bluuebunny/crossref_metadata_2025 huggingface dataset:
MultiModal flow field prediction method fusing operator learning and convolutional neural network
Authors: Xiong Hengli , Li Yubo , Wu Anping , Huang Jun , Wang Qingfeng , Liu Longgang , Liu Feng
Published: December 2024

The introduction of deep learning has resolved the high-cost issues associated with traditional methods in handling complex aerodynamics problems and is commonly used for simulating fluid behavior and optimizing aircraft design. However, flow field prediction based on deep learning typically encodes the freestream conditions and geometric information into the neural network model concurrently. This encoding scheme makes it difficult for the model to distinguish and deal with the intrinsic differences between these two types of information. As a result, the ability of the model to capture complex flow field features decreases and the difficulty of model fitting increases, which in turn reduces the effectiveness of the model. To solve these problems, this paper proposes the Operator-Convolution MultiModal Fusion Network (OCMMFNet), a new neural network architecture to predict the flow fields of airfoils with various geometries and freestream conditions. The proposed network architecture uses a freestream generalization network to encode the input freestream conditions. The resulting approximate flow field information is combined with the airfoil geometry information and fed into a shape feature compensation network to improve the prediction accuracy. We compare the performance of OCMMFNet with those of a deep operator network(DeepONet) and a vision transformer(ViT) model. When generalizing both freestream conditions and airfoil shapes, OCMMFNet reduces the prediction error in the pressure field by 9.71% and 3.76% compared to DeepONet and ViT, respectively. In tests involving extrapolation of Reynolds numbers, OCMMFNet significantly reduces the prediction error in the pressure field by 13.73% and 11.84% compared to DeepONet and ViT, respectively. The results show that OCMMFNet achieves better prediction accuracy than both DeepONet and ViT and displays superior robustness and generalization ability.
More accurate representation of interaction at the fluid–structure interface with an improved smoothed field gradient method
Authors: Wang Xiaofeng , Liu Yangyu , Law Siu-Seong , Yang Qingshan , Yang Na
Published: December 2024

Flexible structures are wind-sensitive with a significant fluid–structure interaction (FSI). The FSI analysis, however, often has poor numerical stability and low convergence efficiency due to drastic changes of the physical fields induced by computation errors in local regions of the fluid–structure interface. This paper aims at addressing these problems with the proposal of a new method to smooth the gradient of the pressure field at the fluid–structure interface for an efficient convergence in the FSI analysis. The smoothed gradient theory is modified by introducing weight coefficients. The field of fluid pressure in each smoothing domain with large numerical fluctuations at the interface is then gradient smoothed with the proposed method and the modified field is obtained from the linear Taylor series expansion. The convergence of fluid and structure solvers for the proposed method is ensured within the commercial software FLUENT and ANSYS adopted. The proposed method is validated with experimental results from the literature. It is also numerically validated with a thin plate in viscous flow with different site categories and average wind velocities through comparison of results from conventional methods. The proposed method is found valid and accurate in the FSI analysis. It is relatively independent of a wide range of parameters with satisfactory robustness and notable improvement in the convergence of the FSI analysis.
Effect of a single water molecule on the conformational preferences of a capped Pro–Gly dipeptide in the gas phase
Authors: Mandal Sourav , Kossov Arsene , Carcabal Pierre , Das Aloke
Published: December 2024

Herein, we have investigated the effect of microhydration on the secondary structure of a capped dipeptide Boc-DPro-Gly-NHBn-OMe (Boc = tert-butyloxycarbonyl, Bn = Benzyl), i.e., Pro–Gly (PG) with a single H2O molecule using gas-phase laser spectroscopy combined with quantum chemistry calculations. Observation of a single conformer of the monohydrated peptide has been confirmed from IR-UV hole-burning spectroscopy. Both gas-phase experimental and theoretical IR spectroscopy results confirm that the H2O molecule is inserted selectively into the relatively weak C7 hydrogen bond (γ-turn) between the Pro C=O and NHBn N–H groups of the peptide, while the other C7 hydrogen bond (γ-turn) between the Gly N–H and Boc C=O groups remains unaffected. Hence, the single H2O molecule in the PG⋯(H2O)1 complex significantly distorts the peptide backbone without appreciable modification of the overall secondary structural motif (γ–γ) of the isolated PG monomer. The nature and strength of the intra- and inter-molecular hydrogen bonds present in the assigned conformer of the PG⋯(H2O)1 complex has also been examined by natural bond orbital and non-covalent interaction analyses. The present investigation on the monohydrated peptide demonstrates that several H2O molecules may be required for switching the secondary structure of PG from the double γ-turn to a β-turn that is favorable in the condensed phase.
A novel generalized photo-thermoelasticity model for hydro-poroelastic semiconductor medium
Authors: Raddadi Merfat H. , Alotaibi Munirah Aali , El-Bary Alaa A. , Lotfy Khaled
Published: December 2024

