retrieve snow depth, which has a high potential for application. The GNSS reflectometry classical algorithm retrieves the snow depth by extracting the frequency of the multipath signal and substituting it into an empirical formula. However, the retrieval errors of high and low snow depths are large due to the influence of factors such as surface vegetation and terrain environment. In this paper, we propose a snow depth retrieval algorithm based on a particle swarm optimized long short-term memory (PSO-LSTM) neural network. The algorithm extracted three characteristic parameters (frequency, amplitude, and phase) from the signal-to-noise ratio (SNR) data as inputs, and optimized the LSTM hyperparameters by the PSO algorithm to improve the retrieval accuracy for low snow depths and snow depths close to the antenna. The snow depth retrieval results of global positioning system L1 band SNR data collected from the P351 station in 2022 and AB33 station in 2017 were evaluated in this paper. The snow depth retrieval results of the PSO-LSTM algorithm for P351 station were in high agreement with the snow depth data provided by the snowpack telemetry network; the coefficient of determination (

R
2

) reached 0.986, and the root mean square error (RMSE) and mean absolute error (MAE) were 7.30 cm and 4.94 cm, respectively. Compared with the classical algorithm, the PSO-LSTM algorithm decreased the RMSE and MAE by 53.0% and 30.4% for the retrieval results of snow depths below 15 cm at the P351 station, and by 76.8% and 84.4% for the retrieval results of snow depths above 117 cm from the 1st day to the 137th day, respectively. Similarly, the RMSE, MAE, and

R
2

for the 2017 retrieval results at AB33 station were 5.90 cm, 4.25 cm, and 0.965, respectively. Compared with the classical algorithm, the PSO-LSTM algorithm decreased the RMSE and MAE by 47.9% and 33.0% for the retrieval results of snow depths below 15 cm at the AB33 station, and by 75.4% and 82.3% for the retrieval results of snow depths above 56 cm from the day 46 to day 120. In addition, the snow depth retrieval algorithm was proposed in this paper does not require antenna height and empirical formulas to realize snow depth retrieval, and at the same time, the algorithm effectively improved the retrieval accuracy for both high and low snow depths with strong robustness.
A review: the application of generative adversarial network for mechanical fault diagnosis
Authors: Liao Weiqing , Yang Ke , Fu Wenlong , Tan Chao , Chen Baojia , Shan Yahui
Published: March 2024

Mechanical fault diagnosis is crucial for ensuring the normal operation of mechanical equipment. With the rapid development of deep learning technology, the methods based on big data-driven provide a new perspective for the fault diagnosis of machinery. However, mechanical equipment operates in the normal condition most of the time, resulting in the collected data being imbalanced, which affects the performance of mechanical fault diagnosis. As a new approach for generating data, generative adversarial network (GAN) can effectively address the issues of limited data and imbalanced data in practical engineering applications. This paper provides a comprehensive review of GAN for mechanical fault diagnosis. Firstly, the development of GAN-based mechanical fault diagnosis, the basic theory of GAN and various GAN variants (GANs) are briefly introduced. Subsequently, GANs are summarized and categorized from the perspective of labels and models, and the corresponding applications are outlined. Lastly, the limitations of current research, future challenges, future trends and selecting the GAN in the practical application are discussed.
Manipulation and enhancement of the performance of Otto cycle in the presence of nonthermal reservoirs
Authors: Huang Rui , Xia Yun-Jie , Man Zhong-Xiao
Published: March 2024

In this work, we investigate the impact of energetic coherence in nonthermal reservoirs on the performance of the Otto cycle. We first focus on the situation where the working substance is a qubit. Due to the existence of coherence of nonthermal reservoir, various anomalous operating regimes such as the engine and refrigerator with efficiencies exceeding Carnot limits, as well as the hybrid refrigerator that can simultaneously achieve cooling and supplying work to an external agent, can occur. We demonstrate that the energetic coherence of the system’s steady state plays a significant role in determining the cycle’s functions by adding an additional stroke implementing dephasing and phase modulation operations in the cycle. The energetic coherence of the system is necessary to trigger the reservoir’s coherence to exert influences on the cycle. We decompose the thermodynamic quantities to the components arising from the populations and coherence of the system, and find that the reservoir’s coherence impacts the cycle from two aspects: one is the modification of the system’s steady-state populations or temperatures, and the other is the direct contributions to the heat in the interaction between the system and reservoirs. We then explore the scenario where the working substance is two identical qubits, and the reservoirs are common to them. We show that the degenerate coherence of the system in the steady state can enhance the performances of the cycle as different machines. Additionally, the energetic coherence of the reservoir modifies the functions of the cycle still through the energetic coherence of the system rather than their degenerate coherence.
Higher-dimensional integrable deformations of the classical Boussinesq–Burgers system*
Authors: Cheng Xiaoyu , Huang Qing
Published: March 2024

