bluuebunny/crossref_metadata_2025 huggingface dataset:
Teachers’ and learners’ beliefs about task-based language teaching
Authors: Dao Phung , Iwashita Noriko , Chi Nguyen Mai Xuan Nhat , Arias-Contreras Carolina
Published: May 2024

This chapter provides a systematic review of studies on learner/teacher beliefs in the context of
task-based language teaching (TBLT). This review aims to identify the foci, conceptualisation, operationalisation of
beliefs in TBLT, methodological characteristics, and major research findings. The results showed a lack of consistent
conceptualisation and operationalisation of the concept of beliefs, and the studies have focused more on teachers’
beliefs about TBLT than learners’. The results also demonstrated a number of methodological issues such as lack of
important background information about the participants and the study’s context, an excessive focus on English as a
target language, an over-reliance on the normative approach (as opposed to the contextual approach), and a lack of
clear and rigorus procedure for construct validation and data analysis. Despite these issues, the results show that
TBLT research on beliefs appears to head toward an appropriate direction by adopting multi-method approaches and using
diverse data collection tools. Also, the results show a promising picture for adopting and implementing TBLT in
diverse contexts from both teachers’ and learners’ perspectives.
Practitioners’ perspectives
Authors: Willis Jane
Published: May 2024

The aim of this chapter is to explore the potential of task-based language teaching to accommodate
a range of learner individual differences (IDs). As such it is different from previous chapters in this volume which
report research findings on separate individual differences. To supplement my own experience, I invited teachers I
knew who practised TBLT to contribute their observations and reflections on the IDs most relevant to TBLT in their
teaching contexts. Their experiences of using task-based language teaching in their classes shed light on how a
task-based approach can support learners with individual differences. The chapter then explores ways in which the
stages in a task-based lesson framework can address particular individual differences. The chapter contains practical
examples which illustrate aspects of task design and implementation that can accommodate one or more individual
differences. These will be of relevance to all language teachers including those in professional development programs
and novice teachers on pre-service teacher education courses.
Teacher IDs and task adaptations
Authors: Gurzynski-Weiss Laura , Bryfonski Lara , Reagan Derek
Published: May 2024

This multi-site study explores how 18 graduate-level L2 teacher participants adapted tasks from
the TBLT Language Learning Task Bank for specific learner needs and teaching contexts, and if their individual
differences (IDs) influenced their adaptations. Participants first completed a questionnaire about their experiences
as L2 learners and teachers, their knowledge of TBLT, and how they search for course materials. They then defined a
teaching context (current, past, or prospective), specified a task need (i.e., communicative practice of a specific
linguistic target), and identified task features to search for in the Task Bank. Next, participants screen captured
and recorded their search and evaluation of possible tasks while thinking aloud, choosing one to adapt to their
context. Finally, participants watched their video and submitted a written reflection. Bottom-up thematic analysis was
used to determine how participants adapted the tasks from the Task Bank, if their IDs related to the ways they adapted
their selected task, and whether these adaptations aligned with their specific teaching context. The results showed
that all 18 teachers were successful in adapting their tasks to align with their stated teaching context and learner
needs, demonstrating that the Task Bank works well for the target audience of diverse teachers. It was also found that
teacher IDs did not play a role in their task adaptations when examined separately. However, a qualitative cluster
analysis showed that more experienced teachers tended to focus on providing linguistic instruction and increasing
interaction in task adaptation while less experienced teachers utilized a wide array of techniques. The minimal ID
cluster profiles that were discernible lend support to the consideration of IDs in tandem with – rather than in
isolation from – each other.
Challenges of Women Working as Leaders in Aruba’s Hotel Industry
Authors: Jadnanansing Madhu S. , Martin Drew
Published: May 2024

The hotel industry tends to underrepresent females in top management positions. Arguably, this problem is more acute in small island nations where few higher management positions are available due to the smallness of the sector. This case study explores female hotel leaders’ perceptions of gender bias in Aruba’s hotel sector. Semi-structured interviews were expanded with the Zoomorphic Forced Metaphor Elicitation Technique (ZFMET). This method surfaces nonconscious memories and offers rich insights on study participants’ perception of the implicit bias barriers that they encountered. These self-reports include their cognitive and behavioral responses to these barriers. Results show how the female managers evolve as they overcame gender bias. Overall, the managers perceive that they have grown wiser, stronger, and more alert to the occurrence of implicit gender bias.

