bluuebunny/crossref_metadata_2025 huggingface dataset:
Progress of anion redox in Na-rich layered transition metal oxides (Na2MO3) as cathode materials for sodium-ion batteries
Authors: Yin Junjun , Huang Shuping
Published: December 2024

Under the background of surging global demand for batteries and scarcity of Li resources, sodium-ion batteries (SIBs) are attracting attention as a potential alternative with their unique advantages, and the layered transition metal (TM) oxides therein are considered to be one of the most promising cathode materials. In this paper, firstly, the diversity of cathode materials for SIBs is systematically introduced, as well as the layered oxide structures among them are categorized, and then it focuses on the O3-type sodium-rich Na2MO3, which is promising for large-scale commercial applications, illustrating the development and mechanism of anion redox. Excess Na transforms the TM layer into the mixed Na1/3M2/3O2 layer, leading to the formation of localized configuration Na–O–Na. Thereby, isolated nonhybridized O 2p states are introduced, which participate in the charge compensation process (O2−/O
n

−) under high-voltage conditions and provide the battery with additional capacity beyond the cation redox reaction. Therefore, the Na2MO3 formed by its TM element located in different periods are classified, discussed and summarized in terms of structural change characteristics, electrochemical properties and anion-redox mechanism. However, this particular redox mechanism is also accompanied by the challenges such as voltage hysteresis, irreversible oxygen loss, TM migration, capacity decay and poor air stability. Therefore, to address these challenges, various improvement strategies have been proposed, including doping of large radius metal ions, light metal ions, TM ions with high covalency with O, nonmetal ions, formation of mixed phases, and surface modification. This work is expected to provide new ways to find and design novel high-capacity Na-rich layered oxide cathode materials.
Comprehensive evaluation of lens and planar circular ultrasonic transducer combinations to enhance C-scan imaging: a phantom study at 10 and 15 MHz
Authors: Elmina Bernadette Carolina Fritzie , Baik Kyungmin , Yusof Nurhalawa Md , Samiudin Nafra M , Doh Il , Kim Yong Tae
Published: December 2024

Objective. To evaluate the imaging capabilities of four polydimethylsiloxane-based acoustic lenses with subsonic refractive indices, focusing on a spherical lens and three designed aspherical lenses with varying focus. Approach. We investigated a spherical lens with a radius curvature of 8 mm (SL-R8), two aspherical lenses with focal lengths of 15 mm and 10 mm (AL15 and AL10), and an aspherical folding lens with a focal length of 10 mm (AFL10). The equation cross-section profile of an aspherical lens is calculated using the assumption that all trajectories passing through the lens have the same flight duration when they reach the focal point. Furthermore, we observed that we can fold this aspherical lens without greatly diminishing its focusing capability. Utilizing circular planar ultrasonic transducers at frequencies of 10 MHz and 15 MHz, we examined the reflected waveforms via pulse-echo tests and measured focal points and beam widths using a needle hydrophone in the acoustic intensity measurement system. The target resolution was assessed using a C-Scan imaging system. Main results. Analysis of the axial and lateral beam profiles revealed that AFL10 and AL10 lenses exhibited narrower beam widths at the focal point. We evaluate the AFL10 and AL10 lenses combined with a 15 MHz transducer for preclinical testing using standard medical phantoms containing microparticles in gelatin- and agar-based matrices. In conclusion, using these twocombinations, C-Scan imaging successfully formed a 25 µm backscatter inside the phantom image. Significance. Due to their high-resolution capabilities, applying cross-sectional profile equations in the lateral plane of the lens surface in linear ultrasonic array probes offers promises for early-stage medical diagnostics.
Groundwater flow velocity and direction measurement sensor based on an equivalent pendulum model and visual measurement
Authors: Tang Zheng , Chen Qili , Li Zhuorun , Wang Kunsheng , Qiu Pengcheng , Li Bo
Published: December 2024

Groundwater plays a pivotal role in the formation and evolution of landslide disasters. To efficiently and environmentally acquire information about groundwater flow velocity and direction, a novel method is proposed that integrates the equivalent pendulum model with visual measurement technology. This method is based on the principle that a tethered buoyant sphere will experience drag and deviate from its initial position until a state of equilibrium is reached when the viscous fluid flows around the sphere. To measure the offset and the angular deviation of the buoyant sphere, a visual technique is employed. Research findings demonstrate a positive correlation between the buoyant sphere’s offset and groundwater flow velocity. Measuring the angular deviation of the buoyant sphere determines the current heading. This approach exhibited significant accuracy during experimentation, with the sensor displaying a precision of 5.6% in measuring flow velocity within the range of 0–0.2 mm s−1, and ±4.31° in measuring flow direction. Compared to conventional methods, this technique allows for the convenient acquisition of groundwater flow velocity and direction data without the need for auxiliary tracing agents. Furthermore, its measurements remain unaffected by factors such as water quality, temperature, pressure, and salinity within hydrogeological boreholes, or environmental conditions, fulfilling the requirement for real-time monitoring of minimal flow rates and directions in landslide groundwater, rivers, and lakes.
A novel large-kernel residual grasp network for robot grasp detection
Authors: Jiang Yanshu , Fang Yanze , Deng Liwei
Published: December 2024

