bluuebunny/crossref_metadata_2025 huggingface dataset:
Reference solutions for compressible single-phase flows in heated and cooled ducts
Authors: Schropff S. , Petitpas F. , Daniel E.
Published: May 2024

Analytical/quasi-analytical solutions are proposed for a steady, compressible, single-phase flow in a rectilinear duct subjected to heating followed by cooling. The flow is driven by the pressure ratio between an upstream tank and a variable outlet pressure. The article proposes a methodology to determine the full flow behavior, as a function of pressure ratio and heat-flux distribution. Following an analogy done with the study of compressible flows in nozzles, a behavioral classification of non-adiabatic compressible flows is proposed through the definition of critical pressure ratios. It is demonstrated that a critical pressure ratio distinguishes subsonic and supersonic outlet regimes and that there cannot be a steady shock wave in such configuration. The behavior of this critical pressure ratio is studied for limit cases of heat flux, delineating physical boundaries. An abacus is also proposed for a given couple of heating and cooling powers, as both values are needed to characterize the flow. Results are studied for parameters such as pressure ratio and outlet heat power. A short validation of a numerical simulation tool is provided, yielding excellent results and very small relative errors.
Exchange coupling in (Co/Pt)2/Nb/(Pt/Co)2 multilayers induced by the Yu–Shiba–Rusinov bound states
Authors: Lu Qi , Li Yaojin , Li Tao , Min Tai , Jiang Zhuang-De , Sun Young , Liu Ming
Published: May 2024

The Ruderman–Kittel–Kasuya–Yosida (RKKY) theory of oscillatory exchange interaction in synthetic antiferromagnetic multilayers results in the oscillation behavior of giant magnetoresistance ratio. In addition, the formation of Yu–Shiba–Rusinov (YSR) bound states will induce an extra antiferromagnetic interaction, which is expected to mediate stronger exchange coupling than conventional RKKY interaction. However, the YSR bound states have only been studied in some superconducting hosts with magnetic impurities. The narrow range of material systems that are not compatible with the device integration architecture limits the practical application of YSR interaction. Here, we observe the RKKY interaction and provide the evidence for YSR interaction in Pt/(Co/Pt)2/Nb/(Pt/Co)2/Pt synthetic antiferromagnetic multilayers by quantitatively determining the coupling energy via ferromagnetic resonance technique.
Electric field response of ferroelectric domains near non-polar precipitates in BaTiO3-based ceramics
Authors: Taylor Odin , Chaffee Ethan , Liu Binzhi , Zhao Changhao , Rödel Jürgen , Zhou Lin , Tan Xiaoli
Published: May 2024

Precipitates have recently been found to significantly enhance the mechanical quality factor in piezoelectric ceramics. Such a piezoelectric hardening effect was attributed to strong interactions between ferroelectric domains and precipitates. In the present work, the response of domains to applied electric fields is observed in situ via transmission electron microscopy in aged (Ba, Ca)TiO3 ceramics with precipitates to reveal the underlying mechanism of this phenomenon. Ferroelectric domains in the Ba-rich matrix grain are observed to be more concentrated near non-polar Ca-rich precipitates. With increasing applied voltage, domains separate from precipitates merge together first, while those near precipitates persist to higher voltages. During ramping down, domains nucleate from precipitates. These direct observations confirm the strong interactions between ferroelectric domains and precipitates in piezoelectric ceramics.
Research on the thermal flow characteristics of viscosity oil in hydrodynamic torque converter
Authors: Zhang Jiahua , Yan Qingdong , Khoo Boo Cheong , Liu Cheng , Ke Zhifang , Wei Wei
Published: May 2024

The increase in power density of hydrodynamic torque converters (HTCs) leads to a sharp rise in temperature within flow channels, affecting the reliability. In order to accurately predict the thermal effect and temperature distribution characteristics of the HTC internal viscosity oil, a multi-physics computational fluid dynamics (CFD) model is proposed. A specialized test bench was established, and the macro and internal flow temperature data were obtained. HTCs with different working conditions and wheel sets were studied. The results indicate that CFD model considering energy equation can accurately predict the overall hydrodynamic performance and the flow field temperature characteristics under different rotating conditions. The prediction error of the overall temperature rise is within 4.92%, and the flow field temperature prediction error of the stator is under 14.3%. The hydraulic characteristics is improved by 6.02%. The analysis of internal flow and energy exchange characteristics indicates the thermal effects and temperature distribution mechanisms caused by energy loss in the flow field within the HTC. The study provides an effective computational model for the prediction and control of the heat generation of the HTC and enhances the depth of research on the flow mechanism of inhomogeneous flow fields caused by thermal effects.
Two-dimensional counter-current capillary imbibition of a wetting phase into a partially submerged porous cylindrical matrix block
Authors: Dejam Morteza , Hassanzadeh Hassan
Published: May 2024