Information

© The Authors 2024
Bipartite binding interface recruiting HP1 to chromosomal passenger complex at inner centromeres
Authors: Sako Kosuke , Furukawa Ayako , Nozawa Ryu-Suke , Kurita Jun-ichi , Nishimura Yoshifumi , Hirota Toru
Published: May 2024

Maintenance of ploidy depends on the mitotic kinase Aurora B, the catalytic subunit of the chromosomal passenger complex (CPC) whose proficient activity is supported by HP1 enriched at inner centromeres. HP1 is known to associate with INCENP of the CPC in a manner that depends on the PVI motif conserved across HP1 interactors. Here, we found that the interaction of INCENP with HP1 requires not only the PVI motif but also its C-terminally juxtaposed domain. Remarkably, these domains conditionally fold the β-strand (PVI motif) and the α-helix from a disordered sequence upon HP1 binding and render INCENP with high affinity to HP1. This bipartite binding domain termed SSH domain (Structure composed of Strand and Helix) is necessary and sufficient to attain a predominant interaction of HP1 with INCENP. These results identify a unique HP1-binding module in INCENP that ensures enrichment of HP1 at inner centromeres, Aurora B activity, and thereby mitotic fidelity.
Black hole interior quantization: a minimal uncertainty approach
Authors: Bosso Pasquale , Obregón Octavio , Rastgoo Saeed , Yupanqui Wilfredo
Published: May 2024

In a previous work we studied the interior of the Schwarzschild black hole implementing an effective minimal length, by applying a modification to the Poisson brackets of the theory. In this work we perform a proper quantization of such a system. Specifically, we quantize the interior of the Schwarzschild black hole in two ways: once by using the standard quantum theory, and once by following a minimal uncertainty approach. Then, we compare the obtained results from the two approaches. We show that, as expected, the wave function in the standard approach diverges in the region where classical singularity is located and the expectation value of the Kretschmann scalar also blows up on this state in that region. On the other hand, by following a minimal uncertainty quantization approach, we obtain 5 new and important results as follows. (1) All the interior states remain well-defined and square-integrable. (2) The expectation value of the Kretschmann scalar on the states remains finite over the whole interior region, particularly where used to be the classical singularity, therefore signaling the resolution of the black hole singularity. (3) A new quantum number is found which plays a crucial role in determining the convergence of the norm of states, as well as the convergence and finiteness of the expectation value of the Kretschmann scalar. (4) A minimum for the radius of the (2-spheres in the) black holes is found (5) By demanding square-integrability of states in the whole interior region, an exact relation between the Barbero-Immirzi parameter and the minimal uncertainty scale is found.
Universality of quantum time dilation
Authors: Dębski Kacper , Grochowski Piotr T , Demkowicz-Dobrzański Rafał , Dragan Andrzej
Published: May 2024

Time dilation is a difference in measured time between two clocks that either move with different velocities or experience different gravitational potentials. Both of these effects stem from the theory of relativity and are usually associated with classically defined trajectories, characterized by position, momentum, and acceleration. However, when spatial degrees of freedom are treated in a quantum way and a clock is allowed to be in a coherent superposition of either two momenta or two heights, additional quantum corrections to classical time dilation appear, called kinematic and gravitational quantum time dilations, respectively. We show that similarly to its classical counterpart, kinematic quantum time dilation is universal for any clock mechanism, while gravitational quantum time dilation is not. We also show that although both of these effects reduce to incoherent averaging of different classical time dilation contributions, there exists an additional quantum time dilation effect that has no classical analog and can be extracted from higher-order corrections to the system’s Hamiltonian.
A new framework for soft x-ray transient gratings
Authors: Foglia L , Mincigrucci R , Doring F , Fainozzi D , Mamyrbayev T , Masciovecchio C , Bencivenga F
Published: May 2024

The capability to use extreme ultraviolet (EUV) light for generating transient gratings (TGs) has enabled the study of thermoelastic and magnetic dynamics at the nanoscale, in thin solid samples and surfaces, without the need of specially modifying them. However, the current mirror-based setup for generating EUV TG limits both its extension to the soft x-ray photon energy range and the attainment of few femtosecond time-resolution. Here we propose to overcome these limitations with an alternative experimental scheme based on diffractive optical elements that has become feasible with the current technology. In addition, some aspects of the discussed setup may facilitate the implementation of the EUV TG approach at table-top high-harmonic generation sources.
Distinguishing methane from other hydrocarbons using machine learning and atmospheric pressure plasma optical emission spectroscopy
Authors: Mansouri Tahereh Shah , Wang Hui , Mariotti Davide , Maguire Paul
Published: May 2024

The ability to detect gas molecule and assign a concentration offers an inventive solution in the field of plasma integrated with machine learning. The most important finding of this work is firstly, to develop an algorithm for gas-molecule identification using three different hydrocarbons (CH4, C2H2, C2H6) and secondly, organize a model for detecting gas concentration (classification). For this reason, initially eight different gases evaluated. The study confirms the present of the unique emission lines as a gas indicator, i.e., a wavelength peak related to hydrocarbons identified via increasing in C
x
H
y
concentration. By means of unique variable important in projection, hydrocarbons can be distinguished. Our proposed Chemometric analysis strategy examined on >1000 samples and results development of suitable techniques that are sufficiently rapid, accurate and innovative. This demonstrates the potential for real-time, portable, and continuous monitoring of trace gases with potential applications in medical, environmental, and industrial gas sensing.
Valley edge states with opposite chirality in temperature dependent acoustic media
Authors: Gulzari Muhammad , Zhang Quan , King Eoin , Tong Lihong , Lai S K
Published: May 2024