This study applies the generalized photo-thermoelasticity theory to investigate thermo-hydro-mechanical interactions in a poroelastic half-space elastic semiconductor material with variable properties. The model represents a novel approach, treating the material as a uniform, fully saturated, poroelastic semiconductor half-space in alignment with the principles of dynamic poroelasticity within generalized photo-thermoelasticity. We initially applied time-harmonic loads, encompassing normal or thermal loads and plasma electron distributions to this medium. The study then explores the differences between coupled thermo-hydro-mechanical dynamic models and thermo-elastic dynamic models. We employed two-dimensional normal mode analysis to solve the resulting non-dimensional coupled equations. Subsequently, we examined the impact of non-dimensional displacement, excess pore water pressure, mechanical stress, carrier concentration (density), and temperature distribution on the poroelastic half-space medium. We then visually represented these effects.
General phase-covariant quantum cloning
Authors: Li Lan-Lan , Zhang Wen-Hai , Zhang Ke , Fan Cheng-Yu
Published: December 2024

Phase-covariant quantum cloning has important applications in quantum cryptography. This paper proposes the unitary transformation of the optimal 1 → 2 general phase covariant quantum cloning in two dimensions and obtains the maximal fidelity of copies. In addition, an experimental scheme is designed to implement this unitary transformation using linear optical elements, and the scheme is feasible under the present experimental technology.
An improved body force model based on a data-driven region-segmentation combinational loss model for a transonic fan rotor under uniform and non-uniform inflow
Authors: Pan Tianyu , Shi Kaikai , Lu Hanan , Ren Zilong , Zhang Jian
Published: December 2024

Boundary layer ingestion (BLI) fans are required to continuously operate under distorted inflow conditions, which severely reduces the fan's efficiency. Therefore, it is necessary to focus efforts on designing a high-performance distortion-tolerant fan. During the preliminary design stage of the fan, it is inevitable to repeatedly evaluate the aerodynamic performances of different design cases through low-fidelity computational approaches. However, the predictive accuracy of these low-fidelity computational methods generally depends on the precision of the loss models integrated into them. These loss models are built using simplified physics or human experience, making it difficult to depict the complex non-linear mapping relationships between losses and their influencing factors under BLI inflow distortion. In this work, a high-accuracy data-driven based region-segmentation combinational loss model is used for the first time to attempt to improve the overall prediction accuracy of the body force model. As a low-fidelity computational approach, the body force model has the ability to predict the spatial distribution of three-dimensional, non-uniform flow under inflow distortion conditions. Various operating conditions, including different rotational speeds, radial inflow, and BLI-distorted inflow, are selected to test the predictive accuracy of this improved body force model based on a region-segmentation combinational loss model. The results show that, compared with the one based on traditional loss prediction approach, the improved body force model in this work has shown higher prediction accuracy for the fan adiabatic efficiency characteristic curve. In addition, further evaluations of the flow loss spatial distributions under BLI inflow distortion conditions indicate that the body force model based on region-segmentation combinational loss model can more accurately capture the radial loss distributions at different circumferential locations. Specifically, for the loss distribution in the tip area, it can capture the sharp increase in variation trend near the end wall, and the average prediction errors can be reduced by more than 10% at different annulus locations under various BLI inflow distortions. Meanwhile, this improved body force model also enhances the accuracy of predicting the loss distribution in the circumferential direction at different span positions, including more accurately capturing the circumferential positions corresponding to the maximum and minimum flow losses.
Reporting Indigenous status, ethnicity, language and country of birth to build equity in international paediatric clinical trials with Australian sites: a scoping review
Authors: Cunninghame Jacqueline , Takashima Mari , Holland Lorelle , Nguyen Linda , Diaz Abbey , Guo Shuaijun , Dufficy Mitchell , Munns Craig F. , Ullman Amanda
Published: December 2024

Objective Ensuring equitable access to clinical trials for children from Indigenous and ethnically and linguistically diverse backgrounds should be central to clinical trial design. This review aims to expansively review the reporting of Indigenous status (Aboriginal and/or Torres Strait Islander origin), ethnicity, culture, location, language and country of birth in paediatric clinical trials with Australian sites. Methods This scoping review systematically searched PubMed, CINAHL and Embase for international clinical trials with Australian sites conducted between 2018 and 2022 involving children (aged <18 years) to determine the reporting of Indigenous status, race, ethnicity, language and country of birth. Results Of the 262 studies included, 154 (58.8%) clinical trials did not report any of the variables of interest. When reported, terms used by authors were heterogeneous. ‘Indigenous status’ was most reported (n = 40, 15.3%) and self-identification was the most common method to determine this (n = 14, 35.9%). International clinical trials had higher rates of reporting for ethnicity, cultural background and race. Overall, more than 60 terms were used to categorise study participants in relation to ‘Indigenous status’, 'ethnicity and cultural background', ‘race’, ‘race and ethnicity’ or ‘natural skin colour’. Conclusions This review demonstrated low rates of reporting of demographic variables in paediatric clinical trials. Clear reporting standards, partnering with consumers to co-design trials and self-identification during collection are required. Ensuring adequate access to clinical trials for Indigenous children and children from ethnically, linguistically and geographically diverse backgrounds is essential in building health equity and ensuring patient safety.
Authorship, ownership, and ethics in datafied discourse on Instagram
Authors: McInerney Erin
Published: December 2024