The purpose of this study is to address the two-dimensional counter-current capillary dominant imbibition of a wetting phase into a water-wet porous cylindrical matrix block partially submerged in the wetting phase. A two-dimensional unsteady-state diffusion equation is used to model the process. The governing equation is solved using a combination of the Laplace and the finite Fourier sine transforms to find and analyze the solutions for the normalized water saturation and the volume of the imbibed wetting phase. The results reveal that the volume of the imbibed wetting phase and the capillary diffusion shape factor for a partially submerged matrix block are significantly lower compared to those of a fully submerged matrix block, highlighting the overestimation of imbibed volume using available models based on full immersion in the wetting phase. It has been observed that the volume of the imbibed wetting phase increases over time until reaching a state of equilibrium. In the case of a partially submerged matrix block, the shape factor is inversely proportional to the square root of time (σ ∼ 1/t) during the early time and decreases sharply as the imbibed wetting phase reaches an equilibrium. In the case of a fully submerged matrix block, the shape factor is inversely proportional to the square root of time (σ ∼ 1/t) during the early time and later reaches a pseudo-steady-state value. The proposed model, along with the findings obtained, advances our understanding of capillary imbibition in porous media.
Breathers, rogue waves, and interaction solutions for the variable coefficient Kundu-nonlinear Schrödinger equation
Authors: Zhang Xi , Wang Yu-Feng , Yang Sheng-Xiong
Published: May 2024

With the inhomogeneity of optical fiber media taken into account, under investigation in this paper is the variable coefficient Kundu-nonlinear Schrödinger equation, which describes the pulses propagation in optical fibers. Based on Lax pair, the Nth-order Darboux transformation is constructed. Depending on plane wave solution, the first- and second-order breather solutions are derived and the interactions between breathers are graphically analyzed. The Kuznetsov–Ma breather, Akhmediev breather, and spatial-temporal breather have been obtained. Moreover, the first-, second-, and third-order rogue wave solutions have been constructed. The usual rogue waves and first- and second-order line rogue waves are observed. The weak and strong interactions between the first-, second-order rogue waves, and spatial-temporal period breather are studied. Furthermore, variable coefficient δ(t) causes rogue waves to produce some interesting evolutionary phenomena, which have been systematically analyzed. In addition, the influences of parameters for the properties of solutions are discussed.
Defining humpback whale (Megaptera novaeangliae) potential distribution in the Great Barrier Reef Marine Park: a two-way approach
Authors: Fariello Consuelo M. , Meynecke Jan-Olaf , de Bie Jasper
Published: May 2024

Context Humpback whale (Megaptera novaeangliae) populations have been recovering from whaling but are now facing threats from changing food availability due to ocean warming and changes in habitat suitability. There is uncertainty over whether opportunistic observations can produce reliable species distribution models (SDMs) and adequately inform conservation management. Aims To compare SDMs for humpback whales in the Great Barrier Reef Marine Park based on different opportunistic sightings datasets and evaluate the impact different sources of opportunistic data have on our understanding of humpback whale habitat relationships. Methods Maximum entropy modelling (Maxent) was used to create predictive models for humpback whale distributions. Sighting data from citizen science and opportunistic observations from various other databases were used. Models were compared to evaluate disparities and predictive capabilities. Key results Distinct environmental variables [bathymetry, distance to the coast] were identified as the most relevant for each SDM. The best-fitting model diverged from an existing model, with humpback whale distribution predicted to be closer to shore. Areas with the highest habitat suitability were concentrated in the north-eastern coastal region across all models developed in this study. Conclusions This study demonstrates that, with careful application and consideration, citizen science data can enhance our understanding of humpback whale distributions and contribute to their conservation. The research underlines the importance of embracing diverse data sources in SDM, despite the challenges posed by opportunistic data. Implications The study provides valuable insights for conservation management and informs strategies to protect humpback whale populations in changing environmental conditions.
Taylor’s law and quasi-experimental hunting of invasive wild boar and axis deer in a protected area of north-eastern Argentina
Authors: Gürtler Ricardo E. , Nicosia Gabriela , Delaloye Aldo , Maranta Aristóbulo A. , Li Puma María C. , Cohen Joel E.
Published: May 2024