Efficient and accurate grasping remains a significant challenge due to the diverse object shapes, sizes, and poses encountered in practical scenarios. Previous grasp detection methods were limited regarding receptive fields. They have demonstrated insufficient capability in extracting relevant grasp features and have not effectively leveraged multi-scale features, resulting in limited detection accuracy. This paper introduces the large-kernel residual grasp network (LKRG-Net), a novel network designed to address these challenges by integrating advanced feature extraction and fusion techniques. Firstly, the proposed model utilizes a dual-encoding UniRepLKNet-ResNet50 backbone encoding grasp features at global and local levels, ensuring comprehensive extraction of relevant characteristics. Secondly, a grasp fusion splicing module effectively splices and merges the dual-encoded feature loss of crucial information. Finally, a selective fusion feature pyramid network decoding multi-scale feature information enhances the utilization of shallow features while altering the information. Comprehensive testing on the Cornell Jacquard and Jacquard_V2 datasets shows that LKRG-Net surpasses existing advanced methods in accuracy and robustness. Grasping detection experiments conducted in real object scenarios further confirm the model’s effectiveness in dynamic environments, providing a solid foundation for future advancements in robotic grasping tasks. The code can be obtained at the following address. https://github.com/Fyzyukk/LKRG-Net.
Coupled oscillations of a double pendulum
Authors: Cross Rod
Published: December 2024

Coupled oscillations are observed when two parallel pendulums are joined by a light spring and can also be be observed if the two pendulums are joined in series as a double pendulum. Experimental results with a double pendulum are presented, showing a strong beating effect when the upper mass is much larger than the lower mass.
Spectral characterization and comparison of EBT3, EBT4, and EBT-XD radiochromic films
Authors: Pecić S , Dević S , Belča I , Mošić M , Kurij Lj , Nidžović B , Stojadinović S
Published: December 2024

This study analyzed the spectral response of EBT3, EBT4, and EBT-XD radiochromic films using absorption spectroscopy. The primary focus was on characterizing the evolution of spectral signatures across a range of absorbed doses, thereby elucidating the unique dose-dependent response profiles of each film type. Ten samples of each film type were subjected to open field irradiation within their designated dose ranges (1–20 Gy for EBT3 and EBT4, 1–50 Gy for EBT-XD). The corresponding absorption spectra were recorded and studied via decomposition and parameterization of dose-dependent spectral features. Lorentzian profiles were employed for spectral decomposition. Each film type displayed unique spectral signatures with distinct absorption peaks: nine for EBT3, eleven for EBT4, and twelve constituent profiles for EBT-XD. Notably, the EBT4 film demonstrated a slight difference in the blue part of the absorption spectrum and a change in the response, relative to its EBT3 predecessor. Orientation dependence of the film spectra was most pronounced for the EBT3 film type, followed by a declining trend across EBT4 and EBT-XD films. Absorption spectroscopy portrayed distinct spectral fingerprints of the studied film types, aiding the selection of the most suitable film for specific applications.
Numerical study of breakdown voltage calculation and discharge characteristics of millimeter-level short air gap with a single water droplet
Authors: Liu Quan , Yang Lin , Hao Yanpeng , Li Licheng , Ding Jiabao , Hu Xingkun
Published: December 2024

Water droplets in the short air gap significantly affect the breakdown voltage. Currently, there is a lack of computational studies on the breakdown voltage and discharge process of short air gaps containing water droplets. In this paper, we establish a plasma dynamics-based model for the discharge in a millimeter-scale short air gap containing a single water droplet under ambient pressure and propose a breakdown voltage calculation method. We discuss typical discharge processes, calculate breakdown voltages for different gap lengths, validate the model through discharge phenomena and breakdown voltage, and analyze the impact of droplet parameters on discharge characteristics. The results show that negative streamer discharge in the cathode-side gap and positive streamer discharge in the anode-side gap occur sequentially, consistent with reported experimental results, with the positive streamer discharge being the primary process leading to gap breakdown. The average error rate between the calculated breakdown voltages for 4–8 mm gaps and reported experimental results is 4.85%, indicating good agreement. The observed streamer branching phenomenon may explain the difference between calculated and experimental breakdown voltages for the 10 mm gap. Under the influence of surface charges, low-conductivity droplets cause the discharge channel to propagate along the droplet surface. In contrast, high-conductivity droplets confine the discharge channel within the two gap sections. Increasing droplet diameter reduces breakdown voltage, with a critical value where the reduction becomes significant. Increased droplet deformation degree raises the breakdown voltage. This effect is related to the deviation of the positive streamer from the axial development and the reverse streamer generated on the droplet’s surface in different cases. The closer the droplet is to the electrode, the higher the breakdown voltage. The discharge is facilitated by the streamers generated on the droplet’s lower surface when it is close to the anode.
The role of volume recombination and resonance radiation transport in constriction of a: DC discharge in argon
Authors: Siasko A V , Pavlov S I , Karasev V Yu , Golubovskii Yu B
Published: December 2024