The valley degree of freedom in phononic crystals and metamaterials holds immense promise for manipulating acoustic and elastic waves. However, the impact of acoustic medium properties on valley edge state frequencies and their robustness to one-way propagation in valley topological phononic crystals remains unexplored. While significant attention has been devoted to scatterer design embedded in honeycomb lattices within acoustic and elastic media to achieve valley edge states and topologically protected nontrivial bandgaps, the influence of variations in acoustic medium properties, such as wave velocity and density affected by environmental temperature, has been overlooked. In this study, we investigate the effect of valley edge states and topological phases exhibited by topological phononic lattices in a temperature-dependent acoustic medium. We observe that a decrease in wave velocity and density, influenced by changing environmental temperature, shifts the topological valley edge states to lower frequencies. Therefore, alongside phononic lattice design, it is crucial to consider the impact of acoustic medium properties on the practical application of acoustic topological insulators. This issue becomes particularly significant when a topological phononic crystal is placed in a wave medium that transitions from incompressible to compressible, where wave velocity and density are no longer constant. Our findings offer a novel perspective on investigating topological insulators in variable acoustic media affected by changing thermodynamic and fluid properties.
Measurement of Si pixel sensor alignment for the ALICE ITS detector
Authors: Satya Wicaksana Ahmad , Prakasa Esa , Di Mauro Antonio , Wardoyo Siswo
Published: May 2024

A Large Ion Collider Experiment (ALICE) experiment is one of the four experiments at the Large Hadron Collider (LHC) designed to investigate the status of matter under very high energy densities produced during heavy-ion collisions. The ALICE inner tracking system (ITS) consists of seven concentric cylindrical layers of monolithic silicon pixel sensors known as ALICE pixel detector (ALPIDE). The sensors are used to reconstruct the paths of charged particles generated in the collisions. The sensor alignment of the detector must be adjusted to a high precision standard. The adjustment objective is to obtain a detector that can undertake high-resolution measurements. This paper introduces a method for measuring the reference markers utilized in sensor alignment determination. Markers engraved at the chip corners have been detected using the Hough transform, Canny edge detection, and template matching techniques. The distances between two markers are measured to determine the accuracy of the pixel sensor alignment before and after assembly. The proposed methods exhibit an accuracy exceeding 99% and demonstrate high speed analysis. The average processing times for detecting the circle and cross markers are 105.9 ms/image and 113.8 ms/image, respectively. The sensor alignment of the detector must be adjusted to a high precision standard. However, recent studies have shown deviations of up to

5

μ

m

above the desired value in the measured sensor position. Such deviations do not represent a major issue, nevertheless it is important to measure them in order to speed-up and make more accurate the recursive track-based alignment procedure used to reconstruct the position of each pixel sensor in the tracking detector. The proposed method offers a promising solution to deliver precise and rapid measurements for a large number of examined objects.
CAC-YOLOv8: real-time bearing defect detection based on channel attenuation and expanded receptive field strategy
Authors: Liu Bushi , Zhao Yue , Chen Bolun , Yu Cuiying , Chang KaiLu
Published: May 2024

Bearing defect detection plays a crucial role in the intelligent production of chemical transmission equipment, where timely identification and handling of defective bearings are essential. However, in practical large-scale industrial production, product surface defects are often complex, diverse, and exhibit significant variations in appearance, posing severe challenges to the discriminative ability and detection efficiency of bearing defect detection algorithms. This paper proposes a real-time bearing surface defect detection algorithm, CAC-YOLOv8, which designs the Channel Attenuation Network (CAN) and Compound Pooling Pyramid Spatial Pyramid Pooling Fast (CPPSPPF) structure. Specifically, the model introduces the Channel Attenuation Network to achieve parallel feature extraction, deep feature processing, and feature fusion under different channel numbers, capturing critical features related to bearing defects and thereby improving the inference speed. Subsequently, based on the concept of overlapped receptive fields, a CPPSPPF structure is constructed, utilizing multiple iterations of max-pooling operations with smaller pooling kernel sizes to prevent information loss while expanding the receptive field, thereby strengthening the capturing ability of features at different scales. The experimental results indicate that the proposed CAC-YOLOv8 bearing surface defect detection algorithm, compared to the YOLOv8 model, achieved a 0.3% improvement in mAP@0.5, reduced model size by 14.4%, and enhanced model inference speed by 33.3%. This enables the CAC-YOLOv8 model to significantly improve the real-time performance of bearing defect detection while maintaining high-precision detection. The performance in practical industrial detection demonstrates that the proposed approach has achieved outstanding results in both speed and accuracy.
An adaptive frequency-based C/N0-constrained multipath extraction and mitigation method for GNSS pseudorange measurements
Authors: Liu Ruofan , Li Wanqing , Huang Xuewei , Song Jiangbo , Dai Zhiqiang , Zhu Xiangwei
Published: May 2024