In this paper, the (1+1)-dimensional classical Boussinesq–Burgers (CBB) system is extended to a (4+1)-dimensional CBB system by using its conservation laws and the deformation algorithm. The Lax integrability, symmetry integrability and a large number of reduced systems of the new higher-dimensional system are given. Meanwhile, for illustration, an exact solution of a (1+1)-dimensional reduced system is constructed from the viewpoint of Lie symmetry analysis and the power series method.
Gaze-contingent processing improves mobility, scene recognition and visual search in simulated head-steered prosthetic vision
Authors: de Ruyter van Steveninck Jaap , Nipshagen Mo , van Gerven Marcel , Güçlü Umut , Güçlüturk Yağmur , van Wezel Richard
Published: March 2024

Objective. The enabling technology of visual prosthetics for the blind is making rapid progress. However, there are still uncertainties regarding the functional outcomes, which can depend on many design choices in the development. In visual prostheses with a head-mounted camera, a particularly challenging question is how to deal with the gaze-locked visual percept associated with spatial updating conflicts in the brain. The current study investigates a recently proposed compensation strategy based on gaze-contingent image processing with eye-tracking. Gaze-contingent processing is expected to reinforce natural-like visual scanning and reestablished spatial updating based on eye movements. The beneficial effects remain to be investigated for daily life activities in complex visual environments. Approach. The current study evaluates the benefits of gaze-contingent processing versus gaze-locked and gaze-ignored simulations in the context of mobility, scene recognition and visual search, using a virtual reality simulated prosthetic vision paradigm with sighted subjects. Main results. Compared to gaze-locked vision, gaze-contingent processing was consistently found to improve the speed in all experimental tasks, as well as the subjective quality of vision. Similar or further improvements were found in a control condition that ignores gaze-dependent effects, a simulation that is unattainable in the clinical reality. Significance. Our results suggest that gaze-locked vision and spatial updating conflicts can be debilitating for complex visually-guided activities of daily living such as mobility and orientation. Therefore, for prospective users of head-steered prostheses with an unimpaired oculomotor system, the inclusion of a compensatory eye-tracking system is strongly endorsed.
Fault detection method of power cable terminal based on infrared thermal imaging signal reconstruction
Authors: Li Yan , Gao Yihang
Published: March 2024

Considering the low efficiency of traditional fault detection methods, this paper proposes a power cable terminal fault detection method based on infrared thermal imaging signal reconstruction. The method includes the following steps: first, establish the thermal resistance network structure of the power cable terminal to obtain the structural relationship between terminal components; second, collect operational data of the power cable terminal and perform calculations; finally, use an infrared imager to capture the infrared radiation of the power cable terminal and obtain fault detection results based on the calculation results. Experiments show that the detected results of this method are completely consistent with the actual situation, with an accuracy rate of up to 99%, and can achieve high-precision detection of power cable terminal faults.
Model construction of coordinated operation mechanism of energy supply chain based on operations research big data algorithm
Authors: Li Yige , Li Junsong , Liu Yu
Published: March 2024

During rapid modernization, the policy of technological upgrading of the coordinated operation of the energy supply chain has been tested over many years of practice, with limited potential for future development, and further emission reductions are facing greater technological and cost pressures. Market trading policies mainly include the carbon emissions trading mechanism and the guaranteed mechanism for renewable energy power consumption, and the above policies will be formally implemented in 2020, which will be the main direction of development in the future. After introducing the low-carbon policies, this paper will focus on the coal-power energy supply chain considering the carbon credit quota and renewable electricity consumption limitations and analyze the impacts of the relevant parameters on the coal-power energy supply chain returns under the above policies in both non-cooperative and cooperative game scenarios. Finally, a preferential price-based green power certificate trading mechanism is constructed to propose a cost-reducing trading proposal for power users to purchase green power certificates to fulfill the amount of renewable energy power consumption.
Coordinated reactive power planning in an industrial park integrated energy system using support vector regression
Authors: Zhang Sheng , Chen Yong , Liu Na , Shen Qianqian , Zhao Ce , Zhou Danying , Xu Xiaolong , Zhou Niancheng
Published: March 2024

In this study, we develop and present a comprehensive multi-objective optimization model for reactive power planning in industrial park integrated energy systems (IPIES), addressing the challenges posed by extensive inductive loads. Our model prioritizes enhancing system resilience through three key objectives: minimizing total costs, improving static voltage stability margins, and enhancing voltage recovery capabilities. We employ support vector regression (SVR) to estimate voltage recovery metrics effectively, using reactive power capacity as input. The optimization process leverages the Non-dominated Sorting Genetic Algorithm-II (NSGA-II) for efficient solution finding. Validation on the IEEE-39 bus system demonstrates the model’s effectiveness, with SVR significantly reducing computational demands while maintaining satisfactory accuracy.