The work is aimed at revealing the influence of volume recombination on the formation of plasma parameters on the example of a diffuse and constricted positive column of a DC discharge in argon depending on the discharge current at pressures of 100–300 Torr·cm. At a qualitative level, the limiting transitions from the diffusion mode to the recombination mode of discharge maintenance are analyzed, which lead either to a rectangle-shaped radial profile of charged particles (arc discharge) or to a compressed profile (constricted discharge). Valuable information about the processes occurring in the plasma volume can be obtained from the ion current flowing toward the wall of the discharge tube since it is determined as a difference between the volume ionization and recombination. Based on a collision-radiative model, the ion current towards the tube wall was calculated and compared with the experimental results of probe measurements. In a diffuse discharge (low discharge current) a satisfactory agreement between the theory and experiment is observed. After the abrupt transition to the constricted regime (high discharge current), the theoretical values become strongly underestimated, and not able to describe the experimental data. The reasons for these discrepancies are analyzed. It is shown that the photoemission from the surface of the probe under the action of resonance photons gives an additional ion probe current which allows eliminating the discrepancies between the theory and experiment. Based on the Holstein–Biberman equation, the influence of the resonance radiation trapping on the discharge properties is revealed. The account of radiation trapping improves the agreement between the theory and experiment, including the values of the critical discharge currents at which the constriction occurs.
Acoustic waves in a halfspace material filled with random particulate
Authors: Piva Paulo S , Napal Kevish K , Gower Art L
Published: December 2024

Particulate materials include powders, emulsions, composites, and many others. This is why measuring these has become important for both industry and scientific applications. For industrial applications, the greatest need is to measure dense particulates, in-situ, and non-destructively. In theory, this could be achieved with acoustics: the standard method is to send an acoustic wave through the particulate and then attempt to measure the effective wave speed and attenuation. A major obstacle here is that it is not clear how to relate the effective wave speed and attenuation to the reflection and transmission coefficients, which are far easier to measure. This is because it has been very difficult to mathematically account for different background mediums. In this paper, we resolve this obstacle. To help comprehension, we present how to account for different background mediums for a simple case: a halfspace filled with a random particulate, where the background of the halfspace is different from the exterior medium. The key to solving this problem was to derive a systematic extension of a widely used closure approximation: the quasi-crystalline approximation. We present some numerical results to demonstrate that the reflection coefficient can be easily calculated for a broad range of frequencies and particle properties.
Synthesis and characterization of undoped and Co-Doped Bismuth Ferrite nanoparticles for photovoltaic applications
Authors: Zemene Samrawit , Yohannes Yonas Beyene , Wubetu Getasew Admasu
Published: December 2024

In this paper, we reported the structural, vibrational, and optical absorption properties of chemically synthesized multiferroic bismuth iron oxide (BiFeO3) (BFO) and cobalt-doped bismuth iron oxide (BFCO) nanoparticles. The nanoparticles were synthesized via sol–gel methods and annealed at 450 °C for a duration of two hours. Characterization was conducted through techniques such as UV–Vis spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), and Scanning Electron Microscope (SEM). XRD analysis revealed average crystallite sizes of 19.1 nm and 20.8 nm for BFO and BFCO, respectively, with no secondary phase observed in the cobalt-doped BFO nanoparticles. Structural analysis via XRD indicated a transformation from rhombohedral to orthorhombic symmetry in the doped BFO nanoparticles. The optical band gap energies were determined to be 2.43 eV for BFO and 2.33 eV for BFCO. The reduction in the band gap in BFCO may be help for relevant for the photovoltaic application. FTIR spectroscopy identified characteristic peaks, including the O–H single bond at 3417 cm−1 and vibrations corresponding to metal–oxygen/Fe–O, Bi–O stretching, and O–Fe–O bending vibrations in BFO and BFCO within the spectral range of 400–1000 cm−1. The morphology and crystallinity of these materials were assed using a SEM, revealing a progressively complex arrangement of flower structures in both BFO and BFCO.
Diffraction managed modulation instability of two-dimensional plane wave in competing cubic-quintic nonlinear media
Authors: Jiang Yumin , Ge Lijuan , Shen Ming
Published: December 2024

Modulation instability of two-dimensional plane wave is investigated in competing cubic-quintic nonlinear media with fourth order diffraction (FOD). Growth rate of modulation instability are obtained analytically with linear-stability analysis. Besides main band, another side band of instability spectra appears in some regions of anomalous FOD. Normal FOD promote, while anomalous FOD and competing self-defocusing quintic nonlinearity always suppress modulation instability. Analytical results are also verified numerically by employing split-step Fourier transform method.
Analyzing Stability and Dynamics of an Epidemic Model with Allee’s Effect and Mass Action Incidence Rates Incorporating Treatment Stategies.
Authors: Qurban Muhammad , Khaliq Abdul , saqib Muhammad
Published: December 2024

This paper focuses on transforming a continuous SIR epidemic model into its discretecounterpart using a non-standard finite difference scheme, motivated by the rich dynamic behaviors often exhibited by discrete models. The study investigates the impact of Allee’s Effecton disease progression by analyzing the existence of equilibrium points and determining theirstability and bifurcation conditions. Augmenting the model with these factors significantlyenhances our capacity to predict the course of the epidemic. Similarly, assessing the impactof treatment on epidemic diseases is pivotal for disease control. A thorough understanding offactors influencing disease dynamics, including Allee’s Effect, is crucial for effective modelingand prediction of epidemic progression. The transmission rate of the disease fluctuates basedon individual isolation or treatment rates, and incorporating Allee’s Effect adds an extra layerof complexity to this dynamic. Analyzing mathematical models based on these and similarfactors, including Allee’s Effect, allows us to glean insights into the disease’s trajectory. Thisresearch investigates epidemic disease models that integrate mass action involving treatment,while also considering the influence of Allee’s Effect. In our investigation, we explore theexistence of equilibrium points and establish the stability and bifurcation conditions of thesepoints in the context of Allee’s Effect. We complement our analysis with numerical examples.To compare the behavior of the epidemic disease models under consideration, including thoseaccounting for Allee’s Effect, we present graphs illustrating the dynamic behaviors of ourpopulations.
Dynamics of the novel multi-cavity hyperchaotic map and its DSP implementation
Authors: Zhang Zeping , Sun Kehui , Zhu Wanting , Wang Huihai
Published: December 2024