Context Overabundant ungulate populations frequently cause ecological and economic damage and are difficult to control. Sustained culling efforts at El Palmar National Park have largely reduced wild boar (Sus scrofa) numbers and damage but have failed to halt the ever-increasing abundance of axis deer (Axis axis) for undefined reasons. Multi-year camera-trap surveys indicated a mismatch between deer core activity and the usual timing of hunting sessions. Aim We used the spatial and temporal forms of Taylor’s law (TL, a power relationship between the sample mean and sample variance) to test whether overnight hunting sessions are more effective for culling axis deer and wild boar than are daytime sessions, and assessed whether they modify ungulate harvest composition. Methods We implemented a quasi-experimental trial (i.e. ‘experiments in which units are not assigned to conditions randomly’), including nine alternating blocks of four to seven hunting sessions each (overnight or daytime) in which an average of 42 hunter groups performed controlled shooting over bait from fixed elevated blinds, retrieved, sexed, weighed and measured all quarry. Key results The relationship between the mean and variance of ungulate crude catch per hunting-party session and crude catch per unit effort (CPUE, where effort is measured in hunting-party hours) by hunting shift satisfied the spatial and temporal TL. On average, axis deer catch was 2.39–2.61 times greater in overnight than in daytime sessions, whereas CPUE indices were 1.54–1.73 times greater. For wild boar, overnight sessions returned catches similar to (0.94–1.03×), and a significantly lower CPUE (0.63–0.67×) than for daytime sessions. The harvest indices were substantially aggregated in daytime sessions only, and were consistently skewed towards yearlings or subadults and males, especially among adult deer. Overnight sessions culled proportionally more adults and more pregnant hinds and sows than did daytime sessions, and significantly heavier deer and wild boar males. Conclusions Overnight sessions were substantially more effective for culling deer than were daytime sessions, and selected for individuals with greater fitness. Stage- and male-skewed harvest most likely explains the steady population growth of axis deer despite increasing hunting pressure over a decade. Implications Adjusting the schedule of hunting sessions to time intervals of peak ungulate activity substantially increased the efficiency of management efforts in terms of removal rates and reproductive value of the culled specimens.
Detecting recollection: Human evaluators can successfully assess the veracity of others’ memories
Authors: Gamoran Avi , Lieberman Lilach , Gilead Michael , Dobbins Ian G. , Sadeh Talya
Published: May 2024

Humans have the highly adaptive ability to learn from others’ memories. However, because memories are prone to errors, in order for others’ memories to be a valuable source of information, we need to assess their veracity. Previous studies have shown that linguistic information conveyed in self-reported justifications can be used to train a machine-learner to distinguish true from false memories. But can humans also perform this task, and if so, do they do so in the same way the machine-learner does? Participants were presented with justifications corresponding to Hits and False Alarms and were asked to directly assess whether the witness’s recognition was correct or incorrect. In addition, participants assessed justifications’ recollective qualities: their vividness, specificity, and the degree of confidence they conveyed. Results show that human evaluators can discriminate Hits from False Alarms above chance levels, based on the justifications provided per item. Their performance was on par with the machine learner. Furthermore, through assessment of the perceived recollective qualities of justifications, participants were able to glean more information from the justifications than they used in their own direct decisions and than the machine learner did.
CISD3/MiNT is required for complex I function, mitochondrial integrity, and skeletal muscle maintenance
Authors: Nechushtai Rachel , Rowland Linda , Karmi Ola , Marjault Henri-Baptiste , Nguyen Thi Thao , Mittal Shubham , Ahmed Raheel S. , Grant DeAna , Manrique-Acevedo Camila , Morcos Faruck , Onuchic José N. , Mittler Ron
Published: May 2024

Mitochondria play a central role in muscle metabolism and function. A unique family of iron–sulfur proteins, termed CDGSH Iron Sulfur Domain-containing (CISD/NEET) proteins, support mitochondrial function in skeletal muscles. The abundance of these proteins declines during aging leading to muscle degeneration. Although the function of the outer mitochondrial CISD/NEET proteins, CISD1/mitoNEET and CISD2/NAF-1, has been defined in skeletal muscle cells, the role of the inner mitochondrial CISD protein, CISD3/MiNT, is currently unknown. Here, we show that CISD3 deficiency in mice results in muscle atrophy that shares proteomic features with Duchenne muscular dystrophy. We further reveal that CISD3 deficiency impairs the function and structure of skeletal muscles, as well as their mitochondria, and that CISD3 interacts with, and donates its [2Fe-2S] clusters to, complex I respiratory chain subunit NADH Ubiquinone Oxidoreductase Core Subunit V2 (NDUFV2). Using coevolutionary and structural computational tools, we model a CISD3–NDUFV2 complex with proximal coevolving residue interactions conducive of [2Fe-2S] cluster transfer reactions, placing the clusters of the two proteins 10 to 16 Å apart. Taken together, our findings reveal that CISD3/MiNT is important for supporting the biogenesis and function of complex I, essential for muscle maintenance and function. Interventions that target CISD3 could therefore impact different muscle degeneration syndromes, aging, and related conditions.
The effect of linguistic and extralinguistic features on EFL adverb placement
Authors: Özkan Miller Vildan , Larsson Tove
Published: May 2024

Larsson et al. (2020) emphasize the importance of taking linguistic
variables (e.g., verb type) into consideration in studies of adverb placement. This study looks at the positional distribution of
15 epistemic adverbs from texts written by L1 Turkish, German, and English students, with the aim of testing whether the findings
from Larsson et al. can be generalized to a different register (argumentative writing) and a typologically more distant language
(Turkish). We also revisit the question of whether there is L1 transfer. The results confirm Larsson et al.’s finding that the
main predictors of adverb placement are linguistic, although some register differences were noted, such as higher frequencies of
adverbs in the argumentative texts. Furthermore, the L1 Turkish students made especially frequent use of the clause-initial
position (e.g.,
probably she is here).
Individual differences and task-based language teaching
Authors: Li Shaofeng
Published: May 2024