Datafication, or the translation of our everyday actions into quantifiable metrics, underwrites a wide set of
contemporary discursive practices. With a specific focus on the social media platform Instagram, this paper analyzes mediatized
landscape signs as ‘datafied discourse’ enmeshed in an entangled apparatus of platforms, algorithms, and online networks. Using a
corpus of 404 public Instagram posts gathered from the Café de Flore geotag, I examine how the vernacular practices of geotagging,
mediatization, and remediatization reflexively construct this ostensibly ‘user-generated’ landscape. I then consider the
implications of these and other discursive practices occurring at the ‘online-offline nexus’ through the dimensions of authorship
and ownership. Finally, amid a confluence of new LL work, I propose to orient scholarship toward an ‘infrastructural’ perspective,
in which datafication, online platforms, and algorithms are understood to exert considerable influence over our landscapes, thus
emerging as relevant to scholars engaged in any genre of LL analysis.
Noncommutative lightcones from quantum SO(2,1) conformal groups
Authors: Adamo Martina , Ballesteros Angel , Mercati Flavio
Published: December 2024

Five new families of noncommutative lightcones in

2
+
1

dimensions are presented as quantizations of the inequivalent Poisson homogeneous structures that emerge when the lightcone is constructed as a homogeneous space of the SO(2,1) conformal group. Each of these noncommutative lightcones maintains covariance under the action of the respective quantum deformation of the SO(2,1) conformal group. We discuss the role played by SO(2,1) automorphisms in the classification of inequivalent Poisson homogeneous lightcones, as well as the geometric aspects of this construction. The localization properties of the novel quantum lightcones are analyzed and shown to be deeply connected with the geometric features of the Poisson homogeneous spaces.
Estimating the internal friction and the rotational inertia of a homemade oscillatory system
Authors: Santos D S , Bispo P A B , Júnior D A S V , Rego V V A , Pereira L O , Dutra R S
Published: December 2024

In this work, we apply the dynamics of translation and rotation to a real system-a homemade mass-spring system composed of a cart-in which the rolling without slipping constraint of the cart's wheels may be violated at any moment. In this case, we demonstrate how modeling combined with video analysis can be powerful in determining the constraint forces acting on the system. In this case, the translational and rotational accelerations are determined, and the temporal behavior of all constraint forces can be identified. Initially, we show how rotations with slipping of the cart's wheels at the return points of the system's motion impact the system's kinematics. Finally, we apply the developed methodology to estimate the system's internal friction and rotational inertia. The estimates are compared with results from the literature and with a theoretical limit, in the case of rotational inertia, achieving good agreement.
Theory and fast learned solver for

ℓ

1

-TV regularization
Authors: Liu Xinling , Wang Jianjun , Jin Bangti
Published: December 2024

The

ℓ

1

and total variation (TV) penalties have been used successfully in many areas, and the combination of the

ℓ

1

and TV penalties can lead to further improved performance. In this work, we investigate the mathematical theory and numerical algorithms for the

ℓ

1

-TV model in the context of signal recovery: we derive the sample complexity of the

ℓ

1

-TV model for recovering signals with sparsity and gradient sparsity. Also we propose a novel algorithm (PGM-ISTA) for the regularized

ℓ

1

-TV problem, and establish its global convergence and parameter selection criteria. Furthermore, we construct a fast learned solver (LPGM-ISTA) by unrolling PGM-ISTA. The results for the experiment on ECG signals show the superior performance of LPGM-ISTA in terms of recovery accuracy and computational efficiency.
W-state generation and verification in linearly coupled waveguide arrays
Authors: Bugarski Kolja , Maluckov Aleksandra , Petrovic Jovana
Published: December 2024

W states are maximally entangled states with excellent robustness to loss. They have been studied in ion, photon and waveguide-mode bases, however the entanglement verification has remained challenging. Here, we theoretically study W-state generation by the quantum walk of a single photon through a linearly coupled waveguide array (WGA) that supports self-imaging of light. We design W states in symmetric and asymmetric arrays with even and odd number of waveguides. Bipartite entanglement is formally proven using the von Neumann entropy of the reduced density matrix. We further use the self-imaging to construct an entanglement witness based on the exclusion principle. A key to verification is the interferometer which extends the length of a W-state generator to the revival length where the photon is fully recombined into a single waveguide mode. In addition, W-state coherence is proven by numerically demonstrating the far-field interference. The sensitivities of the proposed W-state generation and verification protocols to the fabrication tolerances are numerically evaluated in glass, silicon nitride and silicon-on-insulator WGAs, indicating the feasibility of their realisation by high-precision e-beam lithography and laser writing.
A method to determine the phase-space distribution of a pulsed molecular beam
Authors: Mooij Maarten C , Bethlem Hendrick L , Boeschoten Alexander , Borschevsky Anastasia , Fikkers Ties H , Hoekstra Steven , van Hofslot Joost W F , Jungmann Klaus , Marshall Virginia R , Meijknecht Thomas B , Timmermans Rob G E , Touwen Anno , Ubachs Wim , Willmann Lorenz ,   (NL-eEDM collaboration)
Published: December 2024