Based on the mathematical model of the Bernoulli lemniscate, we design a novel hyperchaotic map with a dual-cavity attractor. Through dynamical analyses, the results indicate that the proposed map is hyperchaos and has wide parameter range, large Lyapunov Exponents (LEs), and high Permutation Entropy (PE) complexity. In addition, two types of multi-cavity hyperchaotic maps are constructed by employing the fractal transformation and rotation transformation, respectively. The multi-cavity hyperchaotic maps have complex topological structures. The hyperchaotic maps are implemented on the digital signal processor (DSP) platform for practical application.
Exploring the discrepancy between Planck PR3 and ACT DR4
Authors: Hazra Dhiraj Kumar , Beringue Benjamin , Errard Josquin , Shafieloo Arman , Smoot George F.
Published: December 2024

We explore the scales and the extent of disagreement between Planck PR3 and Atacama
Cosmology Telescope (ACT) DR4 data. Planck and ACT data have substantial overlap in the
temperature anisotropy data between scales corresponding to multipoles ℓ ≃ 600–2500
with complementing coverage of larger angular scales by Planck and smaller angular scales by
ACT. Since the same cosmology should govern the anisotropy spectrum at all scales, we probe this
disagreement in the primordial power spectrum. We use a parametric form of power law primordial
spectrum that allows changes in the spectral tilt. We also reconstruct the primordial spectrum
with a non-parametric method from both Planck and ACT temperature data. We find the
disagreement exists within scales 0.08–0.16 Mpc-1 where ACT temperature data prefers
a scale invariant/blue spectrum. At scales larger and smaller than this window, ACT data strongly
prefers a red tilt, which is consistent with Planck. This change in the spectral tilt can be
identified in the ACT data at 2σ C.L. without using Planck data, indicating that the
tension is driven by different preferences for tilts within the ACT data. The addition of Planck data up to intermediate scales (ℓ ≤ 650) increases this significance to
3σ. Given the large overlap between Planck and ACT within 0.08–0.16 Mpc-1 and considering the internal consistency between different Planck temperature
and polarization spectra, the scope of new physics as a solution to the tension remains
limited. Our results — a strong preference for an intermediate transition in spectral tilt and
the variation of this preference in different data combinations — indicate that systematic
effects can be misperceived as new physics emerging from different non-standard cosmological
processes.
Gravitational waves from primordial black hole isocurvature: the effect of non-Gaussianities
Authors: He Xin-Chen , Cai Yi-Fu , Ma Xiao-Han , Papanikolaou Theodoros , Saridakis Emmanuel N. , Sasaki Misao
Published: December 2024

Ultra-light primordial black holes (PBHs) with masses M
PBH < 5 × 108g
can dominate transiently the energy budget of the Universe and reheat the Universe through their
evaporation taking place before Big Bang Nucleosynthesis. The isocurvature energy density
fluctuations associated to the inhomogeneous distribution of a population of such PBHs can induce
an abundant production of GWs due to second-order gravitational effects. In this work, we discuss
the effect of primordial non-Gaussianity on the clustering properties of PBHs and study the effect
of a clustered PBH population on the spectral shape of the aforementioned induced GW signal. In
particular, focusing on local-type non-Gaussianity we find a double-peaked GW signal with the
amplitude of the low-frequency peak being proportional to the square of the non-Gaussian parameter
τ
NL. Remarkably, depending on the PBH mass M
PBH and the initial abundance
of PBHs at formation time, i.e. ΩPNH,f, this double-peaked GW signal can lie well
within the frequency bands of forthcoming GW detectors, namely LISA, ET, SKA and BBO, hence
rendering this signal falsifiable by GW experiments and promoting it as a novel portal probing the
primordial non-Gaussianity.
Gauge theory meets cosmology
Authors: Bianchi Massimo , Dibitetto Giuseppe , Morales Jose Francisco
Published: December 2024