This chapter provides an in-depth discussion of the theory, research, and practice of individual
difference (ID) factors in task-based language teaching (TBLT). It starts with an overview of the scope and taxonomy
of IDs in second language learning, followed by a discussion of the theoretical models that provide insights into IDs’
roles in TBLT. It then introduces an organizing framework covering: (a) the nature of task IDs, (b) the utility of
implicit IDs in TBLT, (c) the dynamicity of task IDs, (d) the expanded scope of task IDs, and (e) the importance of
research on ID-treatment interaction. Subsequently, the chapter shifts its focus to the research on IDs in TBLT,
including methods, perspectives, and empirical evidence on major ID factors – emotions (anxiety and enjoyment),
language aptitude, motivation, and working memory. Based on the research findings, recommendations are made on ways to
apply research findings to pedagogy from five perspectives: changing ID propensities, adapting instruction to mitigate
or cancel ID effects, matching ID profile and instruction type, using hybrid instruction, and providing choice. The
chapter concludes by providing an overview of the significance and contributions of this volume and highlighting
prominent findings of the included chapters.
Revitalizing agricultural price mechanisms: A review and call for enhancement
Authors: Vohra Mehak , Sharma Vijaylaxmi
Published: May 2024

Indian agriculture has long faced criticism for its lack of a strong price policy, which leaves farmers at the mercy of changes in the market. Although it has been implemented for a few commodities, the minimum support price (MSP) system has not been all-encompassing nor has the implementation of market intervention measures yielded much respite. This study makes the case that a thoughtful combination of the private investments and market intervention schemes (MIS) along with existing regimes of MSP could provide greater results. A strategy like this might offer farmers greater all-encompassing assistance while guaranteeing reasonable prices and stable markets. This study has reviewed two key existing frameworks by examining their strengths and flaws. Based on this analysis, it is possible to move forward by incorporating the best aspects of MIS and MSP. In addition to addressing the long-standing issues Indian farmers confront, this strategy could result in a more egalitarian and sustainable agriculture industry.
Future of Bianchi I magnetic cosmologies with kinetic matter
Authors: Lee Ho , Nungesser Ernesto
Published: May 2024

We show under the assumption of small data that solutions to the Einstein-Vlasov system with a pure magnetic field and Bianchi I symmetry isotropise and tend to dust solutions. We also obtain the decay rates for the main variables. This generalises part of the work (LeBlanc 1997 Class. Quantum Grav.
14 2281–301) concerning the future behaviour of orthogonal perfect fluids with a linear equation of state in the presence of a magnetic field to the Vlasov case.
Effects of p-wave interactions on Borromean Efimov trimers in heavy–light Fermi systems
Authors: Zhao Cai-Yun , Han Hui-Li , Shi Ting-Yun
Published: May 2024

We investigate the effects of p-wave interactions on Efimov trimers in systems comprising two identical heavy fermions and a light particle, with mass ratios larger than 13.6. Our focus lies on the Borromean regime where the ground-state trimer exists in the absence of dimers. Using pair-wise Lennard–Jones potentials and concentrating on the

L

π

=

1

−

symmetry, we explore the critical value of the interspecies s-wave scattering length a

c
at which the Borromean state appears in several two-component particle systems. Our exploration encompasses the universal properties of a

c
and the influence of p-wave fermion–fermion interactions on its value. We find that, in the absence of p-wave fermion–fermion interactions, a

c
is determined universally by the van der Waals radius and mass ratio. However, the introduction of p-wave fermion–fermion interactions unveiled a departure from this universality. Our calculations show that the critical interspecies scattering length a

c
now depends on the details of the fermion–fermion p-wave interaction. And, the presence of p-wave fermion–fermion interactions favors the formation of the Borromean state. Additionally, our investigation reveals that Efimov effect in the

1

−

symmetry persist even when the fermion–fermion interaction reaches the p-wave unitary limit.
Electronic coherences built by an attopulse control the forces on the nuclei
Authors: Cardosa-Gutierrez Manuel , Levine R D , Remacle F
Published: May 2024

Attopulses have an energy bandwidth broad enough to coherently excite several electronic states of molecules. Towards the control of chemical reactivity by attopulses we derive the quantum mechanical expression for the force exerted on the nuclei in such a vibronic wave packet both during and after the exciting pulse. Tuning the pulse parameters allows accessing specific electronic coherences that determine the force strength and direction during and after the pulse. Following the pulse, the force due to the non adiabatic interactions accelerates or slows down the motion of the vibronic wave packet on the excited electronic states and its sign controls the direction of population transfer. Computational results for the LiH and LiT molecules and the probing by the emission dipole are discussed.
Advances in high-power vertical-cavity surface-emitting lasers
Authors: Liu Jilin , Zhao Feiyun , Tang Zhiting , Zhang Xuhao , Ren Aobo , Wu Jiang
Published: May 2024