We demonstrate a method to determine the longitudinal phase-space distribution of a cryogenic buffer gas cooled beam of barium-fluoride molecules based on a two-step laser excitation scheme. Temporal resolution is achieved by a transversely aligned laser beam that drives molecules from the ground state

X
2

Σ
+

to the

A
2

Π

1

/

2

state around 860  nm, while the velocity resolution is obtained by a laser beam that is aligned counter-propagating with respect to the molecular beam and that drives the Doppler shifted

A
2

Π

1

/

2

to

D
2

Σ
+

transition around 797  nm. Molecules in the D-state are detected background-free by recording the fluorescence from the D − X transition at 413 nm. A temporal resolution of 11  μs and a velocity resolution of 6  m s−1 is obtained. In order to calibrate the absolute velocity, we have determined the Doppler free transition frequencies for the X − A and X − D transitions with an absolute accuracy below 0.3  MHz. The high resolution of the phase-space distributions allows us to observe a variation of the average velocity and velocity spread over the duration of the molecular beam pulse. Our method hence gives valuable insight into the dynamics in the source.
Quantum state transfer in a magnetic atoms chain using a scanning tunneling microscope
Authors: Acosta Coden Diego Sebastian , Osenda Omar , Ferrón Alejandro
Published: December 2024

The electric control of quantum spin chains has been an outstanding goal for the few last years due to its potential use in technologies related to quantum information processing. In this work, we show the feasibility of the different steps necessary to perform controlled quantum state transfer and excitation transmission in a

S
=
1

/

2

titanium atoms chain employing the electric field produced by a scanning tunneling microscope (STM). Our results show that the initialization and transmission of a single excitation state is achievable in short times, and with high fidelity. Our study uses spin Hamiltonians to model the magnetic atoms chain, the tip of the STM, the interaction between it and the atoms chain and the electronic response to the fields applied by the tip, employing sets of parameters compatible with the latest experiments and ab initio calculations. The time dynamical evolution is considered in the full Hilbert space and the control pulses frequencies exerted by the tip of the microscope are within the reach of present day technology.
Effect of Fe doping on the electronic properties of CoSn Kagome semimetal
Authors: Vijay Kritika , Ali Kawsar , Bano Najnin , Ahlawat Anju , Gupta Mukul , Choudhary Ram Janay , Shukla D K , Arya Ashok , Banik Soma
Published: December 2024

Quantum phenomena in two-dimensional Kagome materials lead to exotic topological states and complex magnetism. Here, we have investigated the detailed electronic properties of Co

1
−
x

Fe
x
Sn as a function of composition (x) to explore the competing electronic interactions for the origin of complex magnetism and topological properties. We find that the screening effect in the valence electrons increases while the correlation effect decreases with an increase in the Fe doping. Valence fluctuations observed at Co and Fe L

2
,
3

edges showed systematic changes in the magnitude of divalent and trivalent states with the increase in x. Fe 3d states are found to be more screened by the conduction electrons than the Co 3d states. A comparison of the theoretical and experimental density of states showed different natures of localized states with strong screening effects on the surface and dominating correlation effects in the bulk for x

>

0. We have observed localized flat bands on the CoSn (001) surface while quasi-localized flat bands on the Co0.94Fe0.06Sn (001) surface. The distinct character of the bulk and surface band structure is confirmed in the Fe-doped composition. Hence, the bulk-surface interaction present in Co

1
−
x

Fe
x
Sn gives rise to the origin of valence fluctuation, complex magnetism, and topological properties.
Adaptive evolutionary neural architecture search based on one-dimensional convolutional neural network for electric rudder fault diagnosis
Authors: Shi Xinjie , Guo Chenxia , Yang Ruifeng , Song Yizhe
Published: December 2024

The electric rudder is the core actuator of the flight control system. Fault diagnosis of rudders is essential for the production and repair of rudders. While existing methods for rudder fault diagnosis are effective, the manual design of neural network models is a time-consuming and challenging process. Therefore, this paper proposes a fault diagnosis framework for the electric rudder based on an adaptive evolutionary neural architecture search (AENAS-FD). AENAS-FD employs an adaptive strategy to guide the evolution of a one-dimensional convolutional neural network towards achieving optimal diagnostic accuracy. This adaptive strategy adjusts the relevant parameters of the genetic operator based on the relationship between individual and population fitness. This leads to improved algorithm search performance and mitigates premature convergence. The experiments on the real electric rudder dataset demonstrate that AENAS-FD can generate superior network architectures for diagnosing rudder faults, exhibiting better diagnostic accuracy when compared to manually designed networks.
Detection method for microleakage acoustic wave signals in natural gas pipelines based on chaotic oscillators
Authors: Chen Hongyu , Yi Kang , Cai Changxin , Liao Jinwei , Zhao Sheng , Dai Xing , Hong Bin
Published: December 2024