We reconsider linear perturbations around general Friedmann-Lemaitre-Robertson-Walker
(FLRW) cosmological backgrounds. Exploiting gauge freedom involving only time reparametrizations,
we write down classical background solutions analytically, for an arbitrary number of fluid
components. We then show that the time evolution of scalar and tensor adiabatic perturbations are
governed by Schrödinger-like differential equations of generalized Heun type. After recovering
known analytic results for a single-component fluid, we discuss more general situations with two
and three different fluid components, with special attention to the combination of radiation,
matter and vacuum energy, which is supposed to describe the ΛCDM model. The evolution of
linear perturbations of a flat ΛCDM universe is described by a two-transient model, where
the transitions from radiation to matter and matter to vacuum energy are governed by a Heun
equation and a Hypergeometric equation, respectively. We discuss an analytic approach to the
study of the general case, involving generalized Heun equations, that makes use of (quantum)
Seiberg-Witten curves for 𝒩 = 2 supersymmetric gauge theories and has proven to be very
effective in the analysis of Black-Hole, fuzzball and ECO perturbations.
Real-time Collision Detection of Dual Rotating Arm Positioner for Multi-object Fiber-fed Spectrographs
Authors: Zhou 周 Ming 明 , Zhang 张 Yong 勇 , Li 栗 Jian 剑 , Lv 吕 Guanru 冠儒 , Zhou 周 Zengxiang 增祥 , Liu 刘 Zhigang 志刚 , Wang 王 Jianping 建平 , Wang 王 Yingfu 应富 , Zhou 周 Jiahao 家豪 , Bai 白 Zhongrui 仲瑞 , Li 李 Ganyu 甘雨 , Wang 汪 Mengxin 梦欣 , Wang 王 Shuqing 淑青 , Hu 胡 Hongzhuan 红专 , Zhai 翟 Chao 超 , Chu 褚 Jiaru 家如 , Dong 董 Yiqiao 义乔 , Yuan 袁 Hailong 海龙 , Zhao 赵 Yongheng 永恒 , Chu 褚 Yaoquan 耀泉 , Zhang 张 Haotong 昊彤
Published: December 2024

Multi-object fiber spectroscopic survey is pivotal to astronomical research. Most spectroscopic telescopes are equipped with thousands of robotic fiber positioners designed to observe multiple celestial objects simultaneously. Despite this advancement, the risk of potential collisions between adjacent positioners, due to overlapping work zones, poses a significant challenge that could limit the telescope’s observing efficiency. In this study, we present a method based on deep learning to detect the collision of dual rotating arm positioner using the front-illuminated image from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). We employ a deep learning detection model based on the YOLOv5 object detection algorithm to identify and locate the collision zones. Furthermore, the BiSeNet image segmentation algorithm is applied to determine the positioners within these collision zones, ultimately identifying the collided positioners. Experimental results reveal a precision and recall of 90.20% and 85.44% respectively for our method. To verify our results further, we conducted a correlation analysis on the spectral flux in LAMOST survey data via direct measurement. The collision types of the LAMOST positioners are also analyzed, which provides guidance for optimizing the anti-collision algorithm in the future.
Prospects of using novel nonlinear crystals in SU(1,1) interferometry
Authors: Sabanin Artem , Paterova Anna
Published: December 2024

Nonlinear interferometry presents a powerful approach for infrared metrology by enabling measurements with visible or near-infrared detectors. In this study, we evaluate the potential of novel nonlinear crystals for mid-infrared ‘fingerprint’ spectroscopy based on nonlinear interferometry, focusing on the transparency range, nonlinear coefficients, and phase-matching capabilities of nonlinear crystals. We compare established materials like silver thiogallate (AgGaS2) with promising alternatives, including mercury thiogallate (HgGa2S4), barium gallium germanium sulphide (BaGa2GeS6), and barium gallium germanium selenide (BaGa2GeSe6). The selected nonlinear crystals exhibit higher nonlinear conversion efficiency compared to AgGaS2, with BaGa2GeS6 additionally offering a narrower angular spectrum of spontaneous parametric down conversion, advantageous in interferometric schemes. Our findings establish a pathway for integrating advanced crystal technologies into mid-infrared metrology and imaging systems, setting the stage for future developments in nonlinear interferometry and spectroscopy.
Understanding thermal hysteresis of ferroelectric phase transitions in BaTiO3 with combined first-principle-based approach and phase-field model
Authors: Shao 邵 Cancan 灿灿 , Huang 黄 Houbing 厚兵
Published: December 2024

Based on the principles of thermodynamics, we elucidate the fundamental reasons behind the hysteresis of spontaneous polarization in ferroelectric materials during heating and cooling processes. By utilizing the effective Hamiltonian method in conjuction with the phase-field model, we have successfully reproduced the thermal hysteresis observed in ferroelectric materials during phase transitions. The computational results regarding the electrocaloric effect from these two different computational scales closely align with experimental measurements. Furthermore, we analyze how the first-order ferroelectric phase transition gradually diminishes with an increasing applied electric field, exhibiting characteristics of second-order-like phase transition. By employing the characteristic parameters of thermal hysteresis, we have established a pathway for calculations across different computational scales, thereby providing theoretical support for further investigations into the properties of ferroelectric materials through concurrent multiscale simulations.
Temporal variation characteristics of cathode temperature in a magnetoplasmadynamic thruster
Authors: Zhou 周 Cheng 成 , Wu 吴 Peng 鹏 , Song 宋 Yun-Tao 云涛 , Zheng 郑 Jin-Xing 金星 , Li 李 Yong 永 , Wang 王 Ge 戈 , Liu 刘 Hai-Yang 海洋
Published: December 2024

The magnetoplasmadynamic thruster (MPDT) is characterized by its high specific impulse and substantial thrust density, making it a promising propulsion system for deep space exploration missions. In both laboratory experiments and practical applications, cathode ablation has emerged as a critical concern. An optical diagnostic approach based on monochromatic radiation temperature measurement, utilizing plume emission spectra and the selection of an appropriate test band, has been successfully employed. This method provides an accurate temperature distribution across the cathode surface, offering a novel testing technique for the optimization and evaluation of magnetic plasma thruster designs.
Nondestructive detection of atom counts in laser-trapped 171Yb atoms
Authors: Tian 田 Congcong 聪聪 , Zhu 朱 Qiang 强 , Wang 王 Bing 兵 , Xiong 熊 Dezhi 德智 , Xiong 熊 Zhuanxian 转贤 , He 贺 Lingxiang 凌翔 , Lyu 吕 Baolong 宝龙
Published: December 2024