Vertical-cavity surface emitting lasers (VCSELs) have emerged as a highly promising light source with extensive applications in various fields, including consumer electronics, optical communication, metrology, sensing and ranging. Their low-cost, high conversion efficiency, and compact footprint make them particularly attractive for widespread adoption. While considerable success has been made in enhancing the performance and speed of VCSELs for optical communications, achieving high-power VCSELs with properties such as high output power, single transverse mode operation, and temperature stability for remote sensing applications remains a challenging endeavor. This review aims to provide a comprehensive overview of the recent advancements in the development of high-power VCSELs. By examining the advancements in active materials, device designs, array configurations, this review seeks to shed light on the current state-of-the-art and potential avenues for further improvement in high-power VCSEL technology.
A high sensitivity wide bandwidth spectral system for multiple K-edge imaging
Authors: Perion P , Brombal L , Delogu P , di Trapani V , Menk R H , Oliva P , Arfelli F
Published: May 2024

Spectral K-edge subtraction (SKES) is an imaging technique that takes advantage of the sharp rise in the mass attenuation coefficient of specific elements within an object at their K-edge to produce separate and quantifiable distributions of each element. In this paper, a high-sensitivity and wide bandwidth SKES imaging system for computed tomography applications on biological samples is presented. X-ray images are acquired using a wide and continuous energy spectrum that encompasses the absorption edges of the target materials. System characterization shows that high energy resolution (approximately

3
×

10

−
3

) and unprecedented large energy bandwidth (around 15%) are achieved over a field-of-view of several centimeters. Imaging results obtained on contrast elements relevant for biomedical applications, namely silver, iodine, xenon, and barium, demonstrate the system sensitivity to concentrations down to 0.5 mg ml−1. The achievement of a large energy bandwidth allowed the simultaneous imaging of the K-edges of iodine, xenon, and barium and provided an accurate concentration estimation and distinction of co-localized contrast elements, leading the way for future simultaneous cardiovascular (iodine), pulmonary (xenon), and gastrointestinal/inflammatory (barium) imaging applications.
Hexagonal warping effects on Bloch oscillations in proximitized Rashba systems
Authors: Yar Abdullah
Published: May 2024

Bloch oscillations (BOs) in Rashba systems, taking into account the effects of hexagonal warping and proximity-induced band gap, are reported. We find that in addition to real-space trajectories, the group and Berry velocities of Bloch electrons exhibit novel BOs which strongly depend on the crystal momentum. This oscillatory motion is affected significantly by variations in the strength of hexagonal warping and the proximity-induced band gap, originating from the substantial changes in the energy spectrum induced by these factors. In addition, it is shown that the Bloch oscillations are modified considerably under the influence of applied uniform in-plane electric and transverse magnetic fields, which allow for a geometric visualization of the Bloch dynamics. Interestingly, when the system is subjected to these fields simultaneously, it undergoes a dynamic phase transition between confined and de-confined states. This phase transition is tuned by the relative strength of the applied fields and is further influenced by variations in the strength of hexagonal warping and proximity-induced band gap. The appearance of such a transition is attributed to the interplay between the external fields and the intrinsic properties of the crystal lattice. Moreover, we find that the direct-current drift velocity shows negative differential conductivity, which is a characteristic feature of the BO regime.
Considerations on measurement of bidirectional transmittance distribution function of thick samples over a wide range of viewing zenith angles
Authors: Aschan Robin , Manoocheri Farshid , Ikonen Erkki
Published: May 2024

We delve into theoretical and experimental considerations for determining the spectral bidirectional transmittance distribution function (BTDF) of thick samples across a broad viewing zenith angle range. Nominally, BTDF is defined as the ratio of transmitted radiance to incident irradiance measured from the same plane. However, when employing thick samples for BTDF measurements, the viewing plane of the transmitted beam may shift from the front to the rear surface of the sample, altering the measurement geometry compared to using the sample front surface as the reference plane. Consequently, the viewing zenith angle from the sample rear surface increases relative to the sample front surface, and the sample-to-detector-aperture distance decreases by an amount corresponding to the sample thickness. We introduce a method for determining the BTDF of thick samples, considering the transformation of practical measurement results to a scenario where the measurements are conducted at a very large distance from the sample. To validate the method, we utilize a BTDF facility equipped with two instruments that significantly differ in their sample-to-detector-aperture distances. We evaluate the impact of a 2 mm sample thickness on the BTDF by assessing the ratio of transmitted and incident radiant fluxes as a function of viewing zenith angle relative to the sample rear surface. The evaluation is conducted in the wavelength range from 550 nm to 1450 nm in 300 nm steps, and in the viewing zenith angle range from −70° to 70° in 5° steps. Measurements are performed in-plane at an incident zenith angle of 0°. It is concluded that consistent determination of BTDF of a thick sample is possible by converting the experimental parameters of the real measurements at relatively short distances from the sample to correspond to those that would be obtained from measurements at very large distances from the sample.
Research on bearing fault diagnosis based on novel MRSVD-CWT and improved CNN-LSTM
Authors: Guo Yuan , Zhou Jun , Dong Zhenbiao , She Huan , Xu Weijia
Published: May 2024