To address the issue of the low signal-to-noise ratio in detecting microleakage acoustic wave signals in natural gas pipelines, this paper combines the whale optimization algorithm-based variational mode decomposition (WOA-VMD) algorithm with the Duffing chaotic oscillator to propose a new method for detecting such signals. Firstly, the WOA-VMD algorithm is utilized to adaptively decompose the signal, thereby improving the signal decomposition capability. The cubic spline interpolation algorithm is then introduced to reconstruct the characteristic signal obtained from the decomposition. Subsequently, frequency transformation and array are employed to creatively enhance a Duffing chaotic oscillator, enabling the detection of signals with arbitrary frequencies and initial phases, which is applied to the detection microleakage acoustic wave signals in natural gas pipelines. Finally, through systematic simulation analysis and practical experimental verification, it is concluded that the proposed system exhibits strong anti-noise interference capabilities and can effectively detect multi-frequency and multi-phase signals even with the SNR as low as −76.99 dB.
Data imbalanced fault diagnosis of gearbox transmission system under various speeds based on dynamic dual-scale normalized fusion network
Authors: Wang Chaoge , Tian Xinyu , Shao Xinhao , Wang Ran , Wang Lijun
Published: December 2024

Gearboxes play a pivotal role in industrial production, and their reliability and safety are essential for production safety and efficiency. However, gearboxes frequently encounter challenges such as variable rotational speeds and unknown operating conditions. Unfortunately, most existing traditional fault diagnosis methods face the following issues: (1) They heavily rely on expert experience and pre-existing knowledge bases, making them unable to tackle fault diagnosis in unknown working conditions. (2) While addressing various speed issues, they seldom consider the problem of data imbalance in real-world industrial environments. (3) Many transfer learning methods primarily focus on global distribution alignment and knowledge transfer between source and target domains, neglecting the importance of fine-grained distribution alignment between subdomains. To address these issues, a dynamic dual-scale normalized fusion network is proposed for cross-domain fault diagnosis under variable speed and data imbalance. Firstly, the two parallel graph convolution frameworks constructed are used to extract multi-scale fault features. Subsequently, a dual-scale normalization fusion module is adopted to integrate the global and local fault feature information within the subdomains of both the source and target domains, thereby aligning their fine-grained distributions to obtain domain-invariant features. Finally, a dynamic soft threshold feedback strategy is introduced, which assigns pseudo labels to the target domain data, enabling the model to give equal attention to each class of data samples, even under data imbalance conditions, thereby improving the recognition accuracy of minority fault classes. Validating the proposed method on two real cases, our method achieved the highest accuracy compared to other advanced approaches.
Computer vision methods for side scan sonar imagery
Authors: Motylinski Michal , Plater Andrew J , Higham Jonathan E
Published: December 2024

Side-scan sonar (SSS) data presents a significant challenge to analysts due to the size of the material that requires processing. Automatic recognition systems can help in the interpretation and filtration of the data, reducing the time needed for analysis. Deep learning architectures have been employed for computer vision tasks in the underwater domain. The objective of this work is to review current deep learning methods for automatic image classification, object detection, semantic segmentation, and instance segmentation through statistical analysis of published studies. Further, this work includes an inventory of publicly available SSS data followed by a discussion on augmentation methods applied to SSS imagery. The study discusses current challenges in the automatic underwater target detection field, highlights main gaps within the domain and identifies potential research directions. Our proposal includes the creation of a standardised benchmark and the use of a common set of metrics allowing for consistent evaluation of future research works.
IFAL-SLAM: an approach to inertial-centered multi-sensor fusion, factor graph optimization, and adaptive Lagrangian method
Authors: Liu Jiaming , Qi Yongsheng , Yuan Guoshuai , Liu Liqiang , Li Yongting
Published: December 2024

In response to the issues of low accuracy, perception degradation, and poor reliability of single-sensor simultaneous localization and mapping (SLAM) technologies in complex environments, this study presents a novel Inertial Measurement Unit (IMU)-centered multi-sensor fusion SLAM algorithm (IFAL-SLAM) integrating Light Detection and Ranging (LiDAR), vision, and IMU, based on factor graph elimination optimization (IMU-centered multi-sensor Fusion, Adaptive Lagrangian methods). The proposed system leverages a multi-factor graph model, centering on the IMU, and applies a covariance matrix to fuse visual-inertial and LiDAR-inertial odometries for bias correction, using loop closure factors for global adjustments. To minimize the optimization costs post-fusion, a sliding window mechanism is incorporated, coupled with a QR decomposition elimination method based on Householder transformation to convert the factor graph into a Bayesian network. Finally, an adaptive Lagrangian relaxation method is proposed, employing matrix-form penalty parameters and adaptive strategies to enhance convergence speed and robustness under high rotational dynamics. Experimental results indicate that the proposed algorithm achieves absolute trajectory errors of approximately 0.58 m and 0.24 m in large and small complex scenes, respectively, surpassing classic algorithms in terms of accuracy and reliability.
Mechanical behavior of supersonic fine particle bombardment single crystal γ-TiAl alloys based on atomistic simulation: effects of velocity and crystal plane
Authors: Yu Zhaoliang , Cao Hui , Zhou Baocheng , Yang Wenle , Li Haiyan , Chen Tao , Feng Ruicheng
Published: December 2024