We present the experimental demonstration of nondestructive detection of 171Yb atoms in a magneto-optical trap (MOT) based on phase shift measurement induced by the atoms on a weak off-resonant laser beam. After loading a green MOT of 171Yb atoms, the phase shift is obtained with a two-color Mach–Zehnder interferometer by means of ±45 MHz detuning with respect to the 1S0–1P1 transition. We measured a phase shift of about 100 mrad corresponding to an atom count of around 5 × 105. This demonstrates that it is possible to obtain the number of atoms without direct destructive measurement compared with the absorption imaging method. This scheme could be an important approach towards a high-precision lattice clock for clock operation through suppression of the impact of the Dick effect.
TMS-evoked potential propagation reflects effective brain connectivity
Authors: Daly Ian , Williams Nitin , Nasuto Slawomir J
Published: December 2024

Objective. Cognition is achieved through communication between brain regions. Consequently, there is considerable interest in measuring effective connectivity. A promising effective connectivity metric is transcranial magnetic stimulation (TMS) evoked potentials (TEPs), an inflection in amplitude of the electroencephalogram recorded from one brain region as a result of TMS applied to another region. However, the TEP is confounded by multiple factors and there is a need for further investigation of the TEP as a measure of effective connectivity and to compare it to existing statistical measures of effective connectivity. Approach. To this end, we used a pre-existing experimental dataset to compare TEPs between a motor control task with and without visual feedback. We then used the results to compare our TEP-based measures of effective connectivity to established statistical measures of effective connectivity provided by multivariate auto-regressive modelling. Main results. Our results reveal significantly more negative TEPs when feedback is not presented from 40 ms to 100 ms post-TMS over frontal and central channels. We also see significantly more positive later TEPs from 280–400 ms on the contra-lateral hemisphere motor and parietal channels when no feedback is presented. These results suggest differences in effective connectivity are induced by visual feedback of movement. We further find that the variation in one of these early TEPs (the N40) is reliably related to directed coherence. Significance. Taken together, these results indicate components of the TEPs serve as a measure of effective connectivity. Furthermore, our results also support the idea that effective connectivity is a dynamic process and, importantly, support the further use of TEPs in delineating region-to-region maps of changes in effective connectivity as a result of motor control feedback.
Reducing the motion of laser spot using hollow wall design in hohlraum
Authors: Zhang Lu , Jing Longfei , Lin Zhiwei , Li Liling , Zhu Tuo , Hu Xin , Li Jin , Li Xin , Hou Lifei , Che Xingsen , Du Huabing , Kuang Longyu , Zheng Jianhua , Wu Changshu , Song Tianming , Zhao Yang , Xie Jun , He Zhibing , Zhou Wei , Zheng Wudi , Zou Shiyang , Yang Dong , Yang Jiamin , Zhao Zongqing , Ding Yongkun
Published: December 2024

A longer pulse, lower adiabat drive in a low gas-fill hohlraum is an inertial confinement fusion design with potential higher gain, but has challenges such as the less tamped wall plasma. Thus, it is necessary to alter the laser spot regions to control low-mode drive asymmetry when using such laser pulses. The hollow wall is designed [Vandenboomgaerde et al 2018 Phys. Plasmas 25 012713] and has been demonstrated with experiments to be effective in holding back the gold bubble expansion [Depierreux et al 2020 Phys. Rev. Lett. 125 255 002]. This paper presents experimental and simulation results demonstrating that hollow wall hohlraums effectively reduce laser spot motion. Experiment results indicate that the laser spot position in hollow wall hohlraum moves less than that in classical solid hohlraum, similar data are obtained by 2D simulation. This reduction in motion is beneficial for improving P4 drive asymmetry.
Investigation of Ammonia-Sensitive Properties of MXene/TiO2/Nafion Composites at Room Temperature
Authors: Lin Meichen , Fu Yabo , Jin Yingjie , Shi Jiazi , Wei Jiaqi
Published: December 2024

Ammonia (NH3) has been extensively explored in farm, food, and medical applications, therefore a highly responsive ammonia sensor is highly meaningful. The paper reports the successful fabrication of a new NH3 sensor using MXene/TiO2/Nafion composites. The incorporation of Nafion, an ionic polymer, was also found to allow for the formation of a more stable sensor film by the ionic matrix. The composite material was then integrated with this matrix at a prespecified volume ratio. The responses of the sensors were investigated. When the volume ratio of MXene and TiO2 is 1:1, the response and recovery time of the sensor is 33s and 110s, respectively, with a response rate of 98.08% at ambient temperature. A potentially useful material for NH3 gas detection was offered in this study.
Molecular Dynamics Study of the Bonding Mechanism at the Epoxy/Concrete Interface
Authors: Wang Jianzhong , Millare Jeremiah , Nie Zhenjun , Sun Jie , Yin Yuanyuan , Jia Shuhui
Published: December 2024