The multipath effect poses an inevitable challenge for Global Navigation Satellite System (GNSS) receivers, particularly pronounced in smart devices, which are nevertheless the most common means through which the general public accesses GNSS positioning. Therefore, we propose a novel adaptive method for extracting multipath errors, which fully exploits the multipath frequency characteristics, multipath repeatability, and the correlation between multipath errors and carrier-to-noise ratio (C/N0). This approach aims to enhance the susceptibility of smart devices to multipath influences. Specifically, this method uses the code minus carrier method to calculate the noisy multipath error, exploits the correlation between C/N0 and multipath to constrain the frequency range, employs the ensemble empirical mode decomposition method to decompose the error signal, and utilizes the Hilbert–Huang transform method to obtain the frequency information of the signal component. In multipath repeatability, the proposed method can effectively improve the correlation of multipath signals by up to 0.79. By applying the extraction method, the positioning performance of smart devices can be improved by 13.9%. Therefore, the proposed method extracts multipath error more accurately and is highly usable in low-cost devices.
Electron–phonon coupling and a resonant-like optical observation of a band inversion in topological crystal insulator Pb1−x
Sn
x
Se
Authors: Woźny M , Szuszkiewicz W , Dyksik M , Motyka M , Szczerbakow A , Bardyszewski W , Story T , Cebulski J
Published: May 2024

The optical reflectivity of n-type Pb0.865Sn0.135Se and Pb0.75Sn0.25Se solid solutions was measured in the THz spectral region energetically corresponding to optical phonon excitations and in the temperature range from 40 K to 280 K. The first solid solution exhibits an open energy gap with trivial band ordering at all temperatures, while for the second one the transition from trivial insulator to topological crystal insulator phase is expected. The analysis of Pb0.75Sn0.25Se data performed within the dynamic dielectric function formalism revealed an anomaly of resonance-like character in the temperature dependence of LO phonon frequency. The formula for LO phonon energy renormalization reproduced observed anomaly for energy gap equal to zero, the phase transition occurred at T
0 = (172 ± 2) K. This effect was absent for Pb0.865Sn0.135Se. Present results show that reflectivity measurements in the THz range in the vicinity of LO phonon frequency can be valuable experimental method for precise determining of band inversion temperature in narrow-gap topological materials.
A novel analytical technique for analyzing the (3+1)-dimensional fractional calogero- bogoyavlenskii-schiff equation: investigating solitary/shock waves and many others physical phenomena
Authors: Noor Saima , Alyousef Haifa A , Shafee Ahmad , Shah Rasool , El-Tantawy Samir A
Published: May 2024

This work presents a thorough analysis of soliton wave phenomena in the (3+1)-dimensional Fractional Calogero-Bogoyavlenskii-Schiff equation (FCBSE) with Caputo’s derivatives through the use of a novel analytical technique known as the modified Extended Direct Algebraic Method (mEDAM). By converting nonlinear Fractional Partial Differential equations (FPDE) into integer-order Nonlinear Ordinary Differential equations (NODE), and then using closed-form series solutions to translate the NODE into an algebraic system of equations, this method allows us to derive families of soliton solutions, which include kink waves, lump waves, breather waves, and periodic waves, exposing new insights into the behavior and distinctive features of soliton waves in the FCBSE. By including contour and 3D graphics, the behaviors of a few selected soliton solutions are well depicted, showcasing their amplitude, shape, and propagation characteristics. The results enhance our understanding of the FCBSE and show that the mEDAM is a valuable tool for studying soliton wave phenomena. This work creates new opportunities for studying wave phenomena in more intricately constructed nonlinear FPDEs (NFPDEs).
Electric field control of 180° magnetization reversal in a spin-valve multiferroic heterostructure
Authors: Liu Mengli , Wang Liguo , Zhang Li , Zhou Hang , Shen Jianyu
Published: May 2024

Electrical tuning of magnetism, rather than a spin current or magnetic field, has attracted much attention due to its great potential for designing energy-efficient spintronic devices. However, pure electric field (E-field) control of 180° magnetization reversal is still challenging. Thus, we report an E-field-controlled 180° magnetization reversal in a spin valve (SV)/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) multiferroic heterostructure. Via the converse magnetoelectric coupling effect in CoFe/PMN-PT heterostructures, the magnetic anisotropy and coercive field of the CoFe film can be tremendously modulated by an E-field. We fabricated an optimized SV grown on the PMN-PT substrate, in which the magnetic moments of the free and pinned layers are parallel to each other at the initial state. By applying an E-field, the coercive field of the free layer was enhanced, exhibiting an antiparallel configuration between the free and pinned layers. Based on the theoretical and experimental results, a complete 180° magnetization reversal of the free layer can be obtained without a magnetic field. Accordingly, an E-field-controlled giant, reversible and repeatable magnetoresistance modulation can be achieved. This work proposes a feasible strategy to achieve E-field-controlled 180° magnetization reversal, which is critical for exploring ultralow power consumption magnetic memory devices.
An analytical study on the influence of magnetic field-dependent viscosity on viscous and ohmic dissipative second-grade fluid boundary layers
Authors: N Vishnu Ganesh , Sinivasan K , Al-Mdallal Qasem M , Hirankumar G
Published: May 2024