The crystal orientation significantly affects the plastic deformation and mechanical properties of γ-TiAl alloys. However, there are few studies on the mechanical behavior of supersonic fine particle bombardment (SFPB) of single-crystal γ-TiAl alloys impacted with different crystal planes and velocities at the nanoscale. And the characterization of the mechanical properties in the presence of dislocation defects after impact is lacked. Therefore, in this paper, molecular dynamics is used to simulate the impact response and post-impact mechanical response of SFPB single-crystal γ-TiAl alloy. The results show that: at a certain impact velocity, the different ways of inducing dislocation slip due to the number of slip system initiations under crystal anisotropy lead to a smaller depth of subsurface damage on the (001) crystallographic plane compared to the other crystallographic planes; moreover, the yield strength and Young’s modulus of the (111) and (1

1
¯

0) crystallographic planes are the largest after the impact, respectively. Under the same crystal plane, the subsurface damage depths of all crystal planes decrease with the increase of impact velocity; the yield strength of the (111) crystal plane of γ-TiAl alloy gradually increases, the yield strength of the (001) and (1

1
¯

0) crystal planes decreases, and the modulus of elasticity of the (001) and (111) crystal planes after impact is less sensitive to velocity. The angle between the two slip surfaces formed by the L-C dislocation during impact is 70.24°, while the angle between the two slip surfaces formed by the Hirth dislocation is 109.76°. This will provide atomic-scale deformation details of the plastic deformation and mechanical response of single-crystal γ-TiAl alloys bombarded by supersonic fine particles.
SnSe2 thermal conductivity from optothermal Raman and Stokes/anti-Stokes thermometry
Authors: Vallin Micah P , Karkee Rijan , Kucinski Theresa M , Zhao Huan , Htoon Han , Lee Chanho , Martinez Ramon M , Fensin Saryu J , Zhang Richard Z , Pettes Michael T
Published: December 2024

The optothermal Raman method is useful in determining the in-plane thermal conductivity of two-dimensional (2D) materials that are either suspended or supported on a substrate. We compare this method with the Stokes/anti-Stokes scattering thermometry method, which can play a role in both calibration of Raman peak positions as well as extraction of the local phonon temperature. This work demonstrates that the Stokes/anti-Stokes intensity ratio plays an important role in determining the in-plane thermal conductivity of 2D tin diselenide (SnSe2) dry-transferred onto a polished copper (Cu) substrate. The statistically-averaged thermal conductivity of the 108 ± 24 nm-thick SnSe2 yielded 5.4 ± 3.5 Wm−1 K−1 for the optothermal Raman method, and 2.40 ± 0.81 Wm−1 K−1 for the Stokes/anti-Stokes thermometry method, indicating that the Stokes/anti-Stokes thermometry method to calculate the thermal conductivity of a material can simultaneously increase both precision and accuracy. The uncertainty value was also lowered by a factor of 1.9 from the traditional optothermal Raman method to the Stokes/anti-Stokes thermometry method. The low in-plane thermal conductivity of 2D SnSe2, 1.3–2.9 times lower than bulk, is useful for applications in thermal and electrical energy conversion and thermoelectric devices.
Displaced volume versus submerged volume in the floating of a solid
Authors: Landi Salmon
Published: December 2024

This paper describes a new theoretical approach accompanied by experiments that demonstrate that the volume of the displaced fluid cannot be used to calculate the magnitude of the buoyant force when a solid object is floated in a container of only slightly larger cross-section than the object. It is important to emphasize that the discussions conducted here are accessible to high school and first-year university physics students because the concept of hydrostatic pressure and easily understood geometric considerations are applied.
A simple algebraic derivation of the equation for a line of best fit
Authors: Bissell J J
Published: December 2024

We present a simple algebraic derivation of the equation for a line of best fit. Unlike conventional derivations, which require multi-variable calculus, our argument relies on elementary algebra alone, and avoids more advanced notation (such as the sigma summation symbol) by exploiting routine data averages. In this way, our approach demystifies the process of computing a linear regression, and is likely to be of interest to students and instructors alike. We illustrate the main results with a worked example taken from an introductory physics context.
Compressibility of liquids and hydrostatic pressure
Authors: Koumaras Panagiotis , Koumara Anna
Published: December 2024

In this study, we first identify several misconceptions regarding the concept of hydrostatic pressure, as revealed through interviews with 27 secondary Physics teachers. These misconceptions are primarily linked to the assumption that liquids are incompressible. The objective of this research is to enhance teachers’ understanding by illustrating the limitations of the incompressible liquid model. As part of a three-hour instructional intervention designed for the interviewed teachers, we introduced the relationship between hydrostatic pressure, present at any point within a liquid, and the compression or deformation of the liquid’s molecules. The responses from the participating teachers suggest that this clarification effectively addressed the previously noted misunderstandings.
From pages to practice: improving reading comprehension and learning strategies through physics learning
Authors: De Ruyt Pablo , Pulgar Javier , Sánchez Iván , Herrera Edith
Published: December 2024