As a critical component in mechanical equipment, rolling bearings play a vital role in industrial production. Effective bearing fault diagnosis provides a more reliable guarantee for the safe operation of the industrial output. Traditional data-driven bearing fault diagnosis methods often have problems such as insufficient fault feature extraction and poor model generalization capabilities, resulting in reduced diagnostic accuracy. To solve these problems and significantly improve the diagnosis accuracy, this paper proposes a novel fault diagnosis method based on multi-resolution singular value decomposition (MRSVD), continuous wavelet transform (CWT), improved convolutional neural network (CNN) enhanced by convolutional block attention module, and long short-term memory (LSTM). Through MRSVD, the vibration signal is decomposed layer by layer into multiple denoised signals, thus signal noise can be eliminated to the greatest extent to gain the optimal denoised signals; then through CWT, the optimal denoised signals are converted into two-dimensional time-frequency images so that the local and global characteristic information can be fully captured. Finally, through improved CNN-LSTM, feature extraction is greatly enhanced, resulting in high accuracy of fault diagnosis. Lots of experiments are organized to test the performance, and the experimental results show that the proposed method on various datasets has better diagnosis accuracy and generalization ability under different working conditions than other methods.
An integrated high precision absolute angular displacement sensor
Authors: Zhan Bingnan , Wu Changliang , Liu Xiaokang , Huang Pei , Yu Peiyu
Published: May 2024

This paper proposed a high precision absolute angular displacement time grating sensor, and was assembled into an integrated encoder. This absolute angle sensor contains two incremental sensors with N
1 and N
2 measurement period, respectively. N
1 and N
2 are mutually prime, and N
1 > N
2. The induction electrodes of the fine measurement component adopt differential design to minimize the effects of external electromagnetic interference and common mode interference between different sensing units so as to achieve high precision displacement measurement, the phase difference between two incremental sensor is used for absolute positioning. This absolute positioning method reduces the installation requirements and enhances their absolute positioning capability, enhancing adaptability and application prospects. The reflecting ring design simplifies the structure of the encoder and facilitates sensor integration. The induction output signals of different components are cross connected through lead wires to the reflecting ring far away from the measurement component to the first harmonic error during the measurement period. The reading heads adopt a round, uniformly distributed design scheme, and the average effect of the whole circumference closed ring sampling scheme is beneficial for improving measurement accuracy, reduce the influence of edge effects and parasitic capacitance on nonlinear errors within the measurement period and eliminating harmonic errors. A sensor prototype with a diameter of 83 mm was manufactured and assembled into an integrated encoder. Experimental results show that the sensor achieve a precision of 12″ over a full 360° measurement range and a resolution of 0.5″, and it can realize absolute positioning.
Linear response due to singularities
Authors: Bahsoun Wael , Galatolo Stefano
Published: May 2024

It is well known that a family of tent-like maps with bounded derivatives has no linear response for typical deterministic perturbations changing the value of the turning point. In this note we prove the following result: if we consider a tent-like family with a cusp at the turning point, we recover the linear response. More precisely, let T

ɛ
be a family of such cusp maps generated by changing the value of the turning point of T
0 by a deterministic perturbation and let h

ɛ
be the corresponding invariant density. We prove that

ε
↦

h
ε

is differentiable in L
1 and provide a formula for its derivative.
An Arduino experiment to determine the gravitational acceleration using a light interruption apparatus with PLX − DAQ data acquisition tool
Authors: Madey Ahmed
Published: May 2024

In this paper the author is presenting a novel experiment for measuring the gravitational acceleration using simple and cost effective apparatus with a regular pendulum, composed of an Arduino Uno and a light interruption circuit with an light dependent resistor (LDR) and an light emitting diode (LED), the data was recorded using PLX − DAQ data acquisition tool for further analysis, the experiment would be useful for introductory physics courses on the subject.
Effect of using multiple representations in teaching mechanics problem-solving on engineering students’ academic performance in Rwanda
Authors: Theogene Niyomufasha , Ntivuguruzwa Celestin , Mugabo Leon
Published: May 2024

In recent years, the use of multiple representations in physics teaching and learning has become more common. This study sought to determine if engineering students’ performance in Rwanda might be improved by the use of numerous representations when solving mechanics problems. Multiple representations improve students’ comprehension and recall of mechanics ideas, supporting efficient teaching methods and critical thinking. This study employed a quasi-experimental research design with pre-and post-test control and experimental groups. A total of 100 students were enrolled in the study, divided into two groups: the experimental group consisted of 52 students who received instruction using multiple representations, and the control group consisted of 48 students who received instruction using traditional methods. In the study, students’ performance was measured before and after intervention using a mechanics test. The mechanics problem-solving pre-test findings indicated a p-value greater than 0.05 between the control and experimental groups, indicating no statistically significant differences between the two groups. A post-test revealed a p-value < 0.001 between the groups, indicating that the experimental group outperformed the control group significantly. According to the findings, engineering student’s academic performance in physics can be improved through the use of multiple representations in teaching and learning mechanics problem-solving. This study will support the development of Rwandan education policies, instructional approaches, and global pedagogy are all supported by this study.
Symmetry and complexity: a Lie symmetry method to bifurcation, chaos, multistability and soliton solutions of the nonlinear generalized advection-diffusion-reaction equation
Authors: Samina Samina , Jhangeer Adil , Chen Zili
Published: May 2024