This article aims to investigate the magnetohydrodynamic (MHD) boundary layer flow of a second-grade non-Newtonian fluid over a horizontally stretching sheet, considering magnetic field-dependent (MFD) viscosity, as well as viscous and Ohmic dissipations. Analytical solutions for previously unexplored momentum and heat transfer equations involving MFD viscosity are derived. Two boundary conditions, namely Prescribed Surface Temperature (PST) and Prescribed Heat Flux (PHF), are taken into account. Governing dimensional partial differential equations (PDEs) are transformed into non-dimensional ordinary differential equations (ODEs) using similarity transformations. Closed-form analytical solutions for flow are derived, considering stretching velocity, MFD viscosity, second-grade fluid properties, and suction impacts. Heat transfer equations are transformed into Gauss-hypergeometric form, yielding solutions in terms of confluent hypergeometric functions. Analytical expressions for skin friction, local Nusselt number, and non-dimensional wall temperature are derived. A unique solution is obtained for the flow equation. It is found that both second-grade and magnetic viscosity parameters expand the momentum boundary layer while the magnetic parameter reduces thickness. Thermal boundary layer thickness increases with a higher second-grade parameter, magnetic viscosity, and Eckert number. Moreover, analytical solutions are validated against published results for a special case.
Approximate bound state solutions of the Dunkl-Schrödinger equation for a hyperbolic double-well interaction
Authors: Schulze-Halberg Axel
Published: May 2024

We construct approximate solutions to the stationary, one-dimensional Schrödinger equation for a hyperbolic double-well potential within the Dunkl formalism. Our approximation is applied to an inverse quadratic term contributed by the Dunkl formalism in the effective potential. The solutions we obtain are given in terms of confluent Heun functions. We establish parity of these solutions, discuss their elementary cases, and present an example of a system admitting bound states.
A new application of the reproducing kernel method for solving linear systems of fractional order Volterra integro-differential equations
Authors: Amoozad Taher , Abbasbandy Saeid , Sahihi Hussein , Allahviranloo Tofigh
Published: May 2024

In this article, a new implementation of the reproducing kernel method is presented for solving systems of fractional-order Volterra integro-differential equations. Unlike previous implementations, this method does not rely on the Gram-Schmidt process. The reproducing kernel method utilizes various components, including space, inner product, bases, and points. Furthermore, the system of fractional-order Volterra integro-differential equations involves Caputo’s fractional derivative and Volterra integral. However, when using the reproducing kernel method to solve these systems, challenges such as longer execution time and lower accuracy may arise compared to other methods. The present method has overcome these challenges with features such as easy implementation, high accuracy, and lower execution time.
Control of the chaotic dynamics of the RCLSJ model of the Josephson junction by the frequency of an excitation current and the internal resistance of a coil
Authors: Kakpo M A , Miwadinou C H
Published: May 2024

In this paper, we controlled the chaotic dynamics of the RCLSJ model of the Josephson junction by the frequency of an excitation current and the internal resistance of an coil. We have used an alternating current source and the internal resistance of the coil of the inductive circuit is considered. The assembly is coupled to a shunted inductive junction (RCLSJ) model where the non-harmonic dynamics of the model is taken into account. The fixed points of the system are determined and are analyzed from the differential equations which govern its dynamics. The numerical results showed that the model studied can be used in direct and alternating conditions depending on the value of the frequency of the excitation current and the phase difference of the junction. In continuous mode, the model exhibits chaotic behavior at the beginning and is regular thereafter. This initial chaotic behavior has become regular due to the internal resistance of the coil. In the alternative regime, the model presents more complex dynamic behaviors. The system behaves like a current adapter depending on the frequency and phase difference conditions of the junction. Comprehensive study of the system reveals many new forks and pathways leading to chaos that have been verified using hardware experiments in addition to numerical calculations.
Super-resolution Imaging of Telescopic Systems based on Optical-neural Network Joint Optimization
Authors: Sun You-Hong , Zhang Tao , Shi Hao-Dong , Fu Qiang , Liu Jia-Nan , Wang Kai-Kai , Wang Chao
Published: May 2024

Optical telescopes are an important tool for acquiring optical information about distant objects, and resolution is an important indicator that measures the ability to observe object details. However, due to the effects of system aberration, atmospheric seeing, and other factors, the observed image of ground-based telescopes is often degraded, resulting in reduced resolution. This paper proposes an optical-neural network joint optimization method to improve the resolution of the observed image by co-optimizing the point-spread function (PSF) of the telescopic system and the image super-resolution (SR) network. To improve the speed of image reconstruction, we designed a generative adversarial net (LCR-GAN) with light parameters, which is much faster than the latest unsupervised networks. To reconstruct the PSF trained by the network in the optical path, a phase mask is introduced. It improves the image reconstruction effect of LCR-GAN by reconstructing the PSF that best matches the network. The results of simulation and verification experiments show that compared with the pure deep learning method, the SR image reconstructed by this method is rich in detail and it is easier to distinguish stars or stripes.
Supernova 1987A’s Keyhole: A Long-lived Jet-pair in the Final Explosion Phase of Core-collapse Supernovae
Authors: Soker Noam
Published: May 2024