The study presents the effects of an educational intervention designed in the physics and Spanish classroom to encourage reading comprehension and learning strategies for meaningful learning. The intervention includes the reading of popular science books and group-level activities for solving a sequence of physics questions, conducted over an academic semester (2022) in a sample of 9th and 10th grade students from a secondary school in Chile. The study features a pre-experimental design with pre and post-tests to measure reading comprehension, learning strategies, student working networks during the intervention, and academic performance. Statistical comparisons show significant changes in reading comprehension, and improvements in learning strategies consistent with a transition towards strategic and meaningful learning orientations. Analysis of the collaboration networks allows us to understand these changes from a relational perspective, characterising subgroups and their development. These findings highlight the importance of reading exercises and group-level activities for human development, while social interactions offer alternative insights to understand the classroom experience.
Effect of the oblique incidence of radiation beams on emerging radiation behind lead and concrete shields: a multilayer method for dose transmission calculations
Authors: González-López Antonio
Published: December 2024

Objective. For calculating shielding in x-ray rooms, it is often assumed that the beams impinge perpendicularly on the protective barriers. This is not always true, but this premise simplifies the calculations and enhances protection by being a conservative calculation. In this work, a method for calculating radiation transmission through planar shielding that considers the obliquity of the incident beam is presented. Approach. The output of the method produces energy spectra according to the direction of radiation impinging on the shielding. Four angles of incidence on the barrier are considered, along with monoenergetic pencil beams with energies ranging from 10 to 150 keV and two materials: lead and concrete. The direction of emerging photons is discretized into 49 different direction vectors. Monte Carlo calculations are performed for thicknesses of 0.1, 0.5, and 1.0 mm of lead, and 1, 5, 10, and 15 cm of concrete. Additionally, a multilayer iterative method is implemented for calculating attenuation of other thicknesses. Main results. The distribution of radiant energy according to the coordinates of its directional vector illustrates the effect of the obliquity of the incidence and the significance of the shielding material employed. In the case of concrete, the dispersion of radiation away from the original direction of incidence is much more pronounced than in the case of lead at energies below its K-edge. The multilayer iterative method provides highly accurate values of transmitted radiant energy in both monoenergetic and polyenergetic beams, for both lead and concrete, across the various studied incidence directions. Significance. Considering the direction of the photons reaching a shield and the direction of the photons passing through it allows multilayer composite shielding calculations to closely approximate the calculation made for the composite shielding.
An adaptive learning method for long-term gesture recognition based on surface electromyography
Authors: Li Yurong , Lin Xiaofeng , Lin Heng , Zheng Nan
Published: December 2024

Objective. The surface electromyography (EMG) signal reflects the user’s intended actions and has become the important signal source for human-computer interaction. However, classification models trained on EMG signals from the same day cannot be applied for different days due to the time-varying characteristics of the EMG signal and the influence of electrodes shift caused by device wearing for different days, which hinders the application of commercial prosthetics. This type of gesture recognition for different days is usually referred to as long-term gesture recognition. Approach. To address this issue, we propose a long-term gesture recognition method by optimizing feature extraction, dimensionality reduction, and classification model calibration in EMG signal recognition. Our method extracts differential common spatial patterns features and then conduct dimensionality reduction with non-negative matrix factorization, effectively reducing the influence of the non-stationarity of the EMG signals. Based on clustering and classification self-training scheme, we select samples with high confidence from unlabeled samples to adaptively updates the model before daily formal use. Main results. We verify the feasibility of our method on a dataset consisting of 30 d of gesture data. The proposed gesture recognition scheme achieves accuracy over 90%, similar to the performance of daily calibration with labeled data. However, our method needs only one repetition of unlabeled gestures samples to update the classification model before daily formal use. Significance. From the results we can conclude that the proposed method can not only ensure superior performance, but also greatly facilitate the daily use, which is especially suitable for long-term application.
Study on hollow cathode discharge mode with high flow rate
Authors: Yang Yitao , Wu Zhiwen , Huang Tiankun
Published: December 2024

Hall and ion propulsion systems at power levels of ten kilowatts or higher are in development or application stages in recent years, yet research on the operational characteristics of corresponding hollow cathodes remains incomplete. This study conducts experimental research using a hollow cathode with a rated condition of 15 sccm of krypton gas and 10 A of current. By supplying a larger flow rate, the study expands the range of discharge currents to investigate changes in the discharge modes. The plume plasma characteristics and spatial distributions under various conditions were measured using a Langmuir single probe mounted on a planar two-dimensional displacement platform. The experimental results indicate that at krypton flow rates of 25 sccm and 30 sccm, as the current increases, the anode voltage and discharge oscillations increase at first but decrease later. The discharge mode transitions from low-current spot mode to plume mode, and then back to spot mode at high current. The increase in anode voltage and oscillations during the first transition phase is gradual and continuous, while the decrease during the second transition phase is abrupt. Conditions of 10 A, 12.5 A, and 20 A were selected to represent these three modes for single-probe plume spatial diagnostics. The results indicate that in the high-current spot mode, the axial potential gradient is significantly reduced compared to the radial gradient, and the cathode plasma plume is more collimated. This study shows that at high flow rates, hollow cathodes may exhibit nonlinear impedance and undergo multiple discharge mode transitions, with each transition phase displaying distinct characteristics.
Nucleation kinetics and virtual melting in shear-induced structural transitions
Authors: Li Wei , Peng Yi , Still Tim , Yodh A G , Han Yilong
Published: December 2024