The damage to carbon fiber reinforced concrete structures primarily occurs due to the degradation of adhesion at the binder-concrete interface, making it the most susceptible to failure. This leads to the blockage of stress transfer between the epoxy resins and the concrete, which in turn makes the structural durability degraded. This paper establishes a molecular model of reticulated epoxy resin with a high degree of cross-linking and a molecular model of C-S-H gel with a calcium-silicon ratio of 1.69, using sub-dynamic simulation methods. Based on the multi-scale mapping relationship of “CFRP/concrete interface - epoxy resin/concrete interface - epoxy resin/C-S-H interface,” we innovatively developed a molecular model of the epoxy resin/C-S-H interface at the nanoscale. Molecular dynamics simulations were employed to investigate the chemical bonding between the epoxy resin and the C-S-H matrix. This study reveals the bonding mechanism at the molecular level between epoxy resin and C-S-H, providing valuable insights into the epoxy resin/C-S-H interface.
Microscopic Simulation of Carbon Fiber Reinforced Epoxy Resin Composites
Authors: Zhang Haiyun , Wang Danyong , Li Shuhu , Wei Huazhen , An Jing , Xing Wenfang
Published: December 2024

A representative microscopic model of carbon fiber is established by using the micro-scale simulation technology of material analysis in this paper, and its mechanical properties are calculated. The molecular model of TDE-85 epoxy resin and DDS curing agent was established, and the crosslinking reaction of epoxy resin was simulated. The interface model of carbon fiber reinforced epoxy resin is established by combining the obtained cross-linked epoxy resin model with the carbon fiber model. Through molecular dynamics research, the mechanical properties of the interface model are obtained. The data of mechanical properties can be further transferred to mesoscale, and the parameters of cross-scale simulation calculation can be transferred, which provides a basic guarantee for the research of cross-scale calculation of composite materials.
Simulation and Parametric Analysis of Particle Deposition Behavior during Spraying of Hastelloy on 321 Stainless Steel Substrate
Authors: Xuan Yuang
Published: December 2024

In the thermal spraying process, the particle deposition behavior has a large impact on the coating quality. In this paper, based on the coupled Eulerian Lagrangian (CEL) method, three-dimensional single-particle and multi-particle deposition models were constructed to reveal the evolution of temperature, strain and stress fields during particle deposition, and to analyze the relationship between particle size, particle velocity and particle and coating bonding. The results show that using 321 stainless steel as the substrate and Hastelloy as the coating material, and using supersonic flame spraying, the coating bonding is expected to be good and suitable for spraying.
Research on the Characteristics of Braided String Based on Domestic Aramid Fiber for Semi-rigid Substrate of Solar Array
Authors: Yang Shuli , Cheng Zhizhong , Ren Shouzhi , Ma Jingya
Published: December 2024

The substrate serves as a mounting base for the solar cells of the space-based solar array, and the “rigid frame of carbon fiber composite + tensioned mesh structure based on the braided string” constitutes the primary structure of the semi-rigid substrate of the large DFH-5 satellite. Tests and experiments have been conducted in four key areas: the creep characteristics of the braided string and its core under different loads, the creep characteristics of the braided string’s core due to changes in humidity and temperature, and the creep characteristics of the braided string itself due to temperature changes. The results show that the elongation of the braided string is twice that of its core under the same load. To reduce the stress relaxation of the tensioned braided string, it is necessary to perform pre-treatment to mitigate creep in advance. An increase in humidity can cause tension relaxation in the tensioned braided string. To mitigate this, a pre-tensioned core of the braided string can be utilized, and environmental control on the ground is recommended to reduce the impact of humidity on tension relaxation. Thermal pre-treatment is advised, as high temperatures can lead to partial changes in the properties or thermal stress release of aramid III fiber, resulting in the relaxation of the tensioned braided string and irreversible changes. The creep performance of the braided string’s core, however, is not affected by low temperatures. Through these experiments, the creep characteristics and pre-treatment guidelines for the braided string under different environmental conditions have been established, providing a foundation for the large-scale application of this structure in semi-rigid substrates of solar arrays.
Study on Migration Characteristics of Pb and Cu and Stabilization of Fly Ash During Incineration of Domestic Refuse
Authors: Bi Yanliang , Yin Yumin , Liu Liyuan , Zhang Meng , Wang Zihao , Wang Zhenhua
Published: December 2024

Heavy metals are important pollutants in the process of incineration of solid waste and pose a potential threat to the environment. In this paper, two heavy metals, Pb and Cu, were taken as the research objects, and their migration rules in the furnace refuse, slag, fly ash and flue gas were tracked and monitored respectively. The results showed that the concentration ratios of Pb and Cu in the slag and fly ash were 1:3.05 and 1:3.29, respectively, which were consistent with the furnace waste. No Cu was detected in the flue gas, but a small amount of Pb was present. XRF analysis shows that the CaO content in fly ash is 22.24%, Cl 6.64%, SO3 12.28% and K2O 4.37%, and the CaO content in fly ash is significantly reduced. The content of Cl and SO3 is 5.31 times and 2.97 times of the slag, respectively. The migration and storage of Cl and S promote the transformation of Pb and Cu. XRD analysis shows that the content of SO2, CaCO3, Ca(OH)2 and SiCl4 in slag is high. The high NaCl content in fly ash can promote the migration of Pb and Cu from slag to fly ash. Through leaching concentration monitoring and SEM analysis, the surface of fly ash was condensed from loose structure to flocculent structure after chelation, and the porosity was significantly reduced, and the leaching concentrations of Pb and Cu were reduced by 99.9% and 94.7% respectively, which greatly reduced the risk to the environment. The research results of this paper can provide reference for the harmless disposal and resource utilization of slag and fly ash in the incineration disposal of domestic waste.
Effect of Nitrogen Deposition on Diversity and composition of Soil Bacterial in Water-level-fluctuation zone of Mountain Reservoir
Authors: Chen Haisheng , Lu Gaobo , Chen Taolue
Published: December 2024