I further study the manner by which a pair of opposite jets shape the “keyhole” morphological structure of the core-collapse supernova (CCSN) SN 1997A, now the CCSN remnant (CCSNR) 1987A. By doing so, I strengthen the claim that the jittering-jet explosion mechanism accounts for most, likely all, CCSNe. The “keyhole” structure comprises a northern low-intensity zone closed with a bright rim on its front and an elongated low-intensity nozzle in the south. This rim-nozzle asymmetry is observed in some cooling flow clusters and planetary nebulae that are observed to be shaped by jets. I build a toy model that uses the planar jittering jets pattern, where consecutive pairs of jets tend to jitter in a common plane, implying that the accreted gas onto the newly born neutron star at the late explosion phase flows perpendicular to that plane. This allows for a long-lived jet-launching episode. This long-lasting jet-launching episode launches more mass into the jets that can inflate larger pairs of ears or bubbles, forming the main jets’ axis of the CCSNR that is not necessarily related to a possible pre-collapse core rotation. I discuss the relation of the main jets’ axis to the neutron star’s natal kick velocity.
Spectral Fittings of Warm Coronal Radiation with High Seed Photon Temperature: Apparent Low-temperature and Flat Soft Excess in AGNs
Authors: Tang Ze-Yuan , Feng Jun-Jie , Fan Jun-Hui
Published: May 2024

A warm corona has been widely proposed to explain the soft excess (SE) in X-ray above the 2–10 keV power law extrapolation in Active Galactic Nuclei (AGNs). In actual spectral fittings, the warm coronal seed photon temperature (T
s) is usually assumed to be far away from the soft X-ray, but kT
s can reach close to 0.1 keV in the standard accretion disk model. In this study, we used Monte Carlo simulations to obtain radiation spectra from a slab-like warm corona and fitted the spectra using the spherical-geometry-based routine thcomp or a thermal component. Our findings reveal that high T
s can influence the fitting results. A moderately high kT
s (around 0.03 keV) can result in an apparent low-temperature and flat SE, while an extremely high kT
s (around 0.07 keV) can even produce an unobserved blackbody-like SE. Our conclusions indicate that, for spectral fittings of the warm coronal radiation (SE in AGNs), kT
s should be treated as a free parameter with an upper limit, and an accurate coronal geometry is necessary when kT
s > 0.01 keV.
Recent advances in two-dimensional photovoltaic devices
Authors: Wang Haoyun , Song Xingyu , Li Zexin , Li Dongyan , Xu Xiang , Chen Yunxin , Liu Pengbin , Zhou Xing , Zhai Tianyou
Published: May 2024

Two-dimensional (2D) materials have attracted tremendous interest in view of the outstanding optoelectronic properties, showing new possibilities for future photovoltaic devices toward high performance, high specific power and flexibility. In recent years, substantial works have focused on 2D photovoltaic devices, and great progress has been achieved. Here, we present the review of recent advances in 2D photovoltaic devices, focusing on 2D-material-based Schottky junctions, homojunctions, 2D−2D heterojunctions, 2D−3D heterojunctions, and bulk photovoltaic effect devices. Furthermore, advanced strategies for improving the photovoltaic performances are demonstrated in detail. Finally, conclusions and outlooks are delivered, providing a guideline for the further development of 2D photovoltaic devices.
A multichannel thermal bubble-actuated impedance flow cytometer with on-chip TIA based on CMOS-MEMS
Authors: Cai Shengxun , Nie Jianqing , Wang Kun , Guan Yimin , Liu Demeng
Published: May 2024

Electrochemical impedance spectroscopy (EIS) flow cytometry offers the advantages of speed, affordability, and portability in cell analysis and cytometry applications. However, the integration challenges of microfluidic and EIS read-out circuits hinder the downsizing of cytometry devices. To address this, we developed a thermal-bubble-driven impedance flow cytometric application-specific integrated circuit (ASIC). The thermal-bubble micropump avoids external piping and equipment, enabling high-throughput designs. With a total of 36 cell counting channels, each measuring 884 × 220 μm2, the chip significantly enhances the throughput of flow cytometers. Each cell counting channel incorporates a differential trans-impedance amplifier (TIA) to amplify weak biosensing signals. By eliminating the parasitic parameters created at the complementary metal-oxide-semiconductor transistor (CMOS)-micro-electromechanical systems (MEMS) interface, the counting accuracy can be increased. The on-chip TIA can adjust feedback resistance from 5 to 60 kΩ to accommodate solutions with different impedances. The chip effectively classifies particles of varying sizes, demonstrated by the average peak voltages of 0.0529 and 0.4510 mV for 7 and 14 μm polystyrene beads, respectively. Moreover, the counting accuracies of the chip for polystyrene beads and MSTO-211H cells are both greater than 97.6%. The chip exhibits potential for impedance flow cytometer at low cost, high-throughput, and miniaturization for the application of point-of-care diagnostics.
A novel small-signal equivalent circuit model for GaN HEMTs incorporating a dual-field-plate
Authors: Wang Jinye , Liu Jun , Zhao Zhenxin
Published: May 2024