Large shear deformations can induce structural changes within crystals, yet the microscopic kinetics underlying these transformations are difficult for experimental observation and theoretical understanding. Here, we drive shear-induced structural transitions from square (

◻

) lattices to triangular (

△

) lattices in thin-film colloidal crystals and directly observe the accompanying kinetics with single-particle resolution inside the bulk crystal. When the oscillatory shear strain amplitude

0.1
⩽

γ
m

<
0.4

,

△

-lattice nuclei are surrounded by a liquid layer throughout their growth due to localized shear strain at the interface. Such virtual melting at crystalline interface has been predicted in theory and simulation, but have not been observed in experiment. The mean liquid layer thickness is proportional to the shear which can be explained by the Lindemann melting criterion. This provides an alternative explanation on virtual melting.
Analysis, modeling and design of piezoelectric-capacitive hybrid micromachined ultrasonic transducer
Authors: Wang Yan , Lv Ning , He Leming , Ren Junyan
Published: December 2024

This paper proposes a spring-mass-damper model for a piezoelectric-capacitive hybrid micromechanical ultrasonic transducer (HMUT) in immersion. Based on this model, a dual-force actuation mode is identified, where piezoelectric micromachined ultrasonic transducer (PMUT) and capacitive micromachined ultrasonic transducer (CMUT) are strongly coupled to achieve enhanced sensitivity. In order to design HMUT efficiently, an electro-mechanical-acoustical equivalent circuit model (ECM) is constructed and then the round-trip gain is calculated to demonstrate its pulse-echo response. The ECM calculations results align with those of finite element model simulations, showing a relative deviation less than 4%. In the design cases, the transmit sensitivity of HMUT is twice that of PMUT and more than five times that of CMUT. The receive sensitivity of HMUT is 1% lower than that of CMUT, but an order of magnitude larger than that of PMUT. The round-trip gain of the HMUT is at least 24.9 dB higher than that of PMUT and 14.1 dB higher than that of CMUT. These results demonstrate the potential of HMUT in surpassing bulk piezoelectric ultrasonic transducers in pulse-echo imaging. Furthermore, the impact of cell pitch on the pulse-echo response of HMUT arrays is characterize.
Recent developments in applications of G-CuO nanocomposites for photocatalytic dye removal
Authors: Mehmood Arslan , Sandhu Zeshan Ali , Iqbal Muhammad Jawad , Manzoor Ayesha , Elahi Maha , Liyaqat Samreen , Nadeem Iqra , Zainab Syeda Ammer , Bibi Amina
Published: December 2024

The widespread application of synthetic dyes across industries poses significant environmental problems, particularly concerning with degradation of water quality. Concerning the possible solutions, copper oxide (CuO) considered as a feasible candidate. CuO a p-type heterogeneous semiconductor with a bandgap of 1.2–2.71 eV, It is a reasonable choice and widely studied photocatalyst for addressing such challenges. The functionality of CuO deteriorated, when the wavelength exceeded the UV–visible region. In this manner difficulties associated with reproducibility and reusability, as well as rapid electron–hole recombination, prevent the widespread application of this technology. In an attempt to eliminate this defect, researchers have been investigating strategies to activate CuO under visible light, with one promising approach being carbon nanomaterials such as graphene to form carbon-CuO composites. The unique properties of graphene, i.e., its higher surface area and excellent electron mobility, make it a remarkable candidate for the enhancement of CuO photoactivity. This study highlighted the recent progress in the synthesis of graphene-based CuO photocatalysts, with the main characteristic of extending the light absorption capacity of CuO into the visible spectrum. It reveals achievements in material innovations and applications, with a focus on photocatalytic. It has been observed from the documented studies, catalysis is considered as next generation emerging field for the researcher.
On nonclassical symmetries, Painlevé analysis and soliton solutions of three-coupled korteweg–de vries (KdV) system
Authors: Sharmila  , Gupta Rajesh Kumar
Published: December 2024

The three coupled KdV system is investigated for exact solutions and Painlevé analysis. Exact solutions are examined through nonclassical symmetries via Bluman and Cole approach. Derived symmetries are generalizations of earlier obtained symmetries of the considered system. There is power series solution of the reduced ODEs of the examined system. Assuming the solutions in terms of Jacobi elliptic functions, some new soliton solutions of the system under consideration are obtained. These solutions are two-singular soliton, three-singular soliton, multi-soliton, multi-singular soliton, combined soliton, bright solion, dark soliton, and bell shaped soliton solutions. Further, graphical depiction of the exact solutions to the governing system. Using Kruskals method and symbolic software Maple, it is verified that the system has Painlevé property that represents integrability of the governing system.