This paper deals with the complexities of nonlinear dynamics within the nonlinear generalized advection-diffusion-reaction equation, which describes intricate transport phenomena involving advection, diffusion, and reaction processes occurring simultaneously. Through the utilization of the Lie symmetry approach, we thoroughly examine this proposed model, transforming the partial differential equation into an ordinary differential equation using similarity reduction techniques to facilitate a more comprehensive analysis. Exact solutions for this transformed equation are derived employing the extended simplest equation method and the new extended direct algebraic method. To enhance understanding, contour plots along with 2D and 3D visualizations of solutions are employed. Additionally, we explore bifurcation and chaotic behaviors through a qualitative analysis of the model. Phase portraits are meticulously scrutinized across various parameter values, offering insights into system behavior. The introduction of an external periodic strength allows us to utilize various tools including time series, 3D, and 2D phase patterns to discern chaotic and quasi-periodic behaviors. Furthermore, a multistability analysis is conducted to examine the impacts of diverse initial conditions. These findings underscore the efficacy and practicality of the proposed methodologies in evaluating soliton solutions and elucidating phase dynamics across a spectrum of nonlinear models, offering novel perspectives on intricate physical phenomena
Super-X and conventional divertor configurations in MAST-U ohmic L-mode; a comparison facilitated by interpretative modelling
Authors: Moulton D. , Harrison J.R. , Xiang L. , Ryan P.J. , Kirk A. , Verhaegh K. , Wijkamp T.A. , Federici F. , Clark J.G. , Lipschultz B.
Published: May 2024

Measurements are presented, alongside corresponding interpretative SOLPS-ITER simulations, of the first MAST-U experiments comparing ohmically heated L-mode fuelling scans in Conventional divertor (CD) and Super-X divertor (SXD) configurations. In experiment, at comparable outer mid-plane separatrix electron density,

n

e
,
sep,OMP

, the maximum lower outer target heat load was found to be a factor 16

±

7

lower in SXD compared to CD. In simulation, a factor 26.8 reduction was found (slightly higher than the experimental range), suggesting an additional reduction in SXD compared to the factor 9.3 expected from geometric considerations alone. According to the simulations, this additional reduction in the SXD is due to a net radial transport of the energy remaining downstream of the

T
e

=
5

eV location. This energy is carried out of the critical (highest heat load) flux tube by deuterium atoms, demonstrating the importance of a longer legged divertor which provides space for this to occur. Importantly, in both simulation and experiment, the SXD has minimal impact on the upstream ne
and Te
profiles. Spectral inferences of detachment front movement in SXD compare well between simulation and experiment. In regions of high magnetic field gradient, the parallel movement of the front towards the X-point becomes less sensitive to increasing

n

e
,
sep,OMP

, in qualitative agreement with simplified models and previous predictive simulations. Additional aspects, regarding the target ion flux rollover, upstream separatrix temperature and drift effects, are also presented and discussed.
Tokamak divertor plasma emulation with machine learning
Authors: Holt G.K. , Keats A. , Pamela S. , Kryjak M. , Agnello A. , Amorisco N.C. , Dudson B.D. , Smyrnakis M.
Published: May 2024

Future tokamak devices that aim to create conditions relevant to power plant operations must consider strategies for mitigating damage to plasma facing components in the divertor. One of the goals of MAST-U tokamak operations is to inform these considerations by researching advanced divertor configurations that aid stable plasma detachment. Machine design, scenario planning and detachment control would all greatly benefit from tools that enable rapid calculation of scenario-relevant quantities given some input parameters. This paper presents a method for generating large, simulated scrape-off layer data sets, which was applied to generate a data set of steady-state Hermes-3 simulations of the MAST-U tokamak. A machine learning model was constructed using a Bayesian approach to hyperparameter optimisation to predict diagnosable output quantities given control-relevant input features. The resulting best-performing model, which is based on a feedforward neural network, achieves high accuracy when predicting electron temperature at the divertor target and carbon impurity radiation front position and runs in around 1 ms in inference mode. Techniques for interpreting the predictions made by the model were applied, and a high-resolution parameter scan of upstream conditions was performed to demonstrate the utility of rapidly generating accurate predictions using the emulator. This work represents a step forward in the design of machine learning-driven emulators of tokamak exhaust simulation codes in operational modes relevant to divertor detachment control and plasma scenario design.
Experimental investigation of PDI bifurcation of lower hybrid waves during electron density ramp-up in EAST
Authors: Yan G.H. , Ding B.J. , Wu C.B. , Li M.H. , Baek S.G. , Napoli F. , Zhou T.T. , Geng K.N. , Yan N. , Wang M. , Zhang X.J. , Xu H.D. , Yang J.H. , Ma W.Q.
Published: May 2024