An accurate and novel small-signal equivalent circuit model for GaN high-electron-mobility transistors (HEMTs) is proposed, which considers a dual-field-plate (FP) made up of a gate-FP and a source-FP. The equivalent circuit of the overall model is composed of parasitic elements, intrinsic transistors, gate-FP, and source-FP networks. The equivalent circuit of the gate-FP is identical to that of the intrinsic transistor. In order to simplify the complexity of the model, a series combination of a resistor and a capacitor is employed to represent the source-FP. The analytical extraction procedure of the model parameters is presented based on the proposed equivalent circuit. The verification is carried out on a 4 × 250 μm GaN HEMT device with a gate-FP and a source-FP in a 0.45 μm technology. Compared with the classic model, the proposed novel small-signal model shows closer agreement with measured S-parameters in the range of 1.0 to 18.0 GHz.
The study of lithographic variation in resistive random access memory
Authors: Zhang Yuhang , He Guanghui , Zhang Feng , Li Yongfu , Wang Guoxing
Published: May 2024

Reducing the process variation is a significant concern for resistive random access memory (RRAM). Due to its ultra-high integration density, RRAM arrays are prone to lithographic variation during the lithography process, introducing electrical variation among different RRAM devices. In this work, an optical physical verification methodology for the RRAM array is developed, and the effects of different layout parameters on important electrical characteristics are systematically investigated. The results indicate that the RRAM devices can be categorized into three clusters according to their locations and lithography environments. The read resistance is more sensitive to the locations in the array (~30%) than SET/RESET voltage (<10%). The increase in the RRAM device length and the application of the optical proximity correction technique can help to reduce the variation to less than 10%, whereas it reduces RRAM read resistance by 4×, resulting in a higher power and area consumption. As such, we provide design guidelines to minimize the electrical variation of RRAM arrays due to the lithography process.
Proof-of-principle of parametric stellarator neutronics modeling using Serpent2
Authors: Lyytinen T. , Snicker A. , Virtanen J. , Palermo I. , Alguacil J. , Bogaarts Timo , Warmer F.
Published: May 2024

This contribution presents neutron transport studies for the 5-period helical-axis advanced stellarator stellarator using the Serpent2 code. These studies utilize a parametric geometry model, enabling scans in neutronics modeling by varying the thickness of the reactor layers. For example, the tritium breeding ratio (TBR) can be determined by exploring various blanket material options and thicknesses to identify the threshold configuration that meets the TBR design criterion of 1.15. We found out that with the helium-cooled pebble ped candidate option, the TBR criterion is met with a breeding zone thickness of 26 cm, while with the dual-coolant lithium lead the threshold is exceeded at a thickness of 46 cm. Furthermore, the geometry includes non-planar field coils, allowing to study the fast neutron flux in these superconducting coils with a technological limit of

1
×

10

9

1

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cm

2

s

. It is shown that the neutron fast flux is not constant at the coils, necessitating a neutron transport simulation to determine the distribution of the fast-flux at the coils. We show that the peak fast flux can be more than a factor of 2 higher than the average flux, and that the peak flux location rotates helically.
A decision fusion-based method for global sensitivity analysis of complicated experiments
Authors: Jiaxin Hu , Weiwei Liu , Weiwei Cai , Yanwei Zhu , Huan Huang
Published: May 2024

In real world, the relationship between experimental input and output has become more and more complex, which brings great challenges to the sensitivity analysis. This paper proposes a decision fusion based global sensitivity analysis method for complicated experiments, which not only provides quantitative evluation of the input factor influence on experimental results, but also mines the correlation and form the explicit criteria in IF-THEN fomation for further guidance. The theory of decision information system and continuous attribute discretization is presented first for transforming the experimental input and output into a decision table. In order to calculate the sensitivity of the factors and extract valid correlation criterions between conditional attributes and decision attributes simultaneously, the discrimination matrx is utilized for attribute reduction. Then a sensitivity analysis method based on decision fusion is proposed by organically assembling experiment design, attribute discretization, the discrimization matrix, and attribute reduction. Finally, the effectiveness and practicality of the proposed method were verified by the application of sensitivity analysis in hypersonic vehicle re-entry trajectory experiment.
Study on trajectory optimization of satellite rapid orbit formation flying for space object
Authors: He J Y , Chen D H , Liu X C
Published: May 2024

This paper proposes a method of collaborative trajectory planning that utilizes convex optimization and IFPSO to tackle the issue of rapid formation reconstruction by multiple satellites in a low Earth circular orbit. The trajectory optimisation in this study uses convex optimisation and takes into account thrust limitations and safety distance. The time optimal solution is replaced by the path optimal solution, resulting in a suboptimal solution. The time-suboptimal trajectory solving method for formation flying using the CVX software is designed. The IFPSO is used to allocate configurations and waypoints for formation reconstruction, with the aim of balancing fuel consumption across the fleet and reducing the overall fuel consumption of the satellite. The effectiveness of the proposed approach is confirmed by numerical simulation. Despite sacrificing some computational efficiency, the method offered can solve the issues of configuration allocation and trajectory optimization.
Effects of high-temperature and entropy layer of Mach 12 oblique shock wave
Authors: Dai Chunliang , Sun Bo , Man Yanjin , Zhou Changsheng
Published: May 2024