To determine the response of soil bacterial community structure to the difference of Nitrogen deposition concentration in thr RS of Taxodium distichum (L.) Rich. planting in water-level-fluctuation zone of Changtan mountain reservoir, southern-east .part of China. Three levels (0, 30Kg/ha·a, 60Kg/hm·a) were used to simulate nitrogen deposition. The illumina miseq sequencing method was used to study the bacterial community of the RS Taxodium distichum (L.) Rich. planting in this region. The results indicated that the shannon index and Chao 1 index of soil bacterial community structure in water-level-fluctuation zone showed an initial increase and subsequent decrease with increasing nitrogen deposition. Nitrogen deposition addition greatly changed the bacterial community structure in the RS of Taxodium distichum (L.) Rich. planting in water-level-fluctuation zone of reservoir. The relative abundance of Acidobacteria increase with increasing nitrogen deposition, while relative abundance of Actinobacteria decrease with increasing nitrogen deposition at phylum level. The relative abundance of Gemmatimonadetes and Sphingomonas showed an initial decrease and subsequent increase with increasing nitrogen deposition at genus level. Our results can provide a scientific basis for further thoroughly understanding and predicting the influence of future atmospheric nitrogen deposition on ecological functions of bacterial community in carbon and nutrient cycles of water-level-fluctuation zone of mountain reservoir.
Comparison of simulated and measured coincidence time resolution and energy resolution of scintillation crystals coupled to SiPM device
Authors: Nagai A. , Foster J. , Barry C. , Bellis S. , Cashman E. , Couglan B. , Dolinsky S. , Foley S. , Herbert D.J. , Perry M. , Pourashraf S. , Levin C.S.
Published: December 2024

Scintillating crystal coupled to a silicon photomultiplier SiPM is a typical detection solution in many modern radionuclide imaging systems such as positron emission tomography (PET). Coincidence time resolution (CTR) and energy resolution (ER) are two key performance parameters in the field of time-of-flight PET (ToF-PET). Both CTR and ER are system level parameters related to crystal choice dimension, speed and noise of the read-out electronics, calibration and analysis algorithms, and SiPM performance. In this work, the effect of SiPM photon detection efficiency PDE, single photon time resolution SPTR, and correlated and uncorrelated noise on CTR and ER were studied. For this purpose, analytical calculation and Monte Carlo simulation tools for CTR and ER were developed and tested for the onsemi MicroFJ-60035 SiPM device at different operating bias voltages coupled with LYSO and BGO crystals. The obtained analytical and simulation results were compared with experimental measurements performed with a 22Na source and 3 × 3 × 3 mm3 LSYO crystal wrapped in Teflon reflector and coupled to SiPMs using optical grease. Good agreement between measurements, simulation, and analytical calculation was found for ER at all device working range, and the best ER of ∼ 9% for 511 keV photopeak was found for the 3 × 3 × 3 mm3 LYSO crystal. The CTR was simulated for LYSO crystals with different lengths from 3 mm up to 30 mm and varies from 110 ps (3 mm crystal) up to 170 ps (30 mm crystal). It was compared to experimental measurements performed for 3, 5 and 20 mm crystal length, where CTR was measured from 95 ps (3 mm crystal) up to 140 ps (20 mm crystal). A difference from 5 ps up to 20 ps was found between Monte Carlo simulation and CTR measurements depending on the crystal length. The analytical calculation shows on average ∼ 20 ps worse CTR than experimental measurements. The systematic discrepancy between experimental and simulated CTR values might be related to a difference in light collection efficiency and level of electronics noise used in calculations as well as SiPM PDE angular dependency, while the discrepancy between experimental and analytical CTR might be related to read-out electronics noise which seems to have too high effect on analytical calculation.
PETAT — an ASIC for simple and efficient readout of large PET scanners
Authors: Fischer P. , Kerschenbauer T. , Ritzert M.
Published: December 2024

Modern PET scanners based on scintillating crystals use solid state photo detectors for
light readout. The small area of these devices is beneficial for spatial resolution, but also
leads to a large number of electronic channels to be read out, mostly by application specific
integrated circuits (ASICs) containing amplification, noise reduction, hit finding, time stamping
and amplitude measurement. Although each ASIC provides up to ≈ 64 channels, a large number
of chips is required with the need for auxiliary electronic components like voltage regulators or
FPGAs for control and data readout. The FPGAs in turn often require multiple supply voltages and
configuration infrastructure, so that PCBs get complicated, cumbersome and power-hungry, in
addition to the significant power requirement of the front-end ASICs. We address this issue in
the latest generation of our PETA readout ASIC for SiPMs by a simplified control scheme and, in
particular, by a hierarchical serial data readout which does not require any additional FPGA. In
addition, it provides a time-sorted stream of hit data, allowing early on-detector data reduction
and hit pre-processing like the removal of hits with no coincident partner. The simplicity of
this readout facilitates a supply scheme where power/ground of multiple ASICs are connected in
series instead of the standard parallel connection. This `serial-powering' approach can
reduce supply current (while increasing overall supply voltage) so that voltage drop issues in the
supply are alleviated.