The effect of parametric decay instability (PDI) on the current drive efficiency of 4.6 GHz lower hybrid (LH) waves in EAST is investigated experimentally, showing the PDI channel bifurcation of LH waves for the first time in EAST. First, experiments with three platforms of LH power were performed, achieving the LH power required for the PDI occurrence. Second, PDI bifurcation experiments were further carried out by ramping up the plasma electron density. The loop voltage increases with an increase in density, implying a decrease in the current driven by the LH wave. PDI bifurcation during electron density ramp-up was studied by analyzing the parallel refractive index (

n
∥

) and the frequency spectrum broadening, which is measured with a radio frequency magnetic probe array recently installed close to the LH antenna. It is observed for the first time that they both first increase with density, then there is not much variation and a clear sideband in the frequency spectrum is also observed when the density is up to

4
×

10

19

 

 m

−
3

, suggesting a change in the PDI channel. Calculation of the mode growth rate driven by PDI shows that when the edge electron density is up to

1.9
×

10

18

 

 m

−
3

, the growth rate of the ion cyclotron quasi-mode (ICQM) will exceed that of the ion sound quasi-mode (ISQM), quantitively explaining that with an increase in density, the PDI channel partly transits from the ISQM to the ICQM channel. Studies provide a possible way to reduce the power deposition in the edge region and improve drive capability by means of mitigating PDI behavior.
Aerodynamic characteristic analysis of blast wave lateral sweeping aircraft based on CFD transient numerical simulation method
Authors: Yuhong Cai , Jianchao Niu , Duojia Huang , Mailiang Li , Zijie Chen
Published: May 2024

Blast wave overpressure and dynamic pressure significantly change the surface pressure distribution of the aircraft and resulting in transient aerodynamic forces when the blast wave sweeps the aircraft laterally. These transient aerodynamic forces will pose a serious threat to flight safety. In this paper, the aerodynamic parameters of aircraft components under lateral sweep of blast waves are studied by the Computational Fluid Dynamics (CFD) numerical simulation method, and the waveform characteristics of the dominant aerodynamic parameters of the aircraft key components are analyzed according to the CFD simulation results. The research method can provide reference and guidance for the study of aircraft flight safety under blast wave sweeping.
Researches on the aerodynamic and stealth characteristics for flying wing fighter
Authors: Shi Longlong , Xia Lu , Zhang Meng , Deng Jun , Zhang Wei
Published: May 2024

Flying wing configuration fighter is very promising for the advanced fighter in the future. This paper studies the aerodynamic and stealth characteristics of flying wing fighter. Firstly, the effect of sharp leading edge on the subsonic, transonic lift and drag characteristics and stealth characteristics of the fighter are studied. The results show that the sharpen of leading edge of the inboard wing could greatly improve the lateral stealth characteristics while maintaining the subsonic and transonic lift characteristics. In order to furtherly improve its aerodynamic and forward stealth characteristics, the aerodynamic/stealth collaborative design optimization method based on discrete adjoint is carried out. And the results presented that there are obvious contradictions in the subsonic, transonic and supersonic lift characteristics of the flying wing fighter, and the improvement of the forward stealth characteristics will also damage the subsonic lift characteristics. Therefore, it is necessary to make a compromise between the subsonic, transonic and supersonic lift characteristics, drag characteristics and stealth characteristics in the shape design of flying wing fighter.
Stochastic robustness analysis of wing-aileron flutter suppression systems
Authors: Vindigni Carmelo Rosario , Mantegna Giuseppe , Esposito Antonio , Orlando Calogero , Alaimo Andrea
Published: May 2024

In this work a stochastic robustness analysis approach is used to compare the performances of two non-linear flutter suppression systems designed for stabilization of a wing-aileron lifting structure. A reduced order modelling approach based on an alternative aeroelastic beam finite element is presented and used for the flutter suppression systems design, which are driven by a simple adaptive controller and a sliding mode controller, respectively. A heuristic algorithm is used to determine the simple adaptive controller invariant parameters at the design point while a simple parametric study is performed to tune the sliding mode controller. The performances of each closed loop system are evaluated taking into account mass, stiffnesses, and aerodynamics uncertainties of the aeroelastic plant also considering the presence of discrete gust disturbances.
Drag reduction study based on boundary layer combustion on single expansion ramp nozzle
Authors: Chang H , Sun B , Gan Y Z
Published: May 2024

In hypersonic flight, frictional drag is an important factor affecting the overall engine performance. The wall frictional drag analysis and drag reduction technology of a unilateral expanding tail nozzle under typical working conditions are carried out by means of two-dimensional Reynolds-averaged N-S equations and SST k − ω turbulence model. The effects of hydrogen injection and combustion with different mass flow rates under different jet positions on the wall friction resistance are analyzed and compared, and the results show that, under the appropriate opening position, a better drag reduction effect can be obtained by injecting hydrogen with a mainstream flow rate of about 2.5%, which can achieve a reduction of 43.7%.