In the current study, we numerically investigate the high-temperature inviscid flows over the 15-degree wedges with the sharp and blunt leading-edges. Firstly, the vibrational non-equilibrium effects in sharp wedge flow with different deflection angles are analyzed. Then, the influence of the vibrational non-equilibrium effects on the flow parameters behind the oblique shock wave is provided. Lastly, we discuss the high-temperature non-equilibrium flow over the 15-degree wedge with the entropy layer.
Analysis of the shimmy in the landing gear of a general-purpose helicopter for different payloads
Authors: Akkaya B , Bal H
Published: May 2024

Landing gears, which are designed to absorb impact energy in order to provide support to the aircraft during landing, take-off and ground operations, are important components of the structure. Shimmy, which is one of the causes of aircraft failures, is a vibration that occurs as a result of the interaction of tire and landing gear dynamics and can cause an accident. In this study, the shimmy behavior of a helicopter used for civil, military and air ambulance purposes are investigated at different load and taxiing velocities. A landing gear single degree of freedom mathematical model is obtained and a Von Schlippe stressed spring tire model is included. The eigenvalues of the equations of motion are analyzed and stability maps of the system for different operating conditions are obtained. Runge-Kutta method (MATLAB ode45) is used to solve the equations of motion and a viscous damper is proposed. To obtain the damping, versions of the non-Newtonian silicone oil in the damper with different kinematic viscosities were evaluated. Apparent viscosities were obtained using the rheological values of the silicone oil and the analysis was repeated. As a result of the shimmy analysis at the initial velocities and maximum loading values required for the helicopter to taxiing, it was seen that damping was achieved in all conditions by using versions of the silicone oil with higher kinematic viscosities.
Effect of different particle sizes on combustion characteristics of DCR engines
Authors: Zhao Dongsheng , Wei Zhijun , He Duanyang , Dalin Li , Chujiu Huang
Published: May 2024

The ramjet engine has undergone rapid development in recent decades, and the dual combustion chamber ramjet (DCR) engine was proposed in the last century. Boron, with its high volumetric and gravimetric heating values, is one of the most attractive fuel additives for ramjet engines. However, due to the problem of low combustion efficiency, boron is difficult to achieve high efficiency combustion in practical applications. In order to investigate the combustion characteristics of boron-containing gas solid phase components in DCR engines, the Realizable k-ε model, finite rate/vortex dissipation model and boron particle King model ignition combustion calculation program were written. A three-dimensional full-scale two-phase flow numerical simulation was carried out in the combustion chamber of the DCR engine to calculate the effects of different particle sizes on the combustion characteristics. Through the analysis of the simulation results, the particle size affects the ignition time of boron particles and is positively correlated with the combustion efficiency, but with a non-linear growth. A smaller particle size can promote the ignition of boron particles, improve the solid phase combustion efficiency and achieve efficient combustion.
Design of ignition control system for failed spacecraft array solid thruster
Authors: Liao Tenghui , Deng Hanyu , Tang Yuqing , Pu Yantao , Cao Ping
Published: May 2024

The life of micro-nano spacecraft is generally short. In order to solve the problem of space debris endangering space safety after its failure and make it deorbit quickly, this paper has carried out the hardware system design and software system design of the ignition control system of the failed spacecraft attitude adjustment solid thruster. In order to facilitate the realization of high integration, the hardware system adopts the array arrangement circuit and selects the MOSFET as the driving switch. The software system receives the ignition command from the spacecraft platform and enables the row and column control terminals of the ignition circuit to achieve addressing ignition. The results show that the control module can correctly receive the instructions from the spacecraft platform and make the correct ignition action, successfully complete the attitude adjustment task, and improve the reliability of the deorbiting of the failed spacecraft.
EHFE refinement and extension for variable physical Earth radiation in spacecraft uncertainty thermal analysis
Authors: Fu X , Liang L , Ma W , Cui H , Zhao Y
Published: May 2024

Spacecraft uncertainty thermal analysis is an important part of ensuring robust and reliable spacecraft thermal control system design. The calculation of the Earth external heat flux is an important part of it, however, the current model for calculating the Earth external heat flux is the constant physical Earth radiation model. In this paper, a model of the Earth’s variable physical radiation is developed based on the long-term averaging method. We refine and extend the application of the external heat flux expansion (EHFE) formula to accommodate our proposed model. This study further includes an uncertainty analysis of Earth radiative external heat flux, utilizing the enhanced EHFE formula in the context of a representative spacecraft. We provide statistical data, such as mean values, standard deviation, and probability density functions, derived from our analysis. The augmented EHFE formula, when properly generalized, can be applied to compute the celestial body’s variable physical radiative external heat flux affecting the spacecraft. This methodological advancement offers theoretical underpinning for the thermal design of spacecraft intended for deep space